Dock

You're saying the cross drilling is responsible for all that damage? There are cracks all over the place; many that are not even close to any hole at all.

AndyMc

My car has standard wheels and brake ducts and the rotors have not seen salt.

Here is another pic of the rotors from the car I had before the sti (don't know why I kept them) as you can see they are completely worn out but haven't cracked at all, they did 6 track days and lasted 20k miles.

I have to congratulate you on getting 57k from your rotors, I wish I could!, and also on your many helpful and knowledgeable posts which have helped me learn about these cars, but the very fact you have got that many miles also reveals that you must seldom use the full performance of your car, I do however and find the standard kit lacking for that type of use as do a lot of other people in this thread.

Before I bought the turbo I watched all the Porsche promotional vids on youtube and they were going on about how the Turbo was a state of the art sports car and had a braking system amongst the most powerful fitted to any car, this gave me the impression they would be up to the job and last a reasonable length of time, even if the full performance of the car was used, but that’s not my experience and I just wanted to share it, especially as I've not had the same problem with previous cars

Andy

AndyMc

Found one of the vids mentioned above

http://www.youtube.com/watch?v=2-pYen94aPc

Macster

I know nothing of the STI.

The rust problem that seems to be quite common in the UK and in this context affects Porsche brakes is not about salt, per se. Many an owner has posted of a problem with rusty rotors and has not driven the car in wintery condtions and exposed the brakes to salt.

Simply driving in wet, damp weather or even leaving the car parked in wet/damp weather is enough. There is some or was some belief that the brake rotors were defective to develop this severe reaction to the exposure of moisture. AFAIK, Porsche never agreed this was the case, though IIRC some owners (very few) received new brake rotors under warranty. It may have been who complained the loudest, though my take is Porsche at least in GB can withstand a lot of volume before it reacts.

My intent is not for you to get the same (or more) miles from your car's brakes. I was only making an observation that what I saw was in my opinion a sign based on what I have seen of other brakes of rust coupled with overheating had occurred and made the brakes look the way they did.

The rust generates alot of dust. This dust collects in the brake rotor holes. As I think I mentioned when I first got my Turbo (used) its brake rotor holes were quite full if not full (at least some of them) with rust/brake dust. I assumed alot of rust was in the dust cause I have seen many a car on a lot with rusty rotors. Rain splash and the almost daily rinsing these cars are subject to coupled with little use is the cause. Had I pushed my car's brakes hard with these holes plugged I would not have been surprised to see signs of brake overheating.

Furthermore, I have not tracked my Turbo. It could be that even with the best of driver skill the Turbo brakes are prone to overheating and even the brakes of this driver's car would resemble the brakes on your car.

Sincerely,

Macster.

Dock

I'd be surprised.

While open rotor holes do provide for a decrease in temperature over rotors without holes (everything else being equal), I seriously doubt that the temperatures caused by even 100% of the holes being completely clogged would be enough to cause rotor damage.

Dock

Here is a picture of a rotor from a '98 Viper RT/10....no holes present, yet it has cracks. If cross drilling is the reason some believe Porsche rotors sometimes exhibit cracks, then how are the cracks in this rotor explained? Seems to me not to be a function of "holes".

Photo credit to "Chuck" at the Viper Club of America forum...

Mikelly

The above post is ignorant. Plain and simple...

All rotors will crack. They DO. THey're WEAR items. The question has never been if a rotor will wear to thin and crack. Rotors with driled holes run the risk of cracking sooner and running out to the edge of the rotor, reaching across to other holes, and causing a portion of the rotor to lodge in the caliper, lock the wheel and cause the car to lose control.

This happened to me 20 years ago. More recently it happened to a local competitor who died when his car slammed into a concrete barrier after the wheels locked. Yea, it was at the track, but this could easily happen on a road near you. Cross drilled rotors only accelerate the dangers shown in "Docks" pic Above.

Mike

Dock

Andy -

Reference the following comment you made about your Turbo rotors..."They would be fine if they were not drilled". The rotor pictured above, just like the picture you posted of a rotor from your Turbo, exhibits thermal checking or cracking that can happen under severe braking conditions. Major wear of the rotor is not a prerequisite for thermal checking/cracking (you had these issues with just 7000 miles on the rotors. How many fewer miles were on the rotors when the issues first appeared?), and "holes" are not the reason thermal cracking/checking occurs (obviously, because the Viper's rotors have no holes yet have checking/cracking).

I think you're blaming the holes in your rotors for something they did not contribute to.

Macster

Damage not so much from the increased heat from the plugged holes but from the hot dust contaminating the brake pad friction surface.

