Kyosho motor

[TimmyMallett]

Basically I've been bequeathed a nitro RC car from my Dad who I dont think has run it in many years and bought it from someone else assembled years before that. I've had a Traxxas Stampede notro version but that was 15 years ago so I'm well out of the loop on repairs.

My plan was to get some fresh fuel and see if it runs but I've spotted a bit of an issue in that it's had a replacement engine swap at some point (I know this as it came with the old one) but the output shaft appears to be missing a bearing and circlip? And I have no idea where to start looking for a spare.....

Edited by TimmyMallett on Friday 25th June 10:58

Edited by TimmyMallett on Friday 25th June 10:58

Edited by TimmyMallett on Monday 28th June 11:40

[dr_gn]

Looks to me like the pinion is completely wrong for the car - or at least for that output shaft. The gear tooth profile also looks like it might not be compatible with the driven gear.

If by bearing you mean something to take the shaft/pinion gap up, that would be called a bush or spacer.

A circlip is usually used just to retain something axially - looks like the pinion shaft might need a pinion with a grub screw to tighten onto it rather than a circlip, which in itself wouldn’t transmit any drive from shaft to gear. You’ll probably find the larger gear’s bore is shaped to fit over a flat on the shaft, and that transmits the drive (or some alternative engagement method); the circlip will just stop the gear coming off the shaft.

I’d look online for a new pinion, first checking the number of teeth you need, and the shaft diameter. It’ll probably only be a few £.

I sold my Nitro rc car a few years back, and it wasn’t Kyosho, but those are my thoughts. Could be wrong.

[TimmyMallett]

Thanks, that's really helpful. I has a suspicion that it's been run like this in it's current bodged state and the force of the drive shaft cog just pushes into the drive cog but it will end up just stripping it.

Now I know its a pinion, a quick Google and a vernier caliper and I can figure something out I think!

Something like this?

https://www.ebay.co.uk/itm/Tamiya-AV-Pinion-Gear-S...

Does the grub screw tighten the pinion using the output shafts groove?

Edited by TimmyMallett on Saturday 26th June 12:58

[dr_gn]

TimmyMallett said:

Thanks, that's really helpful. I has a suspicion that it's been run like this in it's current bodged state and the force of the drive shaft cog just pushes into the drive cog but it will end up just stripping it.

Now I know its a pinion, a quick Google and a vernier caliper and I can figure something out I think!

Something like this?

https://www.ebay.co.uk/itm/Tamiya-AV-Pinion-Gear-S...

Does the grub screw tighten the pinion using the output shafts groove?

Edited by TimmyMallett on Saturday 26th June 12:58

I can’t see your original images anymore, but from memory, it wouldn’t have run as it was. To work properly, any two gears have to:

Be compatible in terms of profile

Be meshed together to the correct depth

and

Mounted stiffly enough so that the mesh is consistent and doesn’t change under load (within a small tolerance anyway).

A grub screw would usually tighten onto a flat on a shaft. If there’s a groove in the shaft, that’s usually called a keyway, and there would be a corresponding keyway in the pinion. A single key (square or rectangular section strip of metal) would then fit into the keyways to transmit torque.

If I were you, I’d join a kyosho group on Facebook, and post the images there. You’ll probably get a definitive answer in a matter of hours, and might even be able to buy a gear set (or whatever you might need to get running) from the group members.

My son was recently given a Schumacher Bosscat, and the advice from PH was to join a specialist FB group. I did this, and have had great advice and also been able to buy some fairly rare spares for a decent price.

[TimmyMallett]

After further dismantling it appears to be a Tamiya motor with a Kyosho exhaust manifold but some sort of spring loaded centrifugal clutch underneath the current pinion.

[dr_gn]

TimmyMallett said:

After further dismantling it appears to be a Tamiya motor with a Kyosho exhaust manifold but some sort of spring loaded centrifugal clutch underneath the current pinion.

If it’s the original clutch and output shaft, it should be fairly easy to get a new pinion I’d have thought. Is there a keyway in the shaft, or a flat on it anywhere, or any sign that a screw has been tightened onto it? BTW, a keyway runs along the shaft - looks like a circular groove on the end of yours?

[TimmyMallett]

Behind that clutch assembly there is a flywheel type part which appears to be the braking system that the throttle servo presses some sort of brake lever onto it.

That has some pins on the pins on the back that aligns onto the output shaft hub. There's no keyway that I can see anywhere on the length.

I think the best option as you say is to try and find a replacement clutch and pinion assembly. How do I find the engine model, is it underneath where it mounts to the chassis?

[TimmyMallett]

I think I found it!

https://www.modelsport.co.uk/product/answer-rc-14t...

[dr_gn]

Ah I see what it is now - all makes sense. Your initial photos I think showed a loose fitting pinion on a shaft, and I thought you were looking for some kind of spacer. In fact the pinion must have sheared off the clutch bell that must have been in the background. And you were right - the space would have been taken up with a bearing or bush.

Clutch bell and pinion are integral, so a circlip makes sense to hold that assembly onto the shaft.

If it’s the right one in your link, you’re sorted.

[TimmyMallett]

Thanks for the tip on Facebook. Within seconds someone pointed out its missing a roller bearing, washer and circlip and I found an ebay seller selling upgraded bearing race that should fit for £7

[dr_gn]

TimmyMallett said:

Thanks for the tip on Facebook. Within seconds someone pointed out its missing a roller bearing, washer and circlip and I found an ebay seller selling upgraded bearing race that should fit for £7

No problem - apologies for the initial wrong info - I thought we were looking at some king of gearbox output shaft with the wrong pinion slid onto it.

Anyway, sounds like you're sorted now.