NOTE: I posted this on the GT3 board as well...

Well I finally got the GT3 out on the track at Miller Motor Sports Park (East Track) last Saturday. The GT3 is truly amazing! It was a "mixer" event with BMW CCA and one of the local Porsche dealers (Ken Garff), so I was able to play with a few 997s, Turbos and Boxsters, a Cayman S, several track ready M3s, a few street M5s, a Louts Exige, an Aston Martin DB9, a few Corvettes, a Camero and a few Subaru WRXs. Finding the line was my biggest challenge for the day, and I never left 3rd gear as the short front straight away it peak speeds of 105 (so I never really got too close to redline). Anyway, I am now preparing the car for the next DE this weekend at MMP (Fri/Sat/Sun), and have tech inspection tomorrow evening. A few notes:
1) Put 192 miles on the GT3 on the track
2) Averaged 8.3 MPG
3) Spent over $100 for gas for the day (91 octane)
4) Ran tires at 32psi F/34psi R due to another GT3 owners recommendations

Now that I have the car home, I have noticed the following and have a fee questions:

1) Rear right tire has significant interior wear. This may be attribued to the "left turn" loop and underinflation. Is that correct? The ambient temperature never got above 60 degrees (chilly day in Utah, even at high noon). Note: both rear tires are new this month (MSPs)
2) Front rotors have very *slight* cracking, but certainly do not connect between holes... From previous Renn posts, I presume that this is okay.
3) Front rotor holes are filled with black gook (very fine sediment). I presume this is a mix of brake dust and road tar? Do I need to clean this stuff out before the next DE?
4) Took the car for a spin today and the brakes feel a but mushy. How many DEs should I get out of Porsche stock brake pads? Is this a do-it-myslef to replace?

So I am sitting here petrified that I will not pass the tech inspection tomorrow, and will lose all three weekend days at the track -ending my 2006 year with 1 DE day under my belt... Any feedback would be appreciated!

Thanks,
-Blake

 

Now that I have the car home, I have noticed the following and have a fee questions:

1) Rear right tire has significant interior wear. This may be attribued to the "left turn" loop and underinflation. Is that correct? The ambient temperature never got above 60 degrees (chilly day in Utah, even at high noon). Note: both rear tires are new this month (MSPs)
2) Front rotors have very *slight* cracking, but certainly do not connect between holes... From previous Renn posts, I presume that this is okay.
3) Front rotor holes are filled with black gook (very fine sediment). I presume this is a mix of brake dust and road tar? Do I need to clean this stuff out before the next DE?
4) Took the car for a spin today and the brakes feel a but mushy. How many DEs should I get out of Porsche stock brake pads? Is this a do-it-myslef to replace?

So I am sitting here petrified that I will not pass the tech inspection tomorrow, and will lose all three weekend days at the track -ending my 2006 year with 1 DE day under my belt... Any feedback would be appreciated!

Thanks,
-Blake[/QUOTE]


I'll answer a few of your questions. You shouldn't have an issue at tech:

1. I'll pass on this one. However, you will want to get into the habit of checking tire pressures before & after each run and bleed the pressures down.
2. the slight cracking is ok. Make sure that the cracks don't start to go toward other holes or to the outside edge of the rotor, as this would be an issue.
3. The black "gook" is brake dust. I generally will spray them with a hose after they are cool and this will remove the dust. At the track, you can also simply press a small drill bit or screwdriver into the hole .
4. You probably need to bleed your brakes. What fluid do you have in there? You can buy a pressure bleeder and do it yourself. You can buy them for less than a dealer will charge for a fluid flush and do it whenever you want.

Also, when at the track, do not use your e-brake as it can warp the hot rotors. And get into the habit of checking your brake pads. After they reach 50%, they go down VERY quickly.


Steve
2003 996

 

94Speedster,

I know from your previous posts that you bought your car used a few months ago, did you change out the brake fluid since you bought it?

 

Hi Blake - welcome to the slippery slope!

Take a look at your brake pads to make sure they aren't too worn. You can see them once you take the front wheels off. If you are using the car primarily for the track, it's best to replace them once they get about halfway worn.

Probably a good idea to pick up a couple of cans of brake fluid and bring them with you to the track. If you know what kind of fluid is in the car, just get some of that. If not, you can get some OEM fluid at Strongs, or you can switch to Motul RBF 600 or if you have deep pockets Castrol SRF. Both of these are available at Motorsport in SLC.

I have a Motive bleeder and you are welcome to use it. I'll be hanging out with the Air Power Racing group, look for Les' enclosed trailer with the Air Power sign.

