Kyosho Optima for NVC

[Hcp22]

You are putting pressure on me Jason…

I like to hear your opinion on prolonging the wheelbase with 18mm to modern standard with the LWB Optima MID belt?

[Coelacanth]

Although I've never done that, I can say that the original Optima had issues with understeer on acceleration...lengthening the wheelbase would probably make that worse, assuming you left the front:rear weight distribution similar. What I can say with the mods I did to my Barney Optima is that widening the front & rear track, and perhaps using the bigger 2.2" wheels & tires, reduced or all but eliminated the understeer. Granted, it's quite a bit heavier and more powerful, but maybe those 2 factors balance each other out.

[terry.sc]

Extending the wheelbase should be easy to do, just new chassis rails and a longer top deck. But as said above the Optima will understeer, so much so that the Optima Pro top deck moved the battery pack forwards where the servo is mounted and moved the steering servo behind the battery. It runs and jumps fine as it is so I wouldn't think it is worth going to all the trouble of extending the wheelbase.

[Hcp22]

There is always a risk when you prolong a chassis if you don’t rebalance the car. I did prolong my VONats Tomahawk R with 12mm, and that made it much steadier. And sins I almost never practice I prefer a car with some understeer rather than oversteer. And this Oslo track’s surface is made out of Astroturf and carpet.

I’m thinking about using a saddle-pack and make it adjustable length wise. Another alternative is to use a shorty on one side and all the electronics on the other side to balance it up.

The Oslo track

[Coelacanth]

Beautiful track!

[Hcp22]

Although I've never done that, I can say that the original Optima had issues with understeer on acceleration...lengthening the wheelbase would probably make that worse, assuming you left the front:rear weight distribution similar. What I can say with the mods I did to my Barney Optima is that widening the front & rear track, and perhaps using the bigger 2.2" wheels & tires, reduced or all but eliminated the understeer. Granted, it's quite a bit heavier and more powerful, but maybe those 2 factors balance each other out.

Extending the wheelbase should be easy to do, just new chassis rails and a longer top deck. But as said above the Optima will understeer, so much so that the Optima Pro top deck moved the battery pack forwards where the servo is mounted and moved the steering servo behind the battery. It runs and jumps fine as it is so I wouldn't think it is worth going to all the trouble of extending the wheelbase.

Maybe I have to build two cars, one with standard length and on prolonged. I think I have parts enough for two cars, then do some track tests.

[Bormac]

That's the spirit Lars.

I have driven my Optima on the same 2.0" tyres which I used back in the 80's, the OT-66's and found the car a little slippery on dusty tracks but definitely capable of making some nice laps. The car didn't feel like it had any under steer in these conditions with these tyres.

[Coelacanth]

The more "offroad" the track, the better the Optima should handle it. It was, after all, the offroad buggy to beat in the mid-80's. Nothing could touch it. But when you drive it on asphalt or low-bite smooth-ish surfaces, that's where you'll really notice the understeer. Unfortunately, understeer is more difficult to correct than oversteer.

[Bormac]

It's funny cause I've had to change the caster blocks to the later increased caster ones to keep this car from over steering. I find that with the motor in the rear the weight tends to over pendulum and make the car soon out in the dusty corners.

[Hcp22]

Sins I don't have any of the top deck's I would like the distance from the center of the battery holder to the rear shock tower both for the Optima, Optima Pro and the Turbo Optima. Then I will get a hint where to start mounting the Li-Po.

[Hcp22]

I got measurement from my "Miss Javelin" between the center of battery holder and the rear shock tower. I got 101mm, and I don't know if that differ from Optima and Turbo Optima. The only thing I know what terry,sc said that the Optima Pro's battery holder is mounted forward compared with the rest.

[GoMachV]

I just looked in my parts compatibility sheet and the same upper is used on the javelin, optima, turbo and salute. Looks like the Pro was on its own

[Hcp22]

Thanks!
Interesting list you have there gomachv, where can I find that?

[GoMachV]

If you follow the link in my sig "my garage" it will take you to my website, which is in progress.

Under "links" (not sure why it ended up there, it will end up in documents when I can fix it) you will find a link to the 1990 Parts Guide, and it's a big download but hosted on google so it should be fast. The compatibility area is in the back. It's an amazing manual to have, showing exploded views of many of the cars along with part numbers. Also has a section on the shocks and diffs. Enjoy

[terry.sc]

All Optimas except the Pro use the same top deck. The Pro top deck moves the battery around 20-25mm forwards, which means the servo has to go behind the battery and Kyosho used a long linkage to get the steering to the servo saver.