Super Hang On Mini Sit Down Restore

Finally acquired the final missing piece – the elusive dash plastic. Couldn’t be happier. During installation, I noticed one thing – there is a small hump in the plastic between the RPM meter and the start button. I have seen multiple cracked pieces where the damage seemingly starts here. While installing I did some inspecting to see if there was anything that could be causing this inside and sure enough, the stock set screw for the accelerator pot is a smidge too long. What happens it when this piece is secured down, that set screw ever so slightly rubs back and forth on the plastic from the inside, causing it to warp, weaken and eventually crack. A huge design flaw! The easiest solution would have been purchasing a shorter set screw, but I would have had to do that regardless if an error was made. So instead I simply removed my set screw and using a fine tooth hacksaw trimmed it down 2mm or so and filed the end to be smooth. After that, I was able to reinsert it into the coupling flush. No more rubbing.  TLDR: Sit down owners: check your set screw to make sure it isn’t damaging your plastics!

Illuminated button working again. I think this 24mm button is actually from a Super Hang On Stand Up. It’s just placeholder regardless.

As mentioned in an earlier post, the original coin mechs (Asahi Seiko KWM/740) were thrashed. I spent a countless amount of time trying to track these down. I ordered new plates from Mike’s Arcade and they were too small. I emailed Asahi Seiko for information directly and they sent me back to Mike’s Arcade. It was a seemingly never ending loop of dead ends. Upon further research the best I could determine was Asahi made a variant labeled the “740-L” (presumably L for the face plate being longer) but finding more information on that was tough. I wanted nice shiny mechs without screwdriver scratches all over them, and I also wanted the machine to run on JPY (¥100) like other machines from that era in Japan. So I purchased some Asahi Seiko 730-A/B 100¥ mechs from Yahoo Auctions Japan for the low price of $4 each assuming I would have to fabricate a custom mounting plate for them. Once the mechs arrived I went into illustrator to begin redrawing the base mounting plate. I had the outer measurements from earlier work on this so this seemed pretty straightforward. Did a few iterations, cut by hand to test fit. Everything was looking good so I took the test print down to the cabinet for a final fitting and sure enough – it was the same size mech! TL:DR version: It appears that in the US, Sega used a 25$ Asahi Seiko KWM-740 mech with a modified or perhaps even custom faceplate. Size wise, the Asahi Seiko 730-A/B is the exact same.  This is great news for all Super Hang On owners as the 730-A/B is still widely available in a variety of configurations for European, US and Japanese markets. 

- Source dash plastics, sad they are still missing at this point.  - Still want to upholster the seat with a nice padding and some leather. That will come soon. - My Asahi Seiko 740-L coin mechs are still pretty beat up, need to source those.  - Need to install the de-suicided 68k and freeplay roms. Just a nice to have.  :)

Years back a friend of mine turned me onto a product called Rapid Tac. I cannot recommend this stuff enough for this type of work. It allows you to freely position your stickers before committing. Once the sticker is in a good place you simply squeegee the Rapid Tac out from behind, removing all bubbles and leaving a nice clean seal. 

Time for rivets, and the point of no return. I knew once this step was completed there is no easy way to go back into the sub frame or mess with any of the wiring that runs through it. Also if I have to remove the shell again, that means more damage to the plastic and a repaint. Needless to say I took my time with every single rivet. As mentioned before, I slightly increased the diameter of the rivets to 3/16″ to mask the damage caused by drilling the 1/8″ rivets out, and to give everything additional strength. The rivets got easier the further I went and I am thankful that none of them went wrong. 

One thing to note: the line between the blue and the white will be covered with NOS red/white striped decals. Brilliant design on Sega’s part as this not only adds a cool detail to the bike, but masks any errors that would have occurred during painting. 

The gray paint masking for the “motor’ turned out pretty great. To prep for the next step, i masked the white and gray parts that were painted off so I can finish painting the rest of the bike blue. 

Grabbed a cool A2 size fold out poster from Yahoo Auctions. It contains all the pro strategies!

Pending a light brushing with steel wool, I consider white to be finished. 2 colors left to go.

Kind of glad I had to pause on painting because I had forgotten to widen the rivet holes. As mentioned in a previous post, removal of the rivets gave me mixed results with some gouges in the plastics. I’ll be replacing the original 1/8″ rivets with a slightly larger 3/16″ set. It will cover the errors, theoretically increase the hold strength ever so slightly and all the rivets will be shiny and new.

Some quick research told me that this is from uncured primer. Meaning: since the base layer wasn’t sanded correctly the primer never adhered to it properly. This is quite a set back as I have to sand, prime and re-paint about 25% of the plastics.  If I can’t get this right on a second attempt the pieces will be going over to a body shop. 

The remaining NOS parts I needed to wrap the controls up arrived today. A set of original grips, an accelerator housing mount plate and the mylar washer that sits between the grip and plate. After a couple frustrating hours, everything is installed, tuned and fully functional. 

Huge shout out to @moftsoft for tuning the original Sanwa monitor to a brilliant state. Can’t do anything about the burn in, but at least it’s burn in from this game. 

Since the dash plastics are still missing there wasn’t anywhere to mount the start button. I drew a few little holster options that utilize the mount for the dash lamp and holds a typical Sanwa 24mm button. I drew a few options up in Illustrator and had them cut out of Derlin at Ponoko. Fast, cheap and strong – all you can ask for with a hack like this. 

Gave the shells an all over sanding with 800 grit and dropped a quick coat of 2x plastic bonding primer onto them.  I did not paint them on the (filthy) carpet they are pictured on but rather a clean concrete floor. The point of this exercise was add increased visibility to all the damage in the shell so doing this in a sterile paint environment was not necessary. I’m going to let this dry overnight and then sand the damaged areas again and begin a light bondo fill. 

Received the missing pieces for throttle functionality in the mail this past weekend. Once again a huge shoutout to Arcade Fix It. I don’t know what I would do without the stash of parts this guy has. Pretty simple task of disassembly, cleaning grease off of brass components and reassembly (with new gear and pot coupling). Pictures don’t do it justice but this thing feels absolutely great now and functionality + controls are officially restored 100%.