Automotive

tight brake pad - piston not fully retracting?

  • Last Updated:
  • Jun 28th, 2019 10:25 am
[OP]
Newbie
Aug 13, 2017
15 posts
2 upvotes

tight brake pad - piston not fully retracting?

i replaced the rotors and pads on the rear of am Acura EL/Civic Si. Pax side went on fine, but the drivers side caliper piston would not stay fully retracted. I would twist in completely and it would turn back about 1/8'". Ino rder to get it over the new pads i had to keep pressure on the piston and even then it went on very tight.

The other thing is the old pads were wearing unevenly top to bottom. Much more pressure on the bottom/inside of the rotor.

The rotor does not spin freely after install. Drive is fine, but there was considerable heat being generated.

What should i do?
- Bleed the brakes again? maybe flush the whole system?
- let them ride until the new pads wear down?
- throw one of the old pads back on and let them wear a bit?
- replace the caliper?

I don't do a lot of this stuff, but this is an old car and i'm not interested in spending much more money on it.

Thanks.
10 replies
Deal Addict
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Oct 16, 2007
1147 posts
415 upvotes
replace the caliper
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Deal Addict
Sep 8, 2017
2466 posts
2492 upvotes
Vancouver
Sounds like the caliper is seized.

The pads wearing unevenly is one (or all) of these 3 things:
1) seized caliper
2) seized slide pins
3) rust build up in caliper bracket
Deal Guru
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Feb 11, 2007
11772 posts
11391 upvotes
Oakville
User714911 wrote:
Jun 27th, 2019 10:31 am
i replaced the rotors and pads on the rear of am Acura EL/Civic Si. Pax side went on fine, but the drivers side caliper piston would not stay fully retracted. I would twist in completely and it would turn back about 1/8'". Ino rder to get it over the new pads i had to keep pressure on the piston and even then it went on very tight.

The other thing is the old pads were wearing unevenly top to bottom. Much more pressure on the bottom/inside of the rotor.

The rotor does not spin freely after install. Drive is fine, but there was considerable heat being generated.

What should i do?
- Bleed the brakes again? maybe flush the whole system?
- let them ride until the new pads wear down?
- throw one of the old pads back on and let them wear a bit?
- replace the caliper?

I don't do a lot of this stuff, but this is an old car and i'm not interested in spending much more money on it.

Thanks.
It might be seized, but the first thing you can try is to open the bleeder when you're pushing the piston back in. You might even try just opening the reservoir first.
Deal Expert
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May 10, 2005
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You did open the brake fluid reservoir cap??
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Newbie
Jun 26, 2019
3 posts
1 upvote
As others have mentioned, you can try opening the bleeder valve or the brake reservoir cap when you twist the piston back in (I'm assuming you have the ratcheting type rear caliper with the integrated parking brake). However, I suspect you may need to replace the caliper as it should not come back out after you have twisted the piston back in.

Having said that, if you don't plan on keeping the car for much longer, and the car drives fine then perhaps you can just leave it.

If you do want to fix it, perhaps you can consider rockauto.com. They have very reasonably priced parts.
Deal Addict
Sep 8, 2017
2466 posts
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Vancouver
OP said the brake is generating a considerable amount of heat. That means the brake is dragging and therefore not driving fine.
Deal Addict
Feb 6, 2011
1470 posts
1135 upvotes
Not sure on your vehicle but does yours have a pin on the pad that aligns with the slot in the piston? If it does and its not aligned, it may explain the uneven wear and some of your problems.
Jr. Member
Mar 8, 2016
178 posts
34 upvotes
Does the car have special
Inner and outer pad. Some cars have two different shaped pads like on ford f150s so the caliper won’t go on unless it’s the right configuration. Also first try removing and slider pins and cleaning them with steel wool and greasing them to see if it helps otherwise a new caliper or rebuilt one would be a good idea.
Deal Expert
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May 10, 2005
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derass wrote:
Jun 27th, 2019 11:17 pm
OP said the brake is generating a considerable amount of heat. That means the brake is dragging and therefore not driving fine.
But that is after the piston and pad were already installed, probably improperly.
Best line I have heard in a very long time LOL "I don't argue....I educate." Anonymous
Deal Guru
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Nov 27, 2005
11561 posts
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You need to open the bleeder valve when rotating the rear caliper piston.

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