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Clutch Liner replacement made easy

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Clutch Liner replacement made easy

Old 07-31-2017, 01:50 PM
  #26  
fyrstormer
 
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Yeeeah, I figured that much out. But what purpose does the liner serve? Other types of nitro RCs have clutch shoes that contact the clutch bell directly, with no liner between them. Why do helis have clutch bell liners?
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jnayjaso (04-05-2020)
Old 10-25-2018, 08:13 PM
  #27  
so65imp3s3s
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Originally Posted by fyrstormer View Post
Yeeeah, I figured that much out. But what purpose does the liner serve? Other types of nitro RCs have clutch shoes that contact the clutch bell directly, with no liner between them. Why do helis have clutch bell liners?
Wow! This is an old thread!
Anyways; With 1/10-1/8 RC stuff (mostly),you have composite(hi-temp plastic/artificial asbestos/plain old silica sand) or aluminum clutch shoes being spun up against the inside of a steel(mostly) or hardened aluminum alloy clutch bell. This does two things: 1) It allows a sacrificial material(the shoes) to wear down without destroying the clutch bell itself, therefore only the shoes need replacing over time. And 2) It also allows the quick release of the shoes when you let off the throttle, allowing the vehicle to come to a stop without killing the engine.

Now,with nitro helis; The object of the game is spin the engine up to speed and maintain that speed by creating a positive centrifugal/friction force temporarily locking the clutch drum to the clutchbell with no slippage. Hence the lining of the clutchbell with the liner which is a softer/pliable version of the composite shoes mentioned above.

Please don't quote me on any of this,as I only am making an educated guess based on a lot of years of owning a bunch(7 so far)of used EK4 S-2's I've snagged off of eBay that use the drum/liner/bell setup this thread is pertaining to. Unfortunately,my liners are adhesive backed,are rare as hens teeth and are quite expensive if you do find them for sale. I probably should have just ponied up the $35 bucks plus shipping two years ago when some douchebags' dad or uncle died and he realized some of that RC stuff in the garage/storage unit was made of gold. Oh well, that's what they make OFNA Titans and HPI Savages for; So you have something to bash when your Thunder Tiger is busted! Nitro forever!!!
Old 03-22-2020, 10:36 PM
  #28  
fyrstormer
 
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Originally Posted by so65imp3s3s View Post
Wow! This is an old thread!
Anyways; With 1/10-1/8 RC stuff (mostly),you have composite(hi-temp plastic/artificial asbestos/plain old silica sand) or aluminum clutch shoes being spun up against the inside of a steel(mostly) or hardened aluminum alloy clutch bell. This does two things: 1) It allows a sacrificial material(the shoes) to wear down without destroying the clutch bell itself, therefore only the shoes need replacing over time. And 2) It also allows the quick release of the shoes when you let off the throttle, allowing the vehicle to come to a stop without killing the engine.

Now,with nitro helis; The object of the game is spin the engine up to speed and maintain that speed by creating a positive centrifugal/friction force temporarily locking the clutch drum to the clutchbell with no slippage. Hence the lining of the clutchbell with the liner which is a softer/pliable version of the composite shoes mentioned above.

Please don't quote me on any of this,as I only am making an educated guess based on a lot of years of owning a bunch(7 so far)of used EK4 S-2's I've snagged off of eBay that use the drum/liner/bell setup this thread is pertaining to. Unfortunately,my liners are adhesive backed,are rare as hens teeth and are quite expensive if you do find them for sale. I probably should have just ponied up the $35 bucks plus shipping two years ago when some douchebags' dad or uncle died and he realized some of that RC stuff in the garage/storage unit was made of gold. Oh well, that's what they make OFNA Titans and HPI Savages for; So you have something to bash when your Thunder Tiger is busted! Nitro forever!!!
I just saw your reply. Thanks for replying.

With RC cars and trucks, the clutch shoes don't actually let-go until the vehicle coasts down to a speed where the transmission is spinning near the engine's idle RPM. The shoes in a RC car/truck clutch are designed to drag when accelerating (i.e. the shoes trail behind the pivot-pins); a side-effect of this is the clutch shoes jam into place a little bit when the vehicle starts coasting, because this reverses the driveline torque as kinetic energy starts being transferred from the wheels, through the transmission, and back into the engine. At least, that's how trailing-shoe centrifugal clutches work; there is a different design called "Centax", where a single ring-shaped clutch shoe is pressed forward against a conical clutch bell; I haven't operated one of those clutches myself so it's possible they might let-go the instant the driver releases the throttle, regardless of the vehicle's speed.

After spending a few years occasionally contemplating the design of helicopter clutches, it looks to me like they are designed to function mostly like trailing-shoe centrifugal clutches, but with instant disengagement regardless of rotor speed, to allow for autorotation. Autorotation is, of course, a feature unique to helicopters, so their clutch needs are also unique.

You could probably get away with making your own clutch liners from a roll of automotive gasket material, though I couldn't say whether the fiber-only material or the rubberized-fiber material would be better.
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jnayjaso (04-05-2020)
Old 05-15-2020, 06:37 AM
  #29  
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Since it's been updated in 2020, I'll jump in as well. I just acquired a very nice Raptor 90 SE last week and currently setting it up. It's got a YS 91 ST
How often should I change the liner? Apparently this heli has not flown in 2yrs.
Hovered it yesterday

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