Build Thread OG Kyosho Mid resto-mod

[CertifiedMike]

This is the car as I bought it from auction.
Its in tough shape.
I've already torn down and cleaned up a fair amount of the car.
I have fitted a re-re slipper and have it set up with a gear diff rear and one way diff in front.
The transmission was a mess. A missing bearing made the topshaft lean on the mid gear, that wore the diff gear funny...
Thorp hardened mid gear, rere top shaft, new "old" gear cases and new bearings.
New belt.
I started polishing aluminum and quickly found bent, twisted and dented parts. Chassis included!
I started building it back with polished aluminum spares and decided pretty quick that it was getting too heavy to be a nimble SWB carpet car sooooooo...
I started with Koswork carbon fiber and CV's.
I still have the polished alum dinged chassis for now.
I'm thinking maybe to try it because the low CG is going to be helpful on the track but the weight might kill the overall "quick" this car will need to be competitive.
More pics when I take them.

 

[CertifiedMike]

And so it begins... Sort of.
This is the new, rerelease chassis plate. I picked it up on ebay with the rest of the metal, frp and a 260 lowfriction belt for $20+ship!
This way I have no dents or bends to start.
Hopefully the track will be a little happier too... The new chassis has countersunk hardware. The original chassis did not.

 

[CertifiedMike]

Some of the parts going into this build...

The ball diff isn't a def for this car yet.
Kosworks has been supplying some very nice parts!
My initial plan is to stay SWB and maybe go carbon fiber on the chassis but I found an old JG LWB fiberglass conversion that I might use.
Chassis changes will be made after some drive time at the track.

 

[CertifiedMike]

Andy's A-arms!!! They cameon the car! They would be WAY cooler if it was a complete set!!!

I tried to get the camera to show the damage to the metal parts. The front shock tower and chassis plate got smacked up good at one time or another!

 

[WickedFog]

Cool! Sweet ride man. Watching!

 

[CertifiedMike]

Thanks! I'm excited to get this on the track!!!

 

[CertifiedMike]

So... its been a bit since I've updated. Mostly its been a few mins here and there while parts trickle in, slow and spotty progress.
I picked up a stock alum re-re chassis plate and started swapping stuff, fitting, shimming... a lot of assembly and unassembly to get things fitted.
Kosworks universals and carbon fiber is amazing!
Now I'm waiting on some parts from Japan.
I got a bunch of new screws to rebuild with when the parts land.
While I wait, I am going to install some new speed bearings and turnbuckles from Avid. Also some titanium pillow balls to swap out.
I bought some Ultima Arms to mess with. I hope I can get them to work. Another rabbit hole to work thru.
I put some foam on road tires on it just to start setting it up. Really, I just got tired of looking at a half assembled chassis.

 

[9x19]

I think there's a tooth missing on the belt...

Otherwise it looks good, looks real good.

 

[CertifiedMike]

I think there's a tooth missing on the belt...

Otherwise it looks good, looks real good.

Thanks! Its shaping up!

 

[CertifiedMike]

Not even close to done shopping!

Its coming apart... again!

 

[CertifiedMike]

All strapped in!!!
They were kind of a pain to install actually!
I'm glad I found the Kyosho straps.
They look good on the chassis I think.
I got a pair of 5mm pinions for the new HobbyWing motor.
Most of the parts are here for a re-rebuild. Hopefully much closer to how I want it to be when I'm done with this build...
Done with this build... Riiiiiiiiiiiiight!!!

 

[CertifiedMike]

Thread 'Optima Mid steering update/upgrade'

Mar 15, 2025

As many of you know, I have an OG Kyosho Optima Mid that I have been building, modding and restoring in hopes of racing on an indoor carpet track.
The car is an original, not a re-release... YES IT MATTERS!!!
Lots of parts LOOK similar... the fitment is a different story though!!!

Theres lots of misinformation and ppl who look at pictures and THINK they know...
I bought it all, I measured, I took pics and I'm sharing it here!

As the title states, Optima Mid update/upgrade steering is what I'm showing today.

Optima Mid stock steering blocks are aluminum. They are tough but heavy...

