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

I'm talking about the normal Optima/Turbo Optima, not the Mid (though it appears the parts would be the same, at least for the short wheelbase Mid). I wonder what are the exact parts needed to convert a chain drive to belt drive? As everyone knows, the Kyosho Option House belt conversion kit is virtually impossible to find, but what's included in the kit? I picked up a belt-cogged front diff from the LHS "random box 'o' parts". It seems to me you get the right belt and a rear belt-cogged diff and you're good to go. Is that correct?

In addition to the belt and diff cogs, the transmission case is slightly different because there's an extra grooved belt guide that spins on a small shaft. It's possible it may work without it, though.

You need the belt, front and rear belt diffs, re-designed rear gearbox, idler pulley and lexan cover. See the attached belt-drive conversion instructions. The belt and diffs are the same as in the Optima Mid, but the gearbox, idler and lexan cover are Optima specific.

Ahh...thanks guys! Too bad...I guess it's not practical to try to piece one together. I suppose I'll just sell the front belt diff I bought. I didn't pay much for it, at least.

RichieRich wrote:In addition to the belt and diff cogs, the transmission case is slightly different because there's an extra grooved belt guide that spins on a small shaft. It's possible it may work without it, though.

I think the idler raises the belt up a little so it doesn't rub on the guides. So, without the idler, it may work a little while .

I think my friend Rob runs this kit even without the roller.

I use to run my belt conversion without the special gearbox. Just make sure that your belt is tensioned the right way and you're set.

If you're really concerned, you take a file and "round" the edge of the gearbox so the belt doesn't get hung up.

It is a pretty easy conversion to do. I am currently building one (pics up in a few days ), and all you need is the belt, pulleys, and an idler. You can modify the existing tranny case. As for the idler, you would be hard presssed to find a spare original, but the optima mid idler is the same pitch, just a little larger. Just cut the case as shown in the pics posted here, and drill holes for the idler assembly a little lower than instructed in the instruction that come with the conversion. the only part you will be missing is the gear cover portion, but it isn't very usefull to begin with. The conversion I have is an original from about 20 years ago, and I seem to remember having to cut and modify the tranny case for the conversion. I don't remember it coming with special cases? Is my memory fading ? -Jeff

Check out this link:
http://theoptimahouse.blogspot.com/search/label/PARTS