The Autonerdz Community Forums - Antilock brakes locking

broncwonk

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Antilock brakes locking
Aug 27^th, 2009 at 7:59am

I have recently been experiencing intermittent lock-up on the rear drum brakes on my 2002 Pontiac Sunfire. The right rear wheel particularly, will grab and hold briefly on gravel (like my driveway and the road we live on), especially when the car has been sitting overnight. When I stop the car, within five seconds I will hear something that sounds like a "thunk" from one of the rear brakes. None of this affects movement, except when I apply the brakes. That is, I'm not noticing any dragging while driving. I changed the rear linings at 150,000. Is there something I could have missed or moved or failed to do in that procedure?

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Kevin Claybrook

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Re: Antilock brakes locking
Reply #1 - Aug 27^th, 2009 at 12:54pm

I am doubtfull that this is an abs issue but would bet it is a base brakes issue. Are you braking when rear brakes grab? I would pull the drums back off for another inspection to start. Make sure you don't have any wheel cylinders leaking. Brake fluid on shoe linnings can make them sticky and can cause brake grab. Did you have the drums turned when you replaced shoes?? Out of round drums could be an issue also. If you don't find anything scuff the shoes and drums with sand paper and clean both with brake cleaner and go from there.

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brandonb Super Nerd Picogroup Offline Posts: 1,414 arizona Arizona USA	Re: Antilock brakes locking Reply #2 - Aug 28^th, 2009 at 6:38pm i agree with kevin, i see this all the time.........warped drums.......sometimes a brake adjustment can remedy it but not usually......you can get them turned at car quest for 20 bucks?
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Mike Lappert Freshman Member Picogroup Offline Posts: 48 Middlefield Ohio USA Gender:	Re: Antilock brakes locking Reply #3 - Sep 1^st, 2009 at 4:58pm I've had good luck replacing the hardware springs for this. If the springs are too weak, they'll let the shoes come out too early, too hard. Also keep your adjustment on the loose side. The drum should spin free, with no drag.
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broncwonk Freshman Member Offline Posts: 3	Re: Antilock brakes locking Reply #4 - Sep 13^th, 2009 at 7:38am Sorry to be so late getting back to this. The out of round drum sounds reasonable. I have replaced the sprng set, so this week I will pull both drums and turn them. Thanks for the advice.
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Randy H.

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Re: Antilock brakes locking
Reply #5 - Jan 5^th, 2011 at 1:03pm

Yeah I agree with these guys. Be sure to CAREFULLY inspect everything before you disassemble it - look for fluid leaks, etc. One good test is to take a coiled brake spring on the concrete floor. It should go thud and not bounce a lot. if it makes a twang and bounces up you have found a bad spring. (this will not work with the big unisprings - only coiled springs) Also hold them up to the light and see if you can see any gaps in the coils - if you can they are bad.

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Randy Hatton
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Randy H.

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Re: Antilock brakes locking
Reply #6 - Jan 5^th, 2011 at 1:06pm

Also I have noticed on some brake linings that they will actually freeze to the drum when it gets cold. the lining will get wet, freeze to the drum, then grab hard when you drive off. Once this happens, it will ruin your return springs too. Also, make sure you didn't accidentally put the adjuster on the wrong side, parking brake is adjusted properly, and make sure you didnt lose the wave washer off the adjuster. Finally, did you lubricate the backing plate ledges?

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Randy Hatton
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Brad H Super Nerd Offline Elevation 367 metres Posts: 1,115 Kalgoorlie Western Australia Australia Gender:	Re: Antilock brakes locking Reply #7 - Jan 5^th, 2011 at 4:24pm I also dab a SMALL amount of coppercote lubricant on the contact surface of the backing plate where the shoe sits. This helps the shoes return to the correct position & not get hung up. I also file a small chamfer on the leading & trailing edge of the liner. Brad
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Randy H. Super Nerd Picogroup Offline Tools are only as good as the Tech holding them Posts: 1,692 Bardstown, Kentucky Kentucky USA Gender:	Re: Antilock brakes locking Reply #8 - Jan 5^th, 2011 at 11:36pm What is coppercote Brad? Have never heard of it... I always use SYLGlyde barke lube. Is coppercote better?
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Brad H Super Nerd Offline Elevation 367 metres Posts: 1,115 Kalgoorlie Western Australia Australia Gender:	Re: Antilock brakes locking Reply #9 - Jan 6^th, 2011 at 2:36am It's like anti-seize but it doesn't go everywhere
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