What Limited slip diff for a C2?

thecarfixer · 29 Jan 2019

I'm planning on getting the gearbox off my C2 to get it rebuilt as the final drive pinion bearing is gradually getting noisier, and it's not going to fix itself.

My main question is - allowing for a bit of upgraditis 'whilst it's apart':

Is it worthwhile fitting an LSD or ATB type diff, and if so, what would you fit given the choice?

I'm coming from the camp of 'I don't know I need one' as the car is incredibly grippy and I've rarely had a time where I've spun up on one side only, but does having a (correctly set up) LSD improve the driving dynamics for fun?

rdodger · 29 Jan 2019

If I was to fit one it would be an ATB as they are fit and forget.

Do you need one? Probably not unless you are on track every day in which case a plate type would be better anyway but require maintenance to adjust as they wear.

As you say these cars grip like mad and even in the Alps I didn't miss having one. I think on the road you would never notice the difference unless you go out in the wet drifting around roundabouts! :cop:

crash7 · 29 Jan 2019

I have been over this a million times in my head, and gotten nowhere.

996 grips very well, in a C2 with circa 300-320 bhp, with a 285 profile of quality rubber the back end is fairly unflappable, stable and predictable, unless provoked.

Under heavy braking however, read track, the car wants to moves about more and I feel that a LSD would be more beneficial under braking than under power.

An ATB does not help under braking, at all, Wavetrac allude to different, but it is not the case, lots of feedback from the M3 mob.

So if you want the best of both worlds, power and braking you need a proper plated diff, the issue with them is that regular maintenance is required and they are a consumable.

The standard M220 LSD plates are not available from Porsche separately so you need to go aftermarket or use Cup plates these as you can imagine are not cheap and you have the agro of having to remove the diff regularly to inspect to ensure that that its not worn and gone open.

Does you car have PSM? If so this needs to be taken into account as this could counter act the LSD, the Anni cars that were fitted with PSM and an LSD ran with different ramps to the standard M220.

Good luck!

thecarfixer · 29 Jan 2019

No PSM as it's a super early C2, the only thing it has is ABS!

I'm minded towards a plate type for the reason of limiting cross torque under braking as said. I don't drive the car anywhere near ten tenths, but, you know, it's always nice to optimise

wasz · 29 Jan 2019

I'd argue that an LSD is for bragging rights only in a road going 996.

If you are driving that hard on track better to spend the money on modifying the oil system before exploring all ten of those tenths.

Martin996RSR · 30 Jan 2019

I have a 220 in mine and I believe it would be unnecessary if I didn't run 245 tyres on the back and drive like a loon. I enjoy going sideways and have drifted a lot of different cars, some with LSD and some without. If you're going sideways it's far less tricky with an LSD. If you're well behaved on the road and only rarely let your hair down on an empty B road then an LSD, ATB or plate, would be a waste. The money would be better spent on either making it lighter or be better suspended.

That said, I wouldn't be without mine.

What Limited slip diff for a C2?

thecarfixer

Monza

rdodger

Spa-Francorchamps

crash7

Imola

thecarfixer

Monza

wasz

Paul Ricard

Martin996RSR

Montreal

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