The bike is a 1990 GL1500 SE. I have rebuilt the master cylinder, replaced the steel line with SS line, rebuilt the caliper. The caliper has new OEM seals and pistons. The pins are greased and it is free to slide side way as it should.
Because I have a side car, I disconnected front and rear brake. The main port now goes to the rear brake and the pressure regulated port goes to the side car.
The system was bleed with my vacuum pump and it all appears to work fine in the shop. Went for a test ride and not long after the rear wheel was locked solid. The pedal was as hard as rock. I relief the pressure at the quick connect for the sidecar brake line and the rear brake let go immediately. I let every thing cool down somewhat and returned home without touching the rear brake. I bleed the system again and all went well for a couple of weeks. Then last weekend, it did it again! Same deal, relief the pressure and go back home.
I am sure that I cleaned the pressure relief hole in the master cylinder but I can’t understand why it build pressure in the line like that... When I bleed the line, I can see the level go down in the reservoir which tend to indicate that it is opened!
If anyone has any suggestions I would really appreciate it. I am trying not to have to remove the master again... even if it looks like it is going to happen
