Parking brake issues with new rear calipers

[jcp]

After a brake system overhaul, I've been having a really hard time getting my parking brake to work normally. I replaced both rear calipers with rebuilt units from Centric (purchased from RockAuto), and bought a new parking brake cable from IAP, since it had snapped on one side.

I followed the handbrake adjustment procedure (pull up 2 clicks then tighten adjustment nut until wheel won't move), but the cable has to be EXTREMELY tight for the piston to move and the pads to compress. There's roughly an inch of movement in the cable lever on my calipers, but when I squeeze it by hand, the piston doesn't move at all. There's only a slight amount of stopping power when enough tension is applied to move it an extra fraction of an inch.

I've even tried adjusting to the point where the handbrake lever won't even pull up. At this point, the wheels take some muscle to spin by hand, but the car can still easily roll down a moderate incline.

My question is: were these calipers rebuilt incorrectly? As far as I can tell, they stop the wheel fine normally with hydraulic pressure. What could possibly be causing them to be unresponsive to the handbrake tension?

[azruss]

first of all, the hand brakes are just good enough to keep the car from rolling on a 1% grade If you jacked up the car and let the rear axle dangle, you have locked the compensator and that will cause greif during adjustment. try jacking from the pumpkin or the bottom of the rear shocks.

[narfire]

I guess they are still on the car eh.
Before I installed mine after I overhauled them myself , I had them in a vice and activated the mechanical lever and watch to make sure the piston moved.
Installed and like you, fiddled with them until the set-up and tension stopped the car. I still should tighten a couple of turns.
I recall they did not move out a whole lot as a brake application got the piston close to the disk and the handbrake did the rest. My memory is rusty, but I thought the piston moved between maybe 1/8-1/4 inch max on mine with the hand brake.
If the brake works with the pedal, sounds like you have the piston right side up. (line on the top side of the slot)

[Exit98]

jcp,

Hey I'm no expert, but I've adjusted mine and others without much problem. And my emergency brake hold fine on inclines (I still leave it in gear though just in case).

Anyway, my book says 3 clicks is the right number. Focus on the simple stuff first before you start pulling apart calipers. Recheck how the cable attachs to the calipers to make sure it seems to be fitted correctly on both sides. As you know the cable sheath fits onto the back of the caliper lever and the cable itself attaches to the front. Is the cable routed correctly passed the exhaust and by the trailing arms?

Try a different adjustment technique. Leave the emergency brake off. Get under the car (safely) and release the 2 nuts so you have some slack. Pull up the handbrake handle, does everything seem to work smoothly? If so, release it and get back underneith (a partner helps) and tighten up the adjusting nut. As it begins to tighten up have the assitant start checking how many clicks it takes then release it and continue until you get 3 to 4 clicks to bring it tight. See if that helps.

Good luck.

[jcp]

Thanks for the replies. As far as the cable adjustment goes, I think I've done just about everything possible. The cable fits into the caliper properly, and I think it functions as it should (at least in terms of how it's installed).

On these rebuilt calipers, I can't seem to find a line/notch on the piston, so I'm not sure which way it should face. My pads have a small nub on the backs so the notch has to be perpendicular to the caliper body (that is, horizontal when installed). They seemed to bleed OK when I had the pumpkin jacked up. Would piston orientation even affect parking brake operation though?

[So Cal Mark]

the hydraulic part can work fine but if the pieces of the ebrake mechanisim are assembled incorrectly the piston won't apply with enough force to hold the car with the parking brake. We've gotten several rebuilt calipers that were assembled incorrectly. It's easier to assemble them incorrectly than it is to do it the right way

[narfire]

Would piston orientation even affect parking brake operation though?

Nope it does not. It sounds like, as I mentioned, that the pistons are orientated correctly. There is a thin "scored" line just above the slot. It has to be up or towards the bleed valve or bleeding evidently won't happen. Not an issue with the mechanicals. Just a heads up if you had to take the calipers off and re-install.
I believe Mark likely has it. They are finicky to put back together and are , as mentioned, easy to muck up the assembly.
Chris

[jcp]

Thanks Mark and Chris. I just ordered the rubber seal kit so this weekend I'll try to rebuild these correctly. I've seen the one mirafiori guide, but are there any other resources on proper assembly? I'll be referencing the diagram in the shop manual, and I'll probably take it very slow and take pictures along the way.

[Weelan]

Along the lines of caliper assembling, I got the pistons to start screwing down on the peg, but they stopped now and won't budge... one of the pistons seems flush for the larger diameter compared to the caliper sleeve, but the slot is not aligned to be horizontal when installed. The other piston is still about 1/8" from being flush from the larger diameter of the piston to the caliper's sleeve. It won't budge... I don't really know what to do now... Help?

[jcp]

I've been ignoring this problem lately as I've been trying to enjoy the last few days of convertible weather, so sorry for the lack of updates.

One question though: the piston moves about 1-2mm when I push the lever by hand. Could it be that I simply have the piston screwed in too far where it won't compress the pads enough? I was thinking of letting the piston out to a point where the assembly can barely slip over the rotor. Will this help with the parking brake?