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  #1  
Old 03-04-2007, 06:48 AM
Tassie Tiger
 
Join Date: Sep 2004
Location: Melbourne, Victoria, Australia
Posts: 69
1967 W108 250SE front brake problem

I replaced my front disc brake pads last weekend and noticed that car pulled to the left during braking. After about 20 minutes of driving I could smell burning friction material and the LHS front wheel and hub cap were hot. The RHS was normal.
Today I drove for about 20km and the same smell and heat were evident. I removed the LHS wheel when I arrived home and removed the disc pads. The disc surface was covered with black spots/marks and the pads had a similar appearance on their surface. I noticed some black flakes inside the caliper.
I put my old pads back in and the brakes performed fine.
What could be the problem here? Is it possible to have faulty brake pads? The new pads on the RHS are OK. I would appreciate your comments and advice.
Regards,
Tassie Tiger
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  #2  
Old 03-04-2007, 08:11 AM
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Did the piston on the left hand side compress all the way when you replaced your pads?
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  #3  
Old 03-04-2007, 08:54 AM
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Did you replace the brake hoses in recent memory? Those rubber hoses age and constrict. That keeps fluid from escaping after you hit the brake.

They have a lifespan of about 5 years.

-CTH
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  #4  
Old 03-04-2007, 09:09 AM
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Addition to CTH post:
Jack up that wheel and press brake pedal down hard. Try hand rotation of wheel. If stuck , open bleeder. If bleeder trick now allows wheel to turn freely, change the brake hose on that side. [ if you have to do one side , do the other..they are cousins]
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  #5  
Old 03-04-2007, 09:30 AM
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Addition to addition. Press brake pedal down hard AND THEN RELEASE. Try hand rotation, etc.
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  #6  
Old 03-04-2007, 09:38 AM
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Yeah................don't HOLD the pedal down...kinda goes without saying, but I hear ya...
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  #7  
Old 03-05-2007, 12:10 AM
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I would guess that you need brake hoses AND a caliper rebuilt -- likely the rubber in the caliper seal is rock hard and contributes to the pads not retracting. You need new fluid, too, if you haven't changed it recently.

Also, make SURE you get all the crud out of the slot the pads fit in -- if you don't, they can stick on the rust and drag.

Peter
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  #8  
Old 03-05-2007, 12:20 AM
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The Pedal/Bleeder test tip posted is to distinquish between a hose that is restricted or the caliper is frozen/binding.
If the wheel does not turn freely when bleeder is opened , you then know the caliper is the problem, and not the hose.
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  #9  
Old 03-05-2007, 01:59 AM
Tassie Tiger
 
Join Date: Sep 2004
Location: Melbourne, Victoria, Australia
Posts: 69
Thanks for your responses. I will try both suggestions tonight and advise results. As the brakes are performing fine with the old pads in place (LHS only), would this indicate that the brake hose is fine and possibly the caliper is malfunctioning when the pistons are displaced to accommodate the new, thicker brake pad?
Regards,
Tassie Tiger
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  #10  
Old 03-05-2007, 09:56 AM
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Possible ..the crap/rust on the piston usually accumulates on the seal end due to leaky dust cover/seals, so new pads [ being thick] push the piston further into the cavity and then they stick b/c the crap line on the piston is now in the cavity.
....do the test..that will tell you and that is why it was posted.

Last edited by Arthur Dalton; 03-05-2007 at 11:25 AM.
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  #11  
Old 03-05-2007, 05:43 PM
Tassie Tiger
 
Join Date: Sep 2004
Location: Melbourne, Victoria, Australia
Posts: 69
I opened the bleeder on the caliper and the disc still required a firm force to turn it. I removed the caliper and disassembled it. After I removed the pistons, the bore had all sorts of crud inside and I assume that when the piston was pushed back into the bore to accept new pads, this made the piston stick and not return. I will clean up the caliper and reinstall this weekend.
I appreciate your comments and advice. Thank You.
Regards,
Tassie Tiger
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