Brake damper stuck in piston.. what to do?

[JeffKay]

I was doing the brakes on my 06 C2 Cab. They probably have not been done before, the car has 34K on it. WHen I did my 996 brakes. the dampers fell out.

 

The dampers were difficult to remove and one is outright stock in the piston. They seem to have rusted together. The inside of the piston seems like surface rust or some buildup.
 

Any ideas?

Last resort is a piston rebuild kit. If so where should I get one? One vender has single piston rebuild kits… I think.

 

Thanks

Jeff

 

[1schoir]

Remove the caliper with the stuck piston and flood that piston and its bore with PB Blaster and let it set overnight.  Then, while using a C-clamp to hold the other piston on that side in place (and similarly restraining the two pistons on the other side of the caliper), use compressed air to force the stuck piston out.

 

BE VERY CAREFUL when applying the air pressure as the piston could come flying out with great force.

 

If it's still stuck, you could try to first compress the piston further into the bore with a large C-clamp before applying the air to force it out.

 

Again, I cannot overemphasize that you must be very careful when applying the air pressure.

 

Once you have the piston out you will have to examine the surface of the sides of the piston and the surface of the cylinder bore in which the piston was housed to see if they only have minor surface rust.  If so, you can polish them with FINE emery cloth with some clean brake fluid.  It will be easy to see if the surface comes out completely free of any rust stains or pitting.  

 

If necessary, you can then use the rebuild kit to replace the seals (and the pistons if the kit comes with it).

 

Regards, Maurice.

Edited August 22, 2014 by 1schoir

[Ahsai]

Maybe you can try to remove the center screw on the damper and replace it with a longer screw that you can pull while holding the piston in place with something.

[JFP in PA]

I would concur with Ahsai in soaking the part with penetrating oil and letting it sit, perhaps over night.  Worst case scenario is having to rebuild the caliper with a new piston, but this is the exception rather than the rule as they usually come out once the penetrant does its thing. 

 

This happens due to corrosion, particularly on cars that have seen salted winter roads.  Once removed, be sure to coat the parts with anti seize compound to prevent this from happening again.

[JeffKay]

Thanks for the info everyone.

 

I'm going to pop the piston out today and soak it overnight.

 

I'll post my results!

 

Jeff

[dphatch]

Am thinking you've already discovered this but, the short version of the instructions called for soaking the piston, then using the air to pop it out, not the other way round. So if you method didn't work try the methods suggested by JFP and .

[JeffKay]

Thanks for all the input.

 

I removed the piston and tapped the center for a M6 bolt. I used a socket with a fender washer and tried to draw it out, it did not budge.

 

The piston came out of the caliper easy, but the damper inside was welded in. No way of getting it out except for using a grinder.

 

I just bought a new piston and boot, put it right in.

 

One problem out of the way!

 

Thanks again.

Jeff

[Mijostyn]

al

I would concur with Ahsai in soaking the part with penetrating oil and letting it sit, perhaps over night. Worst case scenario is having to rebuild the caliper with a new piston, but this is the exception rather than the rule as they usually come out once the penetrant does its thing.

This happens due to corrosion, particularly on cars that have seen salted winter roads. Once removed, be sure to coat the parts with anti seize compound to prevent this from happening again.

JFP, to get a stuck piston out couldn't you just restrain the other three pistons with clamps and step on the brake pedal? Containing the caliper in a bucket would catch any brake fluid. Now that we happen to be on brakes, those in my C4S are just not stopping well. I changed the brake fluid and bled the calipers from both sides. If they got any better at all it was probably psychological. The front rotors and pads have only 21k miles on them, the rears are the originals. All parts are OEM Porsche. Got any ideas? Anyone? Edited September 4, 2014 by Mijostyn

[JFP in PA]

al

I would concur with Ahsai in soaking the part with penetrating oil and letting it sit, perhaps over night. Worst case scenario is having to rebuild the caliper with a new piston, but this is the exception rather than the rule as they usually come out once the penetrant does its thing.

