PM calipers rebuild?
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Tourer
Joined: Jul 2023
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From: Florida
PM calipers rebuild?
I'm about to engage on a PM brake caliper rebuild on my 81 shovel.
They were leaking......rotors covered in a black film.
I seems like a pretty straightforward operation.
My question is, a couple of pistons have some ever so slight discoloration and a little roughness on the outer walls.
I've sanded them down and they are pretty smooth.
Is that cause for concern or should I just buy new ones.
I'd post a pic but brakes are still on bike.
Tx!
BTW........so far, my parts search only comes up with hardware and rubber seals......no pistons.
I found a generic piston on Dennis Kirk's site and it's $40 EACH!!
That's $320 for 8 new ones!
For THAT price I'll just buy new calipers!!
They were leaking......rotors covered in a black film.
I seems like a pretty straightforward operation.
My question is, a couple of pistons have some ever so slight discoloration and a little roughness on the outer walls.
I've sanded them down and they are pretty smooth.
Is that cause for concern or should I just buy new ones.
I'd post a pic but brakes are still on bike.
Tx!
BTW........so far, my parts search only comes up with hardware and rubber seals......no pistons.
I found a generic piston on Dennis Kirk's site and it's $40 EACH!!
That's $320 for 8 new ones!
For THAT price I'll just buy new calipers!!
Last edited by 81shovelhd!; Feb 23, 2025 at 09:02 AM.
Seasoned HDF Member
Joined: Jan 2011
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From: Michigan 15 Minutes East Of Hell
I believe we addressed this before ... If the pistons ride on the seal ( grove cut in bore so seal sits in the bore ) It could be a wise idea to replace the pistons ... If the seals are fit in a grove cut in the piston I'd re-use the pistons if the damage is a slight as you have stated ... Good Luck
Seasoned HDF Member
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From: Pennsylvania
1. You need to check the bores also to make sure there is no corrosion in there. Clean as required.
2. Then fit the pistons in the bores with a little brake fluid on them in the bores they came out of and see how tight they are.
3. If they move well in the bore, do not hang up then reuse them with seals and boots applied.
2. Then fit the pistons in the bores with a little brake fluid on them in the bores they came out of and see how tight they are.
3. If they move well in the bore, do not hang up then reuse them with seals and boots applied.
Seasoned HDF Member
Joined: Jan 2011
Posts: 157,524
Likes: 57,080
From: Michigan 15 Minutes East Of Hell
There will be no interference between the bore and the piston unless the bore or pistons are HIGHLY corroded which would have been mentioned already ... The square cut seal ) whether it fits in the bore grove of in the piston groove makes up the fit between the piston and bore ... Did this many many times on more applications that I can remember ... This ( corrosion ) was a common problem with the earlier Corvettes and we corrected it with an overbore of the caliper than installing a stainless steel sleeve to bring the caliper back to oem specifications
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