Brake Problem

cnavarro · 01-28-2008, 06:38 PM

I hate to post what seems such a mundane question, but I am at odds with my front brakes on my 964.

A while back, I had the dealer put on new rotors and pads. It had mild shimmy (felt like warped rotors). It got worse, then they redid the job with yet again another set of rotors. That was just before Rennsport. On the way there, the brakes started shimmying again. Just before leaving for GA, I had my local brake shop (old Porsche guy), take a look at it, and he turned the rotors. They felt absolutely perfect. I just about made it down to GA (750 mi), without any braking shimmy or shake, and then all of the sudden, wham, it's like the rotors are totally warped again.

The obvious- the brakes do not pull. The calipers are also not hanging up or dragging. I checked for both and paid very close attention to the temperature of the calipers and rotors regularly on my drive home.

Any suggestions? Is it just that the rotors the dealer put on are pure crap?

Jeff Alton · 01-28-2008, 09:39 PM

Could be pad material build up, what pads are you running?

Cheers

Jeff Alton · 01-28-2008, 09:40 PM

When you get home you could check them with a dial indicator for run out at differnt radius on the disk. That would rule them out. It only takes a couple of minutes with a magnetic stand for the indicator once the wheel is off.

Cheers

DRACO A5OG · DRACO A5OG's Garage

Bearings Maybe? BTW what brand of pads?

qcwang · 01-28-2008, 09:48 PM

If not the brakes, could that locking bolt not be on tight enough on the bearings or you have bad bearings?

cnavarro · 01-29-2008, 04:51 AM

I don't know what brand pads are there, what the dealer put on.

It's too bloody cold to work in the garage right now, but when I get a warm day that i'm not swamped with work, I'll pull everything out and take a look.

What brand rotors and pads should I use for street?

Bill Verburg · Bill Verburg's Garage

Quote:

Originally Posted by cnavarro

I don't know what brand pads are there, what the dealer put on.

It's too bloody cold to work in the garage right now, but when I get a warm day that i'm not swamped with work, I'll pull everything out and take a look.

What brand rotors and pads should I use for street?

Oem rotors, I've had good luck w/ Metalmaster pads(aka Axxis), other knowledge able folks like Mintex.

pad depostion is a real possibility, try cleanding the rotors w/ garnet sand paper and re bed, as others have noted wheel bearings, worn bushes, thrown wheel weights, worn struts can all cause this sort of thing

cnavarro · 01-29-2008, 05:14 AM

I assume the metalmaster pads have a provision for the sensor, right?

Bill Verburg · Bill Verburg's Garage

Quote:

Originally Posted by cnavarro

I assume the metalmaster pads have a provision for the sensor, right?

One assumes so. I used them on my Audi V8Q and S4 w/ sensors also used Rofrens w/ good luck on those cars

check w/ a Pelican advisor
Metal master pads

aston@ultrasw.c · aston@ultrasw.c's Garage

Apparently "warped rotors" is something of a misnomer,

http://www.powerstop.com/content.wws?fname=truckbrakesolutions.html

cnavarro · 01-29-2008, 11:10 AM

Well, I have new bearings on their way here, along with metalmaster pads and brembo rotors. I'll have it all cryo'ed, and hopefully that will be enough to fix the problem. If not, I'll most definately bump this thread to get more suggestions.

porschenut · 01-29-2008, 03:39 PM

Believe it or not, I brought my car in to a shop today to have them look at the exact same issue. The symptom is a slight pulsing or rhythmic binding that is only noticed during low speed braking, like under 10 mph when approaching a stop.

About 3 years ago I had the front rotors replaced with OEM units, and I started using Metalmaster pads about a year ago. I even used them during a couple of DE's with no problems. The brake symptom started showing up a couple months ago. Like you, I suspect a warped rotor. However, I also have a history of problems with my right front bearing needing to be tightened regularly. As I drove the car to the shop this morning, I noticed some sounds that were very similar to what I heard just prior to having the bearing tightened previously.

This is a guess, but maybe the loose bearing allowed the hub to wobble enough to cause uneven wear on the rotor and/or pad.

I expect to hear something tomorrow.

mtbguy · 02-10-2008, 09:41 AM

Quote:

Originally Posted by porschenut

Believe it or not, I brought my car in to a shop today to have them look at the exact same issue. The symptom is a slight pulsing or rhythmic binding that is only noticed during low speed braking, like under 10 mph when approaching a stop.

About 3 years ago I had the front rotors replaced with OEM units, and I started using Metalmaster pads about a year ago. I even used them during a couple of DE's with no problems. The brake symptom started showing up a couple months ago. Like you, I suspect a warped rotor. However, I also have a history of problems with my right front bearing needing to be tightened regularly. As I drove the car to the shop this morning, I noticed some sounds that were very similar to what I heard just prior to having the bearing tightened previously.

This is a guess, but maybe the loose bearing allowed the hub to wobble enough to cause uneven wear on the rotor and/or pad.

I expect to hear something tomorrow.

Ive been having this problem also- after swapping out most of the components in the system, I am now leaning towards the slightly loose bearing theory- let me know what the shop found out.
I'm hoping I can just tighten the nut on the axle a bit and solve the problem since rotors were just recently turned.