Brake squeal!

[christiandk]

I have a big problem with my brakes on my ´90 S2. The rear brakes squeal a lot since I replaced rotors and pads a year ago.

I bought Textar pads and tried everything to keep them quiet - Copper grease, anti squeal pads etc. Only helped for a short while. Threw out the new Textar pads and bough original Porsche pads.

Still squeals!!! Now the car even squeals when the brakes aren´t applied. When I turn corners it goes Squeak squeak squeak. F.... annoying!

I have regularly sprayed the rotors and calipers with brake cleaner to keep them quiet for a few miles - the result is that the dust seal around the pistons are now sort of swollen/bulged. Think I have ruined them with all the lubrication!

Why does my brakes squeal - and do I need to rebulid the calipers - hope not - they are not leaking!

Ian from 944online, who always is really helpfull suggested that I changed to sopfter pads and used some fine sandpaper on the rotors. I dont want to buy new pads again - the originals have to work - they were the ones the factory used when the car was new!?

I have had the squeal plates of and on many times, so they now stick to the pads with super glue! Mayby I should just eliminate tem - they have not helped at all!

Any ideas ?

[John_AZ]

Ian suggested sand paper on the rotors?

Did he suggest that the rotors should be machined (turned)?

Since you have tried 2 sets of new pads, it would seem possible the rotors need to be turned if still within spec. You can check the thickness with a simple micrometer. The minimum wear tolerance is usually on the rotor. If you are close to minimum, new rotors would be suggested instead of turning the old rotors.

Were the Textar pads ceramic? Some ceramic pads can heat up old rotors and warp them.

GL
John_AZ

[krystar]

if the rotors are still good, yea take some rough sandpaper, like 200 or 300 grit and scuff the face of the rotors. reapply grease on the back of the pad. also try doing a proper bedding of the pads. do 10 soft brakes from 100kph-40kph, drive around for 5 minutes letting it cool. then followed by 10 hard brakes from 100kph-40kph w/o triggering ABS. drive around for 5 minutes letting it cool.

[racer]

It is possible that the rear caliper pistons are not retracting all the way. This will keep slight pressure on the pad. if the rotor has any bit or warp, when the rotor passes by it hits the pad that did not retract. The fact that it happens with 2 different pads, make me think its rotor/caliper and NOT pads that are the issue.

You don't mention which pad material you chose, but yes, certain materials are more prone to squeeking. Track friendly pads in particular squeak like the devil compared to OEM material pads.

[Cocacolakidd]

Best to use "000" steel wool to clean the rotors or "2" steel wool to scuff them. The way you describe the piston seals it may be time to replace the seals - cheaper than the whole piston and seal rebuild. Sounds like they are indeed sticking - this can cause rotor warp in a short time - if not to bad the rotors can be turned if in specs. Try first to scuff the rotors and while they are out have somebody check them for out of round/warped.

[christiandk]

Thanks a lot guys,

The rotors have less than 10000 km on them. The pads are OEM semi metallic.

Coca: Do you mean cange the dust seals only? Can it be done without disconnetcting the caliper from the brake line? Where do I get the seals? Ian has a full kit with pistons and all - but dont think I need it - my car is in good shape and has only 120000 kms on it.

[Grandad#3]

Hi, I have to agree with Racer. Have you ever had the rear calipers rebuilt or replaced? It sounds to me that you have a sticking caliper puck that is not retracting all the way back in when the brakes are released. I just recently had to replace one of mine and it was making the sound you describe and with much less mileage. Spraying brake cleaner will destroy the seals making them swell even tighter until they fail completely.

Cheers,
Larry

[TexasBlake]

I've never replaced pads without machining rotors, no matter how cheap and crappy the car is.

Pad slapping is for immigrants.

[Rasta Monsta]

Got some real progressive thinking down in Tejas, I hear.

[Cocacolakidd]

Back

By saying gisconnect them do you mean the brake fluid lines - doesn't matter because once you pull out the seals and pistons for the rebuild there went the integrity of the brake fluid any way - no longer a sealed system.

The rebuild kits are available with or with out the pistons - the ones with the pistons are rather spendy - especially if you are doing Turbo/S2 or any 4 piston calipers.

Another question; have you figured out what could have caused the caliper to go bad at the piston/seals to need this rebuild? If not what's the chance of rebuilding the caliper then haviong it go bad after a while if the same problem is there - check the rotor or rotors.

[porsche4life]

Originally Posted by Rasta Monsta

Got some real progressive thinking down in Tejas, I hear.

They do.

Which why when I have to go south of the border I tend to not linger...

[christiandk]

coca; I think that Larry hit the nail on the head! Think I have spryed too much gunk on the brkes, which has caused the selas to swell. Hmmm.

But as I said. The rotors and pads were brand new - so I could not undestand why they made so much noise when my old ones did not.

Will try to clean the rotors and pads one last time this weekend before biting the bullet and ordering the reseal kit?

Cant really find the kit for the S2 without the pistons though....

[Cocacolakidd]

Are brand new parts ever bad?

[christiandk]

Guess so...but now i have both tried Textar an OEM . hmmm

[Cocacolakidd]

I have re-read the entire posting here and it seems like something is missing -

Another way and safer for the mechanicals of the brakes there is to blow out the brake dust with compressed air instead of chemicals...Brake dust will cause the squealing along with an over heated pad that becomes glazed (And they can do this in a very short time space).

Is it possible that the rotor is not mounted properly? By this I mean if a small piece of foreign matter was behind the rotor when mounted it could be off orbit this way. I still think that the way you describe the squeak, squeak, squeak instead of just one continuous squeak that something is warped or mounted wrongly.

Keep us informed as to any up-dates

[kvnhpnr]

I have the same problem with both the front and rear brakes. I have replace the pads and sand paper on the rotors but it still does it. I also used brake quiet on them and that worked for a while...I have not had the rotors turned yet, should I try that next?

[imprezasvx]

Hi could the original poster update your results if there was a solution found.
Thanks!