Brake piston stuck

[Synchromesh]

I have an '84 Carrera that I bought not long ago. Upon pre-inspection with my mechanic we saw that one of the pistons on the rear sticks.

After buying the car I took the brakes apart. Basically the right rear outer piston is frozen enough to wear out the corresponding pad to almost 0. I was able to move it with a C-clamp but obviously the pad is junk and I'll have to change all pads.

Now, the other piston appeared to be fine and the pad had about 1/2 of material left, similar to the entire other side. After doing some reading I realized that I will need to do a basic caliper rebuild as the outer piston seals were almost completely gone on both pistons.

Now my questions are: should I rebuild the other side? Do I need to do the lines too? I checked the lines, they seem relatively soft and pliable and I don't believe they were the problem as only one piston was sticking but I'm a little new to this. Thanks!

[BK911]

If it were me, at a minimum:
Replace all 4 rubber brake lines
Rebuild all 4 brake calipers

[fizeus]

Rebuild all the calipers together ... you do not want to drive a car with different brakes efficiency.
If you can't afford 4 calipers rebuild do at least 2 (rear) and leave the front for the next job.

Also carefully inspect pistons for pitting or rust ... if one caliper has rust ... all calipers are rusted and if one caliper need to be rebuilt all your caliper need to be rebuilt. (ask me how I know!!!)

While you are in there I suggest you to replace all internal caliper seals and also the flex lines even if they seems ok. They are cheap and if they fail you can't stop the car.

If you need a top quality rebuild search for PBM Performance ...

[JRSIII]

PMB Performance. Not PBM. You can purchase their rebuilt calipers through our host. Core charge applies.

[Jesse16]

I agree with John if you simply want a high quality rebuild job by a pro to consider PMB, they seem to have a process dialed in for our cars. Not a bad way to go anyway for a first rebuild if things look rough. If you plan to be a frequent track star and brake maintenance is going to be a regular DIY, then may as well learn to do it yourself. If no history, start with new rubber brake lines (not expensive) and flush the system after caliper rebuild. Rebuild kits are fairly cheap for small boxes of rubber bits, get the right ones here. You can spend days reading detailed threads but its really not difficult.

[ganun]

Just FYI , brake lines that look good outside can be almost swollen closed on the inside.
I measured the pin hole to be about 15 thousandths of an inch.

[pampadori]

Many manufactures recommend rubber brake lines be changed every 12 years. Stainless braided lines also might be worth considering.


A trick that might help for removing the seized piston - hook up a grease gun to the caliper (an adapter might be needed) and pump it out.
You can also leave the caliper hooked to the brake line but off the rotor and place it in a bucket while you pump the peddle until it pops out. Careful though, fluid will go everywhere, hence the bucket.

[Targalid]

I had a stuck rear caliper which I freed by pushing in with a C-clamp then pushed out with gentle brake pedal pressure, then repeated several times. Once the piston moved easily the rebuild was no problem.

[Otter74]

A standard grease gun fitting will screw right into the caliper - no adapter needed - and you can pump the piston out with grease.

[Synchromesh]

Thanks guys. I talked to a friend of mine who has a pair of original FRONT calipers off a '72 T he owns (he went with S brakes). Any ideas if these will fit in the back of my Carrera? Is bolt spacing the same?

As for lines, I'll probably get a braided set. No need to take chances. I'll check the fronts shortly and see if they stick at all. If not, I think I can just leave them for now.

[Porboynz]

Originally Posted by Synchromesh

Thanks guys. I talked to a friend of mine who has a pair of original FRONT calipers off a '72 T he owns (he went with S brakes). Any ideas if these will fit in the back of my Carrera? Is bolt spacing the same?

As for lines, I'll probably get a braided set. No need to take chances. I'll check the fronts shortly and see if they stick at all. If not, I think I can just leave them for now.

Fronts and rears are very different calipers. I would avoid braided stainless for street use and stick with regular DOT approved rubber hoses.

[Synchromesh]

This is a bit confusing then as some people say use braided and some people say don't. What's the general consensus? The closest this car will get to the track is the parking lot of one, it's going to be a street-only car all the way.

[fizeus]

Originally Posted by Synchromesh

The closest this car will get to the track is the parking lot of one, it's going to be a street-only car all the way.

So stay with traditional rubber hoses (ATE).
You do not need braided lines.

[pampadori]

Going from 33 year old rubber brake lines to brand new rubber brake lines will be a noticeable improvement in pedal feel. They will expand and swell much less!

Going to stainless will be an even further improvement especially under hard braking.

Here are some numbers:
To give you an idea of how firm high quality ss braided lines are, at 1000 psi of pressure the braided line that I use expanded at a rate of .07 cc/ft. The brand new dual- tightly-woven nylon braided rubber brake line I use expanded at a rate of .11 cc/ft.

At 3000 psi the SS line expanded at a rate of .11 cc/ft and the rubber line at a rate of .30 cc/ft.

As the rubber line ages, it will tend to expand more. I don't have test results from 33 year old rubber but I am sure it is much greater. especially the old rubber line that was used in most vehicles during the 70's and 80's that lacked the nylon braid.

Also, brake fluid is recommended for flush every 2 years by most manufacturers I've dealt with.