Clutch shoes material differences

[Amoeba]

It's another edition of "Amoeba needs edgumakashun". Today's topic of learnin' is clutch shoes.

I've seen hop-ups for aluminum clutch shoes and know that my current fleet are all stock plastic (or very hard rubber?). What, if any, advantages does an aluminum clutch shoe offer? If I understand the mechanics correctly, the clutch shoes flare out with cetripedal force as the flywheel spins faster and they push against the clutchbell sides. This friction moves the clutchbell and pinion, imparting movement to the gears & wheels. Am I right so far?

If so, it seems odd that a less "sticky" material like aluminum would be a better clutch shoe than a softer hard rubber or plastic. What am I missing here? Do the springs come in different tension strengths as well and how would that change things?

Thanks in advance for your knowledge guys!

 

[beason]

the aluminum as far as i know, bite harder (if that makes sense) and wear longer. there are also different types of plastic shoes.

there are different springs (for the 3 shoe clutches I've used) with different tensions. a stronger spring makes for higher rpm before engaging and better "pop" off the line.

there are also race clutches that have multiple shoe choices and adjustable spring tension.

you can even modify the shoes themselves, by cutting them down. a lighter shoe will give the same effect as a stiffer spring. more rpm to engage.

 

[Lessen]

The 'plastic' shoes you see are actually carbon. at least everything I have are carbon. Carbon shoes slip more and wear faster. I'm not very schooled in clutches either but I would guess that carbon shoes have their advantages. You also see carbon shoes in RTR vehicles mainly because of the lower cost. Carbon shoes engage smoother because they slip more which probably has it's advantages in a race setup depending on driving stle and/or track conditions.

 

[Amoeba]

So if you wanted to increase your low-end torque without a gearing change your could go with a "bitey" material like aluminum, a heavier shoe, with a softer clutch spring tension? Better/more solid engagement of clutchbell at lower RPM's...

I'm trying to think what scenarios/driving where you'd want a lighter shoe/higher rpm engagement. If it has the effect of a more gradual engagement I guess it would be ideal for drifting for a more feather-like throttle control... but how would the opposite be helpful? Is it higher strain on the mill at low RPM causing faster engine wear or something?

 

[alpinehyperlite]

You would want a tighter spring, (stiffer) it would take more RPM's to engage it, and thus BAM more torque.

 

[Lessen]

This should turn a very good discussion.

I don't thin a drifter would rely too much on the slippage of the clutch to feather the traction. I would think the feathering is done strictly in the engaged rpm range. I would also think that a drifter would want the opposite actually? a very quick clutch engagement.. the timing I'm not sure of though. Of course I'm just hypothesising so I could very well be completely wrong.

Drag racing would be a good scenario for a later engagement. Also maybe when in general course racing when there is an extreme amount of traction. A high traction scenario will allow you to really get on the gas hard without losing grip, thus allowing you to take more advantage of your available power.

I'm thinking that if track conditions are very dirty then it maybe helpful to have a clutch that engages smoother which may help against breaking traction when you are trying to get back to the throttle. This may be especially helpful if a driver is not necessarily experienced with a soft trigger finger or if that's simply not a drivers particular style.

If anybody can correct me please do. this is just stuff I'm kind of taking guesses on.

 

[Amoeba]

This should turn a very good discussion.

I don't thin a drifter would rely too much on the slippage of the clutch to feather the traction. I would think the feathering is done strictly in the engaged rpm range. I would also think that a drifter would want the opposite actually? a very quick clutch engagement.. the timing I'm not sure of though. Of course I'm just hypothesising so I could very well be completely wrong.

Drag racing would be a good scenario for a later engagement. Also maybe when in general course racing when there is an extreme amount of traction. A high traction scenario will allow you to really get on the gas hard without losing grip, thus allowing you to take more advantage of your available power.

I'm thinking that if track conditions are very dirty then it maybe helpful to have a clutch that engages smoother which may help against breaking traction when you are trying to get back to the throttle. This may be especially helpful if a driver is not necessarily experienced with a soft trigger finger or if that's simply not a drivers particular style.

If anybody can correct me please do. this is just stuff I'm kind of taking guesses on.

Hrm, good points all. We have any racers in the house that would be able to speak to this?

 

[Scrogg]

From my experience..
The stiffer the clutch spring, the later it engages...downside is the shoes wear faster due to the extra initial slippage. 1.1 mm springs are a pretty high stall. I run them on on my Jammin truggy with my .21 engine. It lets the engine get into the powerband before the weight of the truck bogs it down. More snap from a dead stop or rolling out of a corner for a double/triple. i can get around 2 gallons of use with al. shoes depending on the vehicle and gearing.
1.0 mm springs are as light as I ever choose to run. A nice strong engine with 1.0 springs hits just right and the shoes last 2-3 gallons.
I prefer to only use aluminum shoes, as they run much cooler than the carbon and teflon shoes do. Heat kills clutchbell bearings fast.
Aluminum shoes need to be deburred with a dremel or sandpaper every gallon or so.
When you install new clutch bearings you need to blow the excess grease out with a air compressor. If you do not have an air compressor like me, you can run the vehicle for a tank of fuel. Then pull the clutchbell and wipe alll the grease out of it. The grease will find it's way to the shoes and cause slippage and heat, accelerating wear and killing performance. I learned this from Avid RC's site. They are dead right, I found my clutches and bearings lasting much longer this way.
0.9mm springs are what most RTR vehicles come with, along with carbon shoes.
I hate these, they engage way too early and make setting the engine's idle speed without the clutch dragging near impossible. The Savage is a good example. Stock Traxxas clutches are worthless IMO.
M2C Racing hands down makes the best clutches in the RC industry. I have about 4gallons and counting on one of his 3 shoe clutches with 1.0 springs in my Savage. Runs cool and grabs really nice. i had one in my Revo with over 2 gallons and it still had plenty of life left when i sold it.
Dynamite max lifes and Ofna clutch shoes come next on my list.
The stock carbon shoes that come on the LST/Aftershocks are surprisingly good though. They come with 1.0 mm springs and last an easy 4 gallons or more.
Some people do tune their clutches to the surface they are running on.....slippery surfaces they use a lighter spring and vice-versa.

 

[jerry7007]

hmm i use cotton shoes...