Eat, Sleep, Tinker

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Homebrew Trailer Tire Rack

Up until recently I have been carrying my extra race slicks and rain tires in the back of my truck.  Not too long ago I got a mid-rise ARE bed cap, which certainly made it easier to carry and secure all the track extras.  But it was still a pain to crawl up into the bed to get wheels out, especially since I was loading them towards the front for better weight distribution.  They were also taking up a lot of room in the Titan’s short 5.5′ bed.

I’d been wanting to get an aluminum trailer tire rack to match the aluminum open trailer.  Unfortunately there isn’t anything off the shelf that would work, it would have to be completely custom.  I’ve got a MIG welder, but no spool gun for welding aluminum.  So I decided to go the simpler (and cheaper) route and build one out of steel.

I built the rack entirely out of 1.5×1.5″ square and 1×2″ tube, both in 14 ga wall thickness.  I also wanted a better method to store the fuel jugs.  Previously I was strapping them down individually to the tool box, which was time consuming to do and not very clean.  The solution was a couple horizontal bars for the jugs to rest on, with another bar to capture them at the rear.  The front of the jugs rest against the tool box.  I welded on four small tie down rings to hook a ratchet strap into and run through the handles of the jugs.  The jugs are raised off the trailer deck to provide room for the Warn winch located below.

Another feature of the rack is that it is completely removable from the trailer.  The trailer came equipped with stake holders along the perimeter, used to hold 2×4″ wood.  The “feet” of the rack go down into these stake holders to provide lateral and longitudinal support.  Four J-bolts secure the rack to the trailer, which hook into the bottom of the stake holders.

To secure the wheels to the rack I went with the standard method of running a tube though the bores.  To prevent damage to the wheels finish I used a piece of gray electrical PVC conduit as the outer portion of the tube.  Inserted into the PVC pipe is a galvanized steel electrical conduit tube to provide strength.  The two pieces are permanently boded together with black polyurethane sealant.

The tube slides through an oversized hole cut into a piece of plate steel which is secured to the rack using M8 nutserts and stainless bolts.  I cut oblong holes into the plate to allow for adjusting the height of the tube for slightly different tire sizes.  If necessary, a completely different end plate can be made and installed for much larger or smaller wheels/tires.

I drilled a hole through the tube on both ends of the tube to allow for installing a lock.  I did it on both side in case one side is blocked by another trailer/truck in the paddock.  This way I can remove the tube from either side.

I finished off the rack with a coat of Rustoleum red primer, followed by aluminum spray paint.  I know I’ll have to go back and touch up several spots, especially where the tires rub the horizontal bar.  Ideally I would like to get the entire thing powdercoated.

New Post has been published on http://www.eatsleeptinker.com/2015/09/21/cmp-test-day/

CMP Test Day

Note:  This event took place on 30 July 2015, just getting caught back up with posts.

My last test day at Carolina Motorsports Park ended prematurely when my radiator popped off its mount and the belt cut into the coolant expansion tank.  With the car back home I pulled the plugs to check the compression since it saw temperature spikes over 250F.  Fortunately the numbers came back good, actually matching the numbers I had taken when I first installed the engine.

I put the car back together, this time with a new CSF OEM+ radiator and a cooler 80C thermostat while ditching the stock fan, and headed back to CMP to get some testing in.  I knew the car needed to chassis tuning after its first race post-crash.

It was a low turn out at the track, so we were able to double up on track time.  That’s 8 full 30 minute sessions.  That’s a lot of driving in a single day, so I cut a few sessions short and skipped the last one.  What I did discover was that I needed a little more rear end grip.  The week prior I had done some ride height adjustments and corner balanced the car at a friend’s house.  The first couple sessions were a mess, I either spun or got into some serious tail out action.

I brought the car in and decided to stiffen the front bar one notch.  This had an immediate positive impact, the car was much more neutral, at least as much as I could get it on CMP’s slick surface.  Either way it felt much better and gave me more confidence going into my upcoming NASA race at Road Atlanta.

New Post has been published on http://www.eatsleeptinker.com/2015/09/21/custom-oil-temp-sensor-for-aim-mxl/

Custom Oil Temp Sensor for AiM MXL

The AiM MXL datalogger is a great piece of equipment, but it does have a few shortfalls.  One of the major issues is its inability to interpret the BMW stock oil temperature sensor over the CANbus.  I’m no computer scientist, so let’s just say what it does; it reads a constant -54F.  Obviously this is no help to me as the driver trying to determine whether my engine is healthy or not.  Since there was no solution on the horizon from AiM, I decided to just go with an aftermarket sensor.

The best place to check for engine oil temps is the pan, and Turner Motorsports makes a very nice adapter to easily allow you to add a sensor.  The mounting plate actually replaces the stock oil level sensor located in the bottom of the pan.  This isn’t an issue for a race car, you should be checking your oil level the old fashioned way before every outing.

The adapter flange is threaded in M12x1.50mm, allowing you to simply thread in the BMW stock sensor.  Unfortunately I need an aftermarket sensor to connect with the AiM MXL.  AiM only offers the sensor in 1/8″NPT/10mm/5mm, so an adapter is needed.  I used an Auto Meter 2277 adapter, which is a simple brass bung adapter with a copper crush washer.

Note: in the pictures below, the sensor shown is not correct.  AiM accidentally sent a brake pressure sensor.  I caught the mistake before installing in the car, and the correct fluid temp sensor was sent in exchange.

With the new sensor installed and plugged into the AiM MXL, all I needed to do with a hookup the laptop to setup the new sensor.  That’s it, now I had a proper oil temp reading… only one problem; the AiM PT100 temp sensor has no probe.  It’s length terminates at the ends of the threads, so it does not protrude into the oil sump.  This problem is compounded by using the Auto Meter adapter.  Essentially the sensor is located down in a hole, away from the normal flow or oil.  Sure it’s better than no oil reading, but there has to be a better solution.

The photo at the right shows the problem with using the AiM PT100 and adapter.

With no other sensor option from AiM, the only other possibility would be to create a custom sensor.  AiM’s RaceStudio allows for the creation of custom sensor profiles, you just need the resistance readings at various temperatures.  After a little searching on the internet I found a GM Delphi temperature sensor that came in M12x1.5mm thread and had a proper long probe.

See more about the sensor here at Ballenger Motorsports’ website.

Another hurdle to overcome is that the AiM analog inputs use voltage difference sensors rather than resistance based.  So this GM temp sensor would require a pull up resistor soldered inline to achieve a mV reading.  A stripped down AiM 719 (4 pin plastic) patch cable would provide the basis for the harness, and the GM plug on the other end was provided by the same store where the sensor was purchased.

The photo above shows how I soldered in a 1k ohm resistor, bridging from the Blue (Vref) wire to the White (Vout) wire.  The Black wire is ground and the Red wire is 12V and not used.

The following photo shows everything wired up and covered in heat shrink.  The GM sensor uses Weatherpack style crimped pins.  I picked up a cheap set of crimpers from eBay for the job, which is very simple.  You can see the difference between the GM (long probe) and AiM PT sensor in a side-by-side comparison.

Now with everything wired up, installed in the car, and plugged up, you have to build the custom sensor in RaceStudio.  This requires a little math, as you will be converting the resistance based table provided with the sensor to a variable voltage table that the AiM MXL can use.  To make life a little easier, I made an Excel spreadsheet, where all you have to do is plug in the temperature, corresponding resistance values, and the resistance of your pullup resistor.  The reference voltage should be set to 5v for this application.

Since the GM sensor data was provided in Celsius, I also inserted a formula to convert to Fahrenheit.  Essentially plug in the numbers in the green fields to get results in the white fields.  From there you simply copy the Vout millivolt (mV) values and corresponding Fahrenheit temps to your custom sensor in RaceStudio.

