I am doing my rear brake pads. I'm in a bit of a jam as the sun has gone down and I can't seem to get the rear brake caliper piston to go back into its housing.

Do I twist counter-clockwise?

 

righty tighty same as any nut or bolt

 

It's incredibly hard to twist clockwise, especially with one of the 14 mm nuts off (the caliper keeps swiveling on the other 14 mm bolt/nut). But I don't think that's the issue because even when I hold the caliper still, I can't seem to turn the piston clockwise.

I opened the cap to the reservoir where you add brake fluid in the engine compartment on the driver's side. Isn't this correct?

Either there's back pressure somewhere (because I didn't do something) or is it normal for it to be that hard to turn clockwise?

 

yes, normal that its hard to turn

Might want to grease the edges of the boot a little bit if its really hard

also, you might have to push in and turn.

 

handbrake on ?
What are you using to turn it with ? I use a pair of needle nose pliers

Correct for what ? That is where you add brake fluid if that is what you mean

 

handbrake is off. already learned that lesson when i couldn't swivel the caliper initially to remove the brake pads!

i'm using a rear piston tool i rented at autozone. the kit has a bunch of wheels and you select one that fits your car. however, this tool uses a clamp turning mechanism and i'm wondering i'm not getting enough leverage. i'm going to autozone right now to buy the little square/cube thing that people have posted the pic of in this forum. that cube thing uses a ratchet and i believe i can get much more leverage with a ratchet.

i removed the cap to the reservoir to let brake fluid rise and air to get out as i push the piston back in. i should mention that i replaced the front brake pads first and afteward, the brake fluid in the reservoir had risen so much it was almost flowing out. so i used a syringe and sucked out some fluid. i thought this would make pushing the rear pistion in a little easier but it's still really difficult.

i'm off to autozone. thanks for the help so far.

 

All of the above advice is correct.

 

I normally bleed the brakes when replacing pads - just good commion sense . 3-4 pumps per wheel . That gets rid of any excess fluid too .

 

I just use a jumbo needle-nose plier in the grooves.
You do have to lean into it, though. It won't just retract because it is turning.

 

Thanks for all the help, everyone. Based on your comments and advice, I was able to finally get the rear done!

One thing I learned that I'd like to pass on is DO NOT rent the caliper piston kit (or buy it) at the auto parts store. I'm talking about the kit that has all the various wheels of different sizes combined with a clamp type turning mechanism. That device sucks.

The little metal square/cube that works with a 3/8" ratchet works much easier.

Another thing was that turning the piston clockwise was VERY DIFFICULT AT FIRST. For whatever reason, it seems to eventually loosen up and when it does, turning is pretty easy.

The advice to PUSH THE PISTON IN while turning was critical. It's not easy to feel the piston going in, so every now and then I would stop and look from the side to see that the piston was indeed moving a little farther back into its housing.

Also, don't forget to make sure the 4 grooves in the piston (where you put the piston turning tool into) are aligned perfectly at North, South, West, and East relative to the caliper (assuming the caliper is held in a horizontal orientation. This is because the rear brake pads have a circular bump sticking out of them, and this bump has to fit right into the South groove on the piston. Once the caliper is back in place over the rotor and brake pads, you will not be able to visually inspect. That's why you have to have the piston grooves at perfectly north, south, west, and east and assume the bump went into the south groove.

 

glad to hear you got it sussed .
Next time you do a diy - have a look on here first and you may save yourself some grief .

I never thought about having to push it in at the same time - just always did it because the pliers jump out of the grooves if you don't - heh .

 

I don't know how to bleed them. I'll read up on it in this forum so I can do it for the future.

 

I read just about every single thread on changing brake pads! People did not describe in detail the intricacies of turning the piston in. I don't think it was ever said to turn clockwise either.

Another thing is I did not read anywhere on this forum where someone told people to RELEASE THE PARKING BRAKE when changing the rear brake pads.

 

All the more reason to have a friend near by that you can make a phone call to.

 

I pull the cable off completely. Its just in the way, anyway.

 

Wow did this today to install my slotted rotors and for some reason the passenger rear would not go in!!! I finally got it but what a bitch. Grungepup did his car with no issues at all Sorry just venting

 

Passenger side rear is being a pain for me too. Naturally, that's the one I started with!

 

Put some pressure on it. I typically have to brace the caliper against one of the suspension arms and lean my body weight into it before it will start turning in. Otherwise it just sits there and spins where it is.

 

I couldn't find an angle to put enough pressure so it just spun, for an hour. I'll get that cube shaped tool mentioned earlier in the thread and give it another go.

 

It may not be something that's recommended, but I have used a 12" C-clamp to spin and compress the rear pistons. And since the clamp has a swivel end and compresses as it is turned clockwise, it worked for me on both sides. I didn't change the fluids but I removed the cap off the reservior and took out, with a syringe, at least 10 cc of fluids. That brought the level up just below the 'high' line... And still, could slide a credit card between the new pad and the disc brake!

 

The piston should go in with hand forced pressure while turning clockwise. Be careful using a c-clamp while turning as it may ruin the thread inside the piston. The piston is threaded inside and practically acts as a nut that screws into a threaded rod in the cylinder (a screw).

If the piston is fully unscrewed to the point where its thread is not screwed into the rod and is actually SITTING on the rod. Try screwing it back with pressure on the piston. If you some how can't screw it back in, take the the piston out and examine the threads in it.

My piston was sitting on the rod unscrewed due to low pad material. The force developed during braking actually destroyed the threads inside the piston, while the threaded rod in the cylinder was fine (hardened steel). Using a c-clamp can create enough force to do the same damage. A rare situation, but it happens.

 

Here's a cool tip before twisting the rear caliper. Spray a little liquid wrench or wd40 on the boot before you twist. It'll let the caliper turn inside the boot without any worry of ripping the boot

Also a lot of auto stores will let you borrow a caliper tool set for free.