pushing caliper piston

[PoorOwner]

I need to replace 2 warped rotors.

I can get the caliper off with the pads attached. Is there an easy trick to retract the caliper piston a little without removing the pads?

they are the single piston push type.

It may even go back on without doing anything, but just wondering..

 

[jasonphelps]

Open master cylinder cap and use a C clamp is what I do. I would just take the pad out rather than push on it though.

 

[Rmracing]

You could use a big pry bar between something like a strut or something secure with the caliper still attached and pry against the back side of the caliper and push the piston in a little.

 

[MJK]

+2, unless the piston is the screw in type. (I've only ever seen this on rear calipers with integrated e-brake)

Pads are generally very easy to just pop out and I would, if for no other reason than to have a look at the piston and seal. If you are not sure what you are looking at, post up a pic here.

 

[PoorOwner]

I think I have an idea. I will get a hex key between the pads and when I turn it a bit, it should move the pads in a little. I only need to move it a credit card thick.. if even that much.

Worse case I will pop off the pads.

 

[MJK]

In your shoes I would want to know what made the rotors warp in the first place. Are the pins lubed properly, boots not torn, pads not dragging, etc? Might want to check that as well.

 

[PoorOwner]

Heavy crossover over using same brakes as the sedan calipers.
Still got pads left. I was going to turn the rotors but found new blanks for $25 each.

 

[seanb02]

I always just put a screwdriver into a slot in the rotor and up agains the edge of the caliper and give it a bit of movement. Not a lot, just enough to get the caliper off the rotor. Then a C-clamp against the brake pad to fully retract the caliper piston after it is removed from the rotor.

Also I never use a C-clamp up against the caliper piston itself as it can compress the piston too far into the caliper and lock it up. Just my experiences, others will differ.

 

[PoorOwner]

So I put back the caliper and old pads right on the new rotor, and it fitted.
I suppose the rotor being warped had caused the pad distance about the same as a new rotor.
I think when I tighten the caliper bolts it would have pushed the piston, if any.

Opened the fluid cap down the street incase there was any pressure.

 

[driftpin]

I bet people recommend using some-type of solvent on the exposed piston before pushing it in. Also a bit of scrubbing, to remove any residue which remains after the solvent spray.

 

[PoorOwner]

I always just put a screwdriver into a slot in the rotor and up agains the edge of the caliper and give it a bit of movement. Not a lot, just enough to get the caliper off the rotor. Then a C-clamp against the brake pad to fully retract the caliper piston after it is removed from the rotor.

Also I never use a C-clamp up against the caliper piston itself as it can compress the piston too far into the caliper and lock it up. Just my experiences, others will differ.

I didn't understand what you meant yesterday but today I found this technique in this video at 1:13.

I didn't do this but this is an easy way. Thanks

 

[RKA]

Heavy crossover over using same brakes as the sedan calipers.
Still got pads left. I was going to turn the rotors but found new blanks for $25 each.

Most likely not, which means it will happen again. In addition to the causes mentioned above, improperly torqued lug nuts/bolts will cause it. Get yourself a torque wrench and use it correctly anytime the wheels have been removed. Check them again in one week.

 

[rayra]

With the calipers still mounted on the rotors you are replacing, simply put a large screwdriver or prying tool thru the access hole in the top/back of the calipers, inserted into the space in the middle of the rotor and pull the handle of the tool toward you. That will slightly compress the piston and give you enough slack to readily remove the caliper and re-install your used brake pads on the new rotor.

If replacing the pads too, put an old one over the piston and use a c-clamp positioned over the pad / piston and on the back of the caliper over the piston chamber and slowly tighten it enough to push the piston back into the caliper.

You do not and even should not remove the cap on the reservoir when doing this. And be sure to depress your brake pedal when one side is put back together and before you compress the other side, if you don't you'll wind up overflowing the reservoir.

On top of all that, you're doing all the work already, do it right and put new pads on too. Go to rockauto.com and save a lot of money and pick from a wide range of pricing options so you can do the job right, far cheaper than you can get parts from your local chain store.

 

[Skin]

He's in cali, shouldn't need a screwdriver. Just take the fasteners out and pull the caliper toward you using the rotor to push the pad in a bit. Make sure you put a lug back on the rotor so you don't hit yourself.

