I got a pair of stainless pistons and seal kits for the rear of my 1991 TDM 850 from Wemoto.fr last month. Can't fault the service.
A couple of months previous to that I'd stripped the rear caliper, cleaned it in an ultrasonic bath, and rebuilt it with a set of dodgy caliper seals. I can't remember where I got them from ?
However, after a few hundred kilometers, I noticed that the rear brake was dragging somewhat..... and getting worse !
Hence the new pistons and seals from Wemoto.
Stripped the caliper again and double checked that the seal groove was thoroughly cleaned and proceeded to rebuild one side of the caliper. No problems !
The other side was a nightmare ! I had to resort to all sorts of stunts to get the bloody piston out. I'm still in the Memsahib's bad books for using her oven. Eventually I mangled the damn thing out. The piston is now totally unusable now. Again, meticulously checked the groove and bore.... perfect, and went to fit the new piston.
No Chance ! Even with the seals out it wouldn't fit.
I was in a bit of a mood so I rebuilt that side of the caliper with the good original piston, fitted, bled and no more binding after a good few hundred kilometers.
When I saw this post I decided to investigate a bit, here's the pics....
[attachment=13909:Original TDM 850 piston.jpg]
[attachment=13910:Wemoto stainless piston.jpg]
Not much more than a ba' hair, but enough to stop it fitting...... I should really get back to Wemoto about it ?