brake question from a newbie..., my search didn't answer my question.. Options

[red914]

first i will try to describe the problem in a meaningful way. i have newer calipers in the rear (from PO). the right rear has developed a drag problem. it does not seem to release, and hence, drags, heats up, etc. I have tried to decipher the haynes manual, but to no good result. does the brake proportioning valve have anything to do with this? how does one adjust the venting? i messed with that a bit, but the allen screw and lock nut allwo brake fluid to seep out of from arond them when screwed in, and only seem to tighten up when run out. none of which, by the way, effects the drag at all.

i realize this is a rambling question, but i am in over my head at this point. any knowledge out there?

[lapuwali]

The Haynes manual is actually pretty unclear on the venting gap. Or rather, they don't really explain non-intuitive way the adjusters work.

Both adjusters screw into the piston itself. The outboard one is just a simple screw with a sealing flange and an O-ring midway along. If you "tighten" it, it screws into the piston, if you loosen it, it unscrews. Note that the screw does NOT pull the piston away from the rotor, it just goes into the piston. Go far enough and O-ring no longer seals. Leakage ensues. You have to "tighten" the screw, and push the piston away from the rotor. It obviously helps greatly to pull the pads, and get the adjustment loose (pushing the pistons with a big screwdriver works), then replace the pads and use the adjusters to push the pistons towards the rotor to set the clearance. You do this on the outboard adjuster by "loosening" the screw.

The inboard adjuster works differently, in that there's a gear in there because the adjuster isn't directly in line with the screw that goes into the piston, so the loosening direction is reversed. You "tighten" this one to move the piston towards the rotor. When moving the piston back on the inboard side, you need to "loosen" the adjuster a bit (until you hear a racheting sound), then move the piston.

Note also that the dust cap over the inboard adjuster takes a 5mm Allen, while the adjusters take a4mm Allen. The inboard dust cap is NOT optional. It keeps the inboard adjuster screw in place so it won't fall out. The inboard dust cap is often stuck on well tight, and the socket head strips all too easily. If this happens, you'll need to remove the caliper to get the cap off.

If you get lots of leaking when doing this, and it doesn't stop (esp if it appears to be leaking from the e-brake arm), then you need to remove the calipers and disassemble them. An O-ring has failed on the inboard adjuster. PP has the rebuild kit you need to replace all of the seals and O-rings.

You'll also need to re-bleed the brakes after doing this.

Do I sound like someone who just rebuilt their rear calipers?