[quote]Originally posted by zenith993tt:
<strong>Thanks for the advice, looks like you have had similar experience with this transition (44 turbo s). I'm really going to need a track day to figure this thing out- it is almost too fast to experiment with on public roads (in Chicago anyway). Would you recommend any specific suspension tweeks?</strong><hr></blockquote>

Full suspension (shocks/springs/anti-roll bars) seem to do the trick, as does putting really wide tires on, especially up front. The two setups I like the most are the GT2 and the RUF. They serve two totally different needs. The GT2 setup is track only IMO, although it can be driven on the street, but it's stiff. The RUF is a compromise, but a really good one at that.

Both significantly reduce the understeer and make the car feel much more stable. Before you do any of that, check your tire pressures and alignment. All Porsches and especially 911's are VERY sensitive to rear tire pressures. The factory says 36/44 front/rear on the 18" wheels and maybe? on the 17's as well. I would bring the rear down to 38-40psi depending on how rough your roads are (higher for rougher roads to protect the wheel). 44psi is too high IMO, makes the car feel very greasy.

fc-racer

 

[quote]Originally posted by fc-racer:
<strong>Before you do any of that, check your tire pressures and alignment. All Porsches and especially 911's are VERY sensitive to rear tire pressures...44psi is too high IMO, makes the car feel very greasy.

fc-racer</strong><hr></blockquote>

Great advice. 44 psi makes the rear end feel like it's on ice skates. I actually run about 33 fr / 36 rr psi on the street. On the track, I start with 30-32 / 32-34 psi, which usually gives me 40 psi all around hot.

Danny,

I can't afford to do it right now, but I'd also love to bring over a 968 CS (or Turbo S if I could get one of the few) from Europe some day.

 

[quote]Originally posted by zenith993tt:
<strong>Just got 97-993tt, been racing a kelly-moss 968.
</strong><hr></blockquote>

sorry to jump in, so your 993 TT is stock right now?

quick question, what type of center diff does 993 TT have? what's the split bias? was 959 the only production porsche with active diff?

 

The 993 TT has a viscous-coupling center diff, extremely simple design, nothing like the 959's PSK sytem. It takes a while for the power to be transfered to the front wheels b/c the rear wheel plates take a couple revolutions to get the fluid rotating in the center diff.
It's the perfect design for allowing power oversteer yet still allowing for 4wd grip

 

[quote]Originally posted by Stuttgart:
<strong>The 993 TT has a viscous-coupling center diff, extremely simple design, nothing like the 959's PSK sytem. It takes a while for the power to be transfered to the front wheels b/c the rear wheel plates take a couple revolutions to get the fluid rotating in the center diff.
It's the perfect design for allowing power oversteer yet still allowing for 4wd grip</strong><hr></blockquote>

I kinda wish Porsche would come up with a active diff for the TT's... if Mitsubushi can put a active diff in their sub 40k EVO7, surely it can at least be an option in 911... even if the volume is a lot lower in 911 turbo's.

 

Since changing over to the ROW M030 suspension we have been experimenting with a small amount of toe out (-0.07 degrees total)on the front end. My TT's turn in has improved and the car seems to take a nice set.

Although this setup seems more predictable, the slow in/fast out technique is still the rule of the day. I would be curious if anyone has found a particular alignment setup that works well as a street/DE compromise for this AWD chassis.

Thanks,

Fred

 

Ghetto Racer - Everyone I knopw that has driven the Mits EVO VII with active diff much prefers the early VI with torsen diff. Automatic technology doesn't not always result in an improvement. I'm told that the ability to throttle-steer the car is almost totally lost with the active diff. Maybe that's why people with Porsche's AWD usually praise its balance and adjustability...