brake caliper overhaul

[colt45 gto]

today i pulled the N/S/R wheel off in the hope to find this knocking, thinking its a rear wheel bearing (still not ruled this out) i found the rear brake stuck on and on solid. strange as i had this apart two weeks ago to clean and regrease the pads and it didn't appear siezed then.

so i figured that with the brake stuck on it could be causing the knock especially with the groved disks. so being the chap i am i took this off and started to strip it down ready to clean the piston, cylinder and seal and dust cover.

what i found was a rusty mess that i had to clear and clean up.
http://i1106.photobucket.com/albums/h364/David_Healey/gto%20twinturbo/DSCF4899.jpg
http://i1106.photobucket.com/albums/h364/David_Healey/gto%20twinturbo/DSCF4904.jpg

the rust had grown onto the piston seal
http://i1106.photobucket.com/albums/h364/David_Healey/gto%20twinturbo/DSCF4903.jpg
http://i1106.photobucket.com/albums/h364/David_Healey/gto%20twinturbo/DSCF4901.jpg

so the cleanup process started and with an angled dentistry pick i got the rust out of the groove that houses the seal and then run a ball of wire wool on the end of a drill bit to clean the cylinder.
http://i1106.photobucket.com/albums/h364/David_Healey/gto%20twinturbo/DSCF4905.jpg
http://i1106.photobucket.com/albums/h364/David_Healey/gto%20twinturbo/DSCF4906.jpg
http://i1106.photobucket.com/albums/h364/David_Healey/gto%20twinturbo/DSCF4907.jpg

and then cleaned up the piston with 600 grit wet n dry paper and finished with wire wool
http://i1106.photobucket.com/albums/h364/David_Healey/gto%20twinturbo/DSCF4911.jpg

[colt45 gto]

cleaned up the rubber by gently scraping the rust from the edge with a screw driver blade and washed off with brake cleaner
http://i1106.photobucket.com/albums/h364/David_Healey/gto%20twinturbo/DSCF4908.jpg
http://i1106.photobucket.com/albums/h364/David_Healey/gto%20twinturbo/DSCF4909.jpg
http://i1106.photobucket.com/albums/h364/David_Healey/gto%20twinturbo/DSCF4910.jpg

cleaned the whole thing down with brake cleaner and blew it off with an air line, put some brake fluid around the seal and refitted that then a drop of fluid round the piston and slid that back home, cleaned and inserted the dust cover and now it should operate perfectly
http://i1106.photobucket.com/albums/h364/David_Healey/gto%20twinturbo/DSCF4912.jpg

i have to wait for the wife so i can bleed it then i can try it, the noise was worse when it got warm so i am pretty sure this is the problem, there is no play in the rear wheel bearing so it really can't be anything else.

i hope this helps those who wish to try refurb rather than buy new/ second hand or remanned calipers.
tip...remove the caliper as you would when replacing the pads, put a tray beneath the caliper to catch fluid and pump the piston out with the brake, its far easier. dont forget to have a set of grips or pipe clamps ready so you dont loose all the fluid.

[TUFFTR]

Great little write up! That looks very easy to do indeed.
Thanks Colt.

[GTOJOE]

Good write up. It's very easy once you have done it. The hardest thing is getting the piston out when they are rusted like that. SOmetimes we have had to get one person using the piston removal tool and another with an air hose to try to push the piston out. Just keep in mind if the piston has any pits or grooves in it from rust then replace the piston. It will damage the seal and cause leakage.

[speedy25]

Some extra bits to think about if you do this job-

Personally with that much rust I would have declared that caliper a goner. If there is too much clearance between the piston and the bore it will fail. If not now, eventually.

Proper practice is to REPLACE the seal, but I will admit to using a CLEAN one over. When you are scraping rust deposits off, you will probably damage the seal.

That caliper is a GREAT example of why you change brake fluid. Lack of proper maintenance caused the failure. If you cant see through your brake/clutch fluid, change it!

-SP

[colt45 gto]

caliper and seal are fine indeed it is probably working as well as it did when new. i will only replace a seal if it really needs it i hate spending money on something if its simply ''to put a new one on'' especially if its no different than a new one.

the piston was in great shape when i cleaned it up as was the cylinder and seal. no need to replace anything there, and with a constant hard servo assisted pressure there are no leaks and the piston returns as it should. i am a professional i have the ability to judge whats good or bad. and this was the sole cause of the knocking from the rear end. so i am happy :)

also just completed an ABS delete after the ABS pump took a shit. the brakes are now quite a bit more responsive :)
http://i1106.photobucket.com/albums/h364/David_Healey/gto%20twinturbo/DSCF4913.jpg

[jba3]

That's a whole lot of line left for no ABS. Pick up an STM ABS delete kit. All that mess on the fender can be gone. :)

Great job with the caliper piston.

[Nationalmilkman]

Subscribed.

[HLxDrummer]

Nice thread! I did all mine and the worst part was putting the pistons back in and trying to get the dust boots to stay on the front calipers. Got "centrix" rebuild kits which seem to work ok and they were a lot cheaper than the dealership stuff.

[speedy25]

i am a professional i have the ability to judge whats good or bad.

Of course YOU are but look at the audience this thread can attract. They dont all have your skills and may do something that could be catastrophic. Thats why I added my advice to the thread. Think twice about brake parts since they may be the difference between having fun in your can and having a REALLY bad day!

Work smart!!

-SP

[TUFFTR]

Thanks to this write up I rebuilt my Sumitomo's last weekend. great success. Some pistons weren't lubed and felt stuck. All bored and pistons cleaned out and re-oiled (with brake fluid) Problem in the end for me turned out to be a master cylinder but it didnt hurt to do this.
Thanks Colt.

[Nihil]

also just completed an ABS delete after the ABS pump took a shit. the brakes are now quite a bit more responsive :)
http://i1106.photobucket.com/albums/h364/David_Healey/gto%20twinturbo/DSCF4913.jpg

I wanna know more about what's goin on here, did you just use some fittings, or have to modify anything else to rid the ABS pump? This looks like a super cheap and easy ABS delete aside from goin with stock non ABS parts and having to fish everything through the tight engine bay

[BigTyla]

I wanna know more about what's goin on here, did you just use some fittings, or have to modify anything else to rid the ABS pump? This looks like a super cheap and easy ABS delete aside from goin with stock non ABS parts and having to fish everything through the tight engine bay

Best way to do this is to buy some flare unions, cut the old lines from the ABS system, install new flare fittings on the lines, use a flare tool to flare the lines, and thread them in a flare union tee as pictured above. Just make sure you're hooking up the lines correctly, i.e. front in to front outs and rear in to rear outs.