Plastic 2 shoe clutch springless. can't figure it out

[coldvod]

I've been searching on the internet and have come up empty handed. When i start the engine the clutch dont engage, when i push the throttle. The engines an old 21 magnum made by thunder tiger from the late 80s maybe 90s if youve got any ideas id appreciate them. Some photos of the flywheel and how I've installed the clutch.

 

[biggman100]

I've been searching on the internet and have come up empty handed. When i start the engine the clutch dont engage, when i push the throttle. The engines an old 21 magnum made by thunder tiger from the late 80s maybe 90s if youve got any ideas id appreciate them. Some photos of the flywheel and how I've installed the clutch.

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Clutch shoes wore out maybe? I'm not familiar with that style clutch set up, but, one thing i noticed is, how do the shoes move to engage against the clutch bell? It almost looks like the shoes are on fixed pins, and the shoes can't move outwards to engage the bell in any way. I'm more familiar with this style though: https://www.ebay.com/itm/254931318107 and dont really mess with gas or nitro RC, I'm just going by what i know about Go-Kart clutches.

EDIT: I just looked at it closer, and, what it looks like is the shoes only sit on one pin, and, as it turns, the other pin pushes the shoe out to engage the clutch bell. Could the shoes or clutch bell be glazed or oily? If so, the shoes may slide in the bell and not get enough friction to engage.

 

[cbaker65]

I've been searching on the internet and have come up empty handed. When i start the engine the clutch dont engage, when i push the throttle. The engines an old 21 magnum made by thunder tiger from the late 80s maybe 90s if youve got any ideas id appreciate them. Some photos of the flywheel and how I've installed the clutch.

View attachment 166578

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I would buy an entire clutch set up including flywheel!

 

[coldvod]

I would buy an entire clutch set up including flywheel!

I've thought about that but its an odd size. I will do research on ebay to find something similar

Clutch shoes wore out maybe? I'm not familiar with that style clutch set up, but, one thing i noticed is, how do the shoes move to engage against the clutch bell? It almost looks like the shoes are on fixed pins, and the shoes can't move outwards to engage the bell in any way. I'm more familiar with this style though: https://www.ebay.com/itm/254931318107 and dont really mess with gas or nitro RC, I'm just going by what i know about Go-Kart clutches.

EDIT: I just looked at it closer, and, what it looks like is the shoes only sit on one pin, and, as it turns, the other pin pushes the shoe out to engage the clutch bell. Could the shoes or clutch bell be glazed or oily? If so, the shoes may slide in the bell and not get enough friction to engage.

i may have put some oil of some sort after taking it off though i remember when i originally took it had a compound on it. i might have to find a substitute for it

 

[cbaker65]

Another thing you might can do ,is to cut a groove into the clutch shoes for
a tiny spring to fit in an remove 2 of the pins off the flywheel!..

 

[coldvod]

Another thing you might can do ,is to cut a groove into the clutch shoes for
a tiny spring to fit in an remove 2 of the pins off the flywheel!..

ill try that before i buy something thanks !

 

[cbaker65]

ill try that before i buy something thanks !

A bic lighter spring might work if you can bend a hook at both ends
to hook the ends together to rap around the shoes!
Look something like this!

 

[Lukedavis]

I've been searching on the internet and have come up empty handed. When i start the engine the clutch dont engage, when i push the throttle. The engines an old 21 magnum made by thunder tiger from the late 80s maybe 90s if youve got any ideas id appreciate them. Some photos of the flywheel and how I've installed the clutch.

View attachment 166578

View attachment 166579

i feel like the part that the clutch shoes are on moves in and out to engage the clutch and so forth.

 

[biggman100]

A bic lighter spring might work if you can bend a hook at both ends
to hook the ends together to rap around the shoes!
Look something like this!

All the spring does is pull the shoes away from the clutch bell at idle or low engine speeds. His problem is that the shoes don't catch the bell with any sort of force strong enough to spin the flywheel, so, either the shoes are wore out, something slick on either the shoes or bell is causing it to slip, or, the least likely option, it's a ringed clutch bell, which means there is a ring bonded to the inside of the clutch bell that came loose. Another thought I had though, are the shoes upside down? In other words, what happens if you swap which pin on the flywheel the shoes are on? Are the shoes mounted to the flywheel using the right holes?