• CertifiedMike
• Replies: 12
• Forum: Reviews, How-to, & Guides

• 
• 

So I updated my steering and made a separate thread about the whole thing.
A couple things about the upgrade that are sort of specific to my car.
My front CVAs are from Koswork.
They are 63.5mm. Slightly longer than Kyosho OTW125b universals @ 62.5mm
The extra length CVA & slightly more narrow steering blocks equate to binding at about 3/4 suspension compression.
I have a couple feelers out for shorter CVAs. If not, the universals will work. Just not sure if they will allow as much steering angle as CVAs.
The other issue is that I've increased the sweep of travel on the servo saver.
One of the saver's arms is contacting a pivot ball preventing full right turn travel.
I have the parts on the way already.

One step forward, 2 back.

 

[CertifiedMike]

Soooooo... waiting on CVA's to get here, time to get some other stuff done.

Stock Kyosho hard rod ends, hard balls and titanium turnbuckles.
I don't like that they have a hole instead of hex for adjusting but EVERY Kyosho I have has the same set up.
They aren't terrible to adjust and now I have a use for some of the L-hex keys that are all over!
I bought a set of Avid RC turnbuckles to try too. I need more ends for those though.

I used paraffin wax on the turnbuckle threads.
I usually fight when assembling turnbuckles. Its one of my least favorite jobs.

I applied it just like this and they went together pretty easily.
I threaded the ends on clockwise, then switched to counter-clockwise for each end to help the rod ends turn a bit easier.
The turnbuckles are still tight but certainly usable.

I used @Littlemotor 's tip about installing the rod ends 'ring side down' on the balls and titanium ball ends.

I also used the paraffin on the joints like a lube. It works great so far!!! It won't attract dust and the balls swivel and spin smoothly!

There is the front. Mostly complete. Thats a joke at this point really...
The whole car was assembled and it felt tight and smooth.
Then I decided to Install the belt guards, heatsink motor plate and address the play on the top shaft in the trans.
The Mid was assembled, sort of, for about 6 whole hours!

A keen eye will notice, I am switching the shocks to the rear mounted position.
I think if I was running off road, the forward shock position might help soak up some hard jumps but we are on carpet this time so I'll go like this for now and hopefully I'll like it.
I loose the rear sway bar for now but I can fix that pretty quickly I think.

Thats the updates for now.

Sometimes its gotta fall apart for it to all come together!

 

[OnwardGuinevere]

Looking good! You definitely know that car like the back of your hand

 

[CertifiedMike]

Looking good! You definitely know that car like the back of your hand

I am getting reminded of each and every tiny detail!
Thank you!

 

[CertifiedMike]

38 year old transmission, cleaned and de-slimed. No more mystery grease in there!
I am going to order more of these Avid Revolution Aura bearings! Not as expensive as ceramic but soooooo smooth!!! We'll see how they do long-term.
The bearings that were in the car were ok in some cases but I replaced them anyways. I should have spent the extra $ then!

Thorpe hardened gear for OG trsnsmission gears. 32 pitch inside. The spur is that weird 0.6 mod pitch.

Old gear 32p (may actually be .8) and new (re-re gears (in bag) are 48p.

They are different. Mount differently with different hardware, top shaft gear is cut differently too. Would take a bit on a drill press to make the new top gear work. Counter gear might fit with creative bearing sizes and a different shaft in the trans.
I think the only reasonable way to fit new gears into the old car is to replace the entire drive system. Transmissions and all.

BOY am I glad MIP was on point 38 years ago too!!! Thank you Mr Moore!!!

This diff is BUTTER smooth!!! Got a coat of superlube because its not sealed.
Just look at how nice those gears look!!! Not bad considering they are brand new. Well, new, fresh out of a sealed bag...
The old gears were worn funky because a bearing was missing from the transmission! Totally not there, gear sideways!
Pretty sure the previous owner used to stop the car by tossing rocks in the transmission.

For right now, the rere slipper is out but not forgotten! Hopefully we'll see more of it soon!

So now we'll screw it all back together... again...

