MrClifton

At 30,000 miles my brakes squeak. I replaced the front pads and that cured it for about 20 miles and now the noise is back. I used the stock pads from Pelican parts and put the "No squeal" on the back.

I'm going to pull the rotors now but my question is, do we get them turned in the machine shop like the old days or do we buy new rotors? They are about $95 each.

mooty

i don't know what's making the noises if you use stock pads.
but b/n turning rotors and getting new one's, i will get new rotors espcecially at just $95 each. glad you ended up not selling your 993 hope to see you on the next BAR drive.

Stu

My understanding is that on 993's, when you replace pads, it's usually wise to replace rotors as well.

MrClifton

No I didn't put the spiders on. The DIY said they don't help. They were making noise WITH the spiders already. Good point about not turning drilled rotors. I'll get out my credit card. Again.

I want to make a BAR drive. I just need one to line up with a day with no kids.

Mark in Baltimore

When I put my Textar pads back in, I left the spiders out and put a whole bunch of anti-seize on the backing plates. No squealing, but I've only driven about 120 miles on the car with this set up.

kary993

It has been my experience that you should NOT turn the rotors. They get too thin and will readily warp with any kind of heat put into them, specially on the track!

I have used stock rotors and frozen rotors and have found a definite longevity difference between the two. I am able to get through two sets of pagid orange pads for a set of frozen rotors. This has equated to about 16 track days. Before that I would only get about 9 track days using up 1 set of rotors and 1 set of pads (stock stuff). I am still going on this set of frozen rotors and oranges, so I might get to 17 or 18 days as they are near the end. Probably use these up at the TracQuest event at Sears in early December.

Greg Fishman

Kary,
When do you discard your rotors? I don't keep really close records but I can make a set last for a whole season which is usually 5-6 races and 3-4 DE events.

Jim Morton

Mr. Clifton:

Good to see you back !

FWIW (and this is by no means science), there is a lot of issues that relate to brake squeal and the pad/rotor material and the transfer of material between pad and rotor.

Were the rotors always run with stock pads, or was there possibly a different pads used prior to this change ?

Also, what did you do to clean any residue from the rotor at the time of changing the pad ?

Finally. If you only changed the pads and had new pads on old rotors, what proceedure did you follow to bed the pads? Sometimes, pads are a pain to get bedded with old rotors. (here is where things are heavily debated). From personal experience I have run into your descibed sceario with rotors that are overly smooth with stock pads.

There are many "fixes" but this dates back to the "good old days" of tricks.

Best of luck.

Tom W

My $0.02.

I've had some stock pads that squealed like a stuck pig and some that are absolutely quiet. I do not use the "spiders" and have switched back and forth from stock to Pagid Orange without squeal from the stock pads.

I found that the stock pads only started to squeal (and could not be quieted) after use in autox or DE where they got really hot. The one set that comes particularly to mind got hot enough that the glue that keeps the thin anti-squeal shim on the back of the pad broke down and the shim came off. No amount of cleaning got these pads to stop squealing. I replaced them even though they had 50% of the pad left.

I've also had stock pads start to squeal after DE due to brake dust. If I did not get the dust out of the cooling slots in the center of the rotors, the pads squealed. Once I got all the dust out, the squeal stopped.

914und993

Anti-squeal is truly a Black Art. On my old C4, I ran Pagid Oranges (RS4-4) street AND track without any squealing whatsoever after using the Wurth Anti-Squeal spray stuff. Eventually it was time for new rotors, and on those the Pagids screamed like the proverbial stuck pig. Even switching to stock pads for the street only helped a little. All of this despite 'proper' bedding procedures. The only cure was selling the C4 and buying a 993, which for now is quiet as a mouse, but I haven't taken it to the track yet.

Chip

MrClifton

Hi Jim and everyone. My pads were factory pads that were only about 1/3 worn. Please explain "Proper bedding". I didn't do anything to "bed" them. I know it's not a Dodge van but when I've replaced pads on other cars, the new pads usually don't squeak and if they do, surfacing the rotors or new rotors cure the problem.

