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Hello, I’m a new 944 Turbo Owner. My front brake pads, passenger side are rubbing on the rotor...so with further inspection the pistons are not retracting all the way when brake is let off. Are the pistons supposed to sit flush when retracted? This is what mine look like when retracted which is causing rubbing and brake burn. I replaced the brake hose thinking that might be it, but didn't help. Thanks!
Those pistons and seals dont look right , looks like early pistons but those are not scraper seals.
Can you take a picture more from the top of the piston to better see those seals ?
What year is your car ?
Those pistons and seals dont look right , looks like early pistons but those are not scraper seals.
Can you take a picture more from the top of the piston to better see those seals ?
What year is your car ?
My car is a 1986 944 Turbo 46k miles...car had been sitting in a garage and only driven 90 miles in the last 10 years. I've had it for 1 month and have done many repairs to the car. This is the last on the list...
The pictures with the #1 were the original calipers and pistons on the car. The pads were binding so I purchased a rebuilt caliper that is pictured #2. The same problem I was having with the first caliper and pistons, I’m have with the second caliper and pistons. The pistons can manually be pressed flush by hand on set #2 that is currently on the car but once the brake is applied the don’t go back flush and is causing the same binding as before...
Also the piston surface shouldn't be that bright metal color , they should be black with a very smooth clear coating .
Also, should the front caliper have a spacer between the caliper and the mounting point? Maybe this is why I'm getting rubbing?? I notice the rear has a spacer....
The rubber piston seals are beveled on the calipers to slightly pull the piston off the rotor when releasing the brake pedal but the pad will often still contact the rotor ever so slightly and you will hear it if your car is on stands and you spin the hub. The piston does not retract back into the caliper when releasing the brake pedal, the seal is only intended to release pressure off the rotor.
The rubber piston seals are beveled on the calipers to slightly pull the piston off the rotor when releasing the brake pedal but the pad will often still contact the rotor ever so slightly and you will hear it if your car is on stands and you spin the hub. The piston does not retract back into the caliper when releasing the brake pedal, the seal is only intended to release pressure off the rotor.
Any idea what is causing the pad to drag the rotor then and cause excess heat?
Any idea what is causing the pad to drag the rotor then and cause excess heat?
If you're having the same issue with two different calipers on the same wheel, I think you should be considering the other parts of the system. You might have an issue at the spindle/hub. You can have rubbing if the run out is out of spec.
If you're having the same issue with two different calipers on the same wheel, I think you should be considering the other parts of the system. You might have an issue at the spindle/hub. You can have rubbing if the run out is out of spec.
Is it a constant drag or intermittent?
The rub is constant. The rotor can be turned with moderate force.
The rub is constant. The rotor can be turned with moderate force.
10 years is a long time to sit. Obviously if you changed caliper, you bled the system. I wonder if you have some sort of partial blockage causing residual pressure in the line. The fronts run on separate lines, so it could make sense that it's only affecting one of your front wheels.
It could be time for a rebuild or something else all together as mentioned. Over time and with age the rubber seals loose some of their "snap" and are no longer able to "pull" the pistons back.
The brake pads will touch the rotors and grind softly when both are new (both look fairly new) and even in normal use. If you take a look at a rubber seal and the bevel across its section you'll realize how the piston gets retracted and the fractional dimension where talking about.
If you're still concerned video and audio of the sound while you spin the hub might help us get a better idea of what you have going on.
10 years is a long time to sit. Obviously if you changed caliper, you bled the system. I wonder if you have some sort of partial blockage causing residual pressure in the line. The fronts run on separate lines, so it could make sense that it's only affecting one of your front wheels.
I have a new brake hose I just put on, you mean an issue in the hard line that the brake hose connects to? _
If you have the time rebuilding and refinishing brake calipers is a satisfying DIY project.
Here's a before and after of my M030 calipers off an '89 turbo.
Edit: I just went back and read your original post, are you sure there's a problem? It looks like you have new rotors and pads and in my experience they will grind when spinning the hub. Heck, I bet if i went out and spun my wheels I would hear the brakes a little and my pads/rotors have several thousand street miles on them. Its to what degree is acceptable and normal operation. The piston does not get retracted into the caliper when you let off the brake pedal.
I have a new brake hose I just put on, you mean an issue in the hard line that the brake hose connects to? _
Right, somewhere between your new brake hose and up to and including the master cylinder.
I am assuming you aren't seeing the same level of drag on the driver's side front? I know it sucks, but you could throw caliper 2 on the driver's side and compare it to what you have on the driver's side now. It would at least tell you if the problem is the caliper or something else.
On a related topic I had a front piston that was sticking a couple years ago. I sent both of my fronts out to be rebuilt by a company near Chicago. It was around $100 each.. I liked that I was getting my calipers back. Service included splitting the halves, cleaning, all new seals, and pressure testing. Just wanted to let you and other's know that there is an option like that out there. I have bought various rebuilt parts over there years and the quality of the rebuilds was very hit and miss. Anymore, if I can, I try to deal directly with the people performing the work even if it costs more money it might save some headache in the end.
Most likely not related to your problem but that no.2 caliper that you bought rebuilt is weird . Looks like it has early pistons with later type dust seals instead of scraper seals , not sure how thats possible ...
01-30-2019, 06:03 PM
Caliper piston help.
