LSD in an AWD car
 

For you guys that are running this set-up, has there been any conflict between the PSM and the AWD? More interested in on track performance but would also like to hear from street drivers.

No performance gain unless you have a ton of power. You won't know you have an lsd on the street unless its wet.

lsd
 

I have been running the Guards Torque Biasing unit for about one year and have no psm problems, I realize that it is not a true LSD but it works for me. At 550 hp I was spinning the tires getting on the freeway, but not any more. Thats is with a built motor, alpha 30/76 turbos, and all the other goodies.

I disagree I just installed a wavetrac lsd and am impressed with the difference. Im only running a flash and air box. Tonight it was wet and the difference is more then worth it, I anticipate it to be a huge benefit on the race track.

You disagreed and then agreed at the same time.

I've driven it on the track in that configuration. No extra cornering speeds. The only time an LSD is beneficial is when you are going over the limits of rear grip. It's hard enough to get rid of the understeer.

You already have a rear engined car with AWD, rear grip is not usually a problem. Adding an LSD is just adding more rear grip that is not a weak suite for the 996 TT. Unless like I said, it's wet, or you have a ton of power, or maybe run street tires on the track and don't have a lot of grip.

Dont see how i agreed with you, the reason the lsd is a benefit is how the awd work in the 996tt. Any loss of traction at the rear transfers power to the front. My experience at the track leads me to the conclusion that keeping the inside rear wheel from spinning on corner exit will benefit handling as it will keep the power from the front wheels unless complete loss of rear traction which is ideal. On the street there is still a benefit for the same reasons, as for the OP question about psm I can not answer as I turn it off most of the time, especially at the track. But tonight in the near zero C temps and wet i never had the traction control kick in on hard accel in first, not normally the case without the lsd.

Heavy, what are you calling a ton of power?

To make sure I understand it, out 996tt cars do not come with a LSD from the factory? When the inside rear tire unloads and starts to loose traction than power is transferred to the front? Is this correct?

when either tire looses traction, yes, power is shifted to the front, they say to a max of 40%. The PSM acts like an LSD until the power is to much for it. In most cases the power is never to much for it. Even with PSM off, psm is not really off. It will reactivate to save your azz. accelerating in 3rd gear I lost traction in all 4 tires(very cold morning) and psm(which I thought was off) shut me down. If I had had an LSD, psm may not have activated until power was needed to the fronts.

I assure you the awd will react far faster than the lsd, the power will be transfered by the time the lsd kicks in since the lockup threshold on the lsd is likely 60/40. The inside rear does not spin hardly at all as it is. And I drive as hard,on track as anyone else here with a turbo. And at a lot of tracks with elevation changes. This is not speculation.

That depends on the tires. 996 tt is not an oversteer heavy car in awd form, in fact its just the opposite. You need enough hp and some serious setup (ie not street setup) to get rid.of the understeer, so how is an lsd supposed to help that? You might be able to take some ragedy street tires out and spi. The wheels all over, but most track or good street tires it wont be an issue.


So id say upwards of 550 whp.


Spinning the tires on cold tires in 2nd gear or getting on an on ramp is no where near the same level of grip as hot tires on a rubbered in track.

Dez, what power level are you at? Truthfully, I don't want to spend on it if I don't need it. I've never had tire spinning issues on track with just a flash but I'm about to install some power mods and was wondering if I would need the LSD.

Im at 520 rwhp, which might be 500 awhp? However im rwd now, once you have an lsd its too hard not to convert. I tried awd with lsd for a while, but you cant really use the lsd with awd. I never had hardly any oversteer on the track unless it was wet, and that was foot planted exiting several turns. I would spend the money elswhere unless you are considering rwd. Just my honest opinion.

That's good to know. Personally I like the AWD. I find it to be extremely forgiving and with all my suspension mods I got rid of the understeer.

Good read here. From what I extrapolate from what Heavychevy is saying, don't waste money on an LSD unless you intend to go RWD. Now, I was told by Gbox that in order to get the benefits of an LSD on an AWD car it can only be a certain type of LSD. I cannot remember exactly what was said verbatim so maybe he could add further for clarification.