Note: RaceStudio will only accept 20 values per sensor.  Your beginning and ending values must contain your entire range of expected temperature readings.  In other words there is no point in including values of -40F when your car will never see that.  However if you start your values at say 77F and on a cold day your sump is 50F, you will get an error message on the MXL as it doesn’t know how to interpolate a reading off the chart.  So pick the best 20 value range that covers all expected temperature readings.

Click the screenshot of the Excel spreadsheet to download a .zip file containing a copy that you can edit for your own custom temp sensor.  The tables are already filled in for the GM Delphi sensor.  I also included images of how to fill in the custom sensor fields, AiM 719 wiring colors, as well as wiring of a pull-up resistor.

Known Issues:  Your custom sensor will display on you MXL (or any other AiM display logger) just like an AiM proprietary sensor would.  I have my dash set to always display water and oil temps.  Your logs will also capture this information correctly.  Unfortunately the AiM SmartyCam does not handle custom sensors properly.  The SmartyCam overlay will try to convert the Fahrenheit temperature into Fahrenheit, which of course leads to erroneous readings.  AiM (both America and Italy) are aware of this problem, but a fix doesn’t appear to be coming very soon.  The screen capture on the side shows my oil temp at 511F, which of course is incorrect.  It’s a minor nuisance, as the temp is correct where it really counts (on the dash and in the logs.)

New Post has been published on http://www.eatsleeptinker.com/2015/09/21/spec-e46-test-day-ends-early-cmp/

Spec E46 Test Day Ends Early @ CMP

Note: This event originally occurred on 12 July 2015, I’m a bit behind in my posts.

Following my first full race weekend, which was a mad dash to ready the car, I knew I had a few bugs to work out.  Chief among those issues was a persistently warm running engine.  Of course this was in the heat of the South Carolina summertime, but I wanted to get my temps a little lower.

To that end; I installed a larger CSF all aluminum radiator specifically for the E46 non-M chassis.  Unfortunately the mounting points weren’t ideally designed to interface with the factory plastic mounts.  I did my best to modify the mounts to work, installed it, and off I went to Carolina Motorsports Park for a day of testing.

I went out on my first lap and found that the temps were much lower.  Prior to the new radiator I was averaging ~212-215F in the heat of the day.  Now I was sitting at around 202F, much more reasonable.  I pushed on harder for the next couple laps, besting my previous times by more that 2 seconds.  Then on the third or so lap I got a warning light briefly for engine temps.  It went away as I looked down at the dash to decipher what the problem was.  Then a few seconds later it reappeared.  By now I was paying closer attention to the numbers, and I watched as the water temp spiked to over 250F then back down.

I immediately let off the throttle, short shifted, and brought it in to the paddock as quickly as possible using as little engine as possible, coasting the last hundred feet or so with the engine off.  Hopping out I could see steam rising from the engine compartment.  A peek under the car showed hot water dripping to the ground.  This certainly wasn’t any good.  Popping the hood confirmed my concerns about the mounting of the CSF radiator.  It had slipped from its mounts and shifted rearward where the expansion tank made contact with the serpentine belt.   The belt made quick work of the plastic tank, sawing right through it.

My day had come to an early end with a destroyed expansion tank, a radiator that wouldn’t sit securely, and possible engine damage.  Later on, after everything had cooled, I also discovered that high temps had destroyed the expansion tank cap.  The lower portion that retains the sealing o-ring was completely missing.

The good news: CSF was quick to help rectify the situation.  They sent me one of their OEM+ radiators, covered the cost of the expansion tank, and promised to redesign their all-aluminum radiator.  Hopefully they get it corrected soon, because other than the mounting problems, it’s a solid piece.

New Post has been published on http://www.eatsleeptinker.com/2015/09/21/spec-e46-race-carolina-motorsports-park/

Spec E46 Race @ Carolina Motorsports Park

Note: This Event originally took place on 27-28 June 2015, sorry for the delay in posting.

Having finished the requirements for my provisional racing license, I was looking forward to the next opportunity to race my Spec E46.  The upcoming NASA-SE event at Carolina Motorsports Park (CMP) looked very promising, with a possibility of five other SE46‘s in attendance.  One slight hiccup; my car was still in pieces.  Several delays in parts shipping meant I was way behind my anticipated competition date.

I had already committed to this race, having already cancelled the previous Road Atlanta event due to the crash, and I really didn’t want to miss another opportunity to get some much needed track time.  The week leading up to the event became a mad thrash.  I was working until the wee hours of the morning right up to the day before the race.  The good news: CMP is only an hour away from home, so at least the few hours of sleep I did get were in my own bed.

I also needed an annual tech inspection the morning of the event, so everything had to be just right.  I escaped with a few minor discrepancies which were easily corrected and was able to make the race.  I had barely got the car off the alignment rack the night before, so there was zero time to shake down the car, much less tune the chassis.  I’d run what I brung as the saying goes.

I missed the first practice, fiddling with a few last minute things, but was able to go out in one of the HPDE sessions to get a feel.  I knew the track was slick from my previous test day, but having an untested car made it much more of a challenge.  My goal was to just keep the car on track and avoid any contact, speed was way down my list of things I was worrying with.

I qualified at the back of the SE46s, as expected given the all-star veteran competition I was up against.  No big deal, I was here to learn.  We, as a class, decided to start at the back of the Thunder run group in our own separate start rather than gridding on pure time.  The first race started off cleanly, but I was out of it both mentally and physically.  The lack of sleep had caught up with me big time, and I couldn’t maintain my concentration and felt like garbage, my times were reflecting my condition.

I continued to press on, just looking to finish when a red warning light illuminated on my AiM MXL digital dash, water temps.  I was at 230F and it looked as though it would keep climbing.  I had pressed my luck enough already, so I pulled off that lap and putted back to the paddock area.  I couldn’t find any obvious issues with the cooling system, all signs pointed to trapped air bubbles.  This is the price you pay when rushing to get a car ready at the last minute.

I decided to pack up for the day, let the car sit and cool overnight and get some rest.  Another SE46 driver had already had worse luck when one of his rear shock mounts failed, resulting in a destroyed MCS shock.  I left early to get caught back up on sleep and hopefully have better luck on Sunday.

The next day I jacked up the front of the car and bled the cooling system thoroughly.  It looked like my suspicions were correct and the engine had some significant amount of air trapped in it.  Feeling recharged from a long night of sleep I headed back on track, this time in a much better frame of mind.  The car still wasn’t working as well as I had hoped, oversteering terribly on exit and pushing on entry, but it would have to do.

(Note how I was still missing the trim under the headlights and decals from the new fender)

Again I started at the back of the SE46 pack, where we started as group behind the rest of the Thunder field.  This time I felt a little more confident making passes and tried my best to hang on to the back of the SE46 in front of me.  I certainly wasn’t pushing for overtakes, rather waiting for the safest opportunity to get by slower traffic.  Towards the end of the race I could see I was closing back up to the next SE46 up the road, but every time I tried to push, the car would just lose traction on exit.  I was at opposite lock over and over, watching the Mustang and other SE46 in front grow the gap.

Despite the headaches and lack of a good setup, I still had a blast driving with other SE46s and finally getting a chance to mix it up in traffic in an actual race.  This was, after all, the first race where I got beyond the first lap.  It was great to meet and hangout with other racers in the paddock, gleaning knowledge wherever I could.

New Post has been published on http://www.eatsleeptinker.com/2015/09/21/nasa-comp-school-road-atlanta/

NASA Comp School @ Road Atlanta

Note: This event originally took  place on 5 June 2015.  I’m a bit behind in my updates.

When I built the Spec E46, I intended to run it both in the BMW CCA Club Racing series and NASA racing, where the majority of other SE46s in my region were running.  I had completed the BMW CCA race school back in January of 2014 at Texas World Speedway, which allowed me to run my first race at Barber with the CCA.  Unfortunately that didn’t turn out so well and the car was laid up for serious repairs.

