help! - stuck right rear caliper piston

[richardu]

I haven't posted in a while. Hope all of you in the Unique family are enjoying a great Easter Day! Now that the Chicagoland winter seems to be behind me, I decide to get my car ready for some spring driving. I started changing fluids and decided to do a little investigation on my questionable braking performance and rear brake "groan" I've listened to the last two years. It turns out the right rear (inner) caliper piston has seized up and will not budge. I tried freeing it up with brake cleaning fluid with the caliper mounted. I energized the system and applied peddle pressure and it would not move. Not wanting to drive the car in this condition, I decided to remove the caliper (from underneath the car). After three hours of work, I finally got it off the car (one of the toughest jobs I've ever done on my car). Now that I have the caliper on my workbench, I'm looking for some guidance on how to free up the stuck piston. How do I do this? Or should I simply take it to a brake shop to have them work on it?
Additionally, once I get the caliper fixed, does anyone have a technique for remounting the caliper (from underneath the car). I'm expecting it to be a real bear aligning the mounting bolts with the holes in the mounting bracket "blind" with no space for my fingers to reach the bolts to start them?

Thanks
Dick Untch

[GREENHOUSE]

You might try a C clamp to press the piston in and use air line to work the piston out be carfull not to shoot the piston across the room. And the breaks are a pain to get to even when the rear end is out of the car. Take your time and a couple of breaks and you will be back on the road.
Mike

[wlewis]

Is there any kind of recommended periodic servicing to prevent a piston from freezing up?

[richardu]

Thanks Mike! I will try the clamp and air line approach. I'll let you know the how things turn out.

I'm wondering how I can keep this seizing problem from happening again?

My rear calipers leak at the bleeders, and the leaking brake fluid may be the source of the piston seizing problem. The leak is small but the corrosive action from just a small leak is significant. Do you (or anybody else) have any recommendations on how to keep the bleeders from leaking? The only thing I can think of is silicone sealant on the threads, but it doesn't seem right to me.

I'd appreciate your help.

Dick Untch

[GREENHOUSE]

Thread seal will not work its not that kind of leak you need to try new bleeder screws. Napa should carry them. The only way to keep the brakes from freezing up is to keep the fluid moving by driving the car. just starting the car helps with alot of the problems but you still need to move fluids by pressing on the clutch and brake pedals. Even in my other cars if you don't run them you spend more money repairing them from them sitting and freezing up. Had to replace all the calipers on a porsche that set for a year and a half from the same problem.
Mike

[spd4me]

Dick - My knuckles feel for you. My first cobra, I had to remove the rear rotor, interaxle and calipers. Hardest part was getting the nuts off that hold on the rotor. You need to make sure you use the self locking metal nuts when you put it back on. There are apparently two types. A low profile and a taller one. I went with the taller to get more thread contact on the bolt. You have to be carefull of the rubber boots on the pistons. I got most of my parts from a place called "Terry's Jaguar Parts" in Benton IL. I sent one of the caliper to them to rebuild. Phone numbers 618-439-4444 and 618-439-4990. On my new cobra I replaced the 2 bolts that hold the caliper to the rear with some bolts I modified to get a longer shoulder (nonthreaded part of bolt) and longer threads that would go all the way through the support bracket. It took about 30 mins to get the bolt holes lines up to finger thread in the bolts.
Bob

[richardu]

Thanks for the useful info Mike and Bob. I suspect the boots are shot (from my leaking bleeders). Once I get the pistons out, I'll see what they look like. I will probably be contacting Terry's Jaguar Parts in Benton, IL.

Thanks again,
Dick

[RJacobsen]

I picked up rebuilt calipers at CarQuest auto for my car thay also had rebuild seal kits

[pgermond]

I feel your pain - I had the unpleasant experience of removing the inboard rear caliper on my car. Not at the top of my list of things to repeat.