Optima Mid Turbo LWB Custom special Conversion

[cas22]

Probably my first decent (nib) rc car was a TOM Custom special "bathtub" in NZ the custom had the duralinium saddle chassis, plastic shocks, and mechanical speed control but the custom special had a fiberglass saddle pack chassis, golds, and ball diffs.
Pretty sure it was a manufacturer run out prior to the Lazer taking over, but it was a great car.
Rere's are great, I've got one myself, but i had a heap of bits lying around and this SWB "turbo" chassis popped up quite cheap and i impulse snagged it.
Obviously needs shocks and driveshafts etc., but im going to make up a LWB based on it and use it for hardware.
And its a point of difference not to have the new gearboxes with adjustable tension etc., or an EXO Design chassis.
Not that they're not great gear, I'm just wanting old school and i couldn't drive a chassis like that to its potential anyway.
Optima rere universal driveshafts, new bearings and at the moment gear diffs, but i don't really care, it's not going to work very hard and it will be lucky to lose traction in stock 27 turn class anyway.

[cas22]

I appreciate some people would rather restore the turbo mid SWB, but i had one , and it was a bit of a dog compared with the LWB, and it doesnt owe me much so..
Saying that, i bit the bullet and ordered the OT replica chassis and top deck from Fibrelyte, new belt from Tough Racing and shell/belt covers and spur cover from TBG.
I was waiting for a LWB Rerelease chassis from Kyosho, im sure its pending, but the rere is a different length to the original, and then id be committed to new belts, which in turn would determine pulleys, then that would mean gearbox.... you get the idea.
I looked for original stuff, but just silly money 2 or 3 time the EXO Design chassis.

[cas22]

Occasionally on Auction sites you put an opening bid on stuff and are pleasantly surprised when it wins.
This was the case with a bunch of rere Optima and Mid new Kyosho parts.
Paid less than $20 for about 15 packets of bits that were poorly categorized in the auction.
And double that again in postage and local import taxes.
So the mid will be getting as many bits as possible from this pile that I can.
Suspension arms, rear hub carriers (they are quite different) alloy steering knuckles, hinge pins and few other odd ball parts.
And i dug out the XL belt for the LWB from Tough racing, and the optima CVD's.

[cas22]

Also found the Custom special bodyshell, undertray and belt covers, also found a TOMS shell / wing too
The toms is a nicer looking shell i think, but there's a few of those around already.
may change the wing mounts to the Ultima JJ parts, see how it pans out.

[cas22]

Started the strip down, bearings were mostly stuffed, not surprising for a 1986 car, Screws were a mix of stripped kyosho, tamiya and woden slot heat wood screws.
Nice,
Found the screws on the front gearbox were mostly gone, repaired with epoxy and tapped to M3. Wasn't sure if the front gearbox was the same as the rere, appreciate the rear id different due to the belt tensioner.
Bit of a score though, the partial chassis i bought had universal driveshafts in the rear, unusual, so these will obviously ride up front, and i have a set of normal rere dog bones on order for the back

[cas22]

After polishing and cleaning the fun bits.
Rebuilt the gear differentials, added new bearings and shims as i went.
The belt was from tough racing, and the chassis/ radio plate/ gearbox brace from Fibrelyte.
Kept on expecting the inevitable lwb rere, and it associated replacement chassis, but bit the bullet and ordered one.
LWB re-release will Probably be announced? Released in the morning .

[terry.sc]

Wasn't sure if the front gearbox was the same as the rere, appreciate the rear id different due to the belt tensioner.

It isn't, the rerelease uses different size bearings on the diffs. In theory you can use rerelease the front gearbox case, but you will have to get a pair of 8x15x4 bearings to replace the 8x14x4 bearings in the original.

It's good to see an original Mid being resurrected these days, especially to take to the track. Most "vintage racers" these days just wait until the manufacturer brngs out the car they want.

[radioactivity]

First off nice build. And I do really like the Custom special's look, the upgrade graphite chassis is really nice and no platinum shocks.

You may be too far along or are satisfied with your repair but...
When I built my front diff on my TOMSE I did use a new front housing. I could not find a bearing sized 8x15x4mm.

My front housing was much like yours, stripped threaded holes. I had tried C/A glue, epoxy and threaded inserts, didn't really like those options.
This kind of breaks down the difference in the housings and my approach.

Chuck

[cas22]

Wow, thank you so much.
Always amazed at the resources you people have appreciate the support.
Cheers

[cas22]

I realized I'd have to find some shocks, and I have a few sets of original golds, but they are showing their vintage.
I grabbed a few sets of these associated copy shocks from hobby king when they discontinued their BZ‐444 cars.
Quite nice, alloy bodies, headed collars etc.
I purchased some rere gold rears and rethreaded them to 3/4 length for my Triumph project, but got quite pricey. And you need to fill from the bottom.
These were 10% the price on closeout, so reckon that's what I'll try running.
Thanks. Again for the help on the gearboxes.

[cas22]

In the bundle of bits i got from that Suprise auction was OT-267 or the ReRe steering for the new mid.
The ones I pulled off were a bit rough, ground away and worn, so I thought" those mid bits will fit straight on"
Nup.

[cas22]

So FYI they dont.
Took a fair bit of mucking around to get the bell cranks at the correct height to clear the recesses in the gearbox so the throw it smooth and linear.
So i inverted the sprung arm, removed 5mm from the height, and then carefully recessed the other arm to the 8mm bearing would sit nicely.
Then i used some 50mm threaded alloy spacer posts and drilled out some M4 Cup washers to M5. Which somehow were the perfect height for the throw. (4.5mm i think?)
Couple of shimming washers, and all good.

[cas22]

Should of given up and bought some of Jeffs superior factory works ball raced sets by now, but I'm a glutton for punishment so pressed on.
The link between the bell cranks is not correct either.
A bit of careful measuring later turns out that if I used the spare inner holes on the bell cranks, fitted some 4.8mm balls and nylock nuts, then the intermediate length Kyosho ball ends mated up were perfect.
Used a really long M3 Grub screw and threaded them together, shoulder to shoulder.
Initially placed some 0.2mm M3 shims stacked between them to adjust them but ended up removing them to get it correct.

[cas22]

And finally, i copied a very old RC mod from way back and very carefully drilled into that pristine LWB radio plate (cringe) and screwed the posts top and bottom.
Put in some more spacers so the arms cant float up and down.
Turns out very smooth and rigid.
Just waiting impatiently for the rear dog bones to arrive so I can carry on.
May be there after work tonight.