Rear caliper piston won't retract

[Perpetuus]

I spent the morning swapping out my seized rear rotors and put on new rear pads. I rented the rear caliper piston compressor tool, thinking it would be an easy job...not so..

With the tool, I was able to retract the piston only 1/2 a turn clockwise. After that, I had to put the vise grip onto the handle to attempt to turn it more. No luck though...the piston won't turn anymore. I need the piston to retract back about 3/8" more to fit the new pads. The old pads were worn and seized before.

This is on the right hand side of the car, which is the caliper with the parking brake. Is there a trick to get them to retract more? Are they seized? The area around the dust boot and directly underneath the boot looks ok.

 

[Timpanogos Slim]

i found, on my mk4, that when the rear pads are too far gone, that can eff up the caliper. piston ran out of threads or something.

here's hoping there's a trick. I ended up with a rebuilt caliper.

 

[Perpetuus]

i found, on my mk4, that when the rear pads are too far gone, that can eff up the caliper. piston ran out of threads or something.

here's hoping there's a trick. I ended up with a rebuilt caliper.

I got the piston to retract finally. Had to crack open the bleeder valve and open up the master cylinder cap. The tool I rented had a locking pin that came off the collar, so it was free spinning in the beginning. Put the pin back in and it worked like a charm. The right hand side rotor and pads were successfully swapped, but left rear not so..

The problem is that my left rear caliper bracket is seized on badly. I bent a box wrench that I used together with a breaker bar to free the two 14mm triple square bolts, and they still wouldn't budge. Used both PB blaster and a propane torch and still stuck on.

 

[Ignignokt]

I got the piston to retract finally. Had to crack open the bleeder valve and open up the master cylinder cap. The tool I rented had a locking pin that came off the collar, so it was free spinning in the beginning. Put the pin back in and it worked like a charm. The right hand side rotor and pads were successfully swapped, but left rear not so..

The problem is that my left rear caliper bracket is seized on badly. I bent a box wrench that I used together with a breaker bar to free the two 14mm triple square bolts, and they still wouldn't budge. Used both PB blaster and a propane torch and still stuck on.

I was about to ask if you removed the cap, but I didn't want to come off as an asshole. Good on you for figuring it out though. :thumbsup:

This might sound like a condescending question (like "have you tried turning it off and on again"), but I have to ask. Are you sure you're turning the bolt in the correct direction to loosen it?

 

[Perpetuus]

I was about to ask if you removed the cap, but I didn't want to come off as an asshole. Good on you for figuring it out though. :thumbsup:

This might sound like a condescending question (like "have you tried turning it off and on again"), but I have to ask. Are you sure you're turning the bolt in the correct direction to loosen it?

Yeah, I am sure it's being turned counterclockwise. I know it's easy to mix up when you are not facing the bolt straight on, but this was on the left rear of the car, and I had to push the breaker bar down from the rear of the car (counter clockwise). I had a jack supporting that control arm to reduce the flex going into the control arm for better torque to the bolt.

It's hard to remove mostly because I don't have enough room to directly attach a breaker bar to the triple square bit - the car cannot be jacked up high enough for it, and my triple square bit needed an adapter that was a bit too long, which wouldn't let me fit the breaker bar directly. I had to put a 14mm box wrench on the triple square bit, and then the breaker bar at the end of that box wrench. The box wrench trick worked on the right rear caliper bolts, but not on these left rear ones... the wrench bent and the socket where I attached the breaker bar to stripped out. Basically, it was flexing too much.

 

[Ignignokt]

Yeah, I am sure it's being turned counterclockwise. I know it's easy to mix up when you are not facing the bolt straight on, but this was on the left rear of the car, and I had to push the breaker bar down from the rear of the car (counter clockwise). I had a jack supporting that control arm to reduce the flex going into the control arm for better torque to the bolt.

