Classic Audi Technical Mech/Tech Suspension & Brakes » C3 Brakes seizing -help!

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Old 26-05-18, 09:55 PM   #11
Ringmaster
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Quote:
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On my CQ the underbonnet temp gets pretty high I think.....and this is when my brakes would bind.
Does yours have a vacuum servo, if yes it would be easy enough to pull of the vacuum pipe when they're binding and see if they release ?.......if yes then servo not good. If you have vacuum servo!

It's boosted by the PAS pump.
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Old 26-05-18, 09:58 PM   #12
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Thanks chaps.......
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Old 27-05-18, 05:12 AM   #13
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Quote:
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It's boosted by the PAS pump.
That's twice I've asked.

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Old 27-05-18, 09:18 AM   #14
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It is certainly the master cylinder - its well documented on other forums (quattroforum.com for one!)
concensus of opinion says that its a heat soak issue having a detrimental effect on what could be (in your case certainly) very old rubber seals.......

Depending on the age of the MC that is on your car, the only way to get into the unit is to partially destroy it......however, for the cost of replacement its not really worth the hassle.

My 1986 car is now on its 5th replacement master cylinder - everytime displayed the same symptoms...binding brakes.
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Old 27-05-18, 11:25 AM   #15
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The M/C is original, so at 31 years I shouldn't be surprised if it's breaking down on the inside. Bit like me really!

The M/C is accessible to work on, so thankfully no major headaches there.

Thanks for your input chaps.....
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Old 13-06-18, 01:16 PM   #16
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Folks,

Looks like it was the front calipers, especially the front near side. The problem remained intermittent.

Calipers stripped down, cleaned, greased etc., and all seems ok now, but will keep fingers crossed in the short term.

I purchased a new MC anyway as I'm sure a suitable one would get harder to source in the future.

If, like me, you prefer to buy these things from a human being rather than on-line, for those of you in East Sussex I recommend Autolec Motor Factors. They have been able to supply a hard to get part for the C3 before and prices seem fair.
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Old 13-06-18, 01:46 PM   #17
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How does that explain the rears getting hot as well?

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Old 13-06-18, 07:45 PM   #18
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It doesn't.....

But during the last couple of 'episodes' the rears were no hotter than one would expect.

Anyway, I'm not going to consider myself out of the woods until a few incident free weeks have elapsed....... So far so good today.
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Old 13-06-18, 08:05 PM   #19
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Fair enough and hopefully that’ll be that
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