RC10Talk - The Net's Largest Vintage R/C Community

Hmm... 20-25mm sounds a lot

While I'm waiting for some parts to arrive I have gone through my old shock box. And I relished most of them need to be renovated. But do I have look for vintage parts or is there modern parts to be found that will fit my old Kyosho gold shocks? Pressure disks, O-rings, shafts etc...

I've been trying some hardware store ("Buna-N" iirc) black orings and have not been happy with them. They have a sticky feel, very strange. I haven't been able to find that size in silicone. I have tried the CRP ones on eBay and they seem to work well but get expensive. Those are the white ones.

As far as diaphragms i have not found a good replacement. Same with shafts, I'm sure they are out there (traxxas?) but I haven't crossed any sizes over yet

I haven't done anything on my Optima, I feel uninspired...

I have to do something drastic to get going... So I printed the manual to day, and the strategy is to start from the first page or rater page 7.

So I hope I will do some progress during Easter , me and my wife have taken a few day of and are leaving for the country house tomorrow morning. I will pack my old wooden pit box with all I need...

I have there’d down the used one first and started to clean up the old racer from the 25 year old grease that was all over the car. The other chassis is brand new so that one doesn’t need any seriously cleaning…
You can see the amount of dirt on the rear diff-wheel that is partly cleaned.








All parts are now clean and ready to be rebuilt to be a racer ones again… Sins I never raced the Optima back in the days this will be a new experience for me. So if I’m way out of line, then please let me know!

At the front I mounted one-way needle-baring from Trinity (I think) together with new revolution bearings. One-way needle-baring is the best way to go I have been told by “Highwayracer”, he and “terry.sc” and “Coelacanth” seems to be experts on the Optima at the forum as far as I know.




At the rear it will be a gear-diff; this is also a suggestion from “Highwayracer”. On the other had it’s hard to find rear Optima Mid ball diff’s, and the quality of Kyosho’s isn’t that god anyway. But there is Thorp rear diff up for sale on eBay for $100… and I think that’s a bargain compared to my Scorpion diff’s from Thorp.

I put it together with fresh grease and new revolution bearings. The final pinion gear was already upgraded to one in steel, probably Thorp. As you can see this old racer are already belt converted sins back in the days. So no need for me to use the NIP kit I have in my stash.




With the rear gearbox assembled together with the two aluminum plates I mounted the rear shock tower. I have chosen CRP’s FRP-tower, this was made to use with AE-shock’s and are 7mm taller than the original ones made for the medium gold-shock’s. I don’t know if I can use the long gold-shock’s to gain more traveling, because those are about 13mm longer than the medium ones. I have to check this later on when I have mounted the rear suspension arms.






Sins this is the prolonged version I had to order new cassis bars from Pargu. I hesitated, sins he has a bad rep taking long time to answer and deliver. But this time I must have capture him on one of his good days. It only took about 3 weeks before he made them and it came to my post-box. That in compares’ to the front support I ordered two weeks before and that arrived one week later than the cassis rails. You have to be patience and be out in good time when buying parts from Pargu. But he makes so nice things that it is worth whiting for!




Those rails are prolonged with 18mm so I can use the Optima MID (LWB) belt 254 XL. I wasn’t 100% sure if I had got the measurement right, but I did get it exactly as I wanted it!
That’s all for now and comments are more than welcome.

Have you seen the wheel mounted slippers? A little crazy but definitely unique!

Nice progress on your Optima project with the stretched wheelbase. I was wondering why you decided to do that, and use the LWB belt? Are you planning to mount a battery lengthwise, perhaps? Looking forward to what's ahead in your build.

gomachv wrote:Have you seen the wheel mounted slippers? A little crazy but definitely unique!

I have an idea about a slipper, but that would cool to find one of those and give it a test. As you know I love hop-ups...

Coelacanth wrote:Nice progress on your Optima project with the stretched wheelbase. I was wondering why you decided to do that, and use the LWB belt? Are you planning to mount a battery lengthwise, perhaps? Looking forward to what's ahead in your build.

I want the longer wheelbase for the long outdoor tracks and not so twitchy car. Haven't thought about the battery lengthwise, I was thinking to use a adjustable saddle pack setup.

Hcp22 wrote:

Coelacanth wrote:Nice progress on your Optima project with the stretched wheelbase. I was wondering why you decided to do that, and use the LWB belt? Are you planning to mount a battery lengthwise, perhaps? Looking forward to what's ahead in your build.

I want the longer wheelbase for the long outdoor tracks and not so twitchy car. Haven't thought about the battery lengthwise, I was thinking to use a adjustable saddle pack setup.

I think we've talked about this elsewhere, but the Optima wasn't exactly twitchy in stock config...it was the opposite, tending to understeer under acceleration. I wonder if extending your wheelbase might worsen that problem? I guess it also depends on personal driving preference--and also you mentioned long tracks. I was just wondering though.

Coelacanth wrote:

Hcp22 wrote:

Coelacanth wrote:Nice progress on your Optima project with the stretched wheelbase. I was wondering why you decided to do that, and use the LWB belt? Are you planning to mount a battery lengthwise, perhaps? Looking forward to what's ahead in your build.

I want the longer wheelbase for the long outdoor tracks and not so twitchy car. Haven't thought about the battery lengthwise, I was thinking to use a adjustable saddle pack setup.

I think we've talked about this elsewhere, but the Optima wasn't exactly twitchy in stock config...it was the opposite, tending to understeer under acceleration. I wonder if extending your wheelbase might worsen that problem? I guess it also depends on personal driving preference--and also you mentioned long tracks. I was just wondering though.

This track is high bite track I been told, but I will build a standard length car to, so I can compare the two cars. I do have 2 Optimas for this, only a few parts are missing like motor guards, ti-rods and wheels/tires.

Had to test long gold shocks at the rear and they fit perfectly. You can also see that level differ a bit and that depens there is a diffrence in length on the ball ends. The question is if I should chose the long or short vertion, so what do you think?

I guess the ball end length won't make a difference with the shock function, the piston will still plunge the same amount up/down. A longer ball end will push down the control arm a bit more and result in more ground clearance. Choose the ball end to give you the amount of clearance/ride height you want.

Don't forget droop. My Optima uses the same tower and shocks. This allows more rear travel and has worked well for me.

Looking thru my old part box from my racing day I fund a set of Maxxum front arms and remember that “Coelacanth” used those front arms in the OpiMutt project. I also fund a few bags of Lazer C-hubs LA27 and LA59. Then I fund a bag of modified LA27 hubs, I'm not sure on the angle, but I guess it's about the same as the LA59 that is 7 degrees. There was a guy i Sweden who made and sold them before the LA59 was available, but I never got around using my set before Kyosho send me the LA59. Well well, that's history...








If I gone use these Maxxum front arms I need to make another shock tower. The Optima is designed to have the shocks mounted on C-hub, I don't think this will work with Maxxum C-hubs. In order to use the Maxxum's original attaches holes for the shocks I need a higher font shock tower
So I did make a new prototype.

That front end is coming along nicely, looking good Lars! I do like those Maxxum arms...2 of my Optimas have them. I like them because, with the exception of the C-carriers, they're practically a perfect swap for the stock Optima front arms. Nice work fabricating your shock tower, too.