 

[cbaker65]

Sure glad they changed that design an they no longer exist!..

 

[biggman100]

Sure glad they changed that design an they no longer exist!..

They got the design from older Go-Karts actually. I hated that clutch set up, because it worked when it wanted to, and the slightest bit of oil or dirt, and, either the shoes were junk, or they would slip with a horrendous screech.

I've thought about that but its an odd size. I will do research on ebay to find something similar

The one I linked I think is for a .21 engine.

i may have put some oil of some sort after taking it off though i remember when i originally took it had a compound on it. i might have to find a substitute for it

If it was that non-slip coating, it's not available anymore, and I have no clue if there is an alternative.

 

[tudordewolf]

I've seen that style of clutch once before, on another vintage Thunder Tiger, a 1983 Silver Fox... I couldn't figure it out either, since the pins were "solid" and not articulated. I can only guess that the shoes are supposed to just flex outwards while the pins stay in position?

Maybe the old shoes have hardened / gone brittle, such that they're not able to do that...

Seems like a weird solution but I can't think of any other way that would work.

Thunder Tiger did use a strange flywheel arrangement on some of their engines, like they split the difference between threaded and OS-shaft engines - they use a "prop nut" spacer with a brass cone, a flywheel with a 1/4" bore, and then a clutch nut. I made my own by drilling out a 5mm flywheel to 1/4" (6.35mm), to fit a Thunder Tiger Evo-12 engine.

By some strange quirk of stock and supply, Redcat has some of those kinds of flywheels in stock, but on clearance... I bought one and can verify that it is "in between" the 5mm straight-bore and tapered-bored flywheels, by having a 6.35mm straight bore. It might be worth swapping one of those in and using modern, sprung clutches on it.

 

[coldvod]

I've seen that style of clutch once before, on another vintage Thunder Tiger, a 1983 Silver Fox... I couldn't figure it out either, since the pins were "solid" and not articulated. I can only guess that the shoes are supposed to just flex outwards while the pins stay in position?

Maybe the old shoes have hardened / gone brittle, such that they're not able to do that...

Seems like a weird solution but I can't think of any other way that would work.

Thunder Tiger did use a strange flywheel arrangement on some of their engines, like they split the difference between threaded and OS-shaft engines - they use a "prop nut" spacer with a brass cone, a flywheel with a 1/4" bore, and then a clutch nut. I made my own by drilling out a 5mm flywheel to 1/4" (6.35mm), to fit a Thunder Tiger Evo-12 engine.

By some strange quirk of stock and supply, Redcat has some of those kinds of flywheels in stock, but on clearance... I bought one and can verify that it is "in between" the 5mm straight-bore and tapered-bored flywheels, by having a 6.35mm straight bore. It might be worth swapping one of those in and using modern, sprung clutches on it.

Thats a great idea thanks! I've got an 21 from redcat engine lying around going to give it a try though I've lost my clutch for it

i feel like the part that the clutch shoes are on moves in and out to engage the clutch and so forth.

I've tried the other methods and thid is the only way the bell fits sadly

 

[biggman100]

Thats a great idea thanks! I've got an 21 from redcat engine lying around going to give it a try though I've lost my clutch for it

I've tried the other methods and thid is the only way the bell fits sadly

I actually found a video of this clutch set up:

and, according to the video, there is supposed to be a liner in the clutch bell itself. A couple people in the comments of that video said to just remove the center pins, and that way the shoes will swing out towards the clutch bell and engage. I'm not saying it will work, but, it may be worth a shot, as long as you are easy on it at first, so nothing gets ruined.

 

[alfredwong2003]

I have never seen one like that before, but I think the theory is that there should be some wiggle room in the center holes of the clutch pads, so when they spin, it can engage the bell. But this kind of setup will eventually wear the pads and you may need to drill bigger holes so there is more movement.