Sanjeevan

Well i had replaced my stock brake pads for the pagid "sport" brake pads for the last DE a few weeks back, the brakes did not feel any better than OEM and on a last few laps of a 40 minute session the steering wheel was rattling on hard braking, which I was told at that time could be due to to brakes heating up.

Now even on street driving the steering vibrates on braking, is this just cold brake pads, or are my rotors warped ?
Thanks
Jeeva

Jack667

Either that or you have the classic pagid "material transfer" issue, where you have some pad material on the rotors.
Take them to a good shop and they'll figure it out.

Tom T.

Hi,
I had a similar problem with my 993 when I first started doing DE's five years ago. When I changed to a track/racing brake pad the steering wheel vibrations during braking went away. The OEM pads are great but can only take so much heat before failing. Try replacing them with good pads like Pagid Orange, and see if the problem goes away after a day or two of speed at a DE. Good luck.
Tom

kurt M

look at the rotors. Is there an uneven "smear" of gray materal on them? Jack the front up and spin the wheels. Does the wheel drag in the same spot with each rotation?

Sanjeevan

Thanks for the quick replies, if possible I want to keep these pads for atleast a few more DE's as I paid quite a bit of money for them, unless they have to go...if rotors need replacing would you guy's recommending replacing the pads too (I remember reading it's better to bed the rotors with the older pads), I hope I don't have to replace them...damn this DE costs are out of control.

Tom T.

Hi,
If you keep these pads you will likely not enjoy yourself as much, and in addition, you might even warp your rotors. Speaking of which - do yourself a big favor and check them for any cracking.
You can replace pads & rotors at different times. Just bed them in a bit before taking it to the track. I suggest you get the rotors from a Porsche dealer as I've read that aftermarket rotors easily warp (but maybe someone can confirm or deny this). You're right in that DE is expensive, but......
good rotors & pads are very cheap compared to the alternative - losing your braking at high speeds and doing damage to you, your car, a guard rail, and possibly someone else's car. When you think in those terms it kind of changes your point of view.
Tom

Geoffrey

It is most likely pad transfer from the Pagid pads. This happens with them, especially the Orange compound. I would swap back to the street pad and drive the car on the street. This will remove the pad deposits (if that is the cause) and you should be set to go again on the next DE.

jford

I have had brake buildup on the rotors, leading to vibration, from the pagid oranges. I have experimented by swtiching out pads and rotors and feel that the oranges were the cause of my problem. I have read comments from others on the boards relating the same situation. I have switched to hawk blues and after some initial sucess (no vibration) now have it again. This is VERY frustrating and I am searching for the 'perfect' set of brake pads as we speak.

Jon Moeller

http://www.coolrotor.com/whitepapers...otors_myth.htm

jford,
I'd check the above link, it might explain why changing pads didn't fix your problem. I'm going to attempt to have my "warped" rotors turned, to see if I can get rid of my problem. Pad transfer was really poor (I'll take the blame for a horrible bed-in procedure), and I'm hoping that turning will fix my practically new rotors.
-Jon

Matt Marks

Agreed on the pagid orange problems. Though they're cheaper than a true track pad like a performance friction or hawks, they're really more of a performance street pad - and therefore can't handle the heat of serious track use.

I've had continual problems with material transfer on the rotors every time I've used them - basically it will look like someone dripped some splotchy material onto the rotors. Switching to street pads or a more aggressive pad will clean them up in short order.

The pagids also (IMHO) seem to wear much faster than PFC's as they tend to overheat - hence the material transfer.

For what it's worth, I've used PF97's on my 968-engined 944 (3200lbs w/ driver) with big reds and OEM 928 rotors for more than a year now, and after one and a half sets of pads and 20-30 track days including a full season of racing, the rotors show next to ZERO wear. Lots of small heat-induced cracks (none to the edge yet), the rotors are smooth and show no "lip" at the edges, and should last out the year with no worries.

