squealing on light braking

hi there, dumb question - my car just came from its long needed service - clutch, flywheel, wheel bearings, etc etc. now, the car squeaks under light braking ( at the trafic lights ) when is about to stop... if I brake harder or comming from a nice speed, it doesnt. is this normal ? possible dust in the brakes ? wheel bearings have anything to do with it ? how to check and what to do ? thanks

Sounds like that was the big service and you paid out a few quid? I know garages hate the old 'since you seviced my car......' but if you paid big bucks I would demend they check it out. If they have had to do wheel bearings on the front the calipers would have been undone and hung. They may have disturbed the anti-rattle shims (unsure of how they work on Brembo, need to look) if they have, brakes can squeal under light braking. Or the pad may not be pushing up square to the disc... same issue would occur.

I would go for the pad shims having not been refitted. Otherwise the brake housing needs cleaning to allow the pads to "float" properly. The pistons in the calipers may also be a bit sticky. (See a separate thread on this) Either way back to the Servicer to put it right I would suggest. Regards Big Bob

Bob, I am with you on this but the shims are actually glued to the pads from any supplier, Porsche, ATE, Ferrodo etc so I reckon a good dose of brake clean would maybe clear it but as he has had a big service best left to them to correct.

I'm with Big Bob, happened to me. Third party didn't install shims on my car cause they didn't know about them (they're an extra), even got the disks installed the wrong way round! Back to your garage and get them to sort it! Ray :thumb:

Are they? I have never seen them come with any make of pad, they are always additional parts

Time for me to stand corrected. There are some pads that have shims glued to the back, just not 996 fronts. Found some interesting parts while hunting for info, like anti-vibration plates etc.

I'll add that to the mental library for Porsche. As I have my car serviced at an OPC for Vehicle Service History purposes, I have not changed pads on the 996 or on the new 997 GT3. I'm also a liitle wealthier, but older ld: now with several joint problems and dont "get out and get under" as often as in the past. However over a far longer time than I like to remember I've changed pads etc on many makes etc. Most had separate shims. If shims are required and not fitted they will give the symptoms described. However the cleanliness of the Pad Housings, Locating Pins/Clips etc in the Caliper, as well as sticky caliper pistons will also have a similar effect. However glueing the shims to the pads makes economic sense for both Pad Supplier and Assembly Time at the Manufacturer or Service Agent. Thanks again for the info. Best Regards Big Bob

If it's the shims it's a bit confusing. They come with a sticky side to attach to the pad, and I mean it's STICKY! Unless the service garage actually had to remove the pads I don't see how they would come loose. I've only read/seen posts of squeeling when the shims were never used in the first place, not because the caliper had been removed and replaced. As for glueing the shims to the pads, if they did that you'd never get the pads into the caliper when it's still attached to the disc, there's just not enough room to push the new pad and shim in together, hence why they come seperate. I could be completely wrong though :dont know:

I have changed the pads myself. The shims do not come pre glued to the pads, but they are glued by the installer. The shims come with glue on them so you must ensure that the back of the pads are clean and grease free. The shims are an OPC item or via suppliers on this web site. But dont assume that they have been fitted unless your car was maintained by OPC or a good Porsche indy like JZM. Third parties wouldn't necessarily know about the shims and would probably just use copper grease. This doesn't work on Brembos - you need the shims. Ray :bandit:

Spot on I'd say! You can re use the old shims if they are carefully removed from the old pads and cleaned up and new double sided tape is applied The anti squeal pads clip into the caliper piston and the idea is when the piston goes back into the caliper the pads are pulled off the disc and stop the vibration "squeals" you will hear If the piston/pads are fouled up the pad may still be in contact with the disc and vibrate so maybe a good clean with brake cleaner will sort them out