Brake noises again

[mouse]

Just thought I would consolidate the suggestions so far:

Rubbing dust shield when hot
Caliper pins not filed short enough
Knackared/loose wheel bearing
Lack of lubrication
Corroded brake lines
Some sort of hydraulic system problem


If there was a problem with the brake hydraulic system how can different parts of this be tested?

Any other ideas

Six weeks after fitting my 996 setup with 314 x 30 discs this issue has just kicked in for me on the weekend.

On mine I reckon I'd rule out :
- Caliper Pins - all were ground back at least 1.0mm.
- Wheel bearings - new ones installed two and a half months ago.


Could be one of the others

For the record I have the DS2500 pads, Braided lines, and second hand calipers with the old anti squeal shims re-used (I couldnt get the old lube/glue stuff off the back of the old shims too). Dust shields are still on too.

The original porsche pads which came with my capilers were fairly well 'glued' to the anti squeal shims and needed prising away with a sharp blade.
I wonder what porsche recommend to be installed behind their pads and if it is something different to the 'lube' or 'grease' most peolpe on here have tried? Anyone know?

[Alistair E]

I've posted something about this on another thread but I seem to have sorted this problem on mine.

I have the brakes in bits a number of times but have never been able to track down the problem before. I'm running Boxster S calipers fitted on what I believe to be RS2 brackets with DS2500 pads and 314x28 discs.

The droning noises always cleared up with new pads and I assumed that the problem was something to do with how far the pistons protruded from the caliper.

It would appear that with that size disc and the RS2 carriers the pad sits at the very outside edge of the disc. In fact the pads are actually a fraction to far out away from the hub. As the pad wears this allows a lip to build up on the pad. When the pedal is released and the pad withdraws from the disc face, this lip remains in contact with the outside edge of the disc. This is prbably worse when the disc heats up and expands slightly.
The effect would appear to be like running a wet finger around the rim of a glass.

Mine was more noticable on the nearside and I have now removed the lip from the pad with a file. Suddenly, everything went quiet. Fantastic after nine years of torment.

I now have some slight noises returning but I believe these are from the offside which I haven't touched yet. I will be having a look at the offside at the weekend, weather permitting. I will report back after that.

It may be worth those of you with this problem checking to see if this makes a difference on yours. It's a very easy and quick job which may produce a much appreciated result.

Hope it helps and good luck.

[mouse]

I can rule out the above reason too as I have Bambridge's brackets which position the pads fully on the disc face. (about 1 - 2 mm inside the edge).

[Alistair E]

Ah well, worth a mention. What about the inner edge of the pad maybe touching the bell? Worth a look.

[mouse]

Nope, they sit nice and central on the disc face... but I googled a bit and ended up on some porsche parts supplier websites and porsche forums and I have a theory of the cause .... (it seems to be a common occurrence on porsches too)

Apparently new anti squeal shims are recommended to be fitted every time the pads are changed.

The vibration dampers have a sticky side that faces the pads. To install a new set, you insert them into the piston, peel off the paper to expose the sticky surface and then insert the pads. The first time you apply brake pressure, the vibration dampers will get stuck to the pads, which is why you have to pry them off before you can remove the pads.

Some people say you can reuse them and they work ok if they still have some stickyness (but I know mine weren't sticky after prying them off) or suggest a high temperature adhesive but I'm not sure what adhesive will withstand such high temperatures.

So it seems the dampers/shims need to be glued to the pads to be effectively - it could be that the pads can vibrate if they are loose in the calipers and that I had no noise for the first 6 weeks because the pads had no room to be able to vibrate but when they start to wear down they have room to vibrate and squeal. The plastilube or coppaslip may just dampen the vibration for a short time until it works its way out...

What do you think? New dampers or some very high temp glue to solve the problem?

[mouse]

I fitted the 996 set up a few weeks ago - brand new audi discs, new anti squeal shims and new Ferodo pads. ....... Not long after I took it on a 300 mile mainly motorway trip and everything was still quiet. However on the return journey it started making a kind of groaning humming sound .....

Do you know if the waxy paper was peeled off the new anti squeal shims to expose the adhesive?

[coolhand]

One common aspect I noticed in the comments above and also from experience....
The DS2500's seem far more prone to these intermittent issues, the OEM Textars never once gave me the same noises, the main problem being my reluctance to remove the Ferodo pads as they are simply MUCH better at pulling the car up...!

[DH79]

I'm not getting the vibration but just the squeal under light braking and it's horrendous. Just had new OEM RS2 calipers fitted with DS2500 front and EBC greenstuff rear until I can get hold of DS2500 rears....

Really starting to get annoying now. Is this the lubrication issue? Any other clues?

[Robatron]

I've just had a journey from hell thanks to this bloody brake vibration! I've really had enough of it!

Is there way of fixing this problem for good?!

[Sonic]

Have you sanded the face of the discs?

[Robatron]

I haven't, no.

What effect would this have?

[Sonic]

One of the causes when i had mine was the surface of the disc glazing over, which caused the pads to sequel when they weren't being used to brake.

I'd tried everything, from pad shims to copper slip, removing the heat shield and filing down the calliper pad pins.

Scouring the surface of the disc was the only thing which worked for more than a week.

[Robatron]

I'll give it a whirl but I get the impression that once the discs smooth over, the noise will be back again?

The noise was loud enough to give me a headache today and if I touched the brakes to stop the vibration, it would come back as soon as I lifted by foot off the pedal. The only way to stop it was to stamp on the pedal but it would return in about 1-2 minutes.

[Sonic]

I'll give it a whirl but I get the impression that once the discs smooth over, the noise will be back again?

Correct

The noise was loud enough to give me a headache today and if I touched the brakes to stop the vibration, it would come back as soon as I lifted by foot off the pedal. The only way to stop it was to stamp on the pedal but it would return in about 1-2 minutes.

I feel your pain. BTDT many times over, including a trip to Germany and back ~1500 miles

[coolhand]

Try another pad compound...?.... see my previous post !