F82 brake caliper rebuild - some questions

[Mortis]

Hi all,

I managed to toast my brake pistons at a recent track day at Summit Point (dust boots completely destroyed and I think I might also have fluid leakage) so am looking at a full rebuild of all four calipers. I've seen some DIY instructions and also some helpful videos by Kies so it does not look too complicated. For those of you with experience with this, couple of questions:

1. Can I use a portable tire air compressor to get the pistons out (mine has a 100 psi limit), or do I need to get something bigger?

2. What is the risk of air getting in the brake lines? Should I also bleed / flush the brake fluid?

3. Should I also replace the pistons? Have been looking at the steel pistons offered by RacingBrake - do these result in a noticeable difference vs. the OEM pistons with respect to brake heat management?

Am also weighing the possibility of just asking my local shop to do the rebuild, cleaning and piston/boot/seal replacement - how much should I expect them to charge?

Any advice much appreciated, with huge thanks!

[Mortis]

Bumping this. Got an answer to my second question (yes) but counting on you all for the others : )

[m4forum]

Hi Mortis this is not complicated. Just need air compressor and follow basic cleanliness guides.
Follow answer to your questions:
1) home small air compressor is ok. I typically use 40-60 psi as want to go slow and not damage the piston. The tip here is to use wood in order to block/expand all pistons on the same amount so becomes easy to remove they by end as they get close to leave the caliper.
2) before removing the caliper keep the brake pedal pressed so it doesnt drain the line. Need to bleed the caliper anyway.
3) adding stainless steel is not a bad idea as it helps to block heat from pads to caliper/fluid. It wont solve the burnt dust boot but can help to manage brake fluid temperature.

Always keep calipers/piston clean. I would rather do it myself so I know how was done.

[D_SheerDrivingPleasure]

I recently experienced this but wasn't concerned until I noticed that my pistons were exteamly difficult to retract during a pad change. On the track chit chat forum I learned that a seized piston a sign of a worn seal. just ordered high temp replacement front boots and piston seals. hoping this + girodiscs can withstand Watkins Glen. I hear summit point is also a brake roaster.

I am outsourcing the replacement to my shop b/c the piston seal replacement would take me forever to figure out. And brakes are dirty.

[Mortis]

So I did my homework and rebuilt the brakes myself. It was hard at first, especially getting the pistons off the first caliper, but after it went faster and faster. I could not for my life get all four pistons to pop out simultaneously. What finally did the trick was sticking the two brake pads in the space between the pistons. Fitting the boots was piece of cake. Flushing the fluid was the next challenge because it takes a bit of work to get all the air out of the system. I missed air retained in one of the lines and had to do a second flush. All in all saved myself some $$ on what is a labor intensive task and learned something : )

[D_SheerDrivingPleasure]

Originally Posted by Mortis

So I did my homework and rebuilt the brakes myself. It was hard at first, especially getting the pistons off the first caliper, but after it went faster and faster. I could not for my life get all four pistons to pop out simultaneously. What finally did the trick was sticking the two brake pads in the space between the pistons. Fitting the boots was piece of cake. Flushing the fluid was the next challenge because it takes a bit of work to get all the air out of the system. I missed air retained in one of the lines and had to do a second flush. All in all saved myself some $$ on what is a labor intensive task and learned something : )

Bravo for doing this on your own. Did you do all four corners? How did your piston seals and dust boots look?

fwiw, my shop advises against applying brake lube on backside of the pads because it transfers heat from the rear of the pad to the piston dust boot, causing it to deteriorate.

[Polo08816]

Originally Posted by m4forum

Hi Mortis this is not complicated. Just need air compressor and follow basic cleanliness guides.
Follow answer to your questions:
1) home small air compressor is ok. I typically use 40-60 psi as want to go slow and not damage the piston. The tip here is to use wood in order to block/expand all pistons on the same amount so becomes easy to remove they by end as they get close to leave the caliper.
2) before removing the caliper keep the brake pedal pressed so it doesnt drain the line. Need to bleed the caliper anyway.
3) adding stainless steel is not a bad idea as it helps to block heat from pads to caliper/fluid. It wont solve the burnt dust boot but can help to manage brake fluid temperature.

Always keep calipers/piston clean. I would rather do it myself so I know how was done.

The dust boots will melt at the first use with significant temperatures. However, all the above is pretty good advice. I did this in my garage at home and the biggest challenge I had was getting the pistons to come out evenly.

Originally Posted by Mortis

So I did my homework and rebuilt the brakes myself. It was hard at first, especially getting the pistons off the first caliper, but after it went faster and faster. I could not for my life get all four pistons to pop out simultaneously. What finally did the trick was sticking the two brake pads in the space between the pistons. Fitting the boots was piece of cake. Flushing the fluid was the next challenge because it takes a bit of work to get all the air out of the system. I missed air retained in one of the lines and had to do a second flush. All in all saved myself some $$ on what is a labor intensive task and learned something : )

Originally Posted by D_SheerDrivingPleasure

Bravo for doing this on your own. Did you do all four corners? How did your piston seals and dust boots look?

fwiw, my shop advises against applying brake lube on backside of the pads because it transfers heat from the rear of the pad to the piston dust boot, causing it to deteriorate.

I think I would agree. I don't think the brake lube/paste reduces much of the noise anyways.

[m4forum]

the solution to get the pistons out is to use C clamps. First use a piece of thick wood in between all piston apply pressure so all pistons will move but not enough to get outside the hole. After use the C clamps to limit the amount of travel so it get close to exit the hole but not to leak fluid .... for each piston apply pressure. At this point all pistons can be removed by hand. What was a hard task now takes 5 min.

[Mortis]

Originally Posted by D_SheerDrivingPleasure

Bravo for doing this on your own. Did you do all four corners? How did your piston seals and dust boots look?

fwiw, my shop advises against applying brake lube on backside of the pads because it transfers heat from the rear of the pad to the piston dust boot, causing it to deteriorate.

Yes - did all the calipers. Took me two nights (I split the job over two days). The boots were toasted - they were brittle and were literally in pieces (see photo at start of thread), but the seals seemed to be in very good shape. I nonetheless replaced both with high temp versions, produced by RacingBrake. I used to use lube but found it really did not make a difference, aside from creating a buildup of gunk inside the caliper. track pads screeched like mad whether I used lube or not.

Toughest part was flushing all the air out of the system once I re-installed the calipers. Did it twice, including 'poor mans' ABS bleed...

[Mortis]

Originally Posted by m4forum

the solution to get the pistons out is to use C clamps. First use a piece of thick wood in between all piston apply pressure so all pistons will move but not enough to get outside the hole. After use the C clamps to limit the amount of travel so it get close to exit the hole but not to leak fluid .... for each piston apply pressure. At this point all pistons can be removed by hand. What was a hard task now takes 5 min.

Agreed. I didn't have C clamps nor a piece of wood the right thickness, but luckily my brake pads (1/3 life remaining) worked like a charm.