Track day off - what happened?

I run a '99 C4. It's my first 911 but I consider myself to be an experienced road driver and have owned and occasionally tracked a few fastish cars in the past. Last year, I took my C4 to Bedford Autodrome and managed to stuff it into a gravel trap right in front of the pits much to the amusement of all concerned. Even now, I still think about what I did wrong and how I could avoid doing the same in the future particularly on the road where the consequences would be much more severe. So I'm looking for some advice from experienced 911 pilots on this one My car has 18" turbo look wheels with Conti Supercontact tyres - not the best tyres, I know - and pressures were set as standard. Track conditions were dry and hot, with about 25 - 27 deg C air temp. I'd done about 5 laps in the car, gone into the pits for 10mins or so to cool the brakes and then gone out again. After a further 2 laps, I switched off the PSM (perhaps not the brightest thing to do) but completed most of another lap without mishap. There is a right hand bend just before the pit straight which I had been taking at about 75 - 80mph but I felt the car could go harder through this bend so, on this occasion, I entered the bend just a few mph faster. I felt the car push a bit wide just past the apex; now, I know enough to know that backing off the throttle when you're committed to a bend in a 911 is not a great idea so, at this point, I backed off the throttle only very slightly just to tighten the car's line. Immediately, the rear end stepped out but I still had it in my head that backing off further was a bad idea and if I maintained power to the wheels, the C4 drive would transfer more power to the front wheels and pull the car through. So, I steered into the slide and maintained and even slightly increased pressure on the throttle. But the car ploughed pretty much straight on towards the inside of the bend where it clattered ignominuously into the gravel trap. The car was towed back to the pits and after a few minutes blowing bits of gravel out of all orifices with an air line, I gingerly went back out on to the track and completed the track day, albeit somewhat chastened and with the PSM left on. The car itself did'nt seem any worse for the experience once all the bits of gavel had been shaken out of it which is perhaps a testament to the inherent robustness of Porsches. So, a few questions. I know I should'nt have backed off the throttle but what should I have done when the car started to run wide in the bend? Had I left the PSM switched on, how would PSM have sorted this situation out? How would a C2 have reacted in the same circumstances? Why is PSM standard on C4's when logic would seem to suggest that PSM would be even more useful on C2's

Hi Mik, Interesting and concise account of events. I have a C2 Tiptronic without PSM so I cant offer too much advice on the precise handling characteristics of your vehicle. However, you mentioned you had done a few laps and it was a warm day so the tyres were starting to get up to and above temperature. I understand from the various track days I have done the the recommended tyre pressures should be set with the tyres WARM not cold. If they are standard they increase considerably on a track as oppoed to normal road use. I did a track last year in my 996 and after a good few laps the car started slipping and sliding, I pitted and got the pressures down to where they whould be and it transformed the handling. I am tracking next Monday at Brands and will reduced the f/r pressures by a few bar depening on how hot the day/track is and adjust them at the first pit. Hope this helps. Rob

would agree with Rob, I've learnt that I need the correct pressure at Hot as I remember back when I first tracked my 911, that I set off with the corect pressures 36psi all round (17's) but by the 2nd session it was all over the place, when I checked the pressures after speaking to a friend the pressures were about the 42-45psi mark.. so after a bit of testing the hot pressure of about 36-38psi seemed to work well with my car, got home fine and the next morning the cold pressure was about 32PSI

A car will slide when the trye has been pushed past its point of maximum grip. If you were understeering (which I guess you were judging by the description) the only way to eliminate it is to reduce the amount of work that you are asking the tyre to do, which is done in 2 ways, either reduce speed or reduce the turning angle of the tyre (wind some steering lock off) and hey presto the physical grip will be restored to the tyre. Of course this takes practice to do at 80mph, its a balancing act and is great once you have mastered it.The other alternative would have been to give it a big lift off, wait for the rear to break traction and catch it on the oversteer - but you need to be very quick with opposite lock on a Porsche (the best way is to let the steering wheel slip through you hands as it slides and catch it at the right point, but this takes an awful lot of practice in the correct conditions, so I wouldn't recommend it). When people drive on a circuit for the first time, a common problem is a driver turning into the apex too early. If you apex too early in the corner, you run out of road on the exit and start heading for the armco!! At first, it is un-natural to turn in late- but try going into the corner a little deeper before you turn in, and you will find your exit isn't so scary. As mentioned by others, the tyres becoming hot would not have helped, but if a 996 is driven correctly the tyres should heat up almost evenly (the fronts will be a bit warmer) - so the car should still have been "balanced", but if you applied more steering lock while understeering you will have an off. I will be going to Donnington during March and am more than happy to offer you a few pointers - I have an ARDS Instructors license and a Race license, but will not charge a fellow Porsche owner (if you're nice). Feel free to e mail me direct if would like any more advice. Enjoy Brands - Paddock Hill is like driving off the edge of the World. Simon

Mike, good advice to check and lower the pressures after each session (remember to increase at the end of the day) BUT I know Bedford quite well and this corner is quite tricky with a regular procession of offs there. 75-80 entry speed is pretty quick - I do this in my GT3 and I am not the slowest. You were lucky not to hit the armco there. Of course, depends exactly where in the corner you check the speed but my point is, you were going at a reasonable clip and have to be careful how you increase it. Contis arent the stickiest tyres either, so go easy.

People often go off and are mystified by the cause. Usually it is a combination of too much speed and, more significantly, taking the wrong line. This necessitates corrections that, if not caught quickly, result in a visit to the surroundings.

Hi Mik Good thread and some great answers. I am no expert so I decided to take quite a few lessons last year and one of the most useful techniques I was shown was what Simon describes in his post above. If you find you are coming through the corner "too quick" and the car is understeering, unwind some of the lock in order to optimise the yaw. This gives an immediate and uncanny amount of grip back to the wheels and is often enough to pull you through. I would favour this 9 times out of 10 rather than easing off the throttle. As to why you got in that situation it could be a number of things mentioned - high tyre pressures, wrong line, too quick etc. Interesting to hear what people think would happen with: C2 - I think much the same if you exceeded tyre grip PSM - car would have slowed you down through the corner much earlier I think PSM is std on a C4 as people who buy a C4 are more safety conscious??? I can really recommend taking some instruction, try and book someone for half a day and they will teach you a lot (one 20 min session is rarely enough) and spend the afternoon practicing and playing. You will be much quicker than you thought possible, smoother and you will have a much better understanding of your cars behaviour and what to do to correct it. The learning process is great fun too.

Nic, it could be I was looking at the speedo just before the bend and not in the bend but the speed did'nt feel all that fast. I'm no track hero and certainly GT3's and Turbo's were zooming past me all day. I tend to think this off was more about my lack of skill maybe compounded by poor tyre grip than about too much speed Thanks to all for your responses, btw

Best to look at the track and not the speedo!!