troubleshooting brake play?

[grahamkissack]

I just finished rebuilding all my calipers, replacing all the pads, replacing the hoses and then bleeding the system. I ended up vacuum bleeding the system three times to ensure no old fluid or air.

The brake pedal feels pretty hard once its engaged the brakes but I am surprised how far it travels before I start to get to that point. I swear its at least 3" of pedal travel but I start to get feedback. Is this correct? Are there any adjustment points elsewhere in the pedal assembly? Thoughts?

Next weekend's job...tensioner upgrade.

Thanks, Graham

[Early_S_Man]

Graham,

The pads need to be very, very tight in the caliper ... ZERO clearance between pistons and calipers!

The following distant past thread explains the same problem and easy fix ..

Brakes

[Jim Chambers]

The rod from the pedal to the m. cylinder is adjustable. Check Haynes, but my memory says there should be just a perceptable amount of free play before it contacts the m.c. piston. You can feel it by hand. 17mm open end to loosen the lock nut, then turn the rod.
I had the same problem. Adjusting rod helped some. Then I realized that my pedal bushings were gone and there was a lot of slop. Re-bushed the pedal cluster and things improved more.

[conquest]

I found pedal travel increased slightly when I rebuilt calipers a couple weeks ago. My theory is that before rebuilding, the seals in the calipers were very stiff and didn't allow much in-out movement of the piston before the seals repositioned themselves. After rebuilding, the new, pliable seals accommodate more in-out movement of the piston. Thus the piston returns further into the caliper at rest, requiring more pedal travel to move fluid through the system. Of course it's just a theory, and if anyone has a more plausible one, I'm listening.

I currently measure 4" of brake pedal travel, and my brakes are excellent (thoroughly tested them at the track last weekend). The issue from my perspective, however, is not pedal travel, but rather the height of the brake pedal relative to the gas pedal (under heavy braking) because it impacts your ability to heal-toe (which is more correctly a roll of the foot). I found that when I adjusted the brake pedal height for easier heal-toe, the resting position of the brake pedal also changed ... meaning, no decrease in overall pedal travel. I was worried that it would mean I had to lift my foot too far up to get on the brake, potentially misjudging the necessary height under a panic situation (OK, I admit ... it also looked goofy relative to the much lower clutch pedal height). So, I adjusted the brake pedal back to near its original position and adjusted the gas pedal to achieve optimal relative heights for heel-toe.

One more tip ... a couple washers under the right gas pedal bolt will tilt the gas pedal closer to the brake and make heel-toe much easier.

Hope that helps.

[Jdub]

Lots in the archive if you perform a search.

Right now the pads are not conformed to the disks, and there may be play between the pad and disk should you not have removed it all during pad installation.

Consider that, right now, the pad is new and thus cannot be perfectly square to the disk (that happens only after friction and time). This means it must bend somehow to distort to the disk face: that is distance and you feel it at the pedal. Once the pads wear to the disk face you will have removed most all of the slop at those points.

I like to push the caliper pucks in, with the nipple open, just enough to sqeeze the pad in with effort. That ensures no play. Then I cinch up the nipple. That's the best way to get the least play at the pedal to start.

John