Optima - Servo Mount

[NegativeGhostRider]

So here's my q (for either of you): Does the slipper clutch of the re re do a good job protecting the gears?

The reason I ask is that I asked the guy at my local RC shop if I should do the upgrade and get a modern brushless motor and esc and he said it doesn't always work and it would probably result in less durability rather than more. Opinions on whether he's right or wrong?

TIA

So, please correct me if I'm wrong... Your local guy is effectively saying that by rolling out the re-release Kyosho has upgraded the transmission from plastic gears with a torque limiter to metal gears with a true slipper clutch and the result is less durability?

I can't recall exactly what he said, but it was something like the following: I was interested in putting a brushless motor into my vintage car. He said it would ruin the gears. I said I was going to also use the slipper clutch. He said the slipper clutch doesn't always work (i.e., it doesn't slip sometimes) and the torque gets transferred to the gears. And if that happened it would effectively destroy them (or something like that).

I don't know that either of us realized at the time that the gears were metal.

So I guess that leads to a few other questions: 1) is he right that the slipper clutch isn't effective in some non-trivial percentage of cases? 2) does the fact that the gears are metal mitigate damage that might be caused to plastic gears if the slipper doesn't work? 3) if the gears would be ok regardless, what else could fail if the slipper didn't operate?

Really, I'm just wanting to make sure I'm not being naive by trying to drop one of these into my car and then acting like I can mash the throttle any time or drive it off jumps with impunity. I would drive it responsibly, but there are certain young people (who live under my roof and eat all my food) that I anticipate will also drive it and may not be as kind to it as I am.

[Coelacanth]

Also, check out this torque limiting clutch:

https://www.ebay.com/itm/RC-Kyosho-Option-House-Torque-Limiting-Clutch-16-tooth-for-Optima-Ultima/371562707099?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D44040%26meid%3D19eec03dc03a4154acfd293a6895c13a%26pid%3D100005%26rk%3D2%26rkt%3D4%26sd%3D371562678697%26itm%3D371562707099&_trksid=p2047675.c100005.m1851

Has anyone used one?

I haven't, but I've heard they're an expensive option part that doesn't work for crap.

[NegativeGhostRider]

By the way, even if there are no definitive answers to my questions, I'll take anecdata like "Ive run this hard for 2 years without problems," etc. Trying to make a reasonable cost-benefit analysis here. Thanks!!

[XLR8]

I can't offer any such anecdote as I've only purchased my first Kyosho in 30 years just 6 months ago. So I will defer to Coelacanth and others who have owned these cars for many years.
However, imho, the robustness of any transmission will depend greatly upon motor power and driving style. Why don't you go ahead as planned using the stock parts and if the kids explode the trans, then go ahead and do the upgrade. What do you have to loose; you already have the stock parts on hand.

[Coelacanth]

By the way, even if there are no definitive answers to my questions, I'll take anecdata like "Ive run this hard for 2 years without problems," etc. Trying to make a reasonable cost-benefit analysis here. Thanks!!

The end of this old topic discusses the "effectiveness" of the pinion clutch bell, but I've read in a few other threads that it wasn't worth it.

https://www.rc10talk.com/viewtopic.php?f=30&t=39493&p=444406

[NegativeGhostRider]

The metal servo mount arrived, and it's nice.

However, it does not fit the screw holes on the base plate.

I'm debating whether to drill through the plate to be able to mount it. As of now, the servo is mounted with tape onto the plastic piece that hangs down. It works, but the servo shifts around a bit when the wheels are moved. Probably not worth a major effort, but I'm just wondering how difficult it would be to drill through the plate and if it seems like it would be easy to destroy it by doing so.

[DennisM]

You´ve come to a crossroad - either spend a small fortune on re-re radiodeck, gearboxes, diff´s, gears, belt and slipper.
Or buy a new kit.

Other thing you can do, is keep the original as is, buy a re-re radioplate and run it with a mild motor setup.

[Timmahhh]

Dennis is right, if you plan on doing a significant change-over to a rere, just buying a rere is the way to go (possibly even a javelin and sell the cage to offset some cost).

As far as the rere slipper, it seems to be pretty stong, but also would require changing the rest of the transmission to be compatible which is where a lot of the strength comes from. Ive raced my rere with a 17.5, and the drivetrain was perfectly fine (although I did have a couple other breakages). I would expect the original gears to be OK with a mild brushless also, provided that the you're somewhat cautious of things like full throttle landings and extended full throttle donuts. Over time though, they will wear and replacement gears are expensive.

Overall the optima is a really fun occasional driver, but doesn't hold up to big air and really fast motors as well as modern cars would, even in rere form. If you keep the car within its limits though, it should work pretty well and be pretty reliable, at least by vintage car standards.

[NegativeGhostRider]

I got my optima up and running. I think there's something awry with the drivetrain, though. I can get it moving, but I have to start it slowly and build speed. If I gun it, the chain slips. I'm assuming if the differential was stripped, it wouldn't run at all. Is that right? Any ideas as to what could be wrong? TIA.

[DennisM]

The chain stretches over time, You´ll need to take out a link or two.

[NegativeGhostRider]

To be clear, the chain moves, but the wheels don't (or only slowly). This happens if I press it more than just a very slight amount of throttle. If I press the throttle slightly, I can slowly increase the throttle and speed will build.

Does this sound like a loose chain?

[GoMachV]

Chain only drives the front, so if it’s slipping on all 4 wheels there is something else going on. It could be something as simple as the friction fit wheel adapters being loose (although it would have to be one front and one rear loose to do that). It could be a setscrew backed out, or even a loose pinion. Need to go point to point and see where it stops moving

[NegativeGhostRider]

Thanks. I'll work on diagnosing it, though I was hoping to determine whether I have to break down the gear box before actually doing so. What is the "friction fit wheel adapter?"

Also, when I would hold the car off the ground and hit the throttle, only 3 wheels would spin.

[XLR8]

The wheel drive hexes on the vintage cars have a taper fit to the axle shafts. If they are slipping, it might be due to a loose wheel nut. The drive hexes on the re-release cars are pinned to the axle shafts so they can't slip.
Assuming that the dogbones and other drive train parts are in good order, you might check the grub screws that secure the drive cups to the differentials. If one has backed-off, it could explain why only three wheels are spinning.

[GoMachV]

^ what he said

With the car on the ground, wheels stopped from turning, try to spin the gear. Your probably going to see movement somewhere. What you need to figure out is where the movement stops. If you can see dogbones spinning for example you know it’s the drive hubs. If you don’t, then see if the chain is turning. If it’s not, then you have narrowed it down to the top shaft assembly. Figure out where the rotation stops.