sticking brake caliper

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marty1850
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Year and Model: '96 850 GLT
Location: Woodstock, NY

sticking brake caliper

Postby marty1850 » Sun Oct 18, 2009 2:10 am

My front right wheel started heating up - noticed it after the steering wheel began to intermittently vibrate at high speeds.

The wheel won't spin easily so I'm thinking it's probably the caliper. I'm new to this so pardon the dumb question to come. I've got the wheel off, pads seem to have a lot of material on them; first I tried cleaning and regreasing the slider pins but it still gets hot - wheel won't spin freely.

So now I'm wanting to get the caliper off, it moves a tiny bit but won't come out. What is a good way to push back the piston, w/o necessarily having to replace the pads or rotor as a result?
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Re: sticking brake caliper

Postby JDS60R » Sun Oct 18, 2009 2:48 am

This type of symptom needs some attention as it creates a fire hazard.
It is good that is sticking so will know when you have fixed it.(won't stick any more)

You can use a C clamp from any hardware (lowes/home depot/harbor freight) store to push the piston back in. You should open the bleeder while doing this to allow the old brake fluid out rather than forcing it back through the ABS pump.

Occasionally too much silicone grease is put on the slides and a suction is created so the caliper is unable to release itself. Take the caliper off and press the sliding side towards the piston side and then observe it as you let go. If it pushes back then you have an issue and have to repack it. Also -any petroleum based product used to lubricate the slides casues the rubber to swell and can cause the same problem. If you have or think this may be the case get a new set of rubber slide covers from your local parts store and then repack with Sil Glyde or similar.

If this does not work then I would change the flexible line and bleed the system. The flexible line breaks down internally and can casue a restriction when the caliper is trying to release. Sometimes a caliper can get bound up internally but this is extremely rare.

Let us know what you found - it helps others in the future who search for the same problem.
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marty1850
Posts: 9
Joined: Sun Oct 18, 2009 1:37 am
Year and Model: '96 850 GLT
Location: Woodstock, NY

Re: sticking brake caliper

Postby marty1850 » Sun Oct 18, 2009 4:01 am

My problem is not able to remove the caliper to put the c clamp on the piston - I guess that's because it's so tight on there. Is there a way to push it back in - with the bleeder valve opened up - while still on the rotor?
'96 Volvo 850 GLT wagon
'92 Saab 9000S sedan

Craigd2599
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Re: sticking brake caliper

Postby Craigd2599 » Sun Oct 18, 2009 10:02 am

pry bar
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Re: sticking brake caliper

Postby iselloil » Sun Oct 18, 2009 12:21 pm

If its sticking, replace it,its more than likely got a torn dust boot and has had water or trash gaulling the bore.Its just going to stick again.It take a 5.mm hex and ten minutes to get it out.$50.00 for a reman.
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holler1
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Re: sticking brake caliper

Postby holler1 » Sun Oct 18, 2009 12:34 pm

I understand, you have the caliper still stuck on the rotor. With the caliper still on the rotor, if you have a large C clamp, you can put one end of the clamp on the back of the caliper and the other end, the one that has the screw, on the outer brake pad, between the lobes of the caliper. Tighten it down and it will push both pads and the rotor back towards the caliper piston. That won't damage anything as long as you tighten the clamp only far enough to get some room to slide the caliper off the rotor. Then with it off you can reposition the C clamp to retract the piston further.

If no C clamp, try a pry bar between the outer lobes of the caliper and the outer pad. Put pressure on it and give it a few seconds to move.
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marty1850
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Year and Model: '96 850 GLT
Location: Woodstock, NY

Re: sticking brake caliper

Postby marty1850 » Sun Oct 18, 2009 7:17 pm

I have a long pipe clamp that got on there but the rotor will still only turn turn roughly - maybe enough though. Should the caliper be coming out and leaving the pads behind? This started happening as I began rocking the caliper out a few mm. and made me nervous, so I've attached a couple of photos to show what I'm talking about.

Also if I want to open the bleeder valve while trying to push in the caliper piston, what size of tubing goes on there?
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Re: sticking brake caliper

Postby misha » Sun Oct 18, 2009 10:25 pm

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Ozark Lee
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Re: sticking brake caliper

Postby Ozark Lee » Mon Oct 19, 2009 3:56 am

marty1850 wrote:I have a long pipe clamp that got on there but the rotor will still only turn turn roughly - maybe enough though. Should the caliper be coming out and leaving the pads behind? This started happening as I began rocking the caliper out a few mm. and made me nervous, so I've attached a couple of photos to show what I'm talking about.

Also if I want to open the bleeder valve while trying to push in the caliper piston, what size of tubing goes on there?


Wow, from the second picture it almost looks like your inner brake pad delaminated. The part that is dangling shouldn't be there unless it is the steering stop and there should be pad on the inner area on the first picture. From the pictures it is a little tough to tell.

If it were me I wouldn't open the bleeder valve unless you absolutely have to. I just use a big screwdriver and press the piston back by wedging it in between the face of the pad and the rotor and then prying. Slow steady pressure works the best and you may want to pop the hood to observe your brake fluid level so that it doesn't overflow since brake fluid is very bad on the paint.

If you open the bleeder valve you are looking at a full system bleeding, at that point you might as well flush the fluid.

I can't tell you the exact size of the hose but whatever came with my Harbor Fright vacuum pump fit fine - I think it is kinda standard for all brakes.

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polskamafia mjl
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Re: sticking brake caliper

Postby polskamafia mjl » Mon Oct 19, 2009 7:40 am

A lot of people like using screw drivers and pry bars or opening up the bleed valves. I don't like that method too much because it forces your to bleed the system later while using screw drivers and pry bars, well I don't really know what people do with those. lol :D
- Pop the hood and unscrew the cap to the brake fluid reservoir
- With the wheel off, sit on the ground or something else with the rotor/caliper assembly in front of you
- Take both hands and place them behind the brake caliper, aka the far side of the caliper.
- Pull the inboard side of the caliper towards you. This compresses the piston enough so you can slide the caliper off of the rotor. It takes a bit of force to compress the caliper. I had to do this a couple of times until I pushed the piston enough.
Also, it is normal for the pads to stay behind as you pull the caliper off. This is pretty messy so be prepared to wipe your hands on something.
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