Tuesday, July 29, 2008

Track Day #7 -- 2008/07/29

Another great trackday in the pacific northwest! Today was a really good day for me -- nothing broke, nobody crashed (that I could see) and I even learned a thing or two. What more can you ask for?

The day began with rain in the forecast, so I decided to not risk it with the DOT Competition tires. I swapped out the front pads for race brake pads, but left my street tires on the car (Bridgestone RE960AS).

Back in April I ran a track day where I had an odd vibration that I eventually tracked down to under-inflated street tires. The tire was rolling over the sidewall enough to cause a pretty loud vibration that got me meatballed twice (black flag with orange dot in the middle telling me to come into the pits and talk).

Well, not wanting this to happen again, I decided to increase the tire pressure a bit this time around to see if it would keep the noise from coming back. Lucky for me it was the solution I should have done back in April! The noise never came, and I was able to continue the entire day without being meatballed (that really shouldn't be a measure of success, but I'll take anything I can get). The tire pressures were 32 PSI front and 35 PSI rear (cold) which ended up being a perfect 40 PSI all the way around when the tires were hot. Not bad for a complete guess...

I ran the first session with an instructor along to give me pointers regarding any bad habits I might have acquired and to see if I'm ready for the advanced run group.

The main comment in the feedback was that I need to be much smoother through turns 4 and 5; essentially try to take a single arc through 4 and 4a; with maybe a light tap on the brakes to settle the car into T5. His observation was that I was adjusting the wheel a lot in the 4 and 4a combination -- definitely something to work on. I also spent some time working on T10-T11 transition and he (the instructor) suggested downshifting to 3rd into T10 and use the gas to balance the car through to T11. That worked pretty well; I didn't run out of revs and had pretty good control. My best time during the first session was 1:39.2 which is 0.4 seconds quicker than my previous best time (on street tires).

Regarding running in advanced, he mentioned that I'm ready to move up if I need to, but should make the move based on traffic conditions -- essentially, move up when I feel that I'm being held back by other drivers. As it turns out, today was a really good day from a traffic point of view -- I was not running up on people that much today -- that might be different if/when I run the R-Comp tires, but for the moment it was good.

The second session was pretty much more of the same; I'm trying to improve my T4-T5 transitions and keep momentum up in T10-T11. My personal best time improved to 1:38.7. I had quite a few good laps without traffic I could use to try different entries and practise my steering without shuffling.

The real gains came in the third session where I managed a new best time of 1:37.6 which is exactly 2 seconds faster than my best lap from the last time I was on street tires in April -- and is only about 2 seconds slower than my June trackday time using the competition tires!

Due to technical difficulties (read: silly driver forgot to change camera batteries), I don't have video of the third session. But, I do have a comparison plot showing the improvement over the April Trackday:

The red line is the 2008-07-29 best lap and blue is the 2008-04-09 previous best lap. As you can see, I make up most of the time going into T1 and the T10-T11 complex.

Regarding equipment -- it always seems like I'm having one minor issue after another to deal with. Today was (and unlike last time... it really was) a great day for the equipment. I put on some brake temperature paint on the rotors to get the maximum temperature they reach while out there; and I also put on some Alcon temperature strips that you stick on the calipers and tell you the max temperature the caliper gets up to.

So, the rotors are running a bit hot -- the temperature paint turned yellow which means it's running about 1275 F to 1475 F. That's pretty hot for rotors (I'd prefer to see about 1000 F), but not catastrophic (anything above 1500 F is "bad"). The calipers were in better shape, running between 296 F and 330 F. The calipers are OK up to about 350 F before I need to worry. That probably explains why I've never faded my brakes, but managed to crack a rotor. The heat is getting dissipated before it hits the fluid in the caliper but the rotor is running pretty hot.

Given that, I spent some extra precautions at the end of the sessions where I'd drive through some access roads around the track to cool down the rotors and keep the pads from heat soaking the rotor and causing a crack. It seems to work so far, I don't have any cracks yet anyway. I still need to upgrade to 13" brake kit though and have a line on one, so will probably be putting that on before the next season.

There are a few trackdays left in the season I'm looking at (one in September and another in October), but I might call it a season -- I just purchased a motorcycle and will be spending the next few months learning to ride it (before the rain comes!) -- so it's a matter of balancing out the hobbies.

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