brakes, pushing a caliper back in, read carefully?

Question

i have an 89 nissan 240sx i am changing the pads in the back. i went out and bought a c clap to push the caliper back in, i was told by many people this would work, ok i can turn the caliper counter clockwise and it comes out quick and easy. and then i can easily push it back in with the c clamp, but once it gets to where it was when i took the brakes apart, it just stops, i had the c clamp looking like it was gonna snap, and it wont go back in, i have tried turning it, letting the valve open, everything, any ideas?

no parking brake applied.

i havent ruined anything, i said read carefully. plz, i turned it counterclockwise to see if it would come out at all, to make sure there was some movement, and it goes back to where it started from, but i turn it clockwise, nothing happens

fixed it, thx guy, every one on here and friends were telling me to push it in with a c clamp, in the manual it specifically says dont do this. i was turning the piston with channel locks, and it wasnt moving because i did not have any foward thrust on it, it said usse needle nose pliers n push it and turn it clockwise. this worked fairly easily. thx

Answer 1

Certain types of cars have a.... mechanical locking system in the brake calipers.. (that is the best way I can describe it.) My jeep had the same problem. When attempting to use a c clamp to compress the caliper.

What ever you do don't force it. the caliper actually will rotate a direction and go back in all the way. I'm don't remember exactly how we did this.

Get your repair manual (ie chiltons or haynes) and look it up. (I had my step dad who is a professional mechanic help me so I don't remember too much abou the exact process, but it was a pain, and didn't make any sense.)

Look up compressing your caliper in your repair manual. It will tell you how to do it.

Dont force the c clamp, or you will damage the caliper.

Rakel... I think he hasn't tried to turn it at all... Older calipers you could just compress and the fluid would go back into the resevoir. Newer models don't work that way.

what does your repair manual say? It will detail exactly how to do this.

There is some sort of lockign mechanism in some brake calipers that is a pain to deal with.

here is an example.. they are talking about a VW... but may be simialr design
ou need a brake caliper unwinding tool, either a VAG model from Metalnerd, or a universal unwinder (but a 6 piece kit won't work unless it specifies a VAG product). A brake "cube" works if you have the skill to use one. "Cubes" are in the $12 range.

-- end comment from 'unitacx' --

I

You will find a discussion about retracting the rear caliper in detail here.

In addition, my Haynes manual for the VW Golf (and others), 1999-2002 says the pistons have to be rotated to retract them (Chapter 9, pg 9-5, picture 3.6h). As the above link discusses, just how to rotate them is somewhat unclear, but the picture at the top of the link is helpful. If I understand the discussion properly, you can rent this tool from some some auto parts places - I have none in my neighborhood, so I can't comment.

If the comment from "animaniac" 6-12-2005 is understood, the piston has two bores in it's surface, which are intended to accept what is technically called a spanner wrench which is used to rotate the piston (evidently clockwise) and make it retract. (See the McMaster-Carr site, and search on "spanner wrench" for a picture of a spanner. My guess is we need a 5480A11 or similar)


SOMEONE ELSE had the same problem and posted their question here in Yahoo answers.
http://sg.answers.yahoo.com/question/index?qid=20070313182438AAKZ99t

Answer 2

Isn't the brake caliper piston supposed to turn CLOCKWISE, in order to bottom it out inside the body of the caliper? I think you turned it in the opposite direction, moving the piston OUTWARD. Be careful that you haven't ruined the caliper by moving it outward too far!!! You should not have had to open the bleeder screw. Whatever you do, DO NOT force anything. If it won't go, THERE'S A REASON FOR IT!!! I hope you haven't damaged your caliper.

Edit: Make sure you apply penetrating fluid onto the caliper piston rubber boot (so that the boot doesn't tear while the piston is being turned), and turn caliper piston CLOCKWISE while compressing caliper piston AT THE SAME TIME.

Answer 3

Brakes are always fun... Your going about it all wrong. As a mechanic, I suggest this. That car, being an 1989, when doing the brakes, do not replace pads! Go to your parts dealer and order a loaded caliper. You will get a rebuilt caliper with the pads installed. All you have to do is remove the old and replace with new. Always do both sides, and only do one side at a time; so you have a reference.
You will have to bleed the system. You bleed the master-cylinder first, then start at the caliper farthest from the master cylinder , and bleed all four brakes. You may have to bleed more than once.
This sounds like a lot, but it is easier than what you doing know. A loaded caliper is not that expensive. Replace the rotors while your there, worn and scored rotors will quickly ruin new pads.

Answer 4

Sounds like you have crud, perhaps rust, behind the piston in the bore at the point where the pads were set to begin with.

The only cure will be to remove the piston and inspect. You may just have a ridge build up, and a simple honing would fix it. If you find lots of things that don't belong behind the piston then it's time to completely flush the entire system and probably some replacement calipers if there is any major damage.

Have you ever had the brake fluid drained and replaced? It does get water in it (brake fluid attracts moisture) which puts bubbles in the fluid. The heat of braking turns that to steam, which leads to rust. Rust begins to pile up...

Answer 5

Start with the obvious--do you have the parking brake applied? if it is applied you won't be able to push the caliper piston back in

Answer 6

sounds like the caliper is froze.ok, try this,loosen the bleeder and run the piston in and then when its all the way in,then tighten the bleeder.try that and see if it works for you.

Answer 7

Make sure you have the fluid reservior cap off, this may help. Also, opening the bleed screw should allow the pressure to be released, but you may have to bleed the brakes afterward.

Answer 8

it is stuck man you got to buy a new on sorry but thats the deal