I had hoped that the NASA South East region would accept my BMW Club Racing license and allow me to run without attending their Competition School.  Unfortunately they were not willing to do so for a Rookie license.  I’m sure if I had multiple races under my belt it would have been fine.  Since that wasn’t the case, I needed to get registered for their next available school.  My luck was running even more thin when the next upcoming school was coming up in a hurry and I had no car ready to go.  Unlike the BMW CCA school, which allows you to use your street car, NASA requires a fully prepped race car with current annual tech inspection.  Waiting until my car was ready would have meant missing out on a good chunk of the season and having to attend the school at ViR with Mid Atlantic, a place I had never run.

I thought my luck had changed when a NASA-SE regular offered up his Scion FR-S for rent on the day of the Comp School.  We agreed on a fair price, I signed up for the school, and off I went to Road Atlanta.  It felt rather odd heading to the track with nothing in tow and only my driver gear in the truck.  My father and I arrived late Thursday night to meet with the gentleman renting his car and get a test fit.  I had already warned him that I was 6’2″, with much of my height in the torso, but he was confident that with the seat in the lowest position I would fit.  Bad luck struck again; there was no way I would safely fit.  My head was touching the roof cross bar, even scrunching down.  It looked like I would be heading home sans certificate.

Before we gave up, I started making the rounds of the paddock, looking for anyone who might have a ride available.  All the Spec Miatas were already claimed, not that it would be any easier of a fit.  The regional director even tried to get me a Thunder Roadster ride, though that didn’t pan out (probably best for my own well being!)  Then I remembered that a fellow CCA racer had previously offered up his K-Prepared E30 for rent.  I got on the phone and tried to work out the logistics of getting the car from nearby Atlanta.  Then I remembered; the car had to have a NASA annual tech sticker.  Out of luck once more.

By this time the sun was dropping and folks were leaving the track to rest for the following race day.  As a last ditch effort I text messaged a friend who was from the local area, just to see if he had any leads.  He told me to standby while he checked on something.  Perhaps this would be the solution.  As it turns out, he was going to rent a Spec E30 the same weekend and planned to run it in practice on Friday.  He checked with the owner of the car and came back to me, offering to give up his test day so I could complete the comp school.  My luck had finally turned around.

Later on Thursday I tracked down the rental SE30‘s owner and we picked up the car from a nearby shop.  Even better news was that I fit just fine in the car, the seat being a larger size and also on sliders.  We parked the car with the rest of the SE30‘s and went to the hotel, finally able to relax and know that I had a chance to get this school over with.

The next morning started with a sprint which didn’t stop until the day was complete.  See NASA essentially squeezes a two day comp school course into one day.  So there is very little downtime between sessions and class.  You are in the car, then directly to class, then right back out on track.  I was even driving the car directly to the classroom, so that I could hop out and in.  Having my father there as crew chief was a life saver.  While I was in class, he was topping off the fuel, loosening the belts, and torquing the wheels.

The school itself went by without much drama.  NASA does the school in conjunction with test n’ tune sessions, which provides extra traffic to negotiate, mostly much faster traffic at that.  To me it felt as though the major focal point was ensuring drivers were comfortable in close proximity to other cars and obeyed flags.  There was little discussion of race craft, as had been a key point during the CCA race school.  Much of that can be chalked up to the school being on a accelerated timeline, giving very little time to really discuss the nuances of driving in a race.

Just like the CCA school, the day involved side-by-side drills, swapping places in corners, and ended with a mock race.  Our first mock race was an inverted field and standing start.  Apparently I was the fastest SE30, so I had the other E30s and SMs in front of me, with a gaggle of Mustangs, Corvettes, and a really fast GT-R behind me.  I got a clean start, passing everyone in front by turn one and led up to T3, where a Corvette whizzed by.  A full course yellow was thrown about midway though, and we got to practice a restart.

A “Fun Race” was set to conclude the day.  I initially hadn’t planned to participate, as I was going to save tires/fuel and head back home that evening.  That plan was squashed when I was informed the race was not optional and was a requirement for finishing the comp school.  It was an hour long race, so I just planned to complete 50% of the leader’s laps and call it good.  The start/finish stand marshal was kind enough to give a midway signal, and I pulled in unscathed and finished with the school.

I had never even driven a street E30, so I wasn’t sure what to expect.  My M Coupe shares its rear suspension with an E30, so I was a bit worried it’d handle in the same manner (ie short wheelbase + lots of power + semi-trailing arms = never lift), but the SE30 was much more benign.  The lack of power, tall gearing, and sufficient grip meant the car was very forgiving.  I was nowhere close to pushing the limits with it (I certainly didn’t want to buy it) but still had a blast.  The lack of power steering and soft suspension made it seem lethargic in comparison to my SE46, but I can still see why they are a fun class to race in.

New Post has been published on http://www.eatsleeptinker.com/2015/09/08/spece46-wreck-repair/

SpecE46 Wreck Repair

After the Spec E46’s debut at Barber Motorsports Park, I was left with a crumpled and undriveable car.  The initial visual inspection at the track showed that I’d be in need of the following:

Hood

Left Fender

Bumper

Left and Right headlights

Left control arm

left tie rod

Airbox

Left aluminum engine mount

Apex Wheel

Radiator core support

Once I had the car home, I immediately unloaded it directly from the trailer into the shop and up on jack stands.  From there I started to dismantle the front end.  With the hood, fender, and bumper off, I got a much better look at what lay ahead.  I then found the following would need replaced:

Front left wheel housing

Front subframe

Left and right engine mounts

Steering rack

Power steering pump pulley

Radiator

Front bumper crash bar

The whole left front had been pushed to the right and rear, forcing the wheel well up into where the DME box and brake master cylinder/ABS/booster are located.  Several welds had pulled apart, and I don’t think a simple frame pull would get it back to where it needed to be.  So I opted to order brand new OEM sheet metal.  BMW offers the entire wheel housing and frame horn as a replacement part, though it’s certainly a special order item.

The engine came out, which was in surprisingly good order, other than the torn Bimmerworld engine mounts and cracked aluminum mounts.  I got lucky in that none of the bolts pulled from the block.  The crash did manage to put a ding in the Y-pipe, but I decided to leave it alone.

The engine subframe was twisted at the engine mounts, so it went in the trash.  I sourced one from a junk yard, as well as a used core support and crash bar.  The subframe was cleaned up and a set of Turner reinforcements were welded on.

I completely cut away the original wheel well by drilling out all the factory spot welds, leaving the front left firewall completely bare.  The new housing was squeezed into place, and leveled using tape measures and a plumb bob.  I welded it back on using the factory spot weld locations.  The interior of the transmission tunnel needed a patch plate where some original metal tore during removal.

The left control arm bushing had stripped the threads from the frame, so I ended up drilling it up a size and inserting a helicoil.

With the new metal final welded into place, I gave everything a good scuff with a 3M pad, followed by cleaning, then a coat of automotive primer.  I then sealed up the gaps with some plain seam sealer before painting everything a matched 300 Alpine White and a coat of catalyzed clear.

Everything went back together as it did the first time.  I did find that both frame horns slightly shifted (~1/8″) to the right when checking the frame for squareness.  A little extra effort on panel gaps brought everything within factory spec and the car aligned properly as well.  I’ll let the photos do the rest of the talking.

Note: While everything was apart, I took the opportunity to replace the brake master cylinder and booster.  These weren’t damaged in the wreck but were original to the car (~220k miles).

New Post has been published on http://www.eatsleeptinker.com/2015/08/17/first-spece46-race-barber-motorsports-park/

First SpecE46 Race: Barber Motorsports Park

The time had finally come to put the Spec E46 race car to the test in wheel to wheel competition.  I signed up for the May 2015 BMW CCA Club Racing event at Barber Motorsports Park in Leeds, AL.  I had never driven the track, so there would certainly be a lot to take in.