This happens due to corrosion, particularly on cars that have seen salted winter roads. Once removed, be sure to coat the parts with anti seize compound to prevent this from happening again.

JFP, to get a stuck piston out couldn't you just restrain the other three pistons with clamps and step on the brake pedal? Containing the caliper in a bucket would catch any brake fluid. Now that we happen to be on brakes, those in my C4S are just not stopping well. I changed the brake fluid and bled the calipers from both sides. If they got any better at all it was probably psychological. The front rotors and pads have only 21k miles on them, the rears are the originals. All parts are OEM Porsche. Got any ideas? Anyone?

 

 

To me, that approach is kind of "the nuclear option".  Because of the pressure the brake hydraulic system operates at, you could easily create a projectile as well as one Hell of a mess when and if it pops out.  I would prefer pressurizing it with air so that I could control both the blow out and potential mess.

 

I'd check your front rotors for wear thickness and look at the pads and rotors to see if they are glazed on the surface.  You could also have a weakening master cylinder that is producing low pressure, which will significantly reduce braking effort.

[Mijostyn]

Thanx JFP . I've never had a stuck piston so I never had to deal with one. Experience is everything.

What do you do if the surfaces are glaze? How do you measure the pressure coming out of the master cylinder?kir

..

[JFP in PA]

Thanx JFP . I've never had a stuck piston so I never had to deal with one. Experience is everything.

What do you do if the surfaces are glaze? How do you measure the pressure coming out of the master cylinder?kir

..

 

The hydraulic system in these cars can easily generate one to two thousand PSIG of fluid pressure; using that to pop out a piston can be anything from dangerous to having brake fluid everywhere when it comes out.

 

Gazing is the transfer of brake pad material (usually the resin that bonds the pads together ) to the rotor surface and then often back onto the pads themselves.  Glazing can often be removed by lightly sanding the pads and buffing the rotors:

 

 

If the rotors are very glazed, a light cut might be in order if they have enough meat left.

 

Brake system pressure is measured by attaching gauges to either the calipers or the brake lines:

 

 

An additional thought would be to check your power brake booster as well, they tend to collect water and suffer small vacuum leaks, which would also significantly reduce perceived braking efforts.

[Mijostyn]

Thanx JFP . I've never had a stuck piston so I never had to deal with one. Experience is everything.

What do you do if the surfaces are glaze? How do you measure the pressure coming out of the master cylinder?kir

..

 

The hydraulic system in these cars can easily generate one to two thousand PSIG of fluid pressure; using that to pop out a piston can be anything from dangerous to having brake fluid everywhere when it comes out.

 

Gazing is the transfer of brake pad material (usually the resin that bonds the pads together ) to the rotor surface and then often back onto the pads themselves.  Glazing can often be removed by lightly sanding the pads and buffing the rotors:

 

 

If the rotors are very glazed, a light cut might be in order if they have enough meat left.

 

Brake system pressure is measured by attaching gauges to either the calipers or the brake lines:

 

 

An additional thought would be to check your power brake booster as well, they tend to collect water and suffer small vacuum leaks, which would also significantly reduce perceived braking efforts.

Thanx JFP, looks like I have my work cut out for me this week end. Fortunately I already have a wire brush.

[mattyf]

I had a similar story a few weeks back. I didn't read this thread first so I blocked the other 3 pistons with soft wood clamps and gently pressed on the brakes until the piston popped out. Checking its progress between pedal pushing. It actually didn't pop out violently at all. The dust boot held it in place and I was able to gently pull it out without fluid spraying all over the place. I had a bucket underneath the caliper to keep the mess to a minimum. Once the piston was out I clamped a rubber glove over the hole to keep the remaining fluid from leaking out.

 

Here's what the piston looked like:

 

And here's how I got it out. First drilled:

 

Then tapped:

 

 

Then backed it out with a fastener:

 

Ewww, look how nasty:

 

Cleaned out the bore:

 

Then I put it all back together with high temp anti seize just in case. I also ran the abs pump with the durametric and bled the brakes a few times.

 

Cheers,

Matty

Edited November 21, 2014 by mattyf