roche

so this weekend i tried to tackle my squealing rear brake probelm (only at low speeds with gentle pedal application). the PO said he recently performed a brake job, but since the rears are squealing, i assumed he only meant the fronts. anyway, i pull the rear calipur off and the pads are almost brand new. they are textars. the rotors were definitely not replaced when the pads were. could the squeling be because i need new rotors? i stumped.

thanks.

dhicks

Rotors wear does not create squuueeeeaaaaallling, well not in itself anyway.....but to assess wear run your fingernail from the center of the rotor to the outside ... is there a noticible lips at the outside edge....if it is about 1-2 mm then you have a reasonable amount of rotor wear and need to measure rotor width aagainst specs to determine how much wear and how soon to replace...others ...does this sound right?

95 C4 993

My rotors didnt last but 25k when I had them replaced-they were Zimmermans from the PO. The fronts were warped. I turned them at 19k and replaced at 25k all the way around. They squeled quite a bit prior to replacing. The vibrations when slowing down are also gone, which I believe was a direct result of rotors going bad. Im no expert but the rotor and pad replacement fixed all noises and vibrations.

Garth S

Are the rear rotors glazed? - if so, wrap some 100 grit Emery cloth around a wood block and scuff a cross hatch pattern on both faces to clean them ( this works for pads too - if required)

Are there anti squeal shims or 'spiders' on the pads' backing plate - if neither, often a coating of anti-seize grease on the piston contact surface will do.

Lastly, with a flat file - cut a narrow chamfer (~1mm) on the pads leading edges: this allows them to bed nicely and eliminates squealing during this period.

roche

thanks, guys. i'll try a couple of these remedies and see how it goes.

ZombiePorsche44

I never turn rotors, I always just install everything new. I only use factory new ones and really don't think the Zimmerman's are as good, especially on a 993.

It's really important to "bed in" your new pads the correct way to avoid "glazing the pads" & the associated squealing.....

After they are installed bring your car up to around 25 mph a couple of times and do medium hard stops.
Give them a few to cool and bring the speed up a bit (40mph) and repeat a few times, after that they should be good to go.

If you bed them in at higher speeds getting on the pedal real hard, you will "Glaze" the surface of the pads and no amount of grease and shims will be able to stop the squeal.

Good luck!..................ZP44

Bill Verburg

I wouldn't use emery cloth if I were trying to scrub rotors, the aluminum oxides and iron oxides used in normal emery ar not good for the pads. Use garnet cloth.

grease doesn'r go on the pistons it goes on the sliding edges.

It's not ordinary grease. you want, Optimoly HT or Plastilube.

the pistons shoiuld be lubed w/ Unisilikon TK N 2

BillJ

I had used the spiders and they helped not at all. Did a combination of the high temp grease and the anti squeel blue spray and so far not a peep from them after about 1k miles. Keeping fingers crossed!