If you haven’t been to Barber, you should really make a trip to visit it.  It has to be the nicest race tracks in North America, with finely landscaped grounds, excellent facilities, and perhaps the greatest motorsports museums for the motorcycle and Lotus car enthusiast.

This event was put on by the BMW Car Club of America, so there were multiple run groups of DE in addition to the race sessions.  The schedule called for three races, two on Saturday and one on Sunday.  Two other SE46s were in attendance, so at least I would have some company in the class.  The majority of the cars were I-prepared, with a smaller mix of Modified, SE36, and KP cars.

The car ran well during practice and qualifying, though I really didn’t have a good grasp of the track or the handling of the car.  I had a few mental mistakes at various points, just not remembering where the track was going.  Though it’s only 2.38 miles, the course has 15 turns, with a great variety to make things interesting.

Saturday Qualifying

I only ran three laps in qualifying.  I had no idea what a good time was, or even really how to operate the lap timer on my MXL, so I figured no point in running more time off the tires.  My time was a good bit off Damion Moses’, but enough to qualify second in class and 14/24 overall.  BMWCCA club events don’t group cars by class, but by outright qualifying time.  So I was sandwiched between a Super Modified and I-Prepared car.

The first race started well enough, the first few turns were without drama and I didn’t lose any positions.  Then coming onto the front straight the cars pretty much went single file and relatively slow to make it through the hairpin-like turn 5.  Right as I was about to hit the apex I caught a glimpse of something moving very quickly out of my left peripheral.  I had nothing but grass and curbing to my left, so I knew something was wrong.  It happened too fast to avoid, and I got hit hard in the front left.

The impact spun me off into the outside adjacent gravel trap.  The car was still running, so I shut it down.  After sitting for a bit, I cranked it again and attempted to get moving, but I was sunk up to the frame in gravel.  I also had steam coming out of the engine, so better to just wait.  The rest of the pack continued around for about three more laps under a full course caution (turns out another car crashed on the first lap.)  They eventually black flagged the race and I was stuck waiting on the roll-back, who was tending to the other wreck.  The car that hit me was able to be towed out and continued back to the pits under its own power.

Saturday Race Crash

(note: first perspective is from a car behind me, followed by my in-car)

With the EMS personnel on scene, I got out to check over the damage.  The hood was buckled, the fender crushed, the bumper knocked off, both headlights destroyed, the wheel cracked in several places, and after trying to turn the steering wheel I discovered that the left tie rod was also sheered.

Eventually we got the car loaded on the roll back and back to the paddock.  There I discovered the damage was a bit worse than I initially thought.  The engine mount arms were both cracked and separated, the lower control arm was twisted, the steering rack was shattered, the airbox was cracked, the power steering pump pulley cracked, and the core support was twisted.  It was certainly nothing that could be repaired in the paddock, even if I had all the parts on hand.

Thankfully I had recently installed a winch on the trailer, so getting the damaged car loaded wasn’t too difficult.  I stayed the night rather than driving back home in a bad mood and sore from the impact.  The group of racers were all very considerate and sympathetic to my situation.  And eventually the driver who hit me came over to apologize.  I have to say he was very humble and sincere, and I know that this could have happened to any of us.  I was lucky that he hit me where he did, rather then in the door, which could have been much more dangerous and damaging.  Unfortunately his car didn’t fare so well.  The whole right side was crushed in, pushing the door bars, main hoop, and rocker panel inward.

New Post has been published on http://www.eatsleeptinker.com/2015/07/17/diy-homemade-cooling-shirt-system/

DIY: Homemade Cooling Shirt System

Driving a race car usually means driving a car with no air conditioner, no heat insulation in the cockpit, and the windows removed.  Obviously this can make for a very toasty operating environment.  Radiant heat from the engine, exhaust, and even track surface can quickly add 20-30F to the ambient outside air temperature.  Pair this with racing in the southern United States, and just sitting in the car can become a health risk.  I’ve had a close call with serious heat exhaustion in the past, driving my M3 at Texas World Speedway when the on track temps were near 110F.  I swore that when I had a purpose-built race car that it would have every driver cooling aid I could fit.

The most common and certainly the most effective of these is the cooling shirt.  Most folks just refer to them as “cool shirts”, but that’s an actual brand, so I’ll try to avoid calling it that.  These systems have been around for sometime and are fairly common to club-level racing in the hot regions.  It’s a very simple system, essentially cold water is circulated around tubes sewn into the driver’s shirt.  The cold water is held in a cooler mounted in the car and the water is circulated using a 12V pump.

The vast majority of the parts used in the commercially available systems are actually just off the shelf items that anyone can purchase on their own.  For example, the pump is just a 12V boat bilge pump.  The only piece I didn’t make myself was the shirt itself.  Some folks have made their own by simply sewing a length of tube into a plain t-shirt, which certainly helps save even more money.  I decided to pick up F.A.S.T. Alpha shirt, which also has moisture wicking properties.

Here’s the parts list of the items I purchased, their retail cost, and supplier.

Qty Item Source Total Cost 1 Weatherproof Low-Voltage DC Connector Kit, 2 Pole, 16-14 AWG 9171T32 McMaster-Carr $7.71 2

Air and Water Quick-Disconnect Tube Coupling Through-Wall Socket with Valve, 1/4 Coupling, for 3/8″ Tube ID 5012K79

McMaster-Carr $39.66 2 Air and Water Quick-Disconnect Tube Coupling Barbed Plug with Valve,1/4 Coupling, for 5/16″Tube ID 5012K712 McMaster-Carr $14.68 2

Air and Water Quick-Disconnect Tube Coupling Barbed Socket with Valve,1/4 Coupling, for 5/16″Tube ID 5012K672

McMaster-Carr $18.60 1 Masterkleer PVC Tubing 5/16″ Id 7/16″ Od, 1/16″ Wall Thickness, 25 Ft. Length 5233K59 McMaster-Carr $7.25 1 Single Pinch Stainless Steel Hose & Tube Clamp 13/32″ to 31/64″ Clamp Diameter Range, 9/32″Band Width 5435K28 – 25 pack McMaster-Carr $4.97 1 Durable Nylon Tight-Seal Barbed Tube Fitting Reducing Straight for 3/4″x 3/8″ Tube ID, White 5463K648 – 10 pack McMaster-Carr $7.40 1 Engel 13 Quart Dry Box Cooler UC 13 Austin Kayak $43.99 1 3/4″ Clear PVC Hose – 1ft Lowes $1.00 1 3/8″ Clear PVC Hose – 1ft Lowes $1.00 1 500-600 GPH 12v Bilge Pump Wal-Mart $19.99 # Tubing Neoprene Insulation and Cordura Cover Hydation Tube Covers TBD

You’ll also need a few supplies, such as JB Weld and silicone to seal the fittings, zip ties to secure the hoses, and a setup to mount the cooler in the car.  But in total, the homemade cooling shirt cooler cost roughly $175 once shipping is figured in.  A much better proposition than the off-the-shelf models go for, using the same (or better) components.

To start with, let’s mount the pump in the cooler.  This is pretty straightforward, as most of these 12V bilge pumps are meant to be mounted directly to the bottom of the hull.  The cartridge type I purchased (from Wal-Mart’s boating section) comes apart for mounting.  Three simple screws are all that holds it in place.  I drilled pilot holes first, then squirted silicone sealant in and around the holes prior to securing the base-plate.  Make sure you use a silicone that is rated for submersion (many aren’t.)

Also take care to orient your pump so that the outlet hose is pointed to where you want the fittings to be.  If I did this again I would mount the pump slightly closer to center (left of where it is located in the picture above) so that the twist out pump could be more easily removed.

