I’m having clutch (single spring) issues with a recently purchased WM20. All was fine until it started to slip and now 3rd and 4th gear are unusable. I was all set to replace the clutch with a Triumph 4 spring unit but upon stripping it this weekend it looks to be in really good condition but there are a few issues.
For some strange reason the clutch dome was not fitted and the steel plates and friction disks are oil contaminated. There are witness marks on the inside of the primary case so I guess the dome was rubbing at some point and was therefore removed. I’m sure a new cork primary gasket will cure this as the old one is rather compressed. However, can anyone confirm if modern/replacement friction disks are oil resistant and where is the best place to buy new discs?
The second issue is the number of plates. If you take a set as being a friction disk, external notch steel plate, friction disk & internal notch steel plate then I had 3 ¼ – the 4th set was missing apart from a friction disk which was cracked! I know some people reassemble minus 1 steel plate and a friction disk but could just fitting the missing plates take up the slack?
BTW the friction disks are 0.099” or 2.51mm thick on average.
Doesn’t take much oil on these to cause clutch slip...with no dome installed, I’m surprised it would work for any length of time before total slippage. A new cork primary gasket may give the needed clearance for the dome, or you can stack a new gasket on top of the old if it’s in fair condition and well-affixed, to compensate for case distortion which may be the base issue, and which would require further disassembly to resolve.
If your existing fiber plates are in reasonable shape, a good soak in brake cleaner or lacquer thinner will decontaminate them, may be no need to replace or to add the 4th plate.
