997.1 RS slow speed, straight damp road, lost control, why?

997.1 RS slow speed, straight damp road, lost control, why?

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Posh868

Original Poster:

10 posts

134 months

Tuesday 15th April 2014
quotequote all
Lost control in the RS on a straight damp road at 70 mph. very disappointing.

Was driving very normally in middle lane following traffic, was checking the mirrors as car approaching fast in fast lane, felt the car twitch, when I looked up it was pointing right 25 degrees or so, overcorrection spinout results in me crossing all 3 lanes of the motorway, some light damage. but very dangerous!

It felt almost like the car just suddenly lost control, I did nothing to warrant this reaction, was not driving fast, did not see any standing water, did not touch the white line, was not accelerating. It just lost control.

So was chatting to a friend who said that he has heard about this, that the diff is aggressive, more so than the road car and less so than the track car, and when this aggressiveness kicks in, for example if I went over something slick on the road with the right hand rear tyre, that the resulting aggressive torque application on the left rear tyre gives the car a turning moment to the right, contributing to the spinout.

Has anyone come across this? if so I would like to discuss, I now feel that I should not be going over 60mph on a damp and certainly not wet road in this car! fair enough, but I need to get to grips with why this car lost control so it doesn't happen again.

p

V8KSN

4,711 posts

183 months

Tuesday 15th April 2014
quotequote all
Posh868 said:
Lost control in the RS on a straight damp road at 70 mph. very disappointing.

Was driving very normally in middle lane following traffic, was checking the mirrors as car approaching fast in fast lane, felt the car twitch, when I looked up it was pointing right 25 degrees or so, overcorrection spinout results in me crossing all 3 lanes of the motorway, some light damage. but very dangerous!

It felt almost like the car just suddenly lost control, I did nothing to warrant this reaction, was not driving fast, did not see any standing water, did not touch the white line, was not accelerating. It just lost control.

So was chatting to a friend who said that he has heard about this, that the diff is aggressive, more so than the road car and less so than the track car, and when this aggressiveness kicks in, for example if I went over something slick on the road with the right hand rear tyre, that the resulting aggressive torque application on the left rear tyre gives the car a turning moment to the right, contributing to the spinout.

Has anyone come across this? if so I would like to discuss, I now feel that I should not be going over 60mph on a damp and certainly not wet road in this car! fair enough, but I need to get to grips with why this car lost control so it doesn't happen again.

p
What tyres are you running and are you sure your geo is correct?

V8KSN

4,711 posts

183 months

Tuesday 15th April 2014
quotequote all
I had a similar issue with my 997.1 GT3 on the M4 but this was purely down to cup tyres, wet road and an incorrect geo

SimonOcean

317 posts

152 months

Tuesday 15th April 2014
quotequote all
Does not sound right to me.

Get the geometry of the car checked. There was someone on here with a Boxster or Cayman (I can't remember) who recently reported a similar problem. It turns out that the toe in / toe out of his steering geometry was set 4 deg. (the correct setting) but in the WRONG direction. Even though this sounds like a long shot you have to check the geo in case there is a massive screw up here. You would have grounds for compensation if the car was set up incorrectly.

Sorry to hear this. I am glad that nobody was hurt.

Posh868

Original Poster:

10 posts

134 months

Tuesday 15th April 2014
quotequote all
Thanks for the prompt responses!

The accident happened in January between some of those showers we had, so granted tyres were cold, road was damp to wet, it wasn't raining.

The tyres are Michelin Pilot Sport PS2 N2's all round, tread was good although a bit low in the back, 3mm before illegal. I still have them as replaced the tyres afterwards.

The car had been to a MOT, and large service with Porsche about 1000 miles before. The geometry was setup by Porsche Reading 1 year before that, no bumps or mishaps since then, so assuming it was ok.

Really wanted to investigate the 'Differential Aggressiveness' thought though as my bud, who has also had a GT3 RS, has specifically heard that this has caused crashes almost exactly like this, at slower speeds, sometimes as slow as 60mph, as described in the past.

You have not heard of this?

