997 diffrence between 4s & 4???

[uktrailmonster]

Mario149 said:

It's going to be even more complicated than that: in a C4 you have more weight at the front, so the CG is also further forward AND you have the tyres being worked harder as they're transmitting drive to the road so will let go sooner, so a C4 should understeer even more than a C2 with a crate of beer in the front. In my experience of owning both a 4wd and 2wd, on track the 4wd understeered more. But it's all academic really as you can get the geo tweaked to make it do what you want with either anyway. As best I can tell in the real world 4wd just tweaks the steering feel slightly and adds a few more pies to the car to lug around. And I just don't buy the "4wd in a 911 makes me quicker on the road" mantra anyway, especially in 996s and 997.1s, since the rears have to be slipping before any significant drive is sent to the front to start with, by the time the 4wd is helping, you'd have to be sliding like a hooligan everywhere, which people clearly aren't.

Yep that's right, but we shouldn't forget that the 911 in either C2 or C4 format is not inherently an understeering chassis. The weight distribution is still very much rear biased so it's actually an inherently oversteering chassis and any built in "safety" understeer is purely down to setup i.e. massive rear tyres, spring rates, arb rates, damping etc. Both are plenty quick enough on the road, but I do believe the 4wd 997 is actually quicker on track - although largely academic. In the real world it's in the wet where it really makes a significant difference.

[Callughan]

uktrailmonster said:

Mario149 said:

It's going to be even more complicated than that: in a C4 you have more weight at the front, so the CG is also further forward AND you have the tyres being worked harder as they're transmitting drive to the road so will let go sooner, so a C4 should understeer even more than a C2 with a crate of beer in the front. In my experience of owning both a 4wd and 2wd, on track the 4wd understeered more. But it's all academic really as you can get the geo tweaked to make it do what you want with either anyway. As best I can tell in the real world 4wd just tweaks the steering feel slightly and adds a few more pies to the car to lug around. And I just don't buy the "4wd in a 911 makes me quicker on the road" mantra anyway, especially in 996s and 997.1s, since the rears have to be slipping before any significant drive is sent to the front to start with, by the time the 4wd is helping, you'd have to be sliding like a hooligan everywhere, which people clearly aren't.

Yep that's right, but we shouldn't forget that the 911 in either C2 or C4 format is not inherently an understeering chassis. The weight distribution is still very much rear biased so it's actually an inherently oversteering chassis and any built in "safety" understeer is purely down to setup i.e. massive rear tyres, spring rates, arb rates, damping etc. Both are plenty quick enough on the road, but I do believe the 4wd 997 is actually quicker on track - although largely academic. In the real world it's in the wet where it really makes a significant difference.

997 version was the first that was quicker round the ring by 2 secs.

[drmark]

spyderman8 said:

Then you'd better explain why trail braking works to all racing drivers then. The extra weight up front will also reduce the lightness and bobbing.

UKtrailmonster is right I am afraid. Most racing drivers have little clue about physics - or the difference twixt trail braking and bunging bricks in the boot. But they will soon learn if they try and substitute one for t'other