rear disks

[guys427]

need help with rear disk set up on my 80 ws6.rear self ajust dont work had the car since new,never used the park brake for 24 years ,cables aregood and move the arms but it wont hold the car thebr pedal is also a little low. i get some braking from the rear but not enough, anyone has any info. tk's guy

[Joe 1320]

There could be a couple of things...... pad thickness could be too thin, the rear discs could be worn past spec, the factory proportioning valve could be causing an improper front to rear bias, etc....tough to diagnose without hands on.

[guys427]

disk brakes

pads, rotors ,prop.valve are new.no air in lines, hand brakes don't still don't hold,calipers just don't self ajust. am i missing somethinf ?? guy

[Joe 1320]

Time to crawl under the car and check the operation of the parking brake while an assistant applies the brake. The parking brake uses a manual cable...... just don't expect lots of holding power. Disk brakes aren't known for holding power of a parking brake like drums are. The disks will be weaker.

[fastTa]

Your car required the regular use of the parking brake in order to keep the rear brakes adjusted properly. There were many cars that expereinced a failure of rear brakes and/or parking brake from people not regularly applying the parking brake when parking the car. On your car when you pull up on the parking brake lever, the cable pulls on the parking brake bracket and actuator arm, and then in turn turns this little device called an actuator screw or thrust screw within the caliper. The actuator screw is also part of an internal ratcheting system within the caliper. Whenever you set the parking brake, you turn the actuator screw, but when you realease the parking brake, it allows the ratchet part to function and set the pads at that time.

There's a balance spring on the actuator screw assembly that allows the pads to back-off from the disk a little bit before the ratchet mechanism is engaged. This must be done, otherwise full brake pressure would constantly be allowed to apply on the pads everytime the parking brake was released.

What happens is over time, the inside of the caliper gets dirty and the ratcheting mechanism no longer works like it should, especially when the parking brake is never used. The balance spring also can get weak and allow the pads to work themselves all the way out.

You can either take apart the calipers and inspect the actuator screw, balance spring, piston assembly, and 2 way check valve....or you can try to re-adjust the piston apply depth. You'll need to remove the parking brake actuator arm from the back of the caliper and any grommets or washers on the hex. Then using the nut you just removed, jam it back on the hex end by placing a wrench on the hex and then jamming the nut onto the threads. Now back the pads off by turning the jammed nut. Now apply the parking brake just until it feels firm. Now turn the jammed nut back the other way until the pads seat against the brake rotor again. Release the parking brake then turn the jammed nut about 1/3 of a turn. You may need to go more depending on how far of adjustment they are. Now get in the car again and apply the parking brake at least 30-40 times consectively. You can just hold the parking brake release and pump the p-brake pedal over and over.

How long ago did you replace the pads? Did you put the dampening springs back in?

[fastTa]

Your rear brake system should look very similar to this:

[guys427]

rear disks

pads where changed 100 mls ago or less ,don't drive it much, if the spring was there i put them back only changed the pads twice since got the car new in 80, got 102000km's on the clock, tk's for the info. i'll try to readgust like you said, the part from the jamed nut/hex if a little comfusing, at what point do i reinstal the arm guy

[fastTa]

pads where changed 100 mls ago or less ,don't drive it much, if the spring was there i put them back only changed the pads twice since got the car new in 80, got 102000km's on the clock, tk's for the info. i'll try to readgust like you said, the part from the jamed nut/hex if a little comfusing, at what point do i reinstal the arm guy

It's a little hard to describe that process without showing you. I've had to do this on a few 1st-3rd Gen's. Just make sure you back off the actuator screw enough to back off the pads some. Then turn the jammed nut(turning the actuator screw) back until the pads seat. Then you can put the actuator arm and parking brake bracket back on to do the parking brake routine.

If you do decide to remove the caliper and clean the inside, clean it with denatured alcohol really well.