V8KSN

4,711 posts

183 months

Tuesday 15th April 2014
quotequote all
Posh868 said:
Thanks for the prompt responses!

The accident happened in January between some of those showers we had, so granted tyres were cold, road was damp to wet, it wasn't raining.

The tyres are Michelin Pilot Sport PS2 N2's all round, tread was good although a bit low in the back, 3mm before illegal. I still have them as replaced the tyres afterwards.

The car had been to a MOT, and large service with Porsche about 1000 miles before. The geometry was setup by Porsche Reading 1 year before that, no bumps or mishaps since then, so assuming it was ok.

Really wanted to investigate the 'Differential Aggressiveness' thought though as my bud, who has also had a GT3 RS, has specifically heard that this has caused crashes almost exactly like this, at slower speeds, sometimes as slow as 60mph, as described in the past.

You have not heard of this?
I can honestly say that I have NEVER heard of the 997 GT3 diff being described as 'aggressive'!

'Open' and 'like chocolate' - YES biggrin

noneedtolift

846 posts

222 months

Tuesday 15th April 2014
quotequote all
I would also say that your event is more likely to be the result of standing water and/or naff geo. Without a change in torque/speed, I'd doubt even a faulty diff would send you into a spin.

Dblue

3,252 posts

199 months

Tuesday 15th April 2014
quotequote all
Its a surprise you weren't on Cups , thats exactly the symptoms of an aquaplaning GT3 on those tyres.

The diff is aggresive by road car standards but you need to be doing far far more to it than you imply to get that sort of reaction.

I had a straight line spin in my 996.2 GT3 but that was down to a very inadvisable up change from 2nd to 3rd at near max revs with some spinning of the rear wheels going on.

Edited by Dblue on Tuesday 15th April 17:49

Slickhillsy

1,772 posts

142 months

Tuesday 15th April 2014
quotequote all
V8KSN said:
I had a similar issue with my 997.1 GT3 on the M4 but this was purely down to cup tyres, wet road and an incorrect geo
and no driver error whatsoever! lol biggrin

LaSource

2,622 posts

207 months

Tuesday 15th April 2014
quotequote all
Dblue said:
Its a surprise you weren't on Cups , thats exactly the symptoms of an aquaplaning GT3 on those tyres.

The diff is aggresive by road car standards but you need to be doing far far more to it than you imply to get that sort of reaction.

I had a straight line spin in my 996.2 GT3 but that was down to a very inadvisable up change from 2nd to 3rd at near max revs with some spinning of the rear wheels going on.

Edited by Dblue on Tuesday 15th April 17:49
Agreed. Never had that unexpected experience on a number of 996 type GT3/RS cars.

I have had the straight line moment when accelerating hard in third gear on a cold March day in the damp with low tread tyres...naturally the rears started to spin and car beginning to point in a different direction. Fortunately, managed to bring it back under control and nothing serious happended and I learned to change the tyres and not do that again!

V8KSN

4,711 posts

183 months

Tuesday 15th April 2014
quotequote all
Slickhillsy said:
V8KSN said:
I had a similar issue with my 997.1 GT3 on the M4 but this was purely down to cup tyres, wet road and an incorrect geo
and no driver error whatsoever! lol biggrin
hehethumbup

Rockster

1,508 posts

159 months

Wednesday 16th April 2014
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Even with new tires on my Porsches I slow down on damp roads. The tires do not play well with water on the road. And if it is cool, cold, you are just asking for trouble.

3mm tread depth is not worn out by the legal definition but I know from experience tires worn down to this point are slippery on damp roads like would not believe.

Alignment, aka geo, is probably not a contributing factor though bad geo can result in uneven tire wear. Then what you have is are tires that are half good, half no good, if the wear is uneven across the rear tread faces, which is a good sign the geo is bad.

When you replace the tires have the car treated to a proper geo to be sure you and the new tires start out right

Steve Rance

5,435 posts

230 months

Wednesday 16th April 2014
quotequote all
It probably won't be the diff. That only locks under hard braking or acceleration. If you weren't pushing and you were on sports it's unlikely it's your geo unless the car is pretty much undrivable everywhere. More likely to be a pack of oil or Diesil on the road ie something external.