Now you must drill holes for the fittings.  Part 5012K79 listed above is essentially a bulkhead fitting and barb on one side and a quick disconnect fitting on the other.  The wall of the cooler is slightly too thick to allow for installation of the retaining nut on this fitting, so I drilled the hole to be as tight fitting on the barb as possible.  I then sealed around it with some JB Plastic Weld (the putty kind.)

One of these fittings is simply a return port, so it can be left as is.  The other one (it doesn’t matter which one) will be connected to the pump.  The outlet of the pump (fairly standard sizing) is 3/4″, so a reducer is needed to size the hose down.  This is where part 5463K648 comes in.  It reduces 3/4″ down to 3/8″.  I went to Lowes for a foot of 3/4″ and 3/8″ clear PVC hose, which you can find in the plumbing aisle for pretty cheap.

The photos above show the nearly finished product, pretty simple isn’t it?  The last remaining step of modifications needed to the cooler are running the power and ground to the pump.  The pump I purchased came with a long lead (~3ft), so I didn’t need to extend it at all.  Once again, drill as small of a hole as possible to feed the two wires through the cooler’s wall.  I drilled my holes up high, as to avoid prolong submersion which may lead to leaks.  The wires were sealed off with silicone. Note: I found that all the silicones had a difficult time adhering to the plastic of the cooler, I eventually coated all the holes with JB Weld Kwik Weld.

Once the wire was through the cooler wall, I secured it to the outside with a cable clamp riveted to the outer plastic skin (not all the way through.)  To terminate the wires I used part 9171T32, which is a Weatherpack electrical connector.  These connectors are fairly common, work well, and can be assembled with an inexpensive pair of crimpers.  You certainly don’t want to permanently wire your cooler to the chassis, as it is much easier to simply take the cooler out for cleaning and filling.

Before I went much further I bench tested the cooler and my shirt by just hooking it up to a spare car battery and temporarily connecting the lines.  It worked like a charm, even just pumping room temperature water (I had also let water sit in the cooler to insure there were no leaks.)

With the cooler operating properly, it’s time to make the lines which will run to and from your cooling shirt.  First let me note that different brand shirts use different quick disconnects.  The F.A.S.T. brand shirts use the quick disconnects with the metal buttons, which is what I ordered and all the part numbers above are.  The CoolShirt brand shirts use the disconnects with the plastic buttons.  Make sure you know which type you have before ordering.  McMaster-Carr offers both types of disconnects at roughly the same price.  You can even make your own simple patch tube, should you have multiple driver’s with different shirt types.

Decide where you want to place your cooler so that you can determine the length your hoses need to be.  The most popular spots are the passenger seat area and the trunk.  I placed mine in the spare tire well, as I like the option of being able to run a passenger seat.  This should also balance out some of the weight loss effects of removing so many items from the rear of the car.

Once you have that figured out, you can run a tape measure or just temporarily run your uncut water hose to see just how much you need.  Remember to leave a bit of slack at the driver’s end to allow for connecting/disconnecting the lines once buckled in.  Satisfied with the length of hose and routing the hose would take, I then trimmed the 5/16″ ID PVC tube.

Before installing the quick disconnects on the tubing, you must install the insulation.  At first I planned on using the generic dark gray foam rubber pipe insulation, which is available from McMaster-Carr for cheap.  After trying it out, I decided I wanted a cleaner, more finished look, and something less bulky.  Unfortunately it was impossible to find the supplier who provides the insulation for the store brand cooling shirt systems, seems you must purchase their $100+ hose to get it.  That’s when I contacted Hydration Tube Covers to see what they could do.  They were very helpful and had done drink system covers for race cars in the past.

Hydration Tube Covers was able to send me four sections of 4 foot neoprene covers, fitted perfectly to the 7/16″ OD of the tube.  These were slid over the PVC tube by hand, working on in a slinky like fashion.  Once both lines (supply & return) were covered, a protective Cordura wrap was placed over them using a Velcro seam.  The end result is a well insulated and protected set of cold water tube that looks like a true race car part.  These covers were custom sized, so price will vary according to your application, but I guarantee you will save a lot of money over the name brand cooling shirt offerings.  Contact Brandon at HydrationTubeCovers.com for more details.

Finally the tubes were terminated using the remaining quick disconnects with male ends on the cooler side and female ends on the shirt side.  I used the crimp connectors (part #5435K28) to secure them in place.  I wouldn’t recommend using screw clamps, as they can easily cut your hand when trying to connect or disconnect from the car.

So how well does it work?  Extremely well, that’s how!  I’ve used it at Barber Motorsports Park in May, Carolina Motorsports Park in June and July, and all I have to say is that sitting inside the race car on a blistering asphalt grid was just as comfortable as sitting inside an air conditioned car.  The cooling effect is immediate, it almost feels as though cold water were pouring over you.  Heck, after a session I didn’t want to get out of the car because I knew I would immediately be hot.  The 13qt system was plenty for a sprint race format (~30 mins).  I don’t know how much longer it would be good for, but you could always opt for the 19qt Engel dry box for enduros.

What about mounting the cooler?  Since this is going to be car specific, I left this until the end.  As I mentioned previously, I mounted my cooler in the spare tire well.  There are off-the-shelf mounting plates available from the well known companies that produce cooling shirt systems, but I wanted something tailored to my setup.  I wanted the cooler mounted as close to the front of the spare tire well as possible, as I had to have space for my differential cooler and also reduce the polar moment of having extra weight out back.

I used some plain aluminum right angle stock, riveted to the floor on three sides of the cooler.  I cut a slit on the left and right pieces to allow a ratchet strap to pass through, which was also riveted to the floor.  To keep the cooler from tipping forward under hard braking I bent a piece of flat stock aluminum into a brace, which was also riveted to the spare tire well and a cushioning strip of silicone was added.  A simple ratchet strap (the smallest I could find) is used to secure the entire cooler firmly to the floor.

New Post has been published on http://www.eatsleeptinker.com/2015/07/16/spec-e46-first-shakedown/

Spec E46 First Shakedown

Before a race car turns a wheel in anger, it really should be put through its paces in a test or shakedown drive.  Since this car isn’t street legal and you could never truly test in on public roads, you need to schedule some track time.  Fortunately I’m only an hour away from Carolina Motorsports Park (CMP) in Kershaw, SC.  They even have their own track day organizer, Turn One, that has multiple events a month, making it fairly easy to get track time.

After alignment, I loaded up the car on the trailer and headed for CMP to see how all my work handled.  It was a weekday event, so the track was fairly empty, great for some testing and tuning.  Just like any track day event, the car went through a short tech inspection.  Normally this wouldn’t be necessary on a race car, but I hadn’t received an annual tech inspection yet.

The first session was just a an exploratory lap, since I had never driven this track before.  The tires were also fresh sticker and we were receiving some light rain, so it was a bit slippery but grip gradually came in.  That said, CMP is a very slick track, nowhere near as grippy as NOLA, COTA, or Road Atlanta.  It reminded me a lot of Motorsports Ranch Cresson, which is very old pavement and very slick in light rain.

Towards the end of my first session I was black flagged, which was odd because I had no off track excursions and there were only 2 other cars on track.  I pulled into the pit lane and up to the pit exit marshal who told me several corner stations were hearing a loud metallic screeching sound from my car.  He did a quick walk around of the car and noticed a lot of aluminum shavings on the rear left wheel…. great.

I pulled off the pit lane, headed back to the garage to see what had happened.  Turns out I picked up a rock, which became jammed between the caliper and wheel.  It then worked just like a lathe, cutting a 1mm deep groove around the inside of the wheel.  My guess is that I picked it up during the tech inspection, as the tech shed and weigh station is off a gravel road (terrible layout.)

