Stuck brake caliper piston

MDarius · 03-19-07, 11:54 AM

Hey! I searched and didn't find the right details. I was told by a trusted mechanic that the brake caliper piston on the PS front is sticking intermittently. I have noticed some issues while driving and believe it, as well as noting excessive wear on the PS rotor and not on the DS rotor. I am preparing to do the axle seals, birfields, upgrae to 100 series brakes, etc. and have my parts list for this job from CDan. When upgrading to the 100 series pads and rotors the calipers don't need to be replaced unless there is a functional reason to do so. I am not sure if I need to replace the entire caliper, or parts of the caliper, or what. I have never been good at brakes (feel free to mock me openly), and I don't know all the parts that go in to the brakes to know what to replace.

So, can someone counsel me on what parts I need to order to fix my sticking piston? I assume I should replace both sides if I am replacing one. Thanks!

p8nt · 03-19-07, 01:05 PM

There is a rebuild kit available for your situation, but the general consensus is that rebuilding is such a pain your better off just getting a new caliper. My front DS failed in late December and I opted for a new unit.

EricG · 03-19-07, 01:40 PM

Yep, my DS stuck last fall - I just replaced both calipers & rotors while doing the already scheduled birf job. Replacing the calipers was easy, though ther bolts were a bit of a bitch - use lots of penetrating oil and a *BIG* breaker bar. Nothing particularly tricky about it.

I think I got my calipers for about $60/each + core from checker.

jonheld · 03-19-07, 01:40 PM

I rebuilt both calipers on my 91 some years ago. I had at 3 stuck pistons between the pair. Getting them unstuck was a bit of a slow process, but once you have the rebuild kit and pistons and cylinder walls are nice and clean and lubed, the rebuild is easy. The OEM kit doesn't come with enough grease to my liking so I used Amsoil moly for one side.

I used steel wool to clean up the pistons and cylinders, rinsed the whole assembly with solvent and blew the caliper out with air. I didn't split the halves of the caliper as I didn't see the need to go any further.

Been working fine for years.

Scamper · 03-19-07, 04:00 PM

Quote:

Originally Posted by jonheld

The OEM kit doesn't come with enough grease to my liking so I used Amsoil moly for one side.

The grease they provide is a special grease made for brakes. You can buy synthetic brake grease at Autozone or NAPA in small bottles. I would not have used moly grease there...

96Bruiser · 03-19-07, 04:03 PM

My front calipers were sticking and would not retract far enough to install the new 100 series pads. I purchased a rebuild kit from Cdan for like $30 some bucks, I'm very happy with the results. Use compressed air to force the pistons out, clean them up, install new gaskets. a very easy task. Just keep your fingers away from the pistons when your removing them, once you see one come out you will understand! Good luck. Do it! Do it! Do it!

LX_TREME · 03-19-07, 05:53 PM

Quote:

Originally Posted by jonheld

I used steel wool to clean up the pistons and cylinders, rinsed the whole assembly with solvent and blew the caliper out with air. I didn't split the halves of the caliper as I didn't see the need to go any further.

Been working fine for years.

Same as this guy in Japan ->lot's pic inside.

Pete483 · 03-19-07, 08:41 PM

I had three stuck pistons on my front calipers. When 120 psi wouldn't unstick them, I bought some reman. calipers at Advance or one of those places for pretty cheap. Rebuilt the rear though. They have worked great since, as much due to not having 3 stuck calipers as to the fact that I painted them blue as well. They look racy.

cruiserdan · 03-19-07, 08:48 PM

Quote:

Originally Posted by jonheld

I I didn't split the halves of the caliper as I didn't see the need to go any further.

That's a good thing and it bears repeating.

Do not split the calipers in half. They are not supposed to be split, the seals are not serviced and I do not know of anyone who has been able to find anything that will replace them.

jonheld · 03-20-07, 09:56 AM

Quote:

Originally Posted by Scamper

The grease they provide is a special grease made for brakes. You can buy synthetic brake grease at Autozone or NAPA in small bottles. I would not have used moly grease there...

This is not the case anymore. There was a time when certain greases would attack the soft rubber boots around the pistons. Most modern greases do not do so. I had a long discussion with an engineer at Amsoil about this and did my own testing.

The boots/pistons are still in good shape as seen at the last brake pad change. Had to be over 4 years ago.

toylndcrusr · 03-20-07, 01:02 PM

When the pistons are stuck and compressed air won't blow them out, use a grease gun. Unscrew the fitting that attach's to the Zerk fitting and the threads thread into the hole where the bleeder valve screws in. Then pump it with grease until the piston blows out.

Anytime you force brake pistons out of their bores use caution. Keep your fingers out of the way because these pistons can come out with considerable force. Same thing applies to clutch slaves cylinders and the like.

dogcatch'n · 03-20-07, 01:14 PM

Quote:

Originally Posted by p8nt

There is a rebuild kit available for your situation, but the general consensus is that rebuilding is such a pain your better off just getting a new caliper. My front DS failed in late December and I opted for a new unit.

X2........

MDarius · 03-23-07, 08:03 AM

To add alittle more knowledge to this thread, I was talking to CDan and he taught me that in '95 if your truck was built before June you can get refurb calipers for a little more than the rebuild kit. $20 total difference if you're doing both sides. If it was June or later there is no refurb available and the new calipers are MUCH more expensive. I'm a March baby, so it worked out for me.

I'm going for the refurbs as my time is worth more than $10 a side to me.