Trackday experience vs everyday

[GOOFY]

Hi

I recently drove my Boxster on a Brands Hatch trackday, on a damp/ wet day. Even in the wet the grip was astounding. But something puzzles me. At no point at all on the track did the rear end ever step out. This was even with some pedal to the floor acceleration round some very sharpish & wet bends. I did experience understeer around Paddocks, Clarke Curve, but backed off to stick to the line. I don't think I was slow as more powerful machinery (996/997's) were around the same speed around the bends. The point is that driving one day about a year ago to work, with no provocation, the rear end swung round on a very mild curve, at less than 30mph (it was very cold Winter day).
The second point is , how do you get a Boxster to "drift" ? Another driver remarked to me that he expected I would be doing this on the trackday due to the balance of the car.

By the way I do have TC fitted and thought I could feel some "stuttering" on the bends - or was it my imagination ! Please don't tell me I wasn't going fast enough !

 

[JCB..]

In my experience two things are most likely to cause a Boxster rear end to break away.

One is oil or the like and the other is too much right foot.

In the damp and providing your right foot isn't buried to the floor I have found it is the front that is more likely to go first. This does of course depend on how your car is set up and the state of your tyres and pressures. My car has 030 suspension, 32 psi front 34 back with "Nic Doczi's" trackday recommended set up - everything pointing dead ahead with as much negative camber as possible.

I'm led to believe that the Boxster, as it leaves the factory, by design has understeer to compensate for the mid-engine layout. Being mid engined makes the car very stable until the point that traction is lost when it is quite likely to spin very quickly. With all the weight between the wheels drifting a mid engine car isn't going to be easy.

At Castle Combe a few years ago I had the benefit of discovering someone elses sump contents at Bobbies. I actually had a circuit guide in the car at the time and when we hit the oil there was no sensation of losing traction at either end it was, quite literally pointing down the track and then broadside in an instant. Luckily the car flipped back around the once off the oil slick.

TC or PSM? TC doesn't stutter it's more of 'smother' are sure it wasn't the rumble strips around the track edge?

 

[NicD]

Ok, to take control of the car, you must switch the TC off.

I deliberately left this off the options list of current S 'cos so easy to forget to do. I recall a session at Castle Combe, remembered the TC halfway around, but by fumbling around for the off switch, I missed the entry to the chicane, had to go through the barriers and was re-passed by the car I had just overtaken.[:-]

Drifting in a Box can be so gentle you dont know it is happening, but check that you are applying gentle opposite lock without realising. Brands Hatch Clearways (into main straight) - as you pass the second apex, and camber change, very easy to drift out without realising.

A gentle drift can easily turn into a spin, as the feedback isnt so great. I have spun mine only a couple of times on the track over many years of track days, but once it has gone, nothing you can do, though I normally give full brakes and clutch in.

Now why step out on a road and not a track, as John says, oil/diesel on the road, or a bump or camber change. Something has removed contact or grip. Tracks arent like this so much and you learn where any problems are located and drive accordingly.

I have to say, my Box has never (that I can remember) stepped out on the road, and I read the crash stories of this with some wonder. Maybe I drive like a wuss on the road, or maybe correct early, or most likely both.

 

[GOOFY]

Thanks for info.

I do have M030 and TC fitted as standard, and only time I have seen the TC light flicker on was on some brutish acceleration on a wet road - when going over manhole cover. The spin on the road ,well combination of things : the tarmac at that point is very slippery,sometimes my front wheel drive car scrabbles for grip, and I suppose partly my fault as rear tyres were down to 1.6mm - but I thought the TC would have stopped the spin - may be the laws of physics can't be overcome even with TC !

I think the "Stuttering noise" may be something else. Since I had the clutch done , I have noticed a low "vibration/rumbling " noise when accelerating in a high gear at very low revs - i.e. 3rd at 1500 rpm or lower. However on the track on the bends this was still there even at 3-4 k rpm. I think may be loose exhaust mount or engine/ gearbox mount ?

As you say drifting the Boxster is difficult - so I wan't attempt it !

 

[berty987]

I did a carlimits airfield tuition day a few months back , and learnt a lot about the boxster handling as a result. The 987 is fitted with traction control or PSM as standard , so under normal conditions the car settles any untoward responses into a safe and tidy result. With the PSM "off" it soon becomes apparent that the boxster will oversteer if you" lift off" in a bend or coast into a corner. On a track you have far more scope to adjust the steering angle and keep the power to the rear wheels if you find yourself understeering, on the road the natural instinct is to "lift off" to give yourself more time and space to compensate. During the carlimits day , one of the excercises was to drive at speed into a corner and use the brake to make the car go from understeer to oversteer whilst keeping the same steering lock. It takes practice and a gentle modulation of pedal pressure , but I managed to get under , over , under and over steer all in one manouver. I would recommend a driver tuition day to understand the car's handling before a trackday, you will get so much more from the trackday as a result.

