BRAKES
Title: Rear
brake bleeding woes
It worked all right before I had the master cylinder resleeved to a smaller diameter bore for better braking.
PghMike
Post by Kurt on Feb 25, 2007, 3:12am
Did you bench bleed the master cylinder before you installed it?
Post by 62trvler on Feb 25, 2007, 2:21pm
How do you do this?? I'm new to this term.
Post by Kurt on Feb 25, 2007, 6:13pm
I copied this from a website that has information on bleeding brakes.......easier than me typing forever......
If you are replacing the brake master cylinder, be sure to bench bleed the master cylinder before installing it. Some brake master cylinders come with a master cylinder bench bleeding kit to make bench bleeding the master cylinder easier, purchase a bench bleeding kit if yours did not with one. The master cylinder bench bleeding kit consists of adaptor fittings that screw into the master cylinder and tubes that attach to the fittings (the master cylinder bench bleeding kit we sell has aluminum fittings that fit better and are made to last, unlike the plastic fittings included with some master cylinders). Place the brake master cylinder in a vise and attach the brake master cylinder bleeding kit routing the tubes into the master cylinder reservoir. While keeping the tubes submerged in brake fluid, push the master cylinder piston in repeatedly using a screwdriver. You will see air traveling through the tubes into the reservoir by keeping the tubes in the fluid you are preventing air from re-entering the master cylinder when the piston returns. Once there are no more air bubbles going through the tubes you are ready to install the master cylinder on the vehicle. **Caution brake fluid can damage paint, if you get brake fluid on the car, remove it quickly with soap and water** After installing the master cylinder you will need an assistant to pump the brakes. Have them apply brake pedal pressure while you slightly loosen each brake line at the master cylinder to bleed the remaining air from the system. Repeat this process until there is no more air coming out and the pedal feels normal. In some cases you may need to bleed the brakes at the wheels also. You can bleed brakes at the wheels with your assistant or use a vacuum brake bleeder
Post by Cotten on Feb 25, 2007, 6:45pm
Or get a pump-style oiling can and pump the fluid backwards from the cylinder to the master.
...Cotten
Post by Kurt on Feb 25, 2007, 7:50pm
When I do it that way Cotten, I use a really big hospital syringe.....don't know where I got it, but it works great and is big enough to bleed auto brakes......
Post by stroker on Mar 4, 2007, 5:03am
some PM calipers need to be fliped over to bleed with brake pedal. check to see if bleed screw is on top if not take it off and flip it over. also put a spacer between pads equal to disc thickness
Post by pghmike on Mar 5, 2007, 1:16am
When I tried to bench bleed it, I expected a healthy stream of brake fluid to shoot out of the short curved brakeline I attached, but only about 1-2 drops per pedal push came out. So it appears that the unit's not pumping out the fluid instead of air in the line (for now). A tiny amount of fluid seeps out at the pedal end.
The leak may be due to the placement of the o-ring on my rebuild kit's piston not correctly positioned in relation to the two tiny holes in the bottom of the new sleeve. For authenticity's sake I'm using this old-style master cylinder resleeved instead of one of the newer square styles. I'll look at both sets of holes again tomarrow. I would appreciate the travel sequence of fluid from the bowl and how if's related to all three holes.
Thanks to all who've emailed in with suggestions.
Mike in Pittsburgh
