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Posted by: bluhun Mar 4 2010, 03:56 PM

Sometime ago I posted a problem with severe brake squeal following installation of Porterfield R4S pads on my 914-6 conversion car. I'm running Boxster calipers up front and the PMB widened calipers in the rear.

I've been able to trace the problem to the right front caliper. Since the other three calipers don't squeal, I assume that there's some sort of alignment issue between the caliper/pad combo and rotor. However, the caliper didn't squeal before with the Textar pads.

The right side also locks up before the left, with lots of tire skreech and smoke, but nothing from the driver's side. Are these two observations related?


Any suggestions would be greatly appreciated!

Posted by: SirAndy Mar 4 2010, 04:03 PM

Porterfields are noisy ...

If one side locks up before the other, you have a problem, regardless of what pads you use.
Could be sticky pistons. Sounds like a caliper rebuild may be in order ...


My Porterfields:

- Quiet when rolling
- Noisy when the brakes are applied in a normal manner
- Quiet again under hard braking


Andy

Posted by: ericread Mar 4 2010, 04:09 PM

From what I understand, much of brake squeal may be traced back to a brake piston that may contain some irregularities. This allows the pad to supersonically vibrate against parts of the piston, causing a squeal.

There is a tube of stuff you can use to coat between the brake piston and the pad, which is reported to work. I purchased from Perfromance Parts a "Brake Squeal Pad". It's a paper thin piece of rubber that sits between the caliper piston and the pad. Since I began using these, my brake squeal has gone away.

Another cause is based upon how you seated your brake pads when you installed them. Take a look at Eric Shea's PMB website and he has a step-by-step prcess for properly seating Porterfield pads.

Good luck!

Eric Read

Posted by: pcar916 Mar 4 2010, 04:21 PM

QUOTE(SirAndy @ Mar 4 2010, 02:03 PM)

Porterfields are noisy ...

If one side locks up before the other, you have a problem, regardless of what pads you use.
Could be sticky pistons. Sounds like a caliper rebuild may be in order ...


My Porterfields:

- Quiet when rolling
- Noisy when the brakes are applied in a normal manner
- Quiet again under hard braking


Andy

Posted by: Tom_T Mar 4 2010, 04:22 PM

Scoring on the disc from prior pads, brake fluid/oil/etc. on the pad material accidentally, loose bits, etc. can all cause squeal. .... but oil/fluid on the pad can also cause pull IIRC!

BTW - even the OG stock pads caused some squeal - esp. under lighter braking (as per Andy, etc.), so they also came out with those little anti-squeal fiber pads to go under the pads when mounted. Haven't tried them, but understand that they do help some.

But you need to find & fix the pulling problem first.

Posted by: tat2dphreak Mar 4 2010, 04:23 PM

ok, I guess I got lucky. my porterfields(R4s) never make a noise. when I first installed them I did a few hard brakes to get them set up and they have been perfect since.

Posted by: Eric_Shea Mar 4 2010, 04:25 PM

Porterfield R4S Pads should not be noisey.

What procedure did you use to break in the pads?

http://www.pmbperformance.com/page/page/1492423.htm

Posted by: vsg914 Mar 4 2010, 04:51 PM

I was a factory trained Chrysler front end and brake mechanic in the 70's. We had a technical order come from the factory that told us to "cover the back of the brake pad with electrical tape before installation to elimante squeaks". I've used this technique on brake pads for 40 years and never had a squeak or squeal.

Edit: Street cars only!!!!!!!!!!

Posted by: tradisrad Mar 4 2010, 05:18 PM

I've got the street porterfields and they are not noisy. My friend has the racing pads and he has an squeel every time he stops.

Posted by: tat2dphreak Mar 4 2010, 05:22 PM

I don't even think I did the full break-in Eric suggested, I drove mine around a parking lot, and tested it out, and then did some emergency stops... I did use brake squeal stuff from the local flaps. it's similar to RTV that goes behind the pads.

Posted by: ahdoman Mar 4 2010, 09:24 PM

Another thing you need to be careful about is the orientation of the notch in the piston. I don't think that's an issue with your boxster brakes though.

...another thought; did you replace the master cylinder when you replaced the brakes? Make sure both of your front feeder tubes are on the correct spigot on the cylinder. It is possible to swap a front to a rear tube.