brake job question
Thread Starter
Instructor
Joined: Feb 2007
Posts: 142
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brake job question
ive done enought brake jobs to be comfortable on just about any vehicle. however yesterday i came across something ive never seen. the vehicle is a 01 chrysler 300m. the brakes are completely shot. no brake pads. all rotors are destroyed. i pulled front passenger side tire, opened to brake fluid resovoir, removed what was left of the pad and tried to depress the piston. piston would not budge. put a c-clamp on it and it still would not move. any ideas or suggestions.
Le Mans Master
Joined: Sep 2003
Posts: 8,847
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From: Longview Texas
I don't have a manual for a Chrysler, but some pistons take a special tool to rotate the piston to get it back into the bore instead of just being able to push them in.
Also, you might want to crack the bleeder screw to push the fluid out instead of pushing old fluid back into the system.
Is the piston face smooth, or does it have a face that looks like a tool would fit?
Also, you might want to crack the bleeder screw to push the fluid out instead of pushing old fluid back into the system.
Is the piston face smooth, or does it have a face that looks like a tool would fit?
Tech Contributor
Joined: Apr 2007
Posts: 10,924
Likes: 78
From: Forney Texas
Only time I have seen the twisting pistons is on the rear calipers when the e-brake is integrated. Piston is probably just too far extended and off it's axis put a straight edge across it and see if it's square in the bore.
Safety Car
Joined: Aug 2000
Posts: 4,933
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From: San Rafael CA
But, BlownBlue may well be correct, the piston may be out of square and is jammed in the caliper. If it is you can use brake pressure to "pop" it out .... BUT .... be very careful, the piston will come out with incredible force ..... have some shop towels in place to try and slow it/catch it as it comes out of the bore.
Good luck,
Le Mans Master
Joined: Sep 2003
Posts: 8,847
Likes: 795
From: Longview Texas
If you are going to try to push the piston out with hydraulic pressure, I would put a block of wood or some kind of spacer in the caliper so that the piston can move, but cannot blow all the way out. 
Safety Car
Joined: Aug 2000
Posts: 4,933
Likes: 30
From: San Rafael CA
The block of wood is a better suggestion than my original "use shop towels" ....
Tech Contributor
Joined: Oct 1999
Posts: 41,058
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From: Charlotte, NC (formerly Endicott, NY)
Sounds like it is time for 4 rebuilt calipers. Once you figure in the cost of parts required to rebuild the calipers you might as well save yourself some headaches and buy rebuilt calipers. Let the rebuild company figure out how to free up the piston in the old calipers.
Bill
Bill
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Race Director
Joined: Mar 2007
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From: Marlton. Increasing performance one speeding ticket at a time! NJ
Sounds like it is time for 4 rebuilt calipers. Once you figure in the cost of parts required to rebuild the calipers you might as well save yourself some headaches and buy rebuilt calipers. Let the rebuild company figure out how to free up the piston in the old calipers.
Bill
Bill
Completely.
Don't waste your time. Whenever I see a caliper with a piston problem, I don't care how it happened or how to fix it. I just replace the caliper. Brakes are the single most important safety feature on a car........why screw around with potential bad parts?
Instructor
Joined: Mar 2004
Posts: 114
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From: orlando fl
I agree with above - scrap it all, get new rotors, pads, calipers, and bleed the brakes - hopefully the lines are still good, and not collapsed internally. If they have the money, I'd personally replace the front lines at the same time - gotta bleed them anyway, and it's not that expensive for new lines up front. The whoa is more important than the go.
curious how this goes - keep us updated?
curious how this goes - keep us updated?
Thread Starter
Instructor
Joined: Feb 2007
Posts: 142
Likes: 0
thanks for everyones input. rebuilt calipers are CHEAP for his car. thats the route im going. i believe the pistons were overextended and no longer perfectly lined up. but also good point that the caliper was taking alot of heat due to the no brake pad condition. rebuilds all around.