I have put a lovely set of WR rearsets on my NC30, a quick fiddle with the master cylinder to get it all to fit and added a HRC reservoir. I then went for a spin and when I got home found the rear brake was stuck on, there was no travel in the pedal, the disk was almost glowing and I could hardly move the bike it was that stuck.

So I took everything off, cleaned the calliper, fitted a master cylinder repair kit and re-bled the system, went out again today and it did exactly the same. Is it new master cylinder time or is it something else.

help

Pete

I would check the pedal is set correctly and works normally when its cold, replace the fluid, if its still doing it replace the seals.

Do the WR rearsets have a return spring for the pedal? if not use a rubber band. I take it you have checked the caliper piston moves freely? ie, not binding

Thanks for the quick response guys.

The calliper appears fine, when I get back the system is locked out but once I bleed a pedal stroke of fluid out of the calliper the wheel moves fine so I assume the calliper is moving around OK.

The pedal does not have a return spring but seems to return fine under the master cylinder pressure but I will try the elastic band and see what happens. I have replaced the master cylinder internals with a new kit but am wondering if I may have damaged the cylinder somehow. There is no visible damage but I cant work out how the excess fluid is getting into the system.

Have you filled the resevoir too much?

Too much fluid in there, combined with the fact that fluid expands when it gets warm means you can jam the rear brake on.

Best to have the level inbetween min-max.

Neosophist wrote:Have you filled the resevoir too much?

Too much fluid in there, combined with the fact that fluid expands when it gets warm means you can jam the rear brake on.

Best to have the level inbetween min-max.

This ^^

Could be over filled, I have put the HRC jobby on and its about 3/4 full, will try the old reservoir and see if that makes a difference.

pete

also, most times in the MC in the port where the fluid enters there is a larger hole and a very small bleed hole. that small hole can get clogged and will result in dragging or sticking on when heated as the fluid cant bleed back into the reservoir. check that in the current MC before swapping. A smallest guitar string or strand from an electrical wire will work.

If when using your new rearsets you may have tightened the bolt at the bottom of the master cylinder where it fixes to the pivot of the back of the brake lever.
If it's tight it may not allow the master cylinder to fully release.

Cheers for the help guys I have stripped and cleaned the master cylinder, cleaned the bleed hole, 1/2 filled the reservoir and checked all the bolts. Rode in this morning and it is now fine.

Pete