 

[bsaint]

Large channellocks is what I use.

 

[Tallpilot]

Most likely not, which means it will happen again. In addition to the causes mentioned above, improperly torqued lug nuts/bolts will cause it. Get yourself a torque wrench and use it correctly anytime the wheels have been removed. Check them again in one week.

I suppose it is possible in heavy traffic to constantly ride the brakes so much the rotors warp but I’m with you this is most likely going to happen again. The pads should be replaced as well lest they wear the new rotors unevenly.

 

[fasteddie]

Replace the pads, replace the hardware (clips), lube all metal to metal contact points on pads, caliper and bracket and piston face. Lube slide pins with sil glyde or caliper paste. There's a million brake job youtubes out there, it's worth watching a few.

 

[JRas]

stick a smaller prybar between the pad and rotor (open side to rear?), and gently push the piston back in

you could crack the bleeder if needed, obviously rebleed.

 

[u3b3rg33k]

I crack a bleed screw and use hand pressure. no C clamp needed. i used to do that - much slower.

 

[MJK]

Most likely not, which means it will happen again. In addition to the causes mentioned above, improperly torqued lug nuts/bolts will cause it. Get yourself a torque wrench and use it correctly anytime the wheels have been removed. Check them again in one week.

Agreed.

If you change just the rotors, go for a small drive and use your hands to see how hot the rims/wheels are when you get back. If the wheels with the recently replaced rotors are warmer than those that remained warped then the pads are dragging and this will happen again. Could be anything, but here in the desert it seems usually be the pins. Boot can be cracked, or not. Grease gets dirty or dried and there you go. As often as not a clean, regrease and reassemble does it.

 

[Nero]

I crack a bleed screw and use hand pressure. no C clamp needed. i used to do that - much slower.

If you do this in the North, you just broke a bleeder screw off.

 

[u3b3rg33k]

If you do this in the North, you just broke a bleeder screw off.

I live in the north!

i think most broken bleed screws were overtightened prior. I've never broken one.

 

[Nero]

I live in the north!

i think most broken bleed screws were overtightened prior. I've never broken one.

You must live an extremely charmed life; I had one today that was rusted completely off; nothing to grab onto. Caliper wasn't leaking though.

 

[L.Cheapo]

I live in the north!

i think most broken bleed screws were overtightened prior. I've never broken one.

North what, Carolina?

You aren't getting a bleeder screw out on any vehicle in my area thats more that about 5 years old. Not in one piece, anyway.

 

[Tonyuk]

You just need to push a piston back in?

Loads of tools out there for this, big pair of pliers, the winding screw type, the caulk gun type, the air tool type etc..

I use the below;

I also have the type you screw in, and an older air powered one for the rears

 

[u3b3rg33k]

North what, Carolina?

You aren't getting a bleeder screw out on any vehicle in my area thats more that about 5 years old. Not in one piece, anyway.

Wisconsin. we love road salt like fish love water. I bleed my brakes every two years.

 

[astroracer]

A C-clamp and a piece of wood. A short piece of 1 x 3 works excellent. Put the wood on the piston and collapse the piston with the C-clamp. Go slow, the pressure from the clamp will push the brake fluid back into the reservoir. Absolutely no need to crack a bleeder to do this.
Once you get everyhting back together fire the engine and step on the brake pedal a few times to push the pistons back out to the new pad thickness.
I have never had to collapse the piston any amount to pull the calipers off. They should come right off with a bit of muscle.
Mark

 

[u3b3rg33k]

A C-clamp and a piece of wood. A short piece of 1 x 3 works excellent. Put the wood on the piston and collapse the piston with the C-clamp. Go slow, the pressure from the clamp will push the brake fluid back into the reservoir. Absolutely no need to crack a bleeder to do this.
Once you get everyhting back together fire the engine and step on the brake pedal a few times to push the pistons back out to the new pad thickness.
I have never had to collapse the piston any amount to pull the calipers off. They should come right off with a bit of muscle.
Mark

no there isn't. but why push dirty fluid back into the reservoir?

 

[astroracer]

no there isn't. but why push dirty fluid back into the reservoir?

