-nick

My rear calipers have the "blooming-aluminum" corrosion under the brake pad spring plates. I've read the info on here that you need to use acetylene to break the screw free that holds the spring plates on. And then you can clean out the corrosion.

I would much rather just send my calipers out than invest in a torch + headache. I figured that they could use a fresh powder coat at the same time.

Note- I don't have any caliper seal leaks that I'm aware of. So the rebuilding is mostly to clean corrosion.

Any tips on a willing shop? I'll send them all four calipers...

Rocket Rob

Nick - Blair Talbot's shop does it. I attended a workshop last year and it was one of the things he mentioned. http://www.blairtalbotmotors.com/

No affiliations.

DWS964

Please excuse the dumb question - Is this corrosion behind the spring plates the reason that a couple of my pads are Very tight and require a bit of filing to get them to slide in freely?
And, once you torch them to free the bolts, are you required to rebuild them due to damage to the seals?
I have read the threads on the repair, and am also not crazy about tackling the job.

-nick

Thanks Rob - I'll check them out!

Darrell - I would say 'affirmative' to the reasoning why your pads are tight. That would make me concerned about the pads not releasing entirely too.

Not sure about seal damage. I'm more than happy to farm this one out after reading the repair threads.

Rocket Rob

Yes

Dunno. Haven't done it myself. Luckily I was able to scrape out the corrosion enough that my spring places moved back into position. But I was reading the threads too. It sounds like a daunting task.

Sten

Or.. MIG or TIG weld a nut to the spring plate retaining screws. That gives you something to grip to undo the little swines, and the quick burst of localised heat melts the threadlock that Porsche used. Zero damage to the seals.. And then take a file to the calipers and remove any corrosion from under the plates. Re-assemble with copper grease, job done.

boxsey911

I cut slots into the heads and then used a cold chisel. First screw took ages and a lot of patience but once I'd get the hang of it, had the rest out in no time.

Pesty

Right I did mine with the dust covers/pistons/ seals in place.

Onece I had finished I realised I was silly because I then took all that stuff out anyway because I fully stripped them to send them away for powder coating! Doh.

anyway to answer your question No, I managed to get the blow torch on the bolt heads without damageing the dust covers it was hard and restricted the time I could get the heat on the bolts.

then spent lots of time with a chisle tap taping away. Lots of time this is not an easy job IMO

I think if I had put more heat on it would have saved me a lot of time but I'll never know.

DWS964

How did you scrape out some of the corrosion? Seems difficult to get under the plates, but worth a try.

Interesting that only my rear calipers have this issue. And, of course, they are the buggers that are hard to get off.

Rocket Rob

I had the calipers in a vice on the bench and used an Xacto knife, various picks and slim screw drivers. The key was to hold the spring plate up enough to get the knife in but avoiding bending or damaging the spring. It probably took 1-2 hours per caliper. I wasn't able to reach all the way to the bottom of the spring plate, my knife wasn't long enough.

Bottom line - My way definitely helped but taking the spring plates off, scraping and resealing the metal underneath would be the proper way to fix it.

LouZ

I had severe corrosion on a set that I bought to replace my 2-pot rears. The first step is to figure out if the screws are hex or Torx, then get the correctly sized bit. I was able to remove 5 of the 8 (total for both) Torx screws "somewhat" easily.

For the others, I tried butane and propane heat - to no avail. Finally, we used Acetylene. I dialed it to a pencil tip flame and heated the screw head 'till it was cherry red - then removed the flame, waited 10 seconds, then more heat, again till cherry red, waited....then more heat! After the 3rd heat cycle, I unscrewed them with little effort. Now, my reason for 3 heat cycles:
the Locktite is on the bottom of the screw, so by heating the screw head, then waiting, I felt that it allowed the screw shaft to heat up in stages, all of the way to the bottom, without overheating the surrounding caliper metal.

Once off, I scraped and filed off all signs of "blooming" under the spring plates, applied a couple coats of paint, and let them dry.

I bought new spring plates and Torx screws (with the Locktite already applied), and reassembled them. To date......they are in good shape.

Ken D

Goldline brakes. Here's a link:

https://rennlist.com/forums/924-931-...es-photos.html