Mark Hubley

Almost exactly one year (and 17,000 miles) ago I replaced my rotors because they were a bit warped and they were at their thickness limit. About six months ago I started noticing a lot of vibration during braking, and last week I had the rotors resurfaced. The shop said they had to take them down close to the minimum thickness. Granted, I did one day of a PCA-sponsored "high performance driving clinic" back in November, and there was a lot of hard braking. Should I expect one track session to kill a set of rotors?

I purchased the rotors from Vertex. They are supposedly OEM. If I plan to do one or two DE's each year and perhaps some autocrossing, then should I buy different rotors in the future? Should I go with cross-drilled or slotted?

Also, I noticed there is what looks like a dust shield inboard of each rotor. Would removing these allow the brakes to stay cooler?

Thanks for any advice,

Mark

Bill Gregory

You may want to read an article by Caroll Smith on warping rotors <a href="http://www.stoptech.com/whitepapers/warped_rotors_myth.htm" target="_blank">here</a> .

A930Rocket

I used the Vertex rotors once and got a total of 300 miles on the track with them. They are by far inferior to the factory rotors. Use factory rotors next time or try slotted from a reputable supplier. I've gotten many parts from Vertex, but their rotors weren't the best.

Also, removing the dust shields will help, as well as adding brake ducting.

Zeke

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Bill Gregory:
<strong>You may want to read an article by Caroll Smith on warping rotors <a href="http://www.stoptech.com/whitepapers/warped_rotors_myth.htm" target="_blank">here</a> .</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">I read that sometime ago. If all that is really true, then I guess we can buy those sandpaper pads advertised on TV and turn our own rotors right there in the parking lot.

belz

Milt- You might want to re-read the Smith article again ... he explains why "sandpaper" doesn't work. <img border="0" alt="[nono]" title="" src="graemlins/nono.gif" />

Tim Comeau

Also, those aren't "dust shields." They are splash guards. They're on the wrong side of the rotor to be brake dust shields. Their purpose is to keep water, snow, ice, mud, etc., from splashing onto the rotors.

Brian P

For what it's worth, I just replaced my first set of rotors after 34 days of my DE's and 6 days by my wife.

I still had another millimeter of wear left (according to factory standards) but the vibration in the wheel and the strange pad wear patterns led me to believe that it was time to replace the rotors.

So, I would be surprised if you are getting only one event per set of rotors.

Mark Hubley

Thanks for the replies.

On a related note, I just downloaded the tech inspection form for Metro NY PCA Drivers' Ed. It makes a point of saying "NO AFTER MARKET DRILLED OR SLOTTED ROTORS".

Brian P

Oh, and I hate to mention the obvious, but you do try to actually use your cool down lap as a lap where you don't touch the brake pedal, right?

NetManiac

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">use your cool down lap as a lap where you don't touch the brake pedal</font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">I did not know this. But I do now. Thanks Brian.

Brian P

Yeah, it took until my third event where someone told me that the point of the cooldown lap wasn't for me to cool down, but for the car to cool down and specifically, the brakes.

The real trick is to keep enough distance from the guy in front. Generally, if you get too close to the next car, you'll have to tap the brakes to avoid bumping...

A nice thing about the cool down lap is that it also gives you a chance to try to experiment on some of the slower corners and see what kind of speeds you can do while the car is perfectly balanced (i.e., enter the turn at neutral throttle)

Bill Gregory

Couple of points: Porsche and Vertex both sell "drilled" rotors that in fact have cast-in holes which are not drilled. They will still crack, just not as quickly as true drilled rotors.

Not only is the cool down lap to cool down your brakes, when you come into the pits, do you use your brakes to park? Big mistake! You end up pushing your brake pads against the hot rotor to absorb heat into your brake fluid and other sins. Try this: As you come off your cool down lap, use your brakes as little as possible, downshift as much as possible. As you slowly pull towards your parking spot with 1st gear engaged, push the clutch in, turn the motor off, and coast until you want to stop, and feather the clutch to stop your forward movement.

I've been known to slowly cruise around the pits a few times after a session to help aid cooling the rotors down, too.

Bill Gregory

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica"><strong>So, I would be surprised if you are getting only one event per set of rotors.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Heck, I heat cracked my rotors after 3 events. Frozen rotors are on their way....

Renn 951

As to the longevity of Vertex rotors, I installed new ones from Vertex on the front of my 951 back in October and I've done four DE's since then with no rotor problems (my wife also drove at two of those events.)

Sometimes the brake pads can leave deposits on the rotors, and it feels like they are warped when they really aren't. Mark doesn't mention which pads he was using and whether he had a chance to bed them in to the new rotors, but that might have been a source of the problem (?)

I use Hawk Blues on the track, which have a reputation for eating rotors, but I haven't seen any excessive wear yet on mine. I do have a "Cool Brake Kit" which may be helping me out a lot.

A930Rocket

On my 930 using the Vertex rotors, I was also using PFC 90 compound brake pads. As they were drilled and not cast, they were starting to play connect a hole w/in the 300 track miles. I didn't feel comfortable using them.

I have removed the splash guards and have the brake ducting to my front air dam sine day one.

Since changing over to factory rotors, I've put at least 500 track mile with very little cracking.