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I always wondered about that because the picture makes it looks like you just pop off the yellow rings and there you go.

rangerg wrote:I always wondered about that because the picture makes it looks like you just pop off the yellow rings and there you go.

I can say that's definitely not the case. Would that it could be!

Can't you use the idler with the yellow rings? Or is the entire gear wider, or the original Optima conversion kit's belt wider than the Optima MID belt?

I just used some spare diffs (front oneway, rear geared) and belt from a Mid in my Optima. I didn't use an idler at all.

The drivetrain ended up extremely smooth and handled the power from a Novak SS5800 brushless system just fine.

EvolutionRevolution wrote:Can't you use the idler with the yellow rings? Or is the entire gear wider, or the original Optima conversion kit's belt wider than the Optima MID belt?

The belts are the same, but having those yellow plastic rings on the sides of the narrower gear makes for some problems. The rings are a bigger diameter than the gear teeth, which means cutting up your gearbox a whole new way if you want to keep them (the yellow rings) on. If you remove the ring from one side, and cut down the other one (which is fused to the gear, as I mentioned before) you have an issue of the gear sticking out on one side more than the other, which you'll have to address with spacers.

To put it simply, using that Optima Mid idler gear presents a number of new challenges, you can't just install the gear as-is.

As to the idler gear question, why couldn't one use a dremel or small file to trim the yellow optima mids rings down to the contour of the idler thats between them?
As far as the lexan cover, if a fellow had the basic dimensions, what is to say he couldn't take a piece of scrap lexan, warm it with a heat gun and form his own, provided it's for a runner?

Hotshotman wrote:As to the idler gear question, why couldn't one use a dremel or small file to trim the yellow optima mids rings down to the contour of the idler thats between them?
As far as the lexan cover, if a fellow had the basic dimensions, what is to say he couldn't take a piece of scrap lexan, warm it with a heat gun and form his own, provided it's for a runner?

As for your first question, I said exactly that, 6 posts ago. Certainly do-able, but you still have to use spacers to adjust the idler gear to be perfectly dead-center. Since it's narrower than the belt conversion kit gear, centering it will be very important.

In response to question 2, if you saw that little Lexan piece, you'd know there's almost no way in hell you're gonna duplicate that shape with a heat gun and piece of Lexan sheet. Unless you have a micro-heatgun capable of aiming direct heat at areas no more than 1 cm at a time, I suppose.

So what if you left both the yellow rings on the optima mid idler, would it be the right width? I tried finding mine and had no luck. Even if you have to shim, as long as the shaft the idler is on is square to where the belt doesn't want to walk to the left or right, shouldn't really matter, correct?
As for that little lexan cover, I have one around somewhere slated to be installed in a project. You are right in a sense, it has a curved flange at the rear edge. It would be difficult for an average joe to really duplicate perfectly. Sure maybe somebody like Mrlexan could do it with a new/uncut piece, but I couldn't. But the instructions also say something about using silicone sealant. So if it's not perfect, the silicone could fill any gaps and keep the major grime out, correct?
I guess I wondered if this whole project was a pure vintage restoration or an attempt to race a vintage car. If the project requires it to be absolutely perfect, then this is not easily attained without a chunk of change. But if its for a runner running against vintage machines, maybe it's different.

Hotshotman wrote:So what if you left both the yellow rings on the optima mid idler, would it be the right width? I tried finding mine and had no luck. Even if you have to shim, as long as the shaft the idler is on is square to where the belt doesn't want to walk to the left or right, shouldn't really matter, correct?

As I mentioned 2 posts ago, if you leave the yellow rings on--which are a significantly larger diameter than the idler gear itself--that will mean you'll have to cut sections out of your gearbox that are bigger, to make clearance for the yellow rings. I doubt it's even feasible. I think you need to have one of those yellow gears in your hand, your gearbox in your other hand, and see for yourself. Only then you'd know exactly what I'm talking about. You're focusing too much on the picture showing how "similar" the two gears are, but as I said, the picture is misleading and swapping the two is no easy matter. I suppose it'd be possible to trim down BOTH yellow rings, but then you'd probably have to add shims on either side of the rings to prevent them from rubbing on the insides of the gearbox--yet another complication you'd have to deal with.

To reiterate, it's not a simple gear swap.

Trimming down both of the yellow rings was exactly what I was talking about. Trim both yellow rings down to the profile of the new idler gear if it makes it the proper width. Add a shim or two. Or four. I was curious and figured others would like to know as well.
The other issue, provided you have the 'correct' rear transmission case would be the the shaft that runs thru it, which could be machined fairly easily by a machinist.
I have all the proper parts for my conversion minus the sleeve and shaft and proper instructions. I have a few extra tidbits that might be useful to the right person. But if that person is building a 100% correct BITD car they need some serious help on the other tidbits.
Thanks for your take on this, the only belt driven Kyosho I have and have driven is my TOMS version, built box stock with a McAllister Wildcat II body, Hot Trick front arms and associated shocks all the way around.

Why'd you go with AE shocks? That's a downgrade.

I like my shocks, tho in retrospect the kyosho golds were probably just as good. It sure intimidated the other guys I raced with, though.

Back in the day, I heard of more than a few people who ran Kyosho Gold shocks on their RC10's, never heard much of the opposite. About the only thing smoother than nicely set-up Goldies are the modern Kyosho Velvet coated shocks. Kyosho hit home runs with their Golds/Platinums/Velvets.

Coelacanth wrote:Back in the day, I heard of more than a few people who ran Kyosho Gold shocks on their RC10's, never heard much of the opposite. About the only thing smoother than nicely set-up Goldies are the modern Kyosho Velvet coated shocks. Kyosho hit home runs with their Golds/Platinums/Velvets.

Big Time!! but I would disagree about platinums. I loved my golds (ran them up until the Losi shocks with titanium nitride shafts). My JRX2 had losi stocks on the rear and golds on the front. My JRX2 held the track record and was the only vehicle to hit 29 laps (best modified was 28) and I ran stock. Black Magic Motor with 6 cell 1200mah SCR pack. Loved that buggy. Something about the golds on that losi front end made it handle like a dream.

I am bumping this because I would love to know how the Optima 2016 handled this? Did the re-release belt drive do away with the pulley? (it seems to from the pictures I have seen)