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Calipers sticking on

Discussion in 'Audi S4/A4/A4 Cab (B7 Chassis)' started by steve123a, Oct 1, 2009.

  1. steve123a
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    steve123a Member

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    I have just had the front brakes changed on the car, discs and pads. All seemed fine except when they heated up and the calipers were sticking on slightly and at low speeds you could hear it squeaking.

    Took the car back and they stripped the brakes down and checked the calipers and they are completely free and all moving ok, they checked that there wasn't a build up of pressure in the system and that seemed fine. took it back out and all seemed fine until they heat up again and then seem to be sticking on intermittently!

    So took it back again to the garage and they said that the only other thing it can be is the master cylinder rod maybe sticking due to water contamination (rusted)!!!

    Can anybody through some light on this as I am stumped, don't want to have to get a new master cylinder fitted and then have the same issues... Anybody had similar issues??
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  2. NHN
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    & the old brakes didnt do this?
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  3. rowdyboy
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    rowdyboy Member

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    How long ago were they changed?
    They need a few hundred miles to "bed in". New discs and pads are quite a tight fit so when they heat up, they expand and may rub slightly and make a noise.
    Are you saying they are sticking on because of the noise or can you feel them slowing the car without you pressing the pedal?
    If a caliper was sticking on you would feel it more than hear it, either by pulling to one side or feel resistance when driving.
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  4. steve123a
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    steve123a Member

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    No real Issues with the old brakes but they were just very badly worn... not much life left on the discs or pads! Discs were soo bad they had grooves running along where the drilled holes are.
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  5. steve123a
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    steve123a Member

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    you can feel it through the pedal a lot of the time and when driving slowly you can hear it, I had the discs and pads on my S3 changed just before I sold it and they were fine no issues with rubbing or noise!
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  6. NHN
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    TBH mate I'd give it a bit of driving to see if it dies down, how many miles you done on them, you could have them skimmed by say .5-1mm which will probably resolve your issues & I think its just heat expansion as has already been said by someone else.

    I wouldnt rush to spend money on something that might not solve the issue.

    Drive for while, see if goes, if not have skimmed minimally, then test if still problem then look at MC & other parts, but I'd hazard it will go with some more driving.

    Are they oem parts?
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  7. steve123a
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    steve123a Member

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    I have done about 250-300 miles so far, hoping it will die down a bit soon! All OEM parts used. When I get in the car first thing in the morning, it drives lovely and you would never know, after a bit of heat thats when you can feel it... Guess I will wait and see, fed up with spending money on the car, just spent an absolute fortune on the clutch/flywheel and come coilovers and now the brakes...

    Thanks for the advice guys!
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  8. rowdyboy
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    rowdyboy Member

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    Just another thought mate, have you checked the garage have used the correct discs/pads? Disc thickness can vary between model/engine size cars by as little as 1mm but this may cause rubbing. Might be worth asking the question because they should not still be rubbing after 300 miles.
    Also when they checked the pistons for free movement, did they check the sliders were free?
    Not sure if audi's suffer from the same problem but on some cars, when the pistons are pushed back, it can reverse the seals in the master cylinder and restrict fluid movement.
    At the end of the day, if a garage fitted them and they were fine before, they should sort the problem without it costing you.
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  9. rowdyboy
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    rowdyboy Member

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    Ive only just noticed its a DTM you have got, i suspect the brake setup is different to other models so its an even stronger case for checking correct discs. (even if its a main dealer)
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  10. steve123a
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    steve123a Member

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    They checked the sliders and all move ok. I got the discs & pads from TPS they are a main dealer supplier, when they came in we checked the part numbers and size... going to see how i get on till early next week and if they still rub i will be taking the car back!
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  11. M7R
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    they should not be rubbing. you can always push the piston back enough to get clearance.

    by rubbing you will heat the face of the pad up and glaize it, this has prob already happened! and will mean the pads need re-facing by skimming with sand paper or if the resins properly cooked they maybe scrap.

    it will also polish the disc nicely so that will need cleaning up with sand paper too.

    take the pads out, push the piston right back in and then check the sliders operate properly too and clean and re grease if needed.

    clean up the carriers where the pads sit and apply some copper grease to them, and make sure the pad back plates are smooth in this area and dont have any paint drips etc, if they do clean them up with sand paper.
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  12. NHN
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    I agree, its down to them if correct parts ordered & car was full functional before.

    Yeah agreed.

    Worth rechecking against your vin tbh mate, as parts departments & TPS are certainly not perfect given yours isnt a standard A4.
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