As an aside: I had the fact this dust (rust) can affect brake performance from when I washed my VW Golf TDi and failed to take the car out for a drive after I washed it. Of course the brakes rusted but proper usage will remove the rust with no harm. However, I forgot about using the brakes, treating them to a mini-bedding in session (which is just a slow down or two at city street speeds, nothing hot and heavy by any stretch of the imagination).

Before I knew it, I had to perform a hard brake action and brought the car to a complete stop from highway speed. Afterwards the brakes had a slight pulsing feel under light brake application that I was not able to eliminate by re-bedding in the brakes. Fortunately the pulsing was not severe and I tolerated the symptom until I sold the car.

Also, my braking technique is to use the brakes a bit harder than most drivers, that is scrubbing off speed closer to the stop as opposed to those who do light braking way before a stop and ride the brakes all the way up to the stop. My technique results in pretty good brake life cause it avoids the prolonged useage at higher temps.

But after I sold the car the buyer complained right away about the brake feel. She was one of those drivers that shortly after bringing the car up to speed starts using the brakes to slow the car for the next stop. Oh, when I sold the car it had orignal brakes and they had lasted 120K miles.

Anyhow, in the one pic someone else posted of his car's damaged brake rotors alot of the damage appeared to be after the holes, like dust/dirt/whatever was being picked up by the pads.

Sincerely,

Macster.

Dock

Are you saying the hot dust is coming out of the plugged holes back onto the rotor surface?

AndyMc

In my opinion based on my previous experience of wearing out probably 30 pairs of brake rotors over the last 15 years, and many days spent at race tracks etc, if my discs (shown above) had not been drilled they would not be showing any signs of cracking yet, I'm not saying they wouldn't have eventually cracked.

If you use brakes hard ones that are drilled will crack well before solid discs will,this is a plain and simple fact,also its not a sectret, lots of people know this.
I personally get three to four times the life if I avoid drilled rotors. I have also found two piece rotors are better again than one piece.

I don't really understand why you are so adamant about this, how much evidence do you want, your not just playing games with me are you?

I used to play tennis and my mate used to break the same strings that I had no problem with. I didn't keep telling him the strings were fine just because I didn't have a problem

Macster

Yes. The build up of dust and its accumulation in the holes coupled with the violence of braking stirs up this dust and in doing so this dust then contaminates the pads's very hot braking surface. This affects the hot pads' cofficient of friction at the pad/rotor surface interface. The rotors pictured above (in #22) clearly show signs of blue hot spots which are from overheating and other surface damage and most of it is in line with located in ine with the holes.

On the street this dust presence is not a big problem but still should be removed periodically one way or the other (which is what my original post addressed) but on the track when hard, heavy and repeated hard and heavy braking being done, this dust I believe is a real problem and a real threat to brake hardware (rotor at least) integrity. Were I to track my car I'd never show up at the track with any dust in the holes.

If one believes otherwise, he's free to leave the dust buildup in place and if brake degradation doesn't take place, then no problem. If it does then he's free to blame the holes or the lousy Porsche brakes or whatever he wants.

Sincerely,

Macster.

Bob Rouleau

A few observations on the above.

1) Premature rotor wear (cracking mostly on rotors with holes) can be caused by hard braking with pads that have not been bedded. While the car slows well given the powerful brakes fitted, temperatures at the pad/rotor are much higher than normal. It is generally thought that cracks extending from holes are caused by rapid heating and cooling of the rotors.

2) PSM can cause rapid brake wear if the car is driven in such a way as to invoke it. The same goes for ABS, use it a lot and you put a lot of extra heat into the rotors.

3) Worn pads will absorb less heat than new ones which can cause brake fade (on a track) and excess heat in the rotors.

4) My personal experience on the track with rotor holes which are blocked by pad debris is that braking is less effective resulting in higher pedal pressure and of course additional heat generated.

5) My DD is an 09 C4S with over 25,000 miles which includes 4 track days. My rotors are fine although I did have to replace a set of pads. The rotors which have cast holes (not drilled) are fine.

Regards,

Dock

The rotor airflow is through the holes, into the vented areas, and out along the circumference outlets. If there is any opening in the hole at all it seems the airflow would be removing the brake dust rather than expelling it back onto the rotor surface. If the holes were all completely clogged, the rotor essentially becomes a solid surface and behaves similar to a solid construction rotor in terms of brake dust movement..

Dock

So the hundreds of cracks in your Turbo rotor (your posted picture) that are not associated with any hole in the rotor, would not be there if the rotor did not have holes?