I'd get your geo checked as a matter or course though.

Steve Rance

5,435 posts

230 months

Wednesday 16th April 2014
quotequote all
Steve Rance said:
It probably won't be the diff. That only locks under hard braking or acceleration. If you weren't pushing and you were on sports it's unlikely it's your geo unless the car is pretty much undrivable everywhere. More likely to be oil or Diesil on the road ie something external.

I'd get your geo checked as a matter or course though.

Kawasicki

13,041 posts

234 months

Wednesday 16th April 2014
quotequote all
When you looked up?

mikem7709

977 posts

211 months

Wednesday 16th April 2014
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I've just replaced the PS2s on mine with a fresh set as they were 5yrs old. The rears were on 4mm and the fronts still on 6mm, I've put the fronts onto my daily driver and can't believe how little grip they have - they squeal in the dry and light up the ESP in the wet.

Haven't driven the GT3 on its fresh rubber yet but I'm expecting a marked improvement.

mrdemon

21,146 posts

264 months

Wednesday 16th April 2014
quotequote all
What's a fast lane ?

Then you looked up !! , where were you looking ?


Slickhillsy

1,772 posts

142 months

Wednesday 16th April 2014
quotequote all
Kawasicki said:
When you looked up?
Bingo!

Posh868

Original Poster:

10 posts

134 months

Wednesday 16th April 2014
quotequote all
OK, fair enough, I'll keep asking about and investigating the diff angle, but for the time being may have to conclude that one of 2 things happened ..

1- when checking the mirrors, I *must* have hit some standing water (surely, what else?) on the drivers side, (that must have been the twitch I felt,) the car, being lighter than the rest and only doing 70 (so little down-force), must have aquaplaned and pointed slightly right .. the rest is overcorrection/drivers error.

2- when the drivers side tyre lost traction for a second (due to standing water, roadkill, diesel), and I may have been accelerating lightly, the resulting speed differential in the wheels caused the diff to lock, and the resulting jolt forward on the left tyre with traction, further propelled me to the right .. the rest is overcorrection/drivers error.

Whatever happened, better driving skills may have saved me. I never said I was good at handling this car, it seems like a bit of a handful compared to the BMW! When she goes, you've got to be quick and enter the exact right input to save yourself. The BMW would have never aquaplaned there and I do that stretch at 85mph always! I was purposely driving the Porsche 'slow' at 70 to be safe. Not slow enough! .. Oh, and I'll get the geometry checked again ASAP.

So, how fast do you other Porsche guys drive on a (lets say) wet motorway?
Is there anywhere I can go (apart from Silverstone) to learn how to drift this thing safely to improve my handling skills? I'm looking for carparks, flat tarmac'd areas, drift days at venues, lonely wide roads, etc.

Edited by Posh868 on Wednesday 16th April 10:56


Edited by Posh868 on Wednesday 16th April 11:20

mrdemon

21,146 posts

264 months

Wednesday 16th April 2014
quotequote all
GT3 is not really a good road car full stop imo :-)

But you get the lovers and the haters. I love them but not for road use.

As for speeds, most people will be doing a ton plus in their Porsches on motorways even on damp roads on PS2, you see it every day.
Porsche will only sell you a N spec tyre and think that a N spec CUP in the wet is safe as houses and send you on your way, but will not fit you a Pilot supersport and say that's unfit for your car and dangerous !!

Not that you had cups on it, but then why even own A RS and fit PS2 anyway ?

sell it and buy a car better made for the road is my advice :-), these cars are well over hyped on here.

what's that, the 3rd straight line spin at legal speeds this year on this forum even inc the 991 GT3!!!

if you guys are not spinning the things get over 80 mph on a B road and the cars unsettled again, I am sorry but what's the point of these cars on the road ?

This is imho, so the normal posters can do one and not quote me :-) (likes that's going to happen lol )


Edited by mrdemon on Wednesday 16th April 11:30