Notchy clutch

[alexanderfoti]

As per my other thread, I pulled apart my clutch today to investigate the slipping and very notchy clutch .

Firstly, the center piece is wearing a groove in the backing plate, causing lots of metal dust, which wore the friction material away very quickly:



I replaced this with a spare cork based one and no more slipping.

The notchyness was from grooves worn into the clutch basket:



after an hour or so with a metal file, they are now completely smooth, and so is my clutch!

All the bits have been lubricated with grease when being put back together, and the clutch action is much better.

[coachgeo]

What do you suspect caused the center piece to wear away at the other's?

[alexanderfoti]

I'm not quite sure. I think it's because the support bearing is about 3 mm thicker than the backing plate, so it's pushed the assembly out a bit.

Also in normal running the oil the clutch is bathed in would was away the metal.

I will keep an eye on it. Since I have been running it there has always been a bit of metal dust

[pietenpol2002]

I do wonder about several factors that could be contributing to the problem.

1. The presence of any grease in a "dry" clutch could become the victim of centrifugal forces causing the grease to lubricate the mating surfaces in the clutch, resulting in slippage.

2. The presence of grease and/or oil in an exposed dry clutch could serve as a virtual magnet for all manner of abrasive compounds resulting in the proberbial "notchy" cluth and excessive wear.

3. Depending on the makeup of the clutch surfaces, organic compounds (ex. cork) when exposed to water can swell, resulting in both slippage and certrain drag when disengaging.

4. I wonder whether a dry lubricant would be preferable to accompany the dry clutch?

5. These questions/ponderings are partly in self-interest in that I too am building with a dry clutch.

[alexanderfoti]

Yes a large amount of oil gets flung away from the friction surfaces, but the bits I have greased aRe the splined interlocking sliding sections that make the clutch action harder.

Even though my clutch is dry, it spends a lot of its time covered in gearbox oil of some sort (the external faces anyway) which would make a dry lubricant turn into a slushy mixture.

I have not ridden this type of clutch in a wet environment before so I don't now how bad or good it's meant to be.