Third Party Optima Belt Drive Conversion?

[rangerg]

I started this thread here:

http://www.rc10talk.com/viewtopic.php?f=33&t=30588

I think these are for the Optima. I have attached pics of the 17.7 one that I opened. The belt is thicker than than the Optima belt, but it is the same length as the standard 240xl one. Also, if you look, I took the chain portion off the stock Optima diff. and this fits perfectly (and it all turns correctly). Could this be a third party belt drive conversion? Would it just drop into the gearbox? The 18 one is the same, but the gear is larger. I didn't open the 18 one to check the belt size, but I will if you all I think I'm on the right track.

Thanks for the input Kyosho fans.

[DennisM]

Cool stuff!
It makes sense to think of it as a conversion for the Optima rather than a cool third party option for the Mid.
If it is a conversion, I´d guess it came out before Option House made theirs, due to lack of the idler pulley in the bag.

[rangerg]

Dennis,

You're right, it assume it should also fit the Optima Mid and it would be an upgrade/option for a Mid. I don't have Mid diffs to check it out on though. It fits the stock Optima and it doesn't fit on the Kyosho belt drive conversion. If it is for the Optima, I want to know if it works well. Kyosho went to all the trouble to package new diffs, a new gearbox, and a puller in their belt conversion. All they did was replace the top of a gear and then add a belt.

[Coelacanth]

It looks to me like those are just some parts to swap out the stock regular Optima chain-toothed diff halves with belt-toothed halves. That way you don't need to replace the gear on the other half of the rear diff, as that gear is different between the Mid & original Optima diffs.

So, you can use those parts to convert regular Optima diffs to work with a belt instead of a chain. You'll still need the little idler gear and some modding of the rear gearbox to complete the conversion.

[rangerg]

Coelacanth,

I don't know, but would they sell a part where you have to buy another idler gear and cut up the gearbox? Do you think it is just part of a kit? You don't have to cut the gearbox in that it is the stock diff and some people have run the belt without the idler (I remember this from another thread). Isn't it possible that this was the complete conversion, put the new gear half on, add belt, and away you go? It was $55 and all bagged together. I wish there was a label or instructions. Hmmm, thanks for the imput.

[RichieRich]

I have those same aluminum-toothed gear halves. I've been wondering what the heck they go to also. I didn't get the belt with mine, though.

[rangerg]

RichieRich,

That's great, try them with a stock Optima diff and the belt for the conversion kit (the 240xl). I want to see what you think.

I opened the 18 one. The 18 one has a belt the same size, but a larger gear. It fits on the stock diff just like the other one. The 17.7 ones have 17 teeth and the 18 has 18.

[Coelacanth]

I don't know, rangerg, I've never seen those aluminum diff halves before. I did my own belt-drive conversion for Barney involving parts from an Optima Mid, and the crown gear of the Optima Mid diff isn't compatible with the diff half from a normal Optima. So, I assume those aluminum halves could be used with either diff. It makes more sense to me that they'd be sold to convert a normal Optima diff to a belt diff, though they could be used to "upgrade" that half of an Optima Mid diff. I put "upgrade" in quotes because I don't see any point to making that part from aluminum, as the belt diffs NEVER wore out on that half. Only the crown gear on the opposite half would wear out.

People have told me you could do the Optima belt conversion without the little idler gear, if you were careful to cut a section of your rear gearbox to limit/prevent the belt from rubbing. Other than that idler gear, you would only need the belt, belt front & rear diffs, and some rear gearbox modding to complete the conversion yourself.

Kyosho made a full belt conversion kit intended for the original Optima/Javelin series, W0105, that had 2 diffs, belt, idler gear and pre-modded rear gearbox all in one kit.

Some info here if you want to do your own conversion:

http://theoptimahouse.blogspot.ca/2008/05/belt-drive-kit-for-optima.html

[rangerg]

Coelacanth,

I know, I love the Kyosho belt drive kit. I have a full one. I see your point that this could be an upgrade to the Mid, but why like you say? It doesn't swap onto the Kyosho belt drive kit, I tried that just to see.

I think this was a cheaper alternative to the Kyosho kit or maybe it came out before it. I can see how rubbing could be a problem, but maybe the belt is strong enough not to break. It is stronger feeling than the Kyosho one.

So, what would 18 vs 17 teeth do?

[GoMachV]

The length of the belt would tell you quickly if it were for a mid or a original, my bet is on original as I don't see the point in a kit like this for the mid.

[rangerg]

It's the same length as the original belts that I have. I don't have a Mid belt for comparison.

[GoMachV]

A mid belt is longer as it takes a triangular path. I stand by my original thought- one is a stinger and one is a optima conversion

[RichieRich]

Ok, I'll have to dig them out and see how they work. Also, I created a thread a while back asking about these parts on TamiyaClub. They seemed to think they went to a Kyosho Stinger.

http://www.tamiyaclub.com/forum/index.php?showtopic=43532

[rangerg]

I think Gomachv is correct.

[rangerg]

RichieRich, those are definitely the same. Yours are the 18 ones, which consensus is leaning toward being for the Stiinger. The 17 ones are identical but smaller by one tooth, and they fit perfectly on the Optima stock diff and into the stock gearbox. I like the Tamiyaclub thread, I'm sure I have read it before