The Air Power Racing guys that work for Les will be at the track and will be available to do things like brake bleeding if you pay them.

Looks like it's going to be a great weekend!

Cheers,

Jeff
(brown '82 911)

 

the wear on the inner aspect of your rear tires is normal for cars set up for track with some negative rear camber. you will see more and more of it as you drive. the MPS2's really wear there as well. I had to have my MPS's changed from one side to the other before they corded and doing that is ok.
Make sure to keep your rear tire pressures around 38-40 hot and check them often, they really heat up.
I use an air compressor to blow the brake dust out of the cross drilled rotors at the track or use something to poke them out clean, between each session.
change your pads to pagid oranges and follow the proper procedure to "bed" them in.
change to castrol SRF fluid and have the brakes flushed before each event.
the rotor cracks are normal. as long as they are not longer than 7mm, connect between holes, or extend to the edge of the rotor they are fine.
then Blake go have fun at your next event!!
tom

 

I'd certainly wear a mask .... asbestos. Actually, I wouldn't do it. Just get a tool like an ice pick.

 

I agree Dave and do use a pick but ya gotta admit that takes a long time!!

 

Thanks for all of the replies.... Let me answer in turn...

Smankow: I'm using Porsche OEM brake fluid, and was planning to switch to SFR next spring (before the next event). I hope to have the brake fluid flushed this afternoon (dealer) and may pick up SRF if I can find it. I have been very careful with the emergency brake - thanks for the tip!

M3Pete: I had the brakes flushed three weeks ago in preparation of this event. I have not driven the car at all until the DE last week. The hardest part is fuguring out how fast these "wear" items will go...

Jaydubya: It will be good to meet you at MMP this weekend! I hope to tech the car tonight at the airport Hilton, and would liek to have SRF fluid in it by then. So where exactly is MotorSports in SLC? I did a quick google and found a race supplier/ repair shop called "Motor Sports Inc." at 2100S. Did I find them?

tkerrmd: Very good idea. I will have the rear tires swapped as the big course at MMP runs counterclockwise and will only distress the reat right even more over three days... Good idea!

dave morris: A previous poster mentioned using water. That would be the easiest... and issued with that idea?

Thanks!
-Blake

 

I'll take a crack!
1) wear on the inside of the tire usually means too much negative camber. I would have a race shop at least check it out. You don't want to be burning through tires.
2) Most folks (including me) don't replace rotors until you have either a crack that connects two holes or a crack that extends to the edge.
3) The holes should be blown or cleaned out. Don't worry about asbestos as that compound is not allowed to be used any more.
4) I would change the fluid to Castrol SRF as was recommended earlier. You should also at least a track friendly pad. Most DE'ers do use Pagid Orange as was recommended earlier and this is a good pad but for the street it may be noisy and dusty. Brake pads and rotors are very easy for the do-it-yourselfer. There are posts here on how to do it but it is very easy and can be done at the track as well. Some trackies will drive up with stock pads and swap them out for their track pads while at the track.

 

Answers from a GT3 driver:
1) 32 34 hot is correct for Michelin pilot Sport Cup tires - the R compound ones. If you are using street tires you want about 38F/40R hot. 32 34 is too low ofr street tires.

2) Clean out the holes in the rotors. If you don't you will have inferior braking, overheaat your pads and speed up rotor cracking.

3) Rotors are fine as long as no crack is longer than 7mm, cracks do not join more three more more holes; no crack goes right to the edge.

Regards,

 

Well ... I'll stipulate that it MAY not be asbestos that's in the air you'd be breathing .... but ... now, let's see, what is that stuff I'm breathing? That's an easy one for me.

 

And BTW, just as a precaution, I wouldn't go to the dealer for any of this regardless of what your service advisor tells you because once they know you've been on the track, your warrantee comes into question.

 

I think he is using MPS not cups but the recommended hot pressures for MPSC's are 32F 36R

 

Thanks Bob, Mitch & Dave. One last question. Bob mentioned that 38F/40R Hot is correct for MSP street tires. Assuming an 80 degree ambient temp, how much should I allow when setting the tire pressure cold. 6psi? Then, 32F/34R at cold temps would be appropriate.

Thanks,
-Blake

 

Can't confirm that 38/40 is the right pressure because I don't drive on street tires ... but using 5-6 psi as a benchmark is probably going to be close to the mark. It depends on ambient temperature, as you note, how bright the sun is hitting the track and heating it up, how hard/fast you corner the car ... and other things. I like to start just a little high ... so that I can then bleed down. It's a lot easier than adding air to get there. And while you're finding the right hot pressure, take it a bit easy out on the track.