718 GT4/Spyder Is there a handling issue?

[bigmowley]

I am slowly coming round to the way of thinking that the Latest GT4 and Spyder chassis may not be one of Porsche’s finest efforts. I think that something is less than ideal with the rear geometry when you push the car really hard.
Most of this is just supposition and idle gossip but I do have some experience to back it up as well. My Spyder tried to kill me twice during track days and both times it was unexpected rear end breakaway mid corner at high speed and without any warning, I managed to gather it all up both times but it wasn’t nice. This was on a car set up for the track and in perfect condition. I also have many years of experience of racing and track driving under my belt so I know what I am doing. I am not tracking that car again! I had a 981GT4 and it was brilliant on track.
Now the idle gossip! I watched most of this years N24 race, (what there was of it!) and as usual there was lots of midfield BMW and Porsche Cayman GT4 out to play. Literally every other shunt involved a GT4! Barely a few laps went passed without a GT4 falling off the track it was quite funny at times, we ran a book on how long before another one fell off. I was at Silverstone track day yesterday and blow me parked in the barriers was a very sad looking GT4.

So is this all just coincidence or does the latest GT4 chassis have a few quirks?

Any thoughts?

[TDT]

bigmowley said:

I am slowly coming round to the way of thinking that the Latest GT4 and Spyder chassis may not be one of Porsche’s finest efforts. I think that something is less than ideal with the rear geometry when you push the car really hard.
Most of this is just supposition and idle gossip but I do have some experience to back it up as well. My Spyder tried to kill me twice during track days and both times it was unexpected rear end breakaway mid corner at high speed and without any warning, I managed to gather it all up both times but it wasn’t nice. This was on a car set up for the track and in perfect condition. I also have many years of experience of racing and track driving under my belt so I know what I am doing. I am not tracking that car again! I had a 981GT4 and it was brilliant on track.
Now the idle gossip! I watched most of this years N24 race, (what there was of it!) and as usual there was lots of midfield BMW and Porsche Cayman GT4 out to play. Literally every other shunt involved a GT4! Barely a few laps went passed without a GT4 falling off the track it was quite funny at times, we ran a book on how long before another one fell off. I was at Silverstone track day yesterday and blow me parked in the barriers was a very sad looking GT4.

So is this all just coincidence or does the latest GT4 chassis have a few quirks?

Any thoughts?

I heard about the 718 GT4 from yesterdays event also.. into Copse.... not nice.
Interesting comments though.... and there are threads on other forums that raise similar points.
There was a particular thread where a very very seasoned trackday driver and race series competitor in his 718 GT4 had a very high speed incident at Sochi - unexpected rear end breakaway on long high speed sweeper, which he has driven 1000's of times.

In one of the 718 GT4/Spyder handling threads there is some supposition that for the road car at least, the PASM programming and the spring/damper setting for the rear might be making the car spiky? - also many people are just driving the car directly from the dealership and onto track without even getting a geo read to make sure the car is actually straight and not just within OEM range as set by the factory.. where they then don't get touched again even after transportation across Europe and the world.
PASM programming doesn't explain what you observe at N24 - as those race cars are running Passive 2-way or 3-way suspension.

I drove a friends 718 GT4 on a bit of a soon a few months back where we swapped cars for a while - he had complained about rear instability before, so i was cautious with it, because I'm so used to my car which is wearing a pretty good set-up. Pointed the 718 at the twisties, on power and immediately the rear started walking sideways in an unexpected manner.... so decided to keep the pace in check.
He subsequently took for the car for full alignment and its much much better for him now.
The car is particularly sensitive to toe settings on the rear - so need to ensure this is set.

Edited by TDT on Tuesday 10th August 16:52

[130R]

The GT4 Clubsport is a completely different setup from the road car. The front suspension for example is taken from the GT3 Cup. So I don't think race cars falling off the track would have any relevance.

[keepup]

I’ve done over 5,000 miles in mine, mainly on track.

Never had the back stepping out without me lifting off or simply carrying too much speed into the corner. DSC/ Traction Control can help cover a number of driving errors but your on your own pretty much with lift-off oversteer.

Biggest issue is the understeer and lack of available camber on the rear without toe links. As TDT says though, the car needs a geo, if for no other reason than the speed you wreck front tyres without.

[Twinfan]

Yep, there's not enough camber from the factory and you really feel the difference in road holding when you crank it up.

[Romo]

Is this only a concern with track driving? Or is (spirited) road driving also an issue?

If the car needs to be checked on alignment, what settings are recommended?

[Twinfan]

IMHO, as a minimum:

Shims up front to get -2 deg of camber. Toe to taste.

Max the rear camber to -1.5 on standard parts and also set the toe to taste.

Leave ARB settings on mid-mid and ride height as standard.

[TDT]

Romo said:

Is this only a concern with track driving? Or is (spirited) road driving also an issue?

If the car needs to be checked on alignment, what settings are recommended?