 

[Littlemotor]

View attachment 229334

38 year old transmission, cleaned and de-slimed. No more mystery grease in there!
I am going to order more of these Avid Revolution Aura bearings! Not as expensive as ceramic but soooooo smooth!!! We'll see how they do long-term.
The bearings that were in the car were ok in some cases but I replaced them anyways. I should have spent the extra $ then!
View attachment 229336
Thorpe hardened gear for OG trsnsmission gears. 32 pitch inside. The spur is that weird 0.7 mod pitch.
View attachment 229344
Old gear 32p (may actually be .8) and new (re-re gears (in bag) are 48p.

They are different. Mount differently with different hardware, top shaft gear is cut differently too. Would take a bit on a drill press to make the new top gear work. Counter gear might fit with creative bearing sizes and a different shaft in the trans.
I think the only reasonable way to fit new gears into the old car is to replace the entire drive system. Transmissions and all.


View attachment 229337
BOY am I glad MIP was on point 38 years ago too!!! Thank you Mr Moore!!!
View attachment 229338
This diff is BUTTER smooth!!! Got a coat of superlube because its not sealed.
Just look at how nice those gears look!!! Not bad considering they are brand new. Well, new, fresh out of a sealed bag...
The old gears were worn funky because a bearing was missing from the transmission! Totally not there, gear sideways!
Pretty sure the previous owner used to stop the car by tossing rocks in the transmission.
View attachment 229341
View attachment 229343

For right now, the rere slipper is out but not forgotten! Hopefully we'll see more of it soon!

So now we'll screw it all back together... again...

Thorpe… Now there’s a part I haven’t heard mentioned in about 35yrs or better.. Looking killer bro, and those Avids are badass rollerizers… I’m digging the follow along!

 

[CertifiedMike]

Thorpe… Now there’s a part I haven’t heard mentioned in about 35yrs or better.. Looking killer bro, and those Avids are badass rollerizers… I’m digging the follow along!

Thanks! As you know well, its a lot of effort to get things 'just right'. Removing the blackened mystery grease will def help me sleep better tonight!
Thorpe. Gone but not forgotten!
These bearings are just night and day different. I don't know what to expect because the belt always has some tension on it.
It might not be a huge difference from stand still but once the belt starts spinning and rpms stretch it out a bit, this thing is gonna FLY!!!

 

[CertifiedMike]

I have a set of correct offset, 2.2" wheels!!! 2 sets actually!!! So happy to see a aet of 'correct' fitting 2.2" on this car!!!

This has been side-lined for too long. I have a few parts coming for this car from Fibre-Lyte.
I will need softer springs.
With more carbon fiber... it will be the lightest Mid I've ever owned.

Hopefully this CF chassis will be the final assembly.

 

[CertifiedMike]

Its been a while since I did an update on this car...
Lots of changes happenimg. Bearing, gear, carbon fiber, shock rebuild/build is underway! Finally!!!

I have car about half torn down.
Trying to stay organized is silly and usel.... errr, is going well!
I'm doing ok with the mess right now but its quick to get out of hand. These cars have lots of parts and I have lots of parts for the parts and lots of tools to inatall the parts...
Anyway...
I rebuilt the rest shocks. They were as easy to rebuild as they were when they were new.
They got TiNi shafts with groved orings, new pistons, and ends.
Smoothest shocks I own by far!

I thought I'd share the rebuild on the front pair of shocks...
Bit then...

The dreaded G clip in the shocks... tiny little clips in BOTH shocks were like WELDED into place.
I got them out but not before scratching up the shock bodies some.
I cleaned them up. Ordered a set of clips and am waiting... annoyed, cleaning and bummed.

I think the shock bodies will be ok.
Those clips tho... yeah, not so much.

Anyways, the only pics to post were of flying screwdrivers, pliers and fingers... mainly middle.

Here's the stuff I just bought on thebay to fix the problem.

I twisted up those little wire G clips at the bottom of the pic.

Using the new Kyosho shock shafts also means using the new pistons. They are machined differently. The red ones (og) are about 1mm too thick.
A steady hand and a drill or press could fix this issue easily so not a problem really.
I had the black (new) pistons anyways so I used those.

I installed Ultima Meduim soft springs in the rear and I think I love them!

Deconstruction will continue shortly after this pile of stuff gets put up.