Never had a problem doing it this way. I always pull the reservoir cover to check the fluid prior to the brake job. Never noticed any discoloration after compressing the puck. Top the fluid off and put the cover back on. Good to go.
The fluid shouldn't be any "dirtier" then the rest of it in the system unless the brakes have been overheated and boiled the fluid. If that happens you need to do a full flush and replace anyway.
Mark

 

[Tonyuk]

no there isn't. but why push dirty fluid back into the reservoir?

If the fluid is changed as per the service schedule then it wont be "dirty".

 

[redmondjp]

If the fluid is changed as per the service schedule then it wont be "dirty".

But changing the fluid doesn't get all of the old fluid out of the calipers if you just bleed the system - most of the new fluid runs in the hose and right out the bleeder screw.

When you fully depress the piston into the caliper is the only way to get all of the old, moisture-laden fluid out of the caliper. This is precisely when you do want to crack the bleeders and get that old fluid out. You don't even have to flush the rest of the system at the same time.

Plus, if there is debris in the calipers you don't want to force that back up into your ABS unit, which can easily happen on the front of the vehicle since the brake lines are short.

 

[Legion Prime]

I bet people recommend using some-type of solvent on the exposed piston before pushing it in. Also a bit of scrubbing, to remove any residue which remains after the solvent spray.

I'll take that bet, I honestly can't recall ever having heard that especially considering it's not uncommon for the piston to have a boot.

Most likely not, which means it will happen again. In addition to the causes mentioned above, improperly torqued lug nuts/bolts will cause it. Get yourself a torque wrench and use it correctly anytime the wheels have been removed. Check them again in one week.

Not just the torque but the pattern too. Don't just go around the lugs in a circle, use a star pattern first to hand tight then repeat the pattern to torque and then once more to torque. It really doesn't take all that much more time and can make a real difference if you're having issues with warpage.

Replace the pads, replace the hardware (clips), lube all metal to metal contact points on pads, caliper and bracket and piston face. Lube slide pins with sil glyde or caliper paste. There's a million brake job youtubes out there, it's worth watching a few.

Yes! If you are having problems replace all the cheap little stuff that can affect it. I'd replace the caliper pins/bolts as well, they're typically cheap enough. Clean and lube all bearing surfaces, it's the stupid stuff you ignore in a rush that gets you typically. I'll even go one further and say to antisieze all the bolts, it will make your life way easier the next time you break it all down.

 

[Tonyuk]

But changing the fluid doesn't get all of the old fluid out of the calipers if you just bleed the system - most of the new fluid runs in the hose and right out the bleeder screw.

When you fully depress the piston into the caliper is the only way to get all of the old, moisture-laden fluid out of the caliper. This is precisely when you do want to crack the bleeders and get that old fluid out. You don't even have to flush the rest of the system at the same time.

Plus, if there is debris in the calipers you don't want to force that back up into your ABS unit, which can easily happen on the front of the vehicle since the brake lines are short.

And that old fluid will be substantially diluted with the new fluid being added in and ran through.

Solution to pollution is dilution and all that, its a non-issue.

 

[redmondjp]

And that old fluid will be substantially diluted with the new fluid being added in and ran through.

Solution to pollution is dilution and all that, its a non-issue.

True, but if the brake pads are worn down and the piston(s) is/are extended fully, there is a lot of fluid contained inside the calipers, as opposed to the amount in the lines. I'd rather get all of that yucky fluid out at one time, and that time is when I replace the pads and compress the piston back in.

 

[u3b3rg33k]

And that old fluid will be substantially diluted with the new fluid being added in and ran through.

Solution to pollution is dilution and all that, its a non-issue.

bleed screw is at the top. squeezing it back in doesn't get the sediment out. inverting it and squeezing it gets the detritus out the bleed screw into your bucket.

 

[Tonyuk]

bleed screw is at the top. squeezing it back in doesn't get the sediment out. inverting it and squeezing it gets the detritus out the bleed screw into your bucket.

Too much effort for me tbh. Never done it and never had any issues.

I fact i've never seen it done, and the only time i've heard of issues due to not cracking the bleeder while pushing the piston in is on the internet.

 

[joe_pinehill1]

I use large Channel locks. If you can put an old pad in the caliper, press with Channel locks, and both pistons retract. If not, push one then the other until both are retracted.