Brake piston stuck really bad. - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

irocz0r · 03-30-2017, 03:41 AM

I was changing the studs on my FRS, and with the caliper off on one side, I stupidly applied the brakes.

Now one of my rear brake pistons is stuck really good. I took the cap off the brake fluid reservoir to release the pressure. I even opened the bleeder valve on the caliper just to make sure there was no pressure in there. I put a C-clamp on the piston, and squeezed the ever loving hell out of it, but it is not budging.

It is stuck really good. I have a track day on Friday, and I need this fixed tomorrow. Here is an image of what's going on, you can see my C-clamp on the stuck piston: http://i.imgur.com/84urA1t.jpg

I searched Google, I tried everything I could think of. Does anyone have any ideas?

dutchman1 · 03-30-2017, 08:37 AM

Idk about our cars (I haven't messed with my brakes yet since I got it), but a lot of calipers retract with a twisting motion rather than a squeezing motion, try to find something to twist the piston with without messing it up and see if it retracts.

Die$eL · 03-30-2017, 08:43 AM

yip, its probably a twist back

venturaII · 03-30-2017, 09:24 AM

It's not a screw in piston...I just did my pads a few weeks back and I pushed the front and rear pistons in by hand. From my experience, usually screw in pistons are for emergency brake systems that actuate the main caliper, whereas our ebrakes are a small drum setup inside the rotor hat. Sounds like the piston is wedged.

jasonojordan · 03-30-2017, 09:28 AM

Might be worth your time to just disconnect the line to make sure all pressure is relived and try and wiggle it back into place. My guess is it prob maxed out its travel and got cocked in there.

stevesnj · 03-30-2017, 10:56 AM

Quote:

Originally Posted by jasonojordan

Might be worth your time to just disconnect the line to make sure all pressure is relived and try and wiggle it back into place. My guess is it prob maxed out its travel and got cocked in there.

Most likely this, those pistons need to move evenly in the bore, you can get a brass punch and gently tap the piston inside the hollow part with it with small hammer taps on the punch. Ideally you want to keep the piston in the bore but if it comes out just reinsert the piston evenly. I'd remove the caliper and drain any fluid that may be remaining. Just a little fluid could stop movement.

irocz0r · 03-30-2017, 12:40 PM

Hey guys, I fixed it. I removed the two 14mm bolts to open up the caliper, then I was able to put my c-clamp all the way across the piston evenly. Then it went down very smoothly. This is why sometimes you shouldn't drink while working on cars, or maybe I'd have thought of this sooner. Seems simple now.

Since I opened the brake reservoir and opened the bleeder valve, I have to bleed the brakes now, right?

Lynxis · 03-30-2017, 12:41 PM

Quote:

Originally Posted by irocz0r

Hey guys, I fixed it. I removed the two 14mm bolts to up the caliper, then I was able to put my c-clamp all the way across the piston evenly. Then it went down very smoothly. This is why sometimes you shouldn't drink while working on cars, or maybe I'd have thought of this sooner. Seems simple now.

Since I up the brake reservoir and opened the bleeder valve, I have to bleed the brakes now, right?

Yarp.

stevesnj · 03-30-2017, 02:46 PM

Quote:

Originally Posted by irocz0r

I have to bleed the brakes now, right?

Yeppers!

venturaII · 03-30-2017, 03:24 PM

Also, in the future if you're going to use a c-clamp to push the piston back in, you might consider keeping the old pad in the caliper and screwing the clamp against IT, rather than directly on the piston.

03-30-2017, 03:41 AM	#1
irocz0r Member Join Date: Feb 2014 Drives: '88 E30 325i, 2015 FR-S Location: Houston Posts: 44 Thanks: 0 Thanked 11 Times in 7 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	Brake piston stuck really bad. I was changing the studs on my FRS, and with the caliper off on one side, I stupidly applied the brakes. Now one of my rear brake pistons is stuck really good. I took the cap off the brake fluid reservoir to release the pressure. I even opened the bleeder valve on the caliper just to make sure there was no pressure in there. I put a C-clamp on the piston, and squeezed the ever loving hell out of it, but it is not budging. It is stuck really good. I have a track day on Friday, and I need this fixed tomorrow. Here is an image of what's going on, you can see my C-clamp on the stuck piston: http://i.imgur.com/84urA1t.jpg I searched Google, I tried everything I could think of. Does anyone have any ideas? __________________

03-30-2017, 08:43 AM	#3
Die$eL Senior Member Join Date: Jan 2014 Drives: Toyota MR2 Spyder Turbo Location: Midrand, South Africa Posts: 252 Thanks: 22 Thanked 128 Times in 67 Posts Mentioned: 8 Post(s) Tagged: 0 Thread(s)	yip, its probably a twist back __________________

03-30-2017, 12:40 PM	#7
irocz0r Member Join Date: Feb 2014 Drives: '88 E30 325i, 2015 FR-S Location: Houston Posts: 44 Thanks: 0 Thanked 11 Times in 7 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	Hey guys, I fixed it. I removed the two 14mm bolts to open up the caliper, then I was able to put my c-clamp all the way across the piston evenly. Then it went down very smoothly. This is why sometimes you shouldn't drink while working on cars, or maybe I'd have thought of this sooner. Seems simple now. Since I opened the brake reservoir and opened the bleeder valve, I have to bleed the brakes now, right? __________________

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03-30-2017, 08:37 AM	#2
dutchman1 Senior Member Join Date: Nov 2016 Drives: 2017 86 6-Speed Location: Seattle Posts: 138 Thanks: 35 Thanked 74 Times in 36 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	Idk about our cars (I haven't messed with my brakes yet since I got it), but a lot of calipers retract with a twisting motion rather than a squeezing motion, try to find something to twist the piston with without messing it up and see if it retracts.

03-30-2017, 09:24 AM	#4
venturaII Only users lose drugs. Join Date: Nov 2014 Drives: All the time Location: Shrewsbury upon Worcestershire Posts: 1,834 Thanks: 888 Thanked 1,078 Times in 681 Posts Mentioned: 3 Post(s) Tagged: 2 Thread(s)	It's not a screw in piston...I just did my pads a few weeks back and I pushed the front and rear pistons in by hand. From my experience, usually screw in pistons are for emergency brake systems that actuate the main caliper, whereas our ebrakes are a small drum setup inside the rotor hat. Sounds like the piston is wedged.

03-30-2017, 09:28 AM	#5
jasonojordan Senior Member Join Date: Jul 2013 Drives: 2013 satin white brz limited Location: Cottage Grove MN Posts: 1,049 Thanks: 162 Thanked 511 Times in 326 Posts Mentioned: 4 Post(s) Tagged: 0 Thread(s)	Might be worth your time to just disconnect the line to make sure all pressure is relived and try and wiggle it back into place. My guess is it prob maxed out its travel and got cocked in there.

03-30-2017, 03:24 PM	#10
venturaII Only users lose drugs. Join Date: Nov 2014 Drives: All the time Location: Shrewsbury upon Worcestershire Posts: 1,834 Thanks: 888 Thanked 1,078 Times in 681 Posts Mentioned: 3 Post(s) Tagged: 2 Thread(s)	Also, in the future if you're going to use a c-clamp to push the piston back in, you might consider keeping the old pad in the caliper and screwing the clamp against IT, rather than directly on the piston.

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