I pulled the wheel and gave it a good inspection, even called the friendly folks at Phil’s Tire Service to see what they had to say.  I forwarded them some photos, which they in turn sent on to Apex Wheels.  After a close inspection, I determined it was reasonably safe to continue on for the day.  I took it a little more carefully, avoiding the curbing as much as I could.

The car continued to run well throughout the remaining sessions.  Temps were within safe margins and the engine felt decently strong.  I knew the alignment could use a bit more dialing in, and a corner balance was definitely in order.  It was certainly nice to finally be in a true race car with a proper race seat and harness, making it much less physically demanding to drive the car while also easier to feel what the chassis was doing under me.

Then towards the end of the fourth and final session I suddenly lost power steering.  It was a sudden stoppage, like I had experience in my E36 when it popped a line at Road Atlanta.  I pulled back into the paddock to check what happened.  A quick glance under the power steering reservoir cap revealed the telltale signs of a ruined pump, as it was sparkling with a metallic sheen.  And so ended my test day.

Once back home I pulled the power steering pump to discover the pulley shaft was completely disconnected from the pump and free spinning.  No doubt this was a design function, a break-away shaft much like those found on the air turbine starters on jet engines.  I further disassembled the pump to discover the vanes which slide in and out of slots where dislodged and had jammed up the pump.  My guess is that this was the original pump and at 220k miles it had just had enough.

New Post has been published on http://www.eatsleeptinker.com/2015/07/15/spec-e46-build-part-xi-data-acquisition/

Spec E46 Build Part XI: Data Acquisition

Up until this true race car build I have been using my Android smart phone as my source for data acquisition.  The Race Chrono app, paired with an external Bluetooth GPS, has been a great tool, especially for the price.  However, with a dedicated race car, I wanted a dedicated system.

I had picked up a lightly used AiM MXL Pista dash logger from eBay back when I was gathering parts for the E36 GTS build.  At the time I was debating between the AiM and Racepack loggers, ultimately settling on the AiM due to their widespread use at the club racing level of competition.  Having a highly adopted system means it’s easier to get data from other drivers for comparison as well as troubleshooting the system.

The MXL is the previous generation of dash loggers, so the prices were reasonable with the new MXL2/MXS/MXG now on the market.  It still does nearly everything I could ask of it.  It provides a LCD display of all the critical information I choose (temps, pressures, speed, revs, shift lights) and alarms for when user set thresholds are exceeded.  It also provides lapping info, including forecasted (or predicted) lap times.

The other nice thing about the MXL paired with a modern CANbus car is that it can pull almost any available information that the car is already reading.  So RPM, fuel level, temps, steering angle, TPS, etc are already ready to record.  Additional analog inputs allowed me to add standalone sensors for brake pressure, oil temperature, oil pressure, fuel pressure, and differential temperature.

The MXL essentially replaces the stock dash in the Spec E46, so I mounted in directly to the steering column, just behind the steering wheel.  I used some scrap carbon fiber sheet to fabricate a simple mount that is secured using the two screws that hold the wiper and lighting stalks.  The wiring harness run from the back of the MXL to behind the dash where it splits to the analog sensors, power/ground, and the CANbus.  I added a 4-port CAN expansion so that the GPS, Smarty Cam, and a Memory Key could be added.

The other aspect of data acquisition is getting video of your laps.  I’ve been using GoPros for this, but it’s a constant hassle.  The batteries don’t last long, their WiFi remote is very temperamental, and you don’t have any ability for automatic start and stop.  While the video is high quality in resolution and color terms, it’s not very good for the race environment.  The rolling shutter sensor means you get a wavy jello effect of objects in the distance (clouds are the most obvious.)  The other, perhaps most frustrating, negative of using the GoPro is that to truly use the video for driver improvement means hours of post production editing to actually produce a helpful video.

The solution to this is the AiM SmartyCam HD, a truly purpose built motorsports camera.  The price is certainly way above the GoPro, but time and frustrations saved has made it worth it.  The camera interfaces with the AiM MXL dash for both additional data (including GPS) but also means its internal battery is charged by the car and it starts and stops automatically.  It’s pretty much a set it and forget it driver tool.  The raw video is 720p, so not as high def as the GoPros, but the CMOS sensor eliminates the wavy effect and it has light metering functions and stabilization tailored to use in a car.  The end result is actually better video than you can get from any GoPro (for the purpose of in car video.)

The other nice thing about the SmartyCam is that it overlays data on the video in real time.  Speed, lap times, revs, brake pressure, throttle position, temps and pressures are all automatically displayed on the video.  The gauges and graphics are fairly canned when compared to what is possible with RaceRender or Dashware, but it is also much easier to use and saves hours of time.  Because everything is automated means you can simply pull the SD card at the end of a session and have instant feedback from viewing on a laptop.

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Spec E46 Build Part X: Safety & Interior

Much of the safety aspects of this Spec E46 race car build were covered in Part VII Roll Cage, so I’ll just be covering the final touches and refinements.  I intended for the car to be legal in both NASA and BMW CCA Club Racing, so a few additions such as a center net system were necessary.  For the most part, safety equipment legality is pretty universal as long as you are running approved (FIA or SFI) gear.

For a seat I wanted a head restraint (halo) style bucket.  I went with the Racetech 4119 based on the good reviews and the nice addition of a backside cooling air port.  It’s also available in tall/wide, nice for my 6’2″ 200lbs frame.

For floor mounts I used VAC Motorsports matrix style aluminum mounts, which are fairly standard among this level of racing.  For side mounts I went with Motion Motorsport’s innovate competition seat brackets.  These brackets allow for infinitely adjustment and are asymmetrical left and right to allow close mounting to the transmission tunnel.

I opted for Schroth Profi II 6-point HANS belts for my harness.  These belts have 2″ lap webbing for better fit and can be set as pull-up or pull-down operation.  I tried both ways and decided pull-down was easier to get a tight fit when in the seat.

The window and center (right side) nets are both Teamtech mesh nets, which were easy enough to install.  Fortunately my window net doesn’t interfere with seeing the side mirror, and the even if it did, the mesh is certainly easier to see through than grid webbing.  The window net is mounted using a Joe’s Racing kit, which uses nice billet aluminum parts.  The center net is secured to the dash bar, running through a small slit in the dash and held from sliding on the bar by a 1-3/4″ aluminum split collar.

The steering wheel is a MOMO Mod 78 350mm race wheel, mounted using an NRG adapter, NRG short quick release, and NRG 1/2″ spacer.  The NRG products are hard to beat for the money, using all aluminum parts and anodized matte black.  The quick release uses spring loaded ball bearings in a unique pattern that only allows the wheel to go on one way and has a much tighter fit than I’ve seen with spline style releases.

Shifter action is taken care of by a CAE Ultra Shifter.  This is a very impressive piece, made in Germany from quality aluminum and stainless parts.  The shifter has a self-centering action and adjustable stops to keep from pushing the shifter further than the transmission forks can go.  It also has a lock-out for reverse, making it impossible to accidentally shift into reverse.  The shift selector rod is also from CAE and can be adjusted in length and rotation.  The setup requires a bit of tuning, but once setup properly it is absolutely the best H-pattern shifting action I have experienced.

The pedals remain stock, though I did remove the rubber covers.  For grip I added some textured grip tape to the brake, clutch, and dead pedal.  I also replaced the split plastic bushings on the clutch and brake pedals with Delrin units from Rogue Engineering.  These bushings fit much tighter, necessitating a little sanding for the right amount of friction.  The result is much less side to side play.  To keep the clutch from overextending and cut down shift times, a BimmerWorld mini hockey puck clutch stop was installed.  The OE stop is very small and the plastic clutch pedal can inadvertently go beyond it.

Finally the fire system was installed.  I got lucky and found an unused SPA 4L AFFF system, which just needed re-certified to use.  The system is fairly simple, using push on connectors and tubing with an aluminum wall, so bending it shape is very easy.  I mounted the bottle behind where the passenger seat would be.  Because the cage main hoop foot plate was interfering, I mounted the bottle up on two pieces of 1/2″ square aluminum tubing.  The plastic tank cradle is riveted to the square tube, which in turn is riveted through the floor.

