Chads996

Yep, no LSD. Want LSD...eerrrr, Limited Slip that is.

I know Quaife makes one ($$). However, any other recommedations? Porsche used part perhaps? And, is this a p.i.t.a. to perform?

Chad

wwest

If you have Trac or PSM then you have a "virtual" LSD that will probably work better that any mechanical one.

SPR

doubtful that is why gt3's have lsd. My 99 also has lsd-

Chads996

Personal preference...LSD where to buy? Aftermarket or used part? Quaife, Guard? ideas?

Chad

JimB

I really don't think you can compare traction control or PSM with LSD. They help you make the most of the traction you have. LSD gives you more traction. You are right about the price. A good LSD will set you back about $2500 installed.
Jim

stiles_s

Do you need to disable PSM if you install an aftermarket LSD?

wwest

Do you need.......???

Absolutely!

Trac or PSM will brake the slipping wheel with an absolute minimum of slippage, probably less than 1/4 turn.

Even worse, they may interact adversely.

Again, tell me why an LSD is better??

If a wheel is slipping, and Trac/PSM moderately brakes only that wheel to prevent it for doing so, the engine can continue to "build" torque. How can LSD do better than that?

JimB

WWest,
Let me clarify my comments. If you are driving in wet streets or in snow I'm pretty sure that traction control or PSM would be better/safer. If you are trying to go fast, hopefully on the track, would you rather have your bakes keeping one wheel from slipping or would you rather have torque being spread between both rear tires. If your goal is to come out of a corner faster then clearly LSD is better. If you have a very high horsepower car (F1) you would want both LSD to get power to both wheels and traction control to allow you to mash the pedal to the floor without lighting up the tires. We don't have to worry about that too much with our cars. The downside to LSD is that it can induce understeer as you leave a corner.
Jim

wwest

AS I said, I don't believe PSM and/or Trac would allow LSD to ever "engage".

JimB

wwest,
I agree that putting an aftermarket LSD in a PSM/Trac car would not work. I don't know how the 40th anv system with PSM and LSD functions.

Actually I don't think PSM/Trac have any place in a sports car but that's just my opinion.
Jim

SPR

I agree with the latter comments. I odly enough have the 99 with both lsd and traction control. In the wet the traction control is actually useful, only because I have bfg's which are super sticky dry but crap in the wet. Otherwise I turn it off when driving hard. PSM works with an open differential just Like c43 amg's. Many people love psm and the like but I can't stand anything that is that invasive. I bought my 99 c2 specifically for the performance lsd c2 coupe lighter. I only wish it didn't have the sunroof for weight, but I like it occasionally-so whatever.

stiles_s

LSD can do better than that by evenly distributing torque so you hopefully avoid a wheel ever slipping. There have been many occasions (especially in the wet) where LSD would have prevented the inside wheel from slipping, therefore preventing my Trac/PSM from cutting the power.

Yes, I think some LSD systems shift torque based on slippage, which is why I think they had to tweak the sensitivity of the Trac system on the 40th cars to get the two to work in concert.

Given that my car is my daily driver in all 4 seasons, I wouldn't trade my PSM for LSD, but I'd sure love to add LSD to the mix.

jasoncuk

Sure, if the car is never intended for general road use. You can get LSD on the 996 Turbo in Europe for example but not sure if that requires a new PSM programme. Reports from those that have it are that it significantly enhances performance on the twisty stuff even with PSM on (ie it reduces the need for PSM to come in).

wwest

Obviously the factory can modify the PSM firmware such that it isn't a virtual LSD.

Chads996

I think my 996 doesn't have either. There are no switches in the cockpit to turn the trac. control off. And...I checked the rear (tires off the ground) no LSD.

And...obviously, because of the year no stability control. So, I would like to install a LSD fro track use. Thoughts?

C.