Help!! Stuck caliper pistons

mperkins · 09-29-2003, 07:50 AM

after a very frustrating afternoon yesterday, i could not get my caliper pistons to recede on my front left brakes - they are fully extended.

Car is stranded in garage and i really don't want to have to pay for a tow.

this thread offers some help - but i believe the problem is opposite mine - they're trying to get them "blown out."

unsticking calipers

any advice?? thanks.

Neilk · 09-29-2003, 07:52 AM

Use a large C-clamp to get them back in. You might want to investigate why that is happening though. Perhaps bad brake lines.

MotoSook · 08:00 AM

If the piston on one side is out beyond the seal (why you can't easily get it back in), you might as well, pull the caliper and look things over. If the piston is cocked, you'll want to take caliper off too to get things right. Don't force it back in with a c-clamp..if it is cocked or you are beyond the seal..forcing it in could lead to more work. Get it out and put it back in right.

I recently rebuilt my calipers and it was a PITA to get the pistons out, but with new seals, the pistons went back in fairly easily.

Read Bob'd Pelican tech article to familiarize yourself with a rebuild. You'll then understand what's going on with your caliper.

Jdub · 09-29-2003, 08:00 AM

More information needed. Did the wheel bind up in the garage or on the way home? Or were you rebuilding them? Or were you bleeding the brakes without the rotor in there?

Typically to get pucks to go in you open the bleed screw and push. However, you don't want to force the pucks back in against 1) swarf that will score the puck/wall or 2) brake fluid you cannot possibly displace with your hands or a C clamp if it has nowhere to go.

More information will help us here.

John

Rot 911 · 09-29-2003, 08:01 AM

I guess I would need more information although it sounds like what Souk is saying: the piston is out beyond the seal. In that case, pull this piston out and install new seals. Was the piston stuck prior to extending to far? If not, then just go the c-clamp route. If so, might as well blow that sucker out and take a look at the caliper.

mperkins · 09-29-2003, 08:08 AM

alright, this is the brief story. I was in there to just replace the brake pads. No big deal. Immediately, my pistons wouldn't budge, so i thought i'd bleed that caliper to release some pressure thinking that would help me push them in. In doing so, my helper pumped the brakes - the pistons extended - and they've frozen outward.

I removed the caliper from the rotor for more leverage (but did not disconnect the hard brake line). Preceding this i have had absolutely no problems w/ my brakes - i just wanted to insert some new pads for an upcoming DE.

the car has 78K miles and all equipment is original.

thanks for the advice all.
Maurice
1980 SC Coupe

Superman · 09-29-2003, 08:46 AM

You can remove the bleeder and use a c-clamp or c-clamp vise grip to push it back in. The c-clamp should be centered at the back (innermost) portion of the piston. This will help straighten and center the piston. If it gets crooked, it will get wedged in there.

Safest method though, would be to use brake pedal pressure to remove the piston, and then reinstall. If you try this, be sure to secure the other piston, like with the C-clamp.

Jdub · 09-29-2003, 10:04 AM

Maurice:

I hate to say this, but if this equipment is original you are due for fresh brake hoses anyway. You should seriously consider replacing the caliper seals as long as you are at it.

So, you'd want Liquid Wrench or PB Blaster, proper brake line wrenches, a tube of silicone (rubber-friendly) grease, a rebuild kit for each caliper, fresh brake fluid, and a spray can of silver caliper paint to pretty it all up. Believe me, this is a very worthwhile bit of time spent and you can do this all yourself for under $100.00.

John

MotoSook · 09-29-2003, 10:10 AM

How important is stopping to YOU! For less than the cost of a tank of gas, you can rebuild your calipers. For the cost of another tank, you can replace the hoses with the rubber OEM hoses. You obviously have the new pads.