- edit -

Note that PFC's will squeal like a banshee on the street - as will most track pads, so prepare yourself for a lot of funny looks or else get ready to do a pad change each time you come home from the track

aam993

My experience was that I had vibration with Pagid Blacks on the front when I was driving on the streets, but then it disappeared after one DE track weekend. Obviously, my vibration was the case of pad material transfer to the rotor, which got leveled/smoothed out after serious DE braking.

Tom T.

Hmm, that is good to know re:Pagid Orange. I have been using Porterfields up until last season w/o any problems. I'll be on the lookout for buildup on my rotors at my next DE.
Anyone ever try the Pagid Yellow compound?

Sanjeevan

Thanks for all the suggestions,
Kurt, good point and I'll try that and see...

Tom, you are absolutely right about safety...I was just being crafty, or so I thought....safety is number one for me, having spent about $7,000 on my safety equipement (I still have my yellow blinkers ), a few hundrad bucks is not going to make a difference.

But, I want to be certain that I am doing the necessary things only, and it sounds like getting a street legal pad/rotor combo is a hit and miss thing, hopefully the extensive knowledge of this board can streamline the process for me

Also, another variable, the outer edges of my R-compound tires show some chunking due to inadequate camber, could that be causing the vibration, I doubt it would.

Any ways, I'll be taking the car in for alignment, so I'll have my mechanic check it for me.

Cory M

If you do a lot of DEs you should just get a set of race compound pads and swap them out with the street pads the night before the event (after proper bed in of course). It seems like most of the "high performance street/track" pads are noisy, dusty, and too cold on the street but can't stand up to the heat of serious track driving. If you have both street and track pads you won't need to compromise.

RedlineMan

Hey All;

Brake vibration issues almost exclusively stem from three things;

1) The wrong break-in procedure for the pads/rotors
2) The wrong pad for the heat range you operate in.

If brake pads are properly bedded, the oils and excess resins from production are baked out, and there is an even layer of pad compound transfered to the rotor face. This is a CRITICAL step in making sure your brakes work right.

The initial bite characteristics of a pad come from the metalic friction of particles in the pad scrubbing on the rotor face. The secondary stopping mode comes from the heat generated by this metalic friction that softens the compounds in the pads and that same compound that has transfered to the rotor surface. Metalic friction first, then chemical stiction as a result of heat.

If you do not follow the correct bedding procedure, you likely will have an uneven transfer layer on the rotor, .i.e. vibration and discoloration of the rotor face. Allow this to persist, and you will glaze the pads, which VERY QUICKLY spikes up temps, shocks the rotors, and will begin the hard-spotting and/or cracking process.

If you switch pads, YOU MUST GO THROUGH THE BEDDING PROCESS AGAIN! This establishes the proper compound transfer layer for THAT pad on the rotor face. Most pads are not compatible with anything but the same part. To solve this, it is helpful to drive moderately for a while with the new pad, which will wear off the previous transfer layer. You can also sand the rotors lightly with 180-220 grit paper. Then you bed (transfer) the new pad material and you should be good to go.

You should bed new rotors with old pads, as trying to burnish new rotors with all that resin and oil boiling out will give you some very odd posibilities with your rotor face and transfer layer. Yes, you should bed new pads with old burnished rotors too!

And the third?

3) Insufficient cool down before stopping. Correct pad transer is good, but gluing your pads to the rotor by stopping with them boiling hot will transfer CHUNKS of material to the rotor that will shake your teeth out. Cool down means COOL DOWN. Take a 30mph spin around the access roads and let things COOL. Coast to a stop, shut down the engine, and stop the car with the clutch in gear to keep the pads off the rotors if you don't have time for a good cool down.

Don't just go out and turn rotors. Often they will REALLY warp from the reduced heat sinc and heat overload. That, or they will not hold the heat properly, and it will go other places you don't want it, like your pads, calipers fluid, etc. Most of the time, it is the bedding transfer procedure that has fouled you up, not that the rotors are actually out of true.