rear brake question

[jimsey]

Hello all;
I am having a problem with the rear brakes on a 78 gs 1000. the rear caliper does not fully release, the more you pump the harder the brakes apply. you can still turn the rear wheel but it gets very hot. the only way to release the caliper is to crack any one of the bleeder screws. I've rebuilt the caliper and master cylinder. in the master cylinder body there are two holes one goes right trhough the body into the master cylinder and the other is a blind hole which does not go through the body ( or should it ).... the manual does not show a port where the blind hole is. I cannot see how the fluid will return to the resevoir. the check valve looks as though it will only retun fluid into the top of the master cylinder body and not the resevoir. I am stumped here.... Does anyone out there know what the problem could be????? P.S I have thoroughly bled the whole circuit several times and the problem still exists.

[GregT]

Both holes should reach the bore of the master cylinder. the symptoms are typical of the second hole being blocked and pressure not releasing.

[crumbug]

Hey,

Rear brake not releasing. This is my first post so hope I don't do it wrong. I am in the process of resurrecting my 79 GS1000 With spoke wheels from a 17 year sleep. I have owned the bike since new. It has 49750 great fun miles. When I put it to sleep I drained the carbs removed and drained the gas tank and completely filled the motor with oil until it was coming out the breather in the valve cover. Every few months I pumped oil through it by connecting a Chevy v8 oil pump to a remote oil filter and into the oil pressure connection on the right side of the engine and the suction hose into the oil fill hole. Of course I had to make adapters to connect the hoses and used a electric drill to run the pump. Probably overkill but I did not want my baby to rust up. Now to the reason for this post. As part of this process I have rebuilt the calipers with new seals, boots and a couple of new pistons that where pitted. I cleaned the master cylinders but did not replace any parts in them. I also made my own stainless brake lines. The front went well and all is working fine. The back however would not release after using it a few times. Each time the brake was used it got tighter and tighter. Luckily I saw this post because I was not aware that there was a small hole in the cylinder for the fluid to release. This is not shown in the factory service manual that I have. The strange thing is that when I took the cylinder apart to check the hole it appeared to be open. I could see light coming in. I stuck a wire through it to be sure and blew it out good with air. Put it all back together and now it is working fine. So as GregT brought to our attention be sure to check that tiny little hole.

[cowboyup3371]

Crumbug, this is a good reminder for others but the thread is 12 years old and I doubt person is even still active.

[Rob S.]

Crumbug, this is a good reminder for others but the thread is 12 years old and I doubt person is even still active.

No, "Guest" still checks in from time to time.