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Below is a recounting of various car events I've attended along the years, from car club meets, autocrosses, track events, and enthusiast drives.

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2015/10/05 John's private TH track day: My first 1:56 on the original track (with bypass) on street tires, and out in 8
π 2015-10-05 00:00 in Cars
I had just come back from TH a couple of weeks prior and got invited to another day (thanks Arnaud).

I was looking forward to this since I was pretty sure I had gotten faster in my last day, but had no point of refrence on that new track, and wanted to see how I'd do on the original track.
In the morning we were running the bypass and I got down to a 1:56 on one lap (and several laps at 1:57). That's beating my best time ever by a whole 2 seconds on half worn (good) street tires, yeah! The best view is this viewsync video showing front and rear at the same time (i.e. follow the link), or you can have just front and rear non synchronized (in 4K goodness should that be needed :) ):

Sadly, it seems that I was indeed pushing the car and those tires a bit beyond what they could do. The tires got too hot according to my tire pressure sensor, and as those things always go, I got serious understeer in turn 8 and was not able to complete the turn.
I went straight out to avoid problems, but sadly once out I chose to turn right a bit instead of turning left which had me go over some nasty bumps. I may have done this out of memory of the bad ditches that used to be just next to the track (and where people used to flip), but aren't there anymore.
The underside of the car suffered from jumping and landing over those bumps, although nothing major, but the shocks got a bit unhappy from landing while being on their harshes (least travel) setting, and all 4 accumulators need to be replaced (basically they got fluid pressure from the landing that wasn't dampened by the shocks since they were in race mode). The repair bill won't be too major though and thankfully no damage to the bodywork or front of the car.

Of course, I wanted to know how I managed to do this, and thanks to the video and the GPS track, I was able to determine that:

turnin point is almost the same with almost the same speed, and initial turn angle is the same
turnin point is almost the same with almost the same speed, and initial turn angle is the same


  • my entry speed was virtually the same as the previous lap
  • my braking point was almost the same.
  • my steering angle was about the same (I did have a slight twitch right, maybe due to a bump)
  • the GPS track overlay shows that I'm driving in the dirt, but the overlay is just wrong. I checked the rear video just in case and it shows no dirt being kicked.
  • my brakes were working fine, I was doing just 66 before going out instead of 90 on the previous lap.
  • the car is capable of modulating brakes if I overbrake to prevent understeer and allow turning where the wheel is pointing. Clearly that didn't happen there.
  • the tire doesn't look horrible, but I guess it was probably low(er?) on grip
    the tire doesn't look horrible, but I guess it was probably low(er?) on grip

    I also reviewed the tire temperatures, and that's probably a good clue of something wrong
    I also reviewed the tire temperatures, and that's probably a good clue of something wrong

    The video does show that I start turning left and just flinch the wheel to the right a tiny bit as a response to a bump probably, and then continue my left turn. However, by then even though I am slowing down still, I'm just getting understeer. I checked afterwards and my front outside tire was pretty worn (not bare, but worn) and apparently was low on grip.
    Nico told me that 233F is way too hot for a tire, especially a street tire, so that could explain how I ended up in an understeer situation that was non recoverable.

    The best view is this viewsync video showing front and rear at the same time (i.e. follow the link), or you can have just front and rear non synchronized (in 4K goodness should that be needed :) ):

    There is some damage to the underside of the car, but it may not be worse than what you'd get from hitting rocks and/or bottoming out on a bumpy road (which incidently happened to me just 10 days prior). I'll know for sure when I get the car back from service.

    Anyway, this is a bit vexing of course, but looking at it another way it's my first real out at thunderhill in 12 years or so, so it's not too bad looking at it that way.

    During lunch I swapped the front rear tire after removing the weeds and pebbles that were inside my car :) and when the track re-opened I got to do a few laps on the track with the cyclone, the real 3 mile track. Just before getting an error about shock failure, I got a 1:59 which definitely has sentimental value to me since I had never ever broken 2:00 on the original 3 mile track.
    So all in all, despite the off, it wasn't a bad day.

    I guess it could have been a lot worse
    I guess it could have been a lot worse

    After a few laps in the afternoon, I had to come out because a shock accumulator that popped and caused this fluid leak
    After a few laps in the afternoon, I had to come out because a shock accumulator that popped and caused this fluid leak

    A few pictures from others:

    Arnaud and his new car
    Arnaud and his new car


    plenty of colorful porches
    plenty of colorful porches






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