Rough guide:

Fast Road & Light Track Use:
There is quite a bit of variance in how much adjustability people might get out of a completely stock car...
100% OEM range might be the following:

Front: Camber -1.6 to – 2.0; Toe zero, or slightly toe in
Rear: Camber -1.4 to -1.6; Toe in.

Moderate Track Use:
You will need parts for this whether Porsche Motorsport or other aftermarket.
Range might be the following:

Front: Camber -2.5 to – 2.75; Toe zero, (or maybe very slightly toe out)
Rear: Camber -2.0 to -2.25; Toe in.

Aggressive Track Use:
You will need parts for this whether Porsche Motorsport or other aftermarket.
Range might be the following:

Front: Camber -3.0 to -3.5; Slight toe out
Rear: Camber -2.5 to -3.0; Toe in.

[bigmowley]

Oh good not just me them.
Some good points here and certainly the lack of rear adjustment is a Porsche cock up without a shadow of a doubt. We could only just get my Spyder into the Porsche standard rear camber setting window without running out of toe adjustment on the std links. Matt fitted some old RSR links to mine, with a small mod I think, and that allowed a full range of adjustment. There are off the shelf links now I believe.

This was not lift off oversteer by the way but flat out in fifth gear with everything settled and composed, or so I thought!

As to the race cars I will stand to be corrected but the rear suspension is geometrically the same as I understand it just with more adjustment built in through the links and arms?

The characteristics are typical of mid engined cars, but the GT4 does seem mighty sensitive at the limit.

[TDT]

bigmowley said:

Oh good not just me them.
Some good points here and certainly the lack of rear adjustment is a Porsche cock up without a shadow of a doubt. We could only just get my Spyder into the Porsche standard rear camber setting window without running out of toe adjustment on the std links. Matt fitted some old RSR links to mine, with a small mod I think, and that allowed a full range of adjustment. There are off the shelf links now I believe.

As to the race cars I will stand to be corrected but the rear suspension is geometrically the same as I understand it just with more adjustment built in through the links and arms?

The characteristics are typical of mid engined cars, but the GT4 does seem mighty sensitive at the limit.

As you say, lots of options for adjustable rear toe links are available.

Yep race cars are the exact same type of set up... they have slightly different rear wheel carriers for a lower roll center, and use a blade style ARB, and have adjustable toe links already. But it's still a McPherson strut based architecture.

bigmowley said:

This was not lift off oversteer by the way but flat out in fifth gear with everything settled and composed, or so I thought!

Do you have any video to watch the moment back? - that can help you confirm what happened.
I always run my GoPro on track so that i can review stuff. Its good fun!

Edited by TDT on Tuesday 10th August 21:29

[HokumPokum]

TDT said:

Rough guide:

Fast Road & Light Track Use:
There is quite a bit of variance in how much adjustability people might get out of a completely stock car...
100% OEM range might be the following:

Front: Camber -1.6 to – 2.0; Toe zero, or slightly toe in
Rear: Camber -1.4 to -1.6; Toe in.

Moderate Track Use:
You will need parts for this whether Porsche Motorsport or other aftermarket.
Range might be the following:

Front: Camber -2.5 to – 2.75; Toe zero, (or maybe very slightly toe out)
Rear: Camber -2.0 to -2.25; Toe in.

Aggressive Track Use:
You will need parts for this whether Porsche Motorsport or other aftermarket.
Range might be the following:

Front: Camber -3.0 to -3.5; Slight toe out
Rear: Camber -2.5 to -3.0; Toe in.

Tx. great info. will get my spyder set up for fast road once it comes in.

[keepup]

bigmowley said:

This was not lift off oversteer by the way but flat out in fifth gear with everything settled and composed, or so I thought!

Flat out in 5th? What track/corner were you taking? Have you changed geo at all?

Was this pre or post apex? As TDT says, video would help a lot. I’ve never experienced anything like that.

The car is mid engined so it’s going to turn quickly, especially at the speeds you’d be doing flat out in 5th, but I’ve always found it predictable rather than spiky personally.

AFAIK, the Silverstone crash yesterday was more to do with the heavy rain and the car aqua planing rather that any particular handling characteristics, but you were there, what happened?

[bigmowley]

TDT said:

bigmowley said:

Do you have any video to watch the moment back? - that can help you confirm what happened.
I always run my GoPro on track so that i can review stuff. Its good fun!

Edited by TDT on Tuesday 10th August 21:29

I usually have the GoPro running but i hate watching it back . I just get cross with myself every time I make a mistake or don’t hit the apex.
I have got one big twitch on film at the ring. Now in my defense i don’t like the ring and I just haven’t done enough laps there to really build up some pace. I did a track day there on my own last summer to try to learn it a bit better and that helped loads, much better than tourist laps. This one is more about the corner than the car, now I know it’s there I can do it quicker with a bit of corrective lock just before the kick, still scary though, doesn’t look much in the video but it was a right tank slapper

It’s here: https://youtu.be/VimdIR2BCM4

Sorry about the crap editing.