Do it right or don’t drive the car…(I like being this high on my high horse

)

Bob Spindel · 09-29-2003, 11:11 AM

Do what Superman suggests. At this point their either out beyond their seals, or cocked, and trying to get them back in will make it worse. Remove the psitons and reinsert, or, as many have said, remove the pistons, install new seals (that's what rebuilding is) and then reinsert.

makaio · 09-29-2003, 05:03 PM

I'm with Souk on this one. This is a sign that your car is trying to tell you. Even with less than 80K on the odometer, you've got 23 year old brake seals and hoses.

mperkins · 10-08-2003, 01:53 PM

well, the latest update is..
I took you all up on your rec's and rebuilt the front calipers, added new rubber hoses - as well as new metal lines for the calipers. All these products courtesy of PParts - which were shipped rather quickly which was nice..

so, after I properly installed everything - i bled the entire system about 5-6 times. Proceeded to take her for a ride and test it all out.

Huge disappointment! I had to pump the brakes to get them stiff. Obviously i wasn't getting good pressure and there must be leak somewhere. So, I drop her off at the mechanic on Mon. morning and explained what happened.

He calls me back this afternoon, "you need an entire new master cylinder. Plus labor and another bleed - that'll be $545." I'm like what the $#@@*!!" My entire brake system was working flawlessly 7 days ago - then i go to replace some brake pads for an upcoming DE - and i'm now close $700 in the hole.

And does it take a professional mechanic 3 hours to install a MC??

He could not explain to me how rebuilding my calipers led to screwing up the MC. Unfortunately, i have to bite the bullet and pay - cause I'm outta town tomorrow - and the DE is on Mon.

Upside is that i learned quite a bit - but the added $$ - plus all the labor i put in myself - only to end up handing it over to the mechanic for a raping - is aggravating.

Maurice
1980 SC Coupe

Emission · Emission's Garage

If your "helper" pushed the pedal all the way to the floor, he could have ground some of that grime (from 23-years) into the MC. That will score the walls leading to loss of pressure. It happens.

The good news is that your calipers are OK!

juanbenae · juanbenae's Garage

perkins, dont let him touch it until you have "set" the new caliper in. search for some post on mush peddal and you will find that after a caliper rebuild that it will take a few heat cycles to get them set in proper. dont do any track events and be aware of you brakes short comings while doing it.

i rebuilt mu calipers and had the same problem until i drove it a couple times. im not saying you MC is not bad but try bleeding the brakes a couple more times and use the brakes a bit to see if things come back.

MotoSook · 10-08-2003, 02:28 PM

Emission is right…you could have damaged the seal in you MC when you bled the system. I highly recommend you get a Motive Bleeder, especially if you are going to be doing DE’s. You will need to bleed you brake system almost every DE…sometimes at the track! When the hot brakes cool after a session, your brakes will feel spongy until things heat up again or your pads are extended…you can bleed them if you’d like, but mine usually come back to firm after a few jabs in the pit lane. I still bleed before every DE.

It may be cutting it close for you to do it yourself, but it’s not a terrible job. I think it took me about 3 hours on my back with no prior experience! An experienced wrench with the right tools and a lift…could probably do it all in two hours or less, me thinks!

Get the MC on order and it’ll be there when you get home from your trip. Install it and go! You will feel much better to have a fresh braking system. Hardest part was getting the dang clear line’s rubber grommet into the hole in the sheet metal after I pulled it out to get more flex in things.

If you must pump the MC to bleed, try not to go all the way down…just get a Motive bleeder! I got mine for less than 40 bucks!

MotoSook · 10-08-2003, 02:30 PM

Note: Everytime you bleed the brakes, make sure to pump a little with the pedal to extend the pistons to the rotor...do go peeling off and find you have no BRAKES!!! on the first few stops!

Emission · Emission's Garage

Quote:

Originally posted by Souk
Note: Everytime you bleed the brakes, make sure to pump a little with the pedal to extend the pistons to the rotor...do go peeling off and find you have no BRAKES!!! on the first few stops!

... Oh to think how many times I have rolled down my driveway after changing pads then though "Oh *****" as the pedal had nothing under it!

Yes, pump before you back out.

Danskman · 10-08-2003, 02:42 PM

Also... when you have a "helper" pushing the brake pedal, it's important to have them do so slowly. With the bleeder valve open it's very easy to just stomp the pedal down to the floor and invert the cupped seals in the MC. I've had this happen on a race car before.