The fire suppression system lines run from the tank forward along the transmission tunnel, split between cockpit and engine bay nozzles.  There are three nozzles in the cockpit, one on the tunnel facing forward, one pointed at the footwell, and one in the dash pointed at the driver’s torso.  The engine bay line splits, one to the left which has a nozzle pointed at the fuel rail and one to the right pointed over the headers towards the front.  I will probably add an additional one to point down into the engine towards where the headers are, just as a precaution against an oil fueled fire.

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Spec E46 Build Part IX: Electrical

The vast majority of the stock wiring was removed from the car during deconstruction, which I covered in Part I of the build.  Fortunately the stereo harness was completely separate from the rest of the chassis wiring.  I still had to go wire by wire for things like electric windows, seat controls, HVAC, airbags, and interior lights.  I picked up a depining tool set from ECS to help remove the wires completely, all the way to the fuse box.

  This was certainly a daunting task, but taking it one wire at a time and labeling everything helped to insure no needed wires were cut.  The remaining chassis harness was fairly simple, just operating the tail-lights, fuel pump, wipers, head-lights, and instrument cluster.  I left the OEM chassis computer in place so that the wiper stalks to operates as normal with intermittent settings.  I also left the OEM light control unit, so I can still have turn signals, high beam, and flash just like stock.

The engine bay side was fairly simple as well, just removing the emissions related equipment, HVAC control (heater valve, AC compressor wiring), horns, washer level & pump, hood switch, foglights, side markers, and washer nozzle heaters.

Battery

A lot of weight can be lost here by swapping to a lightweight ATV/Motorcycle battery.  I knew my car would be a little heavy with the cooling shirt system and differential cooler at the back (not to mention a heavy driver) so I decided to lose the boat anchor stock battery.  I’ve used the Deka batteries in the past and had decent results.  I wouldn’t recommend one for a daily driver, but they work well for a race car.  These are the same batteries sold under Braille brand and other store brands, yet much less expensive.  This ETX 16 battery weighs in at 16 lbs and easily cranks the M54.

I made a simple battery bracket out of aluminum angle stock, which was riveted to the OE battery floor.  A piece of U-channel aluminum, threaded rods, and wing nuts made for a custom hold down.  The stock grounding lug was used with some longer cable.

  Power Wire

In the photo above you can see the power cable as it runs from the battery positive terminal and forward to the kill solenoid.  (note: the kill solenoid should be oriented with its terminals on top, I have to fix this.)  This is the electrical kill setup from BimmerWorld, which uses a heavy duty solenoid to kill power rather than a mechanical switch and pull cables.  The small circuit breaker is also part of this system.

The stock power system uses two wires running from the battery forward.  One is fused and approximately a 2 gauge wire that runs to the fuse box.  The other larger wire (apprx 1 ga) runs through the firewall to the under-hood jumper lug and then to the engine harness (starter and alternator.)

Since I was pairing down the electrical system to the bare minimum, I deleted the smaller wire and ran a single wire from the battery up to the firewall.  At that point it needed to be split so that power could run to the OE fuse box and continue on to the engine.  To accomplish this I used a GM/Delphi battery terminal box.  I trimmed the plastic a bit to allow the cables to exit, then mounted the box behind the passenger side foot protection bars.

Switches

Also running from the GM battery terminal is a smaller 10 ga wire, used to supply power to switch panel.  I used a Hard Motorsports dash panel kit as my basis for the switch panel.  I got a box full of K4 switches and circuit breakers and mounted everything tightly on the upper (formerly vents) section in the center of dash.  For circuits I planned for the following (from left to right):

1. AiM MXL Dash 2. MyLaps Transponder 3. Radio power (future) 4. USB power (originally for GoPros, now a spare) 5. Differential cooler (two pole, 1. for pump, 2. for fan and pump) 6. Helmet blower 7. Seat blower 8. Cooling shirt pump 8a. Cooling shirt timing rheostat

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Spec E46 Build Part VIII: Differential Cooling

I’ve previously covered the addition of the DiffsOnline LSD differential in Part IV, here I’ll discuss a custom cooling solution for the differential.

A track driven clutch type differential can easily reach temps in excess of 250 F without much effort.  Running a differential hot reduces the life of the clutch packs, which can reduce lock up and lead to poor performance.  The simple solution is running a finned aluminum differential cover, which BMW produced.  But relying on air flow under the car to cool down a race rear end will only do so much and you can still expect hot temps.  You also lose ground clearance, something I’d like to avoid when you may take the occasional off-track excursion.

The other solution is an external cooler.  BimmerWorld produces a kit for this, which is fairly universal.  The GTS E36 build I picked up a while back came with boxes of parts, one being a mostly complete differential cooler.  It’s a pretty simple setup; a self priming pump to draw fluid from the differential, a heat exchanger, a fan, and various fittings and hose.

I placed the cooler at the rear of the spare tire well, mounted on some fabricated aluminum mounts I made from angle stock.  I also used rubber idolater mounts from McMaster Carr to contend with vibrations.

The lines run through the sheetmetal using AN bulkhead fittings.  The setup was pretty compact because I was also mounting my cooling shirt cooler in the spare tire well.  Because of these constraints I had to try a few different AN hose ends to get the angles just right.

Eventually I came up with the right combination and was able to have everything fit nicely.  Under the car, the braided stainless lines run to the differential cover.  The drain and fill plug were replaced with AN adapters from Setrab.

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Spec E46 Build Part VII: Roll Cage

The Spec E46 cage must adhere to the minimum safety rules outlined in the NASA CCRs (or BMW Club Racing or SCCA rules if you run those).  Essentially a generic 6-point (+2) cage will be legal.  Refer to the CCRs for specifics on wall thickness vs. OD, which depends on running weight.  The cage can’t pass though the firewall or be attached to any points other than where the tube terminates on the floor.  So tying the strut towers into the cage or welding the A or B pillars to the cage is not allowed.

Another Spec E46 driver pointed me to SPF Racing in Lugoff, SC, who had just done the cage on his 330Ci.  I was impressed with the photos of the work done and decided to give him a call.  He (I say he, because SPF is a one man at home operation) was booked up for a month, so I took care of almost all the other items before getting the car caged.

I mounted the seats where I wanted them so SPF could build the cage around them and set the height of the harness bar properly.  I did place two seats, just in case I ever want to run the car at an HPDE and have a passenger.  The door bars are the X type, sometimes referred to as FIA cage bars (vs. the NASCAR style bars.)

  I also had center jack points added, which are tied into the door bars.  These are a huge help in quickly getting one whole side of the car up in the air and on jack stands.  Since the rules don’t allow for anymore attachment points, the tube just goes straight through the floor but is not welded to the surrounding sheet metal.

Another request was a floor pan for the driver’s side.  Since the thick OEM insulation and carpet were removed, the floor was now well below the pivot point of the gas pedal.  A simple aluminum floor pan raises it up to the normal height and makes it both easier to operate the pedals and get in and out of the car.  I ended up reworking the floor out of a single piece of aluminum, strengthened with some U-channel aluminum on the bottom.  I added grip tape from a skateboard on the topside to prevent any slipping.  The pan is held in place with large Dzus style fasteners.

Window net mounts were also welded in place.  I used a Joe’s Racing rod to mount the upper side and the lower portion it held in place with steel chain link and a bracket.  The window net is a mesh style from Teamtech.

The stock dash bar was removed, but SPF was able to reattach the fuse box to the dash bar so that it operates normally.  You can still close it in the up position, hidden behind the dash.  The dash itself is secured with a bolt on the left and right side by the A-pillar.  I added an additional aluminum support off the transmission tunnel to keep the dash from moving while driving.