It's hard to remove mostly because I don't have enough room to directly attach a breaker bar to the triple square bit - the car cannot be jacked up high enough for it, and my triple square bit needed an adapter that was a bit too long, which wouldn't let me fit the breaker bar directly. I had to put a 14mm box wrench on the triple square bit, and then the breaker bar at the end of that box wrench. The box wrench trick worked on the right rear caliper bolts, but not on these left rear ones... the wrench bent and the socket where I attached the breaker bar to stripped out. Basically, it was flexing too much.

From what I've seen about seized fasteners, impacting action tends to work for breaking them loose (especially if the area around the fastener has been heated with a torch). If you don't have or can't fit an imact drill in there, perhaps you chould try tapping the bolts with a brass hammer or a brass drift with a hammer so that you don't damage them.

 

[Perpetuus]

From what I've seen about seized fasteners, impacting action tends to work for breaking them loose (especially if the area around the fastener has been heated with a torch). If you don't have or can't fit an imact drill in there, perhaps you chould try tapping the bolts with a brass hammer or a brass drift with a hammer so that you don't damage them.

I've already tapped on the bolts with a hammer, but no dice. The main problem, I think, is the seized part of the bolt that sits in the caliper carrier. It is both hard to access and probably heavily rusted. I blasted a whole lot of penetrating oil in there and it didnt help. The torch couldn't reach that far in, because the dust shield is in the way.

I have limited access to a lift at work, so I'm going to try to see if I can go that route sometime this week.

The other problem is the 14mm triple square bit being too long for my breaker bar to directly fit. That would probably help out alot if the breaker bar can fit directly on it.

 

[Ignignokt]

I've already tapped on the bolts with a hammer, but no dice. The main problem, I think, is the seized part of the bolt that sits in the caliper carrier. It is both hard to access and probably heavily rusted. I blasted a whole lot of penetrating oil in there and it didnt help. The torch couldn't reach that far in, because the dust shield is in the way.

I have limited access to a lift at work, so I'm going to try to see if I can go that route sometime this week.

The other problem is the 14mm triple square bit being too long for my breaker bar to directly fit. That would probably help out alot if the breaker bar can fit directly on it.

Well, damn. I wish you luck at the shop.

 

[Timpanogos Slim]

I'd just like to add that i love my $40 harbor freight electric impact gun

 

[Perpetuus]

Well, damn. I wish you luck at the shop.

I found myself a slimmer profile breaker bar today. It is much slimmer at the head and should be able to do the trick, as long as there is enough room to move the bar! Might not even need to use the lift after all. Just waiting for replacement bolts now.

Old vs. New (in gunmetal)
Inscribed on the new breaker bar is: "do not exceed 350 lb-ft"

 

[Strieg]

Been searching for DIYs... Any good ones? I've done some brake jobs before, are our similar to others? Simple enough no DIYs needed? Ok just gonna be changing rotors, pads, and putting in some SS lines...


Sent from my iPhone using Tapatalk

 

[GIACUser]

Been searching for DIYs... Any good ones? I've done some brake jobs before, are our similar to others? Simple enough no DIYs needed? Ok just gonna be changing rotors, pads, and putting in some SS lines...


Sent from my iPhone using Tapatalk

This is the DIY I used from this forum LINK

 

[Perpetuus]

This is the DIY I used from this forum LINK

That DIY is a good starting point, but I ran into lots of hiccups with mine because of corrosion (from our famously salted winter roads in Canada) and seized parts.

When I have the brakes all done, I'll probably post something too.

 

[Perpetuus]

Success.

I was able to break the bolts loose. Surprisingly, I didn't have to use the large 25" long breaker bar I bought (no room to maneuver it under car), but instead, a 17" long one did the job perfectly.

Ran out of day light to swap the rotor out, but it's smooth sailing from now on!

 

[Perpetuus]

The caliper carrier is off, but that bastard of a rotor won't come off. 6 lb sledgehammer and about 20 hits later, it's still stuck. There are no screws holding it back, of course.