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  #1  
Old 07-20-2003, 03:09 AM
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S.o.s. Help!

OK heres the deal. I was trying to replace my brake pads today, I read the DIY thing and everything was going great until I got to the part where I need to compress the piston back into the caliper. It seems really stuck I tried a C-clamp but to no avail. What should I do. I need to somehow get this thing in. How can I relieve the pressure safely so I can push it in. Please help. Me and my car arent going anywhere until I figure something out. Thanks I know you guys can help I just hope I can fix this before I got to go to work on monday.
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  #2  
Old 07-20-2003, 03:17 AM
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Hello:

Did you try taking the cover off the master cylinder? If you didn't, give it a try but put a towel there to catch the overflow.

Aloha,
Eric
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  #3  
Old 07-20-2003, 03:20 AM
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Loosen the bleeder screw slightly. If it doesn't go then, you've got a stuck piston in the caliper.
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  #4  
Old 07-20-2003, 10:27 AM
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It is not likely that fluid pressure is holding it.

If that is the case your best bet would be to get a rebuilt caliper (or new) as even if you do break it loose it will continue to be a problem.

The way we get the loose (for rebuilding purposes) is to remove the caliper completely and place a special bleeder in place that allows us to pump the caliper full of high pressure grease from a grease gun. Then clean it all up and replace the seals if the metal is not corroded.
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  #5  
Old 07-20-2003, 02:02 PM
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The piston has never given me any problems until now. And I hope that it isnt stuck, cuz Im a little strapped for money right now and I dont think I can afford a new one. Thanks for your help though.
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  #6  
Old 07-20-2003, 02:16 PM
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Put both pads back into the caliper. Use a large channel lock pliers and grip on side the brake pad and the other the outside of the caliper. Try compressing several different times.

Also, with all the pads in the caliper, try alternating between stepping on the brake pedal and compressing as per above.

The reason I don't like using the C-clamp is it can too easily make the piston twist slightly going into the caliper.

Haasman
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  #7  
Old 07-20-2003, 02:38 PM
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Make sure you are pressing directly on the center of the piston -- if you pry or push on the edge, you can get it cocked in the bore and it won't move until you tilt it back.

The last time I had one that stuck I ended up rebuilding the caliper -- idiot PO (or his mechanic) put new pads on a rotor that was too thin, they got cocked and roasted the dust shield. Lots of dirt and corrosion around the top fo the piston, wouldn't go back in. Piston cleaned up fine,though, still works great. Big PITA though.

Peter
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Last edited by psfred; 07-20-2003 at 09:51 PM.
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  #8  
Old 07-20-2003, 06:28 PM
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Yea whenever I step on the brake I can see the piston come out slightly, I did this to make sure that it wasnt stuck in there. Thanks for your help guys, Ill go try and play with it some more.
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  #9  
Old 07-20-2003, 08:23 PM
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Do you think that it would help if tried and get the piston out of the caliper, clean it up a little bit, then try and get it back down in. I stepped on the brake again and the piston is coming out. Now it is moving a little bit, side to side. More help please this thing wont even budge.
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  #10  
Old 07-20-2003, 08:30 PM
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bump...Im desperate
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  #11  
Old 07-20-2003, 08:33 PM
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Do you think that it would help if tried and get the piston out of the caliper, clean it up a little bit, then try and get it back down in. I stepped on the brake again and the piston is coming out. Now it is moving a little bit, side to side. More help please this thing wont even budge.
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  #12  
Old 07-20-2003, 08:45 PM
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craiggotgame

Getting the piston out and then trying to get it back in is not something I would recommend unless you know what you are doing.

I am surprised that the piston is frozen in the caliper in a 1997 Mercedes. Something doesn't sound right.

I got this picture from the DIYer section, does yours look like this caliper?

BTW, prying against the rotor with a screw driver to push the pistons back into the brake caliper is not a good idea in my book.

Haasman
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S.o.s. Help!-compress_piston2.jpg  
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  #13  
Old 07-20-2003, 09:52 PM
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Open the bleeder and try again, you may just have too much back pressure. Make sure the cap is off the master cylinder, they can seal tight enough to prevent moving the piston back.

Also, I think you have a floating type caliper -- piston only on one side on the front brakes.

Peter
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  #14  
Old 07-21-2003, 12:15 AM
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Yea I have the piston on only one side of it. And that picture is not of what mine looks like. Anyways I think I fixed it I took the piston out and cleaned it. Most of the brake fluid came out. But I got the thing in there and it seems to be working ok now. Thanks for the help guys you are awesome. I had no one to call on a saturday night for help like this, we are all very lucky to have this forum full of such knowlegeble people. THANKS AGAIN!!
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  #15  
Old 07-21-2003, 12:21 AM
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This is what you need


http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=35625&item=2424614909
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