First track day - what was wrong with my tyres?
Discussion
Well, I did it at last. Had my first autocross session, which is the local equivalent of hill climbs without the hills I think. It's basically an airfield with a short circuit made up of cones, almost all of it is tight second gear stuff, and each individual lap is timed from a standing start.
Question is why did I struggle to keep it smooth? Now I know as a novice, I didn't expect to demonstrate balletic grace and pace on my first day, but I did experience some problems. My first lap out was a disaster - lots of arm twirling and ugly unsettled dive, squat, pitch and yaw. It got a little faster and more polished as I learnt the lines and developed a sensitivity for the pendulous rear, but I still felt an uncomfortable level of understeer into the tighter turns.
After finishing up for the day, I tried dropping my tyre pressure and found (belatedly) that tight second gear corners had become more manageable. I started the day at 2.5 bar cold (36 psi) as per the manual (it's a facelift Carrera 2 on standard 17 inch wheels, but lowered and with a front strut brace which I find helps to eliminate understeer in fast road driving).
When I checked the pressure a little later it had risen to 2.7/8 (around 40 plus I think), but I didn't have time to adjust (lap turn arounds for competitors were very quick). Should I have let the pressure out to around 2.2 cold at the start of the day? Is this why the car was understeering?
Oh, and I got humiliated by experienced hot hatch drivers, but I am told that 911 drivers don't stand much of a chance on these tiny circuits. That's my story, anyway, and I'm sticking to it.
Question is why did I struggle to keep it smooth? Now I know as a novice, I didn't expect to demonstrate balletic grace and pace on my first day, but I did experience some problems. My first lap out was a disaster - lots of arm twirling and ugly unsettled dive, squat, pitch and yaw. It got a little faster and more polished as I learnt the lines and developed a sensitivity for the pendulous rear, but I still felt an uncomfortable level of understeer into the tighter turns.
After finishing up for the day, I tried dropping my tyre pressure and found (belatedly) that tight second gear corners had become more manageable. I started the day at 2.5 bar cold (36 psi) as per the manual (it's a facelift Carrera 2 on standard 17 inch wheels, but lowered and with a front strut brace which I find helps to eliminate understeer in fast road driving).
When I checked the pressure a little later it had risen to 2.7/8 (around 40 plus I think), but I didn't have time to adjust (lap turn arounds for competitors were very quick). Should I have let the pressure out to around 2.2 cold at the start of the day? Is this why the car was understeering?
Oh, and I got humiliated by experienced hot hatch drivers, but I am told that 911 drivers don't stand much of a chance on these tiny circuits. That's my story, anyway, and I'm sticking to it.
Hi there!!
"Question is why did I struggle to keep it smooth?"
Probably trying to go too fast, too soon.
"developed a sensitivity"
There, you have it!!
"uncomfortable level of understeer into the tighter turns."
Secod gear tight turns? Not my favourite either!
"I started the day at 2.5 bar cold (36 psi)"
Try 32 cold for a track day.
"When I checked the pressure a little later it had risen to 2.7/8 (around 40 plus I think)"
Too high!!!!!! Back end a bit squirrelly??
"Should I have let the pressure out to around 2.2 cold at the start of the day?"
Yes. Try to adjust to, probably 34-36 hot for your car.
"Is this why the car was understeering? "
Partly -911's like being braked into the corner and on the turn in to get the front to load up. It's called trail braking. Needs practice. Also, airfields aren't the best surface for cars compared to a purpose built track.
"911 drivers don't stand much of a chance on these tiny circuits."
I do think the 911 suits more flowing ccts with 3rd and fourth gear corners.
But, did you have a good day???
Rgds
Melv
"Question is why did I struggle to keep it smooth?"
Probably trying to go too fast, too soon.
"developed a sensitivity"
There, you have it!!
"uncomfortable level of understeer into the tighter turns."
Secod gear tight turns? Not my favourite either!
"I started the day at 2.5 bar cold (36 psi)"
Try 32 cold for a track day.
"When I checked the pressure a little later it had risen to 2.7/8 (around 40 plus I think)"
Too high!!!!!! Back end a bit squirrelly??
"Should I have let the pressure out to around 2.2 cold at the start of the day?"
Yes. Try to adjust to, probably 34-36 hot for your car.
"Is this why the car was understeering? "
Partly -911's like being braked into the corner and on the turn in to get the front to load up. It's called trail braking. Needs practice. Also, airfields aren't the best surface for cars compared to a purpose built track.
"911 drivers don't stand much of a chance on these tiny circuits."
I do think the 911 suits more flowing ccts with 3rd and fourth gear corners.
But, did you have a good day???
Rgds
Melv
Thanks Melv! Yes I had a great day, although the 911 will be tougher to master than my previous car, an Integrale, which I think would have suited this circuit very well.
As you say, I was trying too hard first time out. As I relaxed and tried to gain a feel for the car, it started to come together, but I wish I had more time to progress it further, so it looks like I've got the bug and will be back at the next session.
Re the tyre pressures, you're right, it was a bit squirrelly. Next time I'll try your advice on letting it out to 32 cold.
As you say, I was trying too hard first time out. As I relaxed and tried to gain a feel for the car, it started to come together, but I wish I had more time to progress it further, so it looks like I've got the bug and will be back at the next session.
Re the tyre pressures, you're right, it was a bit squirrelly. Next time I'll try your advice on letting it out to 32 cold.
Oh, and I got humiliated by experienced hot hatch drivers, but I am told that 911 drivers don't stand much of a chance on these tiny circuits. That's my story, anyway, and I'm sticking to it.
On most of these hillclimbs little hot hatches are easily faster than most supercars. In England its mainly Minis and Pug 205 GTis that humiliate. Dad had his first sprint/hillclimb at harewood in the cerbera and REALLY struggled for traction all over the place. Great fun though!
Porsches and TVR's seem to be better on wider tracks rather than hill climbs, they are just too big, rear wheel drive and any sharp narrow corners dont mix.
80% of the problem at the moment is almost certainly going to be the way it's being driven. The fastest laps are always those which look the slowest because they are smooth. Trying too hard will cause massive problems with handling characteristics. For instance agressive weight transfer will cause understeer / oversteer problems, and will result in the tyres overheating and going off as the pressure increases inside the tyre, the contact patch will decrease and the tyre will just get hotter. Try going into corners a little slower and powering progressively out of them. Make braking smooth without trying to outbrake yourself at each corner.
You will probably find that it will take a dozen or so track / airfield days to get used to it and that is when lap times will start to tumble. At the moment you probably can't think how to make the car go faster as you are already driving at the limit but believe me you have a highly capable car there which driven well should give the Pugs and other assorted hot hatches a run for their money. (They are quicker at the moment because they are eaiser to drive fast than a Porker but you will start to reel them in one by one!).
Jas
You will probably find that it will take a dozen or so track / airfield days to get used to it and that is when lap times will start to tumble. At the moment you probably can't think how to make the car go faster as you are already driving at the limit but believe me you have a highly capable car there which driven well should give the Pugs and other assorted hot hatches a run for their money. (They are quicker at the moment because they are eaiser to drive fast than a Porker but you will start to reel them in one by one!).
Jas
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