My really big moment was at Goodwood and I didn’t have the camera in for that one. There was a dirty great big set of tyre marks on the track and the tyres were buggered afterwards.

[TDT]

keepup said:

bigmowley said:

This was not lift off oversteer by the way but flat out in fifth gear with everything settled and composed, or so I thought!

Flat out in 5th? What track/corner were you taking? Have you changed geo at all?

Was this pre or post apex? As TDT says, video would help a lot. I’ve never experienced anything like that.

The car is mid engined so it’s going to turn quickly, especially at the speeds you’d be doing flat out in 5th, but I’ve always found it predictable rather than spiky personally.

AFAIK, the Silverstone crash yesterday was more to do with the heavy rain and the car aqua planing rather that any particular handling characteristics, but you were there, what happened?

I wasn’t there, but heard about the incident and it sounds much more like it was down to the conditions and Aquaplaning at those high speeds more than anything else. Shame as not long after it all dried up and was set until end of day.

[TDT]

bigmowley said:

My really big moment was at Goodwood and I didn’t have the camera in for that one. There was a dirty great big set of tyre marks on the track and the tyres were buggered afterwards.

Where at Goodwood…. Fordwater? You do have to be careful there and the circuit moves up and down and can catch people out if you try to stay completely flat.. you need to ‘breathe’ the throttle with the circuit through there in my experience.

[bigmowley]

TDT said:

bigmowley said:

My really big moment was at Goodwood and I didn’t have the camera in for that one. There was a dirty great big set of tyre marks on the track and the tyres were buggered afterwards.

Where at Goodwood…. Fordwater? You do have to be careful there and the circuit moves up and down and can catch people out if you try to stay completely flat.. you need to ‘breathe’ the throttle with the circuit through there in my experience.

Impressive track knowledge yes Fordwater, had done it flat every time before that lap, and afterwards just to check I hadn’t lost my bottle

[Romo]

TDT said:

Romo said:

Is this only a concern with track driving? Or is (spirited) road driving also an issue?

If the car needs to be checked on alignment, what settings are recommended?

Rough guide:

Fast Road & Light Track Use:
There is quite a bit of variance in how much adjustability people might get out of a completely stock car...
100% OEM range might be the following:

Front: Camber -1.6 to – 2.0; Toe zero, or slightly toe in
Rear: Camber -1.4 to -1.6; Toe in.

Moderate Track Use:
You will need parts for this whether Porsche Motorsport or other aftermarket.
Range might be the following:

Front: Camber -2.5 to – 2.75; Toe zero, (or maybe very slightly toe out)
Rear: Camber -2.0 to -2.25; Toe in.

Aggressive Track Use:
You will need parts for this whether Porsche Motorsport or other aftermarket.
Range might be the following:

Front: Camber -3.0 to -3.5; Slight toe out
Rear: Camber -2.5 to -3.0; Toe in.

Thanks, much apreciated !


Can the aliignment change be done at the OPC, or a spelialists job?

Edited by Romo on Wednesday 11th August 06:08

[TDT]

Romo said:

Thanks, much apreciated !

Can the aliignment change be done at the OPC, or a spelialists job?

Edited by Romo on Wednesday 11th August 06:08

Ref OPC, I think it depends.
A number of OPCs are now offering ‘GT car setups’…. but I’d imagine that it they would still fall into the factory ranges for Geos which may or may not be enough for you. You could ask your service dept and see what they say.

So then it’s a specialists/independents job.
There are quite a few about, so it depends on where you are.

[Twinfan]

Romo said:

Thanks, much apreciated !

Can the aliignment change be done at the OPC, or a spelialists job?

Anything outside Porsche specs will need fo be done at a specialist, which is camber greater than -1.5 degrees on either the front or rear axle.

I'd go to a specialist anyway, OPCs don't generally seem inclined to set alignment very accurately, as long as it's within (a wide) tolerance they'll say it's OK.

[TDT]

bigmowley said:

TDT said:

bigmowley said:

My really big moment was at Goodwood and I didn’t have the camera in for that one. There was a dirty great big set of tyre marks on the track and the tyres were buggered afterwards.

Where at Goodwood…. Fordwater? You do have to be careful there and the circuit moves up and down and can catch people out if you try to stay completely flat.. you need to ‘breathe’ the throttle with the circuit through there in my experience.

Impressive track knowledge yes Fordwater, had done it flat every time before that lap, and afterwards just to check I hadn’t lost my bottle

Haha ok. So I’ve seen car off through there including a GT4 that was totalled. There is a line you can take through there which you can stay flat depending on the car but as it rises and falls though there you do need to be careful and just maybe manage the throttle and steering, and ‘breathe gently’ with the circuit.
Looks innocent until you drive it at speed. Great feeling when you get it right, through there though.