981 CGTS vs 718 CGTS 4.0 steering

[dunc_sx]

Porsche911R said:

You have not owned a Elise or Exige then.

Had an S2 Exige and although it tries to rotate faster than a Cayman (probably due to the shortish wheelbase) it's nothing scary. I've just not experienced anything I'd consider to have snap oversteer outside a race car.

People will have had different experiences/scenarios than me though so happy to leave it at that

Dunc.

Edited by dunc_sx on Wednesday 11th November 08:13

[Porsche911R]

dunc_sx said:

Had an S2 Exige and although it tries to rotate faster than a Cayman (probably due to the shortish wheelbase) it's nothing scary. I've just not experienced anything I'd consider to have snap oversteer outside a race car.

People will have had different experiences/scenarios than me though so happy to leave it at that

Dunc.

Edited by dunc_sx on Wednesday 11th November 08:13

maybe not oem as every car is set to under steer.

but get a track geo on the cars and sticky tyres when they let go they let go very fast, you sort of have to know and turn the wheel before it going to happen. You drive Lotus with pin point style.

I have seen 2 or 3 Boxsters spin even just on the road in front of me, which is strange it's been so common in that model and plebs driving.

I could not drift my Cayman R or my 981 GT4 at all, it's very hard. and I mean "properly drift" not just getting the back end out once.
I also spun by 987.2 Spyder on track but that does nee a geo change, that does get a bit all or nothing.

but any mid engine car on cups when hot you will need to have cat like reactions.

2.20 in on my vid, thats how fast you need to be to catch it, and you have no thinking time, that's a subconscious correction.
https://youtu.be/IH5OacjJT50

[Steve Rance]

Not trying to detract but there's nothing in that film that looks like what I would consider to be a 'moment'. Pretty normal little twitch in a slow hairpin. Its when they do it in high speed corners that things get a little more difficult. I did a lot of demonsration driving in the S1 Elise for a year or so. The chasis needed some work that Lotus refused to do but you could drive round it pretty easily. You can 'drift' a Cayman if you so wished but it would require to be deliberately unsettled just after turn in which would be pretty pointless.

There's half a second on the table in the right hander that leads onto the pit straight by the way. It should be relatively straighforward flat in a Lotus elise/exige. Its flat - with a little work - in a 996RS.

[Rocket.]

Backing out of the throttle once it is sliding is usually what causes the spins I've had in mid engined cars (both in Elise S1 and a Cayman) it's still a bit alien and not natural for me not to lift so by the time I've thought about it's generally too late.

I had one of the 1st S1 Elises out of the factory in 1996 and these were definitely not set up to understeer, I think later on once a few had been in ditches they soon changed that!

Edited by Rocket. on Wednesday 11th November 15:35

[bcr5784]

Rocket. said:

I had one of the 1st S1 Elises out of the factory in 1996 and these were definitely not set up to understeer, I think later on once a few had been in ditches they soon changed that!

Edited by Rocket. on Wednesday 11th November 15:35

My S1 was like that when delivered - but was fine when a guy from the factory set it up properly. They did put narrower front tyres on later models - and then the press complained they understeered too much.

[Porsche911R]

S1 were way more drivable out the box, the S2 needed work and did have snap over steer. S1 you could drift out the box.

[Steve Rance]

I kept telling them that the S1 needed a rear ARB. Mid Transverse engine/gearbox layout without rear roll control was only going to end up one way. Dont know whether the S2 got one?

Back to steering. Driving the GT4 at Spa was interesting. When pushing on it oversteered on the exit of Eu Rouge and needed a bit of managing before the crest. Did 5 more laps to try and work out what was going on. The oversteer was consistent and my view was that it was a rear geometry issue. I got no clues at all through the steering which I found vaigue and a little lifeless. Generally I quite liked the car but found it unsettled when changing direction under gradient chages and found that the EPS steering made it difficult to 'connect' to the front of the car. I believe that the geometry issue was later overcome by several after market tuners.

