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Old 09-15-2011, 11:19 AM
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Pilotgeek Pilotgeek is offline
Motorized Bicycle Elite Member
Join Date: Apr 2011
Location: Green Bay, WI
Posts: 403
Default Re: semi metallic clutch pucks

Originally Posted by happycheapskate View Post
Maybe the rubber degraded, or maybe the clutch actually slips some when you take off or hit bumps.

If you use harder pads, will they slip more on the brass plate? Will the brass plate wear out a lot faster?

What is that cartoon guy from? I think I have seen it somewhere on internet joke pages.
The clutch is intended to slip a bit when you take off or hit bumps. That's why it's a clutch and not a hard interlocking mechanism. It breaks a lot less stuff that way.

I've tried compressed fiber/metal compounds, hard rubber compounds, soft rubber compounds, and aluminum pucks. The hard rubber or fiber pucks work the best, with the soft rubber being the worst. You don't want the pucks to be compressible, or they won't hook up because they want to compress further rather than grip (along with making a horrible squawking). Aside from that, it's mostly the coefficient of friction of the puck x the pressure of the plates which will determine how well it will grip. The harder materials tend to have a lower kinetic friction, but high static friction, so they will grab slowly, but once they grab, they're solid. This feels very smooth while engaging the clutch, as well.

The plates are typically mild steel. Something /too/ hard may make the plates wear faster, but it's almost negligible for most materials. The aluminum pucks would probably cause noticeable wear after a while, but they aren't a good puck material anyways.
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