"Mr. Toad" at Laguna Seca (22 October 2021)"Mr. Toad" at Laguna Seca (22 October 2021)
 Top of The Corkscrew in the mist |
 It was a dark and stormy morning |
 Track tires and wheels in the back seat |
 Rain-soaked black Mazdas ... |
 ... with their drivers |
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 Changing tires during lunch |
This was my first time back at Laguna Seca after my miserable experience in September when unexpectedly slippery tires led to a spin and an unprecedented lack of confidence in my equipment. I'm still working on the psychological aspects of that day.
It was also my first track day with Turn 8 and I was happy to find a handful of other Mazdaspeed 3s along with a wonderful loon who was driving a "Mazdaspeed 5." It was the first time I'd seen a minivan on the track and it did ok. Of course it was a Mazda!
Until now, I had been running on stock wheels and progressively better tires. (Well, the Bridgestone RE-71R tires proved to be a retrograde step.) My cheap streak argued against spending money on track wheels, but a quick burn through some good track tires brought the realization that if I hadn't also used them on the street I might have gotten an extra track day out of them. Track wheels suddenly seemed like a bargain, with a positive ROI in a year or two.
That cost-benefit analysis led my to purchase a set of 17x9 König Hypergram wheels, fitted with 255/40R-17 Nitto NT01 tires, for track use. I had previously used NT01 tires, albeit in a size that would fit the stock wheels (235/40R-18), and was very happy with them.
I had planned on using the new tires all day but the track was damp for the three morning sessions so I elected to stick(?) with the slippery Bridgestone RE-71R tires. They still had a fair amount of tread and I didn't want to waste heat cycles of the new tires on a wet track. I switched to the new tires during the extended lunch break.
 Street versus track tires and wheels |
 Wear and OPR after one session |
Best lap of the day
(1:53.530)
My best lap during the three morning sessions wasn't even as good as my best lap on my first track day with Mr. Toad, on another rainy day nearly three years ago. Then, I was learning a new (to me) car and wary of rain, but had confidence in the my equipment. This time rain, poor tires, and a fast run group (with many drivers wanting to pass me) added up to poor times.
The damp weather dried up late in the morning and I switched to the virgin set of track tires and wheels during the lunch break. I hoped they would help me beat my personal best lap time of 1:51.508 and possibly get down to 1:49.xxx. I fell two seconds short of my easy goal, but given all the strikes against me for the day I wasn't unhappy with that result. Disappointed, yes.
The following table summarizes tire pressures throughout the day, in PSI, along with front-brake temperatures, as measured with an infrared pyrometer after each session:
rotor caliper Description Time Ambient LF RF RR LR LF RF LF RF before session 1 0914 61°F 36 36 35 35 34 34 33 33 reset after session 1 0943 55°F 37.5 37 36 36 242°F 237°F 160°F 165°F before session 2 1051 55°F 36 35.5 34 34 33 33 33 33 reset after session 2 1125 57°F 36 36.5 36 35 173°F 158°F 169°F 168°F before session 3 1234 57°F 34 36 34.5 34 after session 3 1303 61°F 40 40 38 37 349°F 432°F 252°F 328°F before session 4 1439 61°F 39 39 39 37 street tires 31 31 31 31 switch to track tires (NT01) and reset after session 4 1555 59°F 39 39 35 36 386°F 368°F 328°F 328°F street 1706 59°F 33 33 32 32 switch back to street tires (RE-71R)
The high pressures (and brake temperatures) after session 3 were mildly surprising, though lap times were dramatically better than the first two sessions. For the afternoon, when I switched to track tires and wheels, I reset tire pressures to bare minimums; pressures still ended up being high after the 24-lap afternoon session but the Nitto NT01 tires held up ok under the stress.
 Right front brake temperature (before) |
 Right front brake temperature (after) |
Tempreature recording strips on the front brake calipers (right caliper
shown at right, before the first session and after the last session)
registered somewhat higher temperatures than the pyrometer
(450+°F versus 328°F) but the strips captured the peak temperatures
whereas the pyrometer measurements were after a few cool-down circuits
of the paddock.
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Copyright © 2021-2022 Karl L. Swartz. All rights reserved. |
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