Another feature to the cage was a dead pedal welded to the foot protection bars.  It was a little hazardous to my ankles so I smoothed out the corners and then welded on a piece of sheet metal behind the foot rest to keep my left foot from becoming trapped underneath.

The following are just additional photos of the cage work.  I find it helpful to review what others have done on their cages when starting a new build.

New Post has been published on http://www.eatsleeptinker.com/2015/06/17/spec-e46-build-part-vi-engine/

Spec E46 Build Part VI: Engine

The Spec E46 rules are purposefully limited to keep competition tight and cost down, so the engine doesn’t receive much work except for mods which help it survive track duty.

9. Engine

1. Regardless of factory specification or procedure, no oversize pistons are permitted. 2. Compression ratio may be changed only within the tolerances affected by resurfacing for trueness and within factory tolerances, and shall not exceed 10.5:1 [exact value TBD] as measured by a whistler device. 3. Time-Sert or similar product may be used with threaded components. 4. Oil pan baffle may be added. 5. Spark plugs may be replaced. 6. Head gasket may be replaced with any gasket having the same or greater compression thickness as stock. Other engine gaskets and seals may be replaced. 7. Stock oil pump assembly may be modified. 8. Oil separator (CCV system) may be replaced. 9. Oil filter housing may be replaced with the E46 M3 part number 11 42 7 839 858. 10. Engine must be controlled by the stock ECU flashed with the Epic Motorsports Spec E46 tune. The Epic tamper proof seal must be intact. 11. Emissions related equipment may be removed. 12. Horsepower or other engine checks may be performed to ensure compliance.

The first decision was whether or not I should continue with the original engine or find a fresher donor.  The original mill had over 220k miles, had a Vanos that sounded like bolts in a coffee can, and was clearly down on power.  I hit up the junk yards and found an M54 out of a Z4 automatic with only 70k miles on the clock.  It had sat idle in the yard for over a year, so it was in need of a quality refresh.

I got it on the stand and begin taking it down to a bare long block.  All the original rubber was mostly dry rotted, some falling apart as it was removed.  The engine got all new CCV plumbing, new cooling lines, new valve cover gasket, and a thorough cleaning.

I went through the normal upgrades that my M3 has also received.  On the bottom end I replaced the standard oil pump with the Greg Smith Racing (GSR) four bolt pump.  This eliminates the weak splined shaft and nut with a much beefier shaft end and sprocket.

With the oil pan off I also installed a baffle from Achilles Motorsports.  I have the same one on my E36 and was pleased with the results.  Since I can’t weld aluminum I took it too a local fabricator to permanently burn it in.

The Vanos (BMW speak for variable valve timing) system is known to wear out overtime, the usual symptoms are noise (like metal rattling in a can) coming from the unit and dead spots in the power curve.  Luckily Dr. Vanos offers rebuilt units with upgraded seals.  I picked up a complete unit and slapped it on the front of the engine.  The old one went back as a core.

You can see the photo above and to the left that the Secondary Air Pump (SAP) flange has a blocking plate covering it.  All emissions and HVAC equipment has been removed, and SAP flange is one of the spots that needs plugged.  The others are the few vacuum ports on the plastic intake manifold that lead to the fuel evap tank.

The cooling system also requires a bit of attention to survive life almost exclusively at the upper end of the RPM range.  One common upgrade is ditching the plastic impeller water pump for a Stewart high flow all metal pump.  These pumps are significantly beefier than the stock components and eliminate the risk of a plastic pump exploding.  I also replaced the weak plastic pulley with an OEM equivalent aluminum pulley.

Another upgrade is the thermostat.  The M54 engine has a electrically actuated thermostat, controlled by the DME.  There is a fail-safe designed into the system, but it can still result in a catastrophic over heating.  A solution was developed by Zionsville Autosport which uses a modified stock housing, an aluminum plate, and a traditional mechanical thermostat.

The exhaust side of the engine must adhere to the Spec E46 rules, so off came the restrictive M54 headers and on went a secondhand set of S52 manifolds.  I picked up this pair for $50, and after a few minutes with the sand blaster they looked brand new.  They went on with new studs, nuts, and gaskets.

The DISA valve is another area of concern on these engines.  This valve is found on the intake manifold and opens and closes to adjust intake track length for different loads.  The valves are known to fail early due to weak plastic.  Best case scenario is you lose some power, worst case is the engine ingests some broken parts.  The DISA valve on my 70k mile junk yard engine was completely shot, just flapping around freely.  Fortunately none of the parts were missing.

Good news is that German Auto Solutions makes a very nice upgrade kit that replaces the flimsy plastic flapper and bell-crank with machined and anodized aluminum parts that pivot on a titanium shaft.  The kit comes complete with a new gasket (unavailable from BMW) and all the other necessary parts.  G.A.S. also provides very detailed instructions on whole procedure.

Since the entire HVAC system was removed, I needed to plug the heater port in the block.  There are several different ways of doing this, but Bimmerworld has produced a very nice kit which plugs the block using a machine aluminum piece with an o-ring and also includes a plug for the expansion tank.

A oil distribution block, also from Bimmerworld, was added to the filter housing.  This provides a means of adding an external oil pressure sensor for the AiM data loger.

New Post has been published on http://www.eatsleeptinker.com/2015/06/14/spec-e46-build-part-v-suspension/

Spec E46 Build Part V: Suspension

Once again, let’s review the Spec E46 rules regarding suspension:

14. Suspension

1. Shocks must be MCS non-remote reservoir single-adjustable (1WNR). 2. Front springs must be Hyperco 6″ 2.25″ ID 750# part number 186A0750. 3. Rear springs must be Hyperco 5″ 2.25″ ID 850# part number 185A0850. 4. Swaybars may be replaced provided they use stock mounting locations and either individual hole or sliding collar adjustment. Remote-adjustable or blade-type bars are not permitted. 5. Swaybar links may be replaced. 6. Adjustable camber/caster plates are permitted. The three front strut mounting holes and center hole may be notched/trimmed to provide clearance for fitment or achieving full range of adjustment. 7. Any OE-spec E46 non-M3 front control arm may be used. 8. Front control arm bushings and housings may be replaced with a non-spherical bearing. 9. Rear upper shock mounts may be replaced. 10. Rear trailing arm bushings may be replaced with a non-spherical bearing. 11. Height adjustable rear spring adjusters may be added. 12. Rear lower control arms may be replaced.

So with that in mind, I did have a few choices.  Again I went with what seemed to be the most common sway bars, end links, camber plates, and bushings.  I had a set of Rogue Engineering rear lower control arms on hand from my E36 build, so I went ahead with those.

  I’ll start at the rear.  The rubber OE bushings were removed and replaced with PowerFlex Race poly bushings (black.)  The outboard upper ball joint and lower rubber OE mounts were replaced with new OE mounts (no upgrades allowed.)  The lower arms (aka “salad tongs”) were tossed in the trash and the alloy Rogue Engineering arms installed.  Finally, Ground Control articulating weight jacks were added to the upper arms which also received new OE rubber bushings.

For anti-sway bars I went with the Hotchkis Sport kit.  This kit is a 30.2mm front and 25.4mm rear.  It also includes new rear end links, and bracket reinforcement plates for both front and rear.

Of course the shocks, struts, and springs are spec’d in the rules.  For the rear shock mounts (RSM) I used Bimmerworld spherical bearing style mounts, so no rubber to deflect under load.  Front mounts are Ground Control camber/caster plates.  I notched the shock towers to gain additional negative camber and positive caster.

I used the new BimmerWorld solid front control arm bushings (FCAB) for the front.  They’re aluminum with a Delrin insert.  I did have to cut them down to clear the aluminum reinforcement panel.  Just removed the nub that had a threaded boss for the E46M3 brace (not allowed.)