Brake noise

[alastairg]

They all do it to a greater or lesser extent. I have been advised to overhaul pistons with new dust seals to ensure they return to the resting position after application. Thus stopping intermittent noise !!

[Doug_S2]

Alastair and Angus - Is this noise only happening after you have braked, and when you start pulling away? If so, it is crud (probably had copper grease in there at some point and that gets the crap sticking to the pistons) that gets baked on the pistons and they do not retract properly when warmed up. I had this problem for a long time on my AP brakes. It was amazing how much rubbish was on the pistons - I don't know how much new pistons are but it might be easier to replace them.

As Alastair says, it is a good idea to get the pistons cleaned properly and while you are at it get the seals replaced.

The stainless sliders for the pads also get a corrosion underneath which cause these to lift and then the pad will not slide as freely as it should.

I should have said earlier - but I don't read brake threads much!

[robo]

I don’t think that will help.
I had this noise come on at 140mph in Germany it was scary I thought it was wheel bearing falling to bits, but it was gone by applying brake pedal gently.
I was doing everything from total refurb to new brake pads.... at the end I bought new 993t with 322mm discs for about £ 900 and NO MORE PROBS fingers crossed.
________
Rob

[super-g]

Before you decide to replace seals or pistons (check condition thoroughly as they should not need replacing until 200,000 miles) bear in mind that the problems you are experiencing with noise and poor brake performance will undoubtedly lead to uneven disc wear. After any caliper work has been carried out check that both sides of the disc are clean with no rust build up i.e. brake pads are moving. Most rumble, bearing type noise come from the rear discs which do not work as hard so the disc wear becomes uneven as the brake pads begin to seize. This uneven wear will be there so you will need to allow at least 5000 miles for the disc to true itself as the caliper piston movement will not compensate for uneven disc wear, for severe uneven wear you are going to have to replace the disc, the inside is usually the worst. This also applies to the front brakes,

If the noise does not disappear after 5000 miles replace the disc, this is when the noise is happening on regular journeys, not confusing it with the occasional very hard use.

Just one other thing worth checking for noise reasons if the brakes are working correctly and the discs have even wear is the drive shaft bolt. I once asked a Audi dealer mechanic about torque setting, he told me they only torque upto 150lbs and not to bother with the angle torque gauge, bad advice when undoubtedly the drive shaft CV rubbers would have been replace at least once on these aging cars so the bolt would have been removed. If this work was carried out by an Audi dealer or others check anyway, this will also keep the bearing in good condition.

PLEASE NOTE. Only change one think at a time that way you can always go back.


Best & Good Luck!

[alastairg]

Fair comment but the noise is from the front and is usually follows gentle application and is solved by firm application. Discs look good and the backs are getting used ! unlike previous S2.
I think best explaination remains poor piston retraction. When I finally get the new propshaft from audi I will get this checked at same time.

[AAH!]

Alastair and Angus - Is this noise only happening after you have braked, and when you start pulling away?

Doug

It was "afhgus" who reopened this thread not me, but I too suffer from break "groaning". For me it comes from the rear brakes and has done for a few years.

Mine seems to be due to corrosian and dissapears whilst breaking and reapears a few minutes later. Sometimes I go for weeks without any noises then it reapears. When it gets really bad, giving the rear callipers a good clean out and getting rid of any build up of corrision helps for a while.

Very hard braking seems to help and keeps the noises at bay, as I discovered out of nesecety this morning when out with Mihnea mapping the car . But thats another thread.

Angus

[robo]

Hi Angus
How did it go , is it all fixed??
________
Rob

[afhgus]

Some crossed wires here! Unrelated but do 968 owners have these problems too?

[super-g]

Hello Alistair,

My last thread relates to front or back. Please allow 5000 miles before you strip down the caliper as mentioned previously, your disc would have been wearing unevenly with sticking pads, is a lip developing on the outer edge of the disc, compare each side. If there is a difference the noise will appear until the disc tries to true its self? The pistons retract equally so if the disc wear is uneven one side of your pads will be touching.

If you have always retained the piston seal shield the dirt build up will be minimal and easily cleaned. Take the pads out and operate the brakes you should be able to see them moving, remember the hydraulic system is working in a vacuum, when you take your foot off the pedal the fluid is drawn back and this sucks the piston in.

We have mentioned minor causes before so again I would give it at least 5000 miles before stripping down a caliper.

Corrosion is a problem with all aluminium calipers but the Brembo/Porsche calipers seem to be the worst.

best

[afhgus]

yes,just had rear calipers,cleaned regreased and handbreak ajusted

[alastairg]

Hello Alistair,

My last thread relates to front or back. Please allow 5000 miles before you strip down the caliper as mentioned previously, your disc would have been wearing unevenly with sticking pads, is a lip developing on the outer edge of the disc, compare each side. If there is a difference the noise will appear until the disc tries to true its self? The pistons retract equally so if the disc wear is uneven one side of your pads will be touching.

If you have always retained the piston seal shield the dirt build up will be minimal and easily cleaned. Take the pads out and operate the brakes you should be able to see them moving, remember the hydraulic system is working in a vacuum, when you take your foot off the pedal the fluid is drawn back and this sucks the piston in.

We have mentioned minor causes before so again I would give it at least 5000 miles before stripping down a caliper.

Corrosion is a problem with all aluminium calipers but the Brembo/Porsche calipers seem to be the worst.

best

Had a good look at the discs. About a mm lip each side with no signs of poor pad contact. That is discs nice and clean.
I will get the garage to look at the calipers next week as the brakes need bleeding and report back.

[alastairg]

Finally got a good look at the standard calipers I replaced with 'big red' upgrade. Partial sticking seems all down to old grease used on replacing pads. With age,exposure to the elements and heat it has become tick black glue that stops free movement.
Suggest dry fitting without copper grease the solution

Any views ?

[Pete_RS2]

This is what Porsche recommend, i.e. dry fitting. I didn't use any grease when I refurbished my calipers at Greg's garage meet. No problems with squealing or sticking since.

[alastairg]

Thanks Pete

I have read differing accounts, some solving noise with grease. I am sure dry fit is the way to go. I will think about asking the garage to clean them up next time !

[VaudiGR]

hello every1,
i have the Big reds and although i had a squecking sound while turning left the steering wheel which seemed to go off after i came to a straight line.At first i didnt know it was the brakes.Now after my shocks replacement the noise is larger,humming,and comes on even on a straight line.Still appears while turning left,but also after a stop,it comes up again,and goes off if i press the brake a few times.
Does cleaning or replacing the metal top holders will remove the problem?Also my brake pedal seems soft and can this also be related to this pad problem?
thanks
Vasilis