Sticking brake caliper piston?

[m3f_Bmwpower603]

I’ve started to notice a vibration over 50mph, and I noticed my passenger side wheel getting very hot.



I put the car on jack stands. And tried giving the wheel a little spin. (Very hard to spin opposed to drivers front wheel)



Looks like I have a bad caliper.



My question is: Do I need to find a certain attachment for my air compressor to remove the piston, inside of the brake caliper.



Or is it a common fitting? What causes this sticking? A combination of the slides/ hardware I assume.

[m3f_tofunin]

Blowing attachment with a rubber tip insert into brake line feed start low 15-20 psi with wood inside the caliper so the piston doesn't fly out and hurt you. If you can't get it to move after 40-50psi I would just go with rebuilt calipers for $40-50 as they usually replace everything(seals, guide pin boots, pins, bracket, and some painted).


Sticking is either worn/dry slide pins and guides or piston corrosion from torn/dislodged dust boot/rust belt salt/high water content in brake fluid from poor maintenance.

[m3f_Bmwpower603]

I removed the caliper. And I compressed the piston all the way flush up against the caliper. The caliper piston was a little rusty. The seal looked okay though.


I greased the caliper guide bolts, and the ends of the brake pads that contact the caliper.


This problem persists. Does changing the caliper guides, and bolts really make a difference?


I want to replace both calipers. But I don’t want to give up my ///M calipers as a core for aftermarket calipers. Do you think if I get these ones rebuilt it will fix the problem?

[m3f_frbz]

Consider the brake lines if they have never been changed. They can swell internally

[m3f_tofunin]

Caliper guides are rubber and they wear unless you choose to go with the brass bushings from Turner.


Piston can be marred beneath the seal or started to develop rust.


Usually calipers cores that get sent in get rebuilt aka new pistons, seals, bushings, guides bolts. The only experience I had with getting ///M calipers back is from A1-Cardone.


New calipers should fix the problem if it was in fact a sticking caliper.

[m3f_Bmwpower603]

I can’t see the caliper guides causing this. Especially after greasing the guide bolts


If I want to have them sent out, or rebuilt. Is there something I can stick in the brake line to prevent it from losing all of the brake fluid? I was thinking I could screw a bolt in the line to stop it from draining out ..

[m3f_tofunin]

I can’t see the caliper guides causing this. Especially after greasing the guide bolts


If I want to have them sent out, or rebuilt. Is there something I can stick in the brake line to prevent it from losing all of the brake fluid? I was thinking I could screw a bolt in the line to stop it from draining out ..

You can go to the auto parts store and ask for vacuum caps and there should be one that will fit over the lines.