 

[JCB..]

http://www.carlimits.com/

 

[channella]

The car will oversteer with PSM on - it just won't let you get too far out of shape, but the car can spin with PSM on, because PSM doesn't change Newtonian physics, or the level of absolute grip available!

On a damp Oulton Park I experienced oversteer out of a few of the corners. Right foot was the cause.

Don Palmer's limit handling course is very useful if you want to understand more.

 

[critch]

in reply to Goofy....

I took my 987S to Castle Coombe for the Boxster day last April and I found that it was possible to get the back end to slide, even in the dry, though this was held in check by the PSM (which I wasn't brave enough to turn off!)

I think it's down to tyres. At Castle Combe I had the original-fit Continentals which seemed much more progressive compared to the Michelin Pilots which I replaced them with. The Michelins have superb grip - to a point - and then let go without much warning.

On the road, oil (or diesel) is the usual culprit especially on a roundabout near a petrol station. I 'lost' the boxster at quite low speed going round just such a roundabout, one that is familiar to me and was always safe at 45+, at least until I hit a patch of diesel. I lost it and bashed a wheel against the kerb, which destroyed the wheel and tyre and required a full alignment check afterwards.

critch

 

[JCB..]

ORIGINAL: critch

in reply to Goofy....

I took my 987S to Castle Coombe for the Boxster day last April and I found that it was possible to get the back end to slide, even in the dry, though this was held in check by the PSM (which I wasn't brave enough to turn off!)

I think it's down to tyres. At Castle Combe I had the original-fit Continentals which seemed much more progressive compared to the Michelin Pilots which I replaced them with. The Michelins have superb grip - to a point - and then let go without much warning.

On the road, oil (or diesel) is the usual culprit especially on a roundabout near a petrol station. I 'lost' the boxster at quite low speed going round just such a roundabout, one that is familiar to me and was always safe at 45+, at least until I hit a patch of diesel. I lost it and bashed a wheel against the kerb, which destroyed the wheel and tyre and required a full alignment check afterwards.

critch

I agree entirely with your comments about the Conti's. Many people believe that their characteristics make them a poor tyre. Needless to say I don't subscribe to that view - they always communicate what the road conditions are very well indeed.

 

[channella]

In reference to an above point, I suggest the Boxster's tendancy to understeer has more to do with safety. I can't say categorically whether that has anything to do with a mid-engined layout, but that will produce a lower polar moment i.e., it is easier to rotate a Boxster than a Z4 say.

Most drivers can cope with some understeer, but not oversteer, so the car understeers first. If you persist with applying the power it can then switch into oversteer. Most cars understeer as a result of needing to compensate for driver skill rather than engine position therefore, because all you do is back-off to tighten the line.

 

[sawood12]

Andrew, you are correct. I recall an episode of Top Gear where JC was test driving the mk2 Elise and he couldn't make it oversteer. A Lotus test driver came in and basically went round the TG track virtually with the back end constantly hanging out to prove that is it possible. However he told JC that the cars come out of the factory with less front end grip to induce understeer as oversteer is more difficult to correct for the average driver. I guess it will be the same with the Boxster as they have to account for those drivers who only ever use it to go to the supermarket and back again.

My 944 is my first RWD car and one think i've learned about RWD is that lifting off mid-bend is bad - in any conditions. Even if you find yourself turning into a bend with a bit more speed than you'd like, lifting off the accellarator is the last thing you should do as lift-off oversteer is a well known technique to get the back end out and there are not many FWD cars that you can use this technique on as they tend not to have much weight in the back end. I guess Boxsters will be a bit more safe than my 944 with their TC and PSM, but in my 4 yrs of 944 ownership I have learned alot about drivng because it is less forgiving of mistakes than a modern FWD car with begnign handling characteristics.

I don't think you can blame TC and PSM for not getting your back end out. At the end of the day these devices can only work if there is any grip available - they will make the most of the available grip but wont find grip where there is none, therefore you can always get your Boxster out of shape by simply going faster. The problem with this is that because the Boxster is such a capable car you'll need alot of speed. It takes alot of guts and faith in your own driving abilities to do it in your nice expensive Porsche though!!