I have an E body GM car (79-85 Toronado, Eldorado, Riviera) with rear disc brakes, and I have a question regarding the rear brake adjustment. I replaced the rear brake pads and adjusted the calipers. In order to ensure they are adjusted properly, the emergency brake cable arm (with the cable detached) should lock up the rear rotor by moving the arm forward 1". I got that on the passenger side, but the driver's side will not lock up with 1" of travel, it actually takes up to 2", which is too much. I moved the e-brake to lock the rotor and inserted a screw driver into the dust seal grove to lock the pad against the rotor. Then I returned it to the resting postion. I could not get it to adjust any better. I am assuming that the caliper must be bad and need to be replaced.

Any one have any thoughts before I plunk down around $100 on a rebuild?

 

Although I've never done this on your model, I believe the caliper has nothing to do with parking brake. The ebrake shoes are behind the rotor and I think your ebrake adjuster may be corroded and frozen.

This should be done with the ebrake disengaged. Take the caliper loose, remove rotor, and see what is keeping it from being adjusted. I always would adjust it so there is little clearance to slide the rotor back on even on both sides of the car. Then adjust the cable so they engage on 2 to 3 clicks of the ratchet assy in side the car.

 

That 79-85 rear disc setup is notorious for being a PITA to get right & keep that way ... tho' the exact details as to how/why escape me at the moment.

For the close to 3 yrs that I owned an 85 Toro w/RD's ... I don't think I was ever able to squeeze much more than 30 days out of them w/o the parking brake becoming useless & having a low pedal. Realistically it was probably much less time than that.

Sure made me miss my 81 Toro's standard rear drum setup.

 

The e-brake set up on these cars is part of the adjustment in keeping the brake pedal height. Believe it or not, it recommended to apply the e-brake each time you put the car in park to keep it adjusted properly. Unfortunately, the one caliper is not adjusting tightly against the rotor.

 

I researched your system and have never worked on those before. Apparently they are very problematic. There is a spring that causes a ratcheting effect in there that allows the caliper to adjust with the ebrake. The caliper needs to come apart. I can't find a parts breakdown, I would assume it would be in the chassis manual.

 

Yea, I wish it had drum brakes on the back, it would be a lot better. I am going to take the caliper apart to see where the issue is. I was just checking to see if anyone here ran into this issue and how you fixed it.

 

Years ago I had a 79 Cadillac Brougham and a 79 Trans Am that both used this design rear discs. I had all the problems described in this post even after rebuilding. I found out the key was to replace the ratcheting piston assembly with NEW parts, never rebuilt. Once I did that both cars worked perfectly. And yes, you do have to use the parking brake regularly to keep them adjusted. The only problem today is new parts may be hard to find.