[bcr5784]

The thing is, what setup makes sense on the road where you won't be getting that close to the ultimate limits, and what you would do on setup for the track are quite different. As a general rule I'd say a good track setup would be far too nervous for an everyday road car, and probably marginal for a weekend hoon car. A good dry race/track setup will be far stiffer than a wet setup. You don't generally have the option to do a quick switch on a road car - and certainly not on cars with "analogue" suspension which many (for reasons quite beyond me) prefer. Bikes are better in that regard.

[James McScotty]

bcr5784 said:

That's definitely an oversimplication. Yes the lower moment of inertia makes it more difficult to make them benign - but modern stability controls outweigh that. Hot hatches of the past such as the first GTI Golfs or Peugeot 205s are FAR more likely to swap ends than the best modern mid engined cars (ask me how I know!) Even with everything switched off my A110 is more benign than those early hatches. Engineering development (as the 911 shows!) can outweigh basic weigh distribution issues.

Once grip is broken, stability aids have no effect.

It's simple physics that mid engine cars rotate faster than front or rear engine, it's also why they turn in faster as well as spin.

[bcr5784]

James McScotty said:

Once grip is broken, stability aids have no effect.

It's simple physics that mid engine cars rotate faster than front or rear engine, it's also why they turn in faster as well as spin.

No one is denying the laws of physics (Jim)!
You are assuming that when the rear starts to step out grip is "broken" - it isn't. Beyond a certain slip angle grip reduces, it doesn't suddenly disappear. It's perfectly possible to drive a RWD car round in circles on full opposite lock - people do it in autotests all the time. So while it is a simple law of physics that a mid engined car (whether front mid or rear mid for that matter) will have a lower moment of inertia to suggest it will defacto be more difficult to catch is simply not true.The setup, the suspension geometry and the tyre characteristices all affect the issue massively. You might expect from moment of interia considerations that any FWD would be benign - tell that to anyone who races serious FWD cars.

Edited by bcr5784 on Thursday 12th November 08:16

[dunc_sx]

bcr5784 said:

So while it is a simple law of physics that a mid engined car (whether front mid or rear mid for that matter) will have a lower moment of inertia to suggest it will defacto be more difficult to catch is simply not true.

Edited by bcr5784 on Thursday 12th November 08:16

I have fond memories of my cayman S sliding round Riches at Snetterton, 80mph (?) double apex corner, on the throttle but keeping the steering fairly neutral (or add a bit more throttle for more angle and countersteer to suit). I remember thinking how well sorted the std handling was, much less snappy than loads of other front rear and fwd stuff.

Dunc.

[Steve Rance]

One of the best corners in the UK

[Steve Rance]

Some interesting Clips comparing steering. The first is a 996 Cup at brands Hatch indy. It is an hour race and the car was on full tanks. It was a Class 2 car and balasted with 50KG to maintain parity within class. For context the Class 1 cars around me on the grid were not required to carry balast and power output was unlimited. Also look out for some lovely cars lines up on the grid - Notably Paul and Pete's beautiful 993 GT2R

The second clip is at 997 Cup at Brands Hatch GP in wet conditions. The passenger is of a similar weight to the extra balast carried in the 996 so the comparison is interesting

If you watch the movement of the steering wheel in each clip you can see how much more lively the 996 steering is. However, it is telling me exactly what is going on and I'm only reacting to what I think requires correction. Because of the extra weight it is carrying it is being quite difficult even on fresh tyres but the steering feel really helps. I trust it to tell me exactly what is going on instantly.

In the 997 clip, the steering wheel is clearly much less 'animated'. More sanitised. It is feeding less information to my hands. As a result I am constantly 'asking' the car what is going on through the steering wheel through my hands. Whilst it looks a more tranquill experience inside the car, I am actually working harder. The 997 also has no abs which - in the wet - adds another set of challenges to the driver. Also the gearbox takes a bit of managing as downshifts require perfect heal toe rev matching to prevent the rear wheels from locking. The 997 chassis is stiffer and more acomplished than the 996 so they are very different cars to drive. Despite all of this, for me the element that separates these cars is the steering. I much prefer the steering in the 996