Before I pull the trigger on new rotors, please explain "bedding" and cleaning the brake dust from the cooling slots. I only wiped the rotors with a towel with lacquer thinner.

Jeff, when you loaned me your oil filter wrench when I first bought my car, you had just completed a brake job. Did you replace the rotors?

Edward

Mr. Clifton,

How used up are the rotors? If they have a pronounced lip on the outer edge, this may be why you're getting noise, and this is probably a good time to replace them anyway. If no lip and is at least minimum thickness (don't know the spec off hand), I'd clean them before replacing them right away.

As for cleaning, make sure the holes aren't clogged. A drill bit which you turn with your fingers is enough to dislodge the grunge. But even if the holes are clear, hose off the (cool!!) rotors liberally in front, behind, and around the radial cooling vents; you'll be surprised how much junk is going to wash out. Let dry well.

Forget the "spiders" and use a good high-temp brake grease, yes grease, on the backs of the pads (I've used sprays and Permatex' red antisqueal goo and these worked for maybe a few K miles. LubroMoly's LM508 antiseize grease does the trick, and yes it's also labeled for brake pads. And it doesn't inhibit pad changes like some of the anti-squeal goop does since it is a hi-temp grease, not a sticky goop).

As for proper bedding...someone chime in with the real answer, eh
What I do (on a clear road w/o fear of traffic and/or local constable) is take it up to about 80 and brake medium hard down to about 10; don't stop the car, keep it rolling!
I do this maybe three times, then do it again to near lock up, but not triggering the ABS; again about maybe three or four times. I also drive a bit between runs so I don't overheat the pads.

The purpose in "bedding" is not only are you mating the pad to the rotor, optimizing the bearing surface, you are also bringing your pads up to temp and getting them "used" to the heat. "Green Fade" is what happens to new pads when they've never been brought up to temp; then they fade when you really need them. This may not be your problem since you've said your pads aren't new.

I've been squeal-free for one set of rotors to the next, so this does indeed work, for me at least. Hope this helps!

EDIT: I just noticed you said you use "stock pads" from Pelican. If they're not in a Porsche box, they're NOT really the same as OE pads, even if they say Jurid or Textar, and this may be the reason for the noise. IMO, the OE Textars are excellent street pads which perform well, remain quiet, and are relatively low dust. I'd go with these.

Edward

JohnM

With Porsche pads I usually get some squealing on light brake application for a couple of weeks following a track day, then all is quiet again. Also have had some squeal on very worn pads after a track day that would not go away, new pads cured it. I have all the Porsche anti-squeal bits attached.

Stu: new rotors at every pad change! Yikes, either you're running the world's most abrasive brake pads or you've got very deep pockets

ksimpson

I only have my C4S about 9 months and haven't needed any brake work. Mine don't squeal under normal driving, but do when the car is being driven hard so I assume it's only a problem when the brakes are hot.

I also notice that I get some vibration through the steering wheel when braking - but only when the brakes are cold. This goes away when they warm up. Is this normal?

kary993

Greg wrote:
I watch the cracks in the drilled rotors carefully to make sure they are not connecting between the drilled hole or making out to the edge of the rotor. I also look at how much dishing is occuring. The rotors I have on now that are on their second set of Pagid Orange pads are going to get replaced because :

1) The dishing is getting fairly deep.
2) The cracks are growing
3) The rotors would not last another set of pads and at the price of these pads it is not worth bedding them in on an old set of rotors just to try and use them on a new set of rotors because there is so much meat left on them.
4) The reality of using multiple pads sets on a single rotors set are they performance degrades from new. The first set of pads and rotors (new) performance better than the next set of pads with used rotors.

So given my track schedule I like the frozen rotors given my experience with regular OEM rotors. I would image that frozen rotors would last longer on the street than OEM rotors, particularly with less aggressive pads as compared to race pads.