Traction Control/LSD?

[andyjwhit]

evening all,

on spirited runs, the traction cotrol light tends to come on, car is a C2 Man with M030 suspension pack and Limited Slip Diff... I am not sure the workings/relationship between traction control and LSD but would have thought the LSD would have prevented any wheel slip and that traction control is more for pulling away from a stand still, or am I missing something?

Assuming everything is OK I can either,

1) Turn off the TC and let the car slide more, and hope I can catch it....
2) Sign up for some track days


Anyone driving C2 with tration controll switched off??

Thanks

Andy

 

[924nutter]

As I understand the function of limited slip differential, once it has started to do its work the rear of the car tends to behave like a go-kart with a solid rear axle and woe betide you if you have got the back out of line when you stamp on the accelerator. In the hands of the inept the car will end up pointing the wrong way; not terrific fun on at the Robin Hood round-a-bout on a drizzly friday afternoon. The pupose of traction control is to limit the amount of power to the wheels, however hard you try to accelerate. In other words limited slip diffs do not restrict power to the driven wheels but overcome the fundamental flaw of the differential in that, in its un-clutched form, it will feed all, of all, the power to the wheel that is slipping, whereas traction control will not let you apply full power however hard you may try, until the speed "differential" between wheels on the same axle, and indeed the speed differential between the two axles is within preset limits. There may even be a steering angle comparison, but as I don't know, I am not going to try to guess. Roughly speaking.

 

[andyjwhit]

Hi John,

thanks for the response, so if if I turn the traction controll off, I end up facing the wrong way?

Bst

A

 

[andywill]

Anyone driving C2 with tration controll switched off??

The PSM (Porsche Stability Management) traction control system was introduced as an option for the 2000 model year. A similar system just called Traction Control was offered in the 1999.
regards Andy

 

[924nutter]

No you will not end up facing the wrong way, it's just that your right foot has to be very gentle. Let me relate this story to you; imagine a young man who has just tuned his beetle with 1835cc engine, two single choke 30 I M P E webers, lightened flywheel, about 105 bhp. Now suppose this man had to dash over to Roe Engineering to pick up some parts for a customer engine. He turns right off the Aldershot road, it is raining and he gives it a big bootful as he winds the lock off. Next thing you know the beetle is sideways and full left lock is required to avoid spinning into the oncoming traffic, then the car snaps the other way and almost fulll right lock is needed, but still the car swerves dangerously into the opposite lane. but under some semblence of control, (luckily the road was clear) and sheepishly the driver steers off the grass verge and back onto the correct side of the road. Ok the swinging arm suspension is nothing like as good as the multi link on the rear of a 996, but you have 6 cylinders hanging out of the rear instead of the beetle's four, when it goes it is going to go big time, and you need to be very good indeed to catch it. Watch the carerra cup race supporting the BTCC this weekend and you will see what happens to a properly sorted 996 with the best set up and arguably some of the most talented drivers, when it spins. I would be very surprised if there was not at least one spin.
How do I know about the beetle? I was driving!

 

[paulus]

I've got a 40th Anniversary model with what sounds like a similar set-up.
However, the driving has to be very "spirited" in the dry - or relatively hard in the wet before the Traction Control light comes on (even with the 345bhp X50 engine in mine).
Have you checked tyre pressures on the rear are OK ?
Are the tyres a decent make ?

I don't turn the PSM / TC off on the road - as I'd have to be driving very hard to notice the advantage & the risks wouldn't be worth it.
However, I do turn it off for the couple of track events I do @ Curborough every yr - where the PSM / TC cutting in when you can drive very hard is definetely a pain & significantly slows the car down in corners.

Initially I was very afraid of the 911's reputation for swopping ends, but at Curborough, where you're the only car on the track & the track is much wider than a normal road, it's relatively easy to get right upto the limit of the rear tyres & if you want, go much further & power slide the car around the bends.
Dry is easyish to control, wet is more challenging as it slides much faster, but generally manageable (cornering speeds upto 60ish - the track isn't that big !)
The car uses up much more road width than you could normally get away with on public roads []

Paul
2004 C2 40th Anniversary