Too add. The 997 has an electric pump but is not a EPS system. There is no software involvement

https://www.youtube.com/watch?v=DQ2DLbZvqlg

https://www.youtube.com/watch?v=Mz1BB-NfRu0

[James McScotty]

bcr5784 said:

No one is denying the laws of physics (Jim)!
You are assuming that when the rear starts to step out grip is "broken" - it isn't. Beyond a certain slip angle grip reduces, it doesn't suddenly disappear. It's perfectly possible to drive a RWD car round in circles on full opposite lock - people do it in autotests all the time. So while it is a simple law of physics that a mid engined car (whether front mid or rear mid for that matter) will have a lower moment of inertia to suggest it will defacto be more difficult to catch is simply not true.The setup, the suspension geometry and the tyre characteristices all affect the issue massively. You might expect from moment of interia considerations that any FWD would be benign - tell that to anyone who races serious FWD cars.

Edited by bcr5784 on Thursday 12th November 08:16

It's clearly never happened to you.

I don't think anyone disputes that break away is much more progressive and predictable in front- or rear-engine cars, hence easier to catch. The corollary is a faster turn-in. No such thing as a free lunch.

[bcr5784]

James McScotty said:

It's clearly never happened to you.

I don't think anyone disputes that break away is much more progressive and predictable in front- or rear-engine cars, hence easier to catch. The corollary is a faster turn-in. No such thing as a free lunch.

Sorry but it has happened to me in FWD, Front engined RWD and mid engined on both road,track and skidpan. With everything OFF the snappiest were early FWD hot hatches cars (nothing to turn off) and, as it happens the most benign was/is mid engined (the A110). Now I'm not saying there aren't snappy mid-engined cars (the 981 is much harder to catch than the A110), but setup and tyre choice has a much bigger part to play in the picture than engine location. As I point out above the 911 is an absolute triumph of development/setup over what the weight distribution would lead you to expect. All things being equal, a mid engined car WILL be more snappy - but they never are equal.

To take tyres for instance see



As you can see the grip of the racing tyre falls off much more quickly as the optimum slip angle is exceeded. The high performance tyre hangs on longer and grip decays more slowly. The typical street tyre hangs on to the highest slip angle and grip decays slowest as optimal slip angle is exceeded. Clearly you will need to much quicker to catch a slide in with the racing tyre than the others and the street tyre will be the most benign.

You can do the same comparisons with suspension geometry. On lift off swing axles for example produce (more) positive camber on the outside wheel and raise the rollcentre increasing weight transfer to the outside wheel. Combine that with soft suspension and sticky tyres and you have a monster. etc etc

[Steve Rance]

I've raced every type of engie/drive config. Generally I would say that the Mid engined were the easiest to drive and the Rear engined RWD were the most difficult.

[James McScotty]

Everything else being equal, mid engine cars rotate faster than other cars. It's kind-of the whole point, for handling.

Front and rear engine cars rotate more slowly. It's physics,

[bcr5784]

James McScotty said:

EVERYTHING ELSE BEING EQUALl, mid engine cars rotate faster than other cars. It's kind-of the whole point, for handling.

Front and rear engine cars rotate more slowly. It's physics,

Isn't that what I actually said?

[Steve Rance]

A mid engined car will rotate quickly. They do require a modicum of car control to manage but they are certainly not difficult. Rotation I’d generally the toughest part of the cornering process and a mid engined car does that for you

[bcr5784]

Steve Rance said:

A mid engined car will rotate quickly. They do require a modicum of car control to manage but they are certainly not difficult. Rotation I’d generally the toughest part of the cornering process and a mid engined car does that for you

From what you say (and from my own knowledge) road going 911s -even "GT3s" are a problem on track because you need to get your trail braking right and that isn't that easy because so much understeer is built in to stop Joe public killing himself. FIA GT3s are different but set up for the track would be a handful on the road.

As an aside does anyone else find it rather naff that Porsche (and others) give GTX monikas to cars which aren't, and aren't intended to be, race cars? I suppose it's no worse (perhaps less) than giving "GT" monikas to cars that are just hot hatches or the F1 title to a McLaren.

Edited by bcr5784 on Thursday 12th November 19:36