KRM911

Hoping to determine if the limited slip differential that was an option for early SC models ever became standard in the 1983 SC or was it only available as an option for all of the SC years? Thanks to anyone who may be able to shed light on the topic.

Bill Verburg

It was an option, M220, on SC & Carrera

If the car left the factory w/ one there is a 12 embossed on the bottom of the trans between the type # & the serial #

KRM911

Thanks so much Bill. Appreciated. I am looking at purchasing an 83 SC and have NOT driven one with the LSD option. For someone planning spirited canyon type driving and not track days is this a critical option to consider in the purchase. Any opinions helpful. Thanks all.

Bill Verburg

LSD is nice but not at all critical for any street driving, Which is why it's an option. In some situations it can actually be a negative

For track use it is far more desirable

aaron.finch

I've been researching limited slip differentials. Granted, there are many opinions about them - both for and against. Of interest to me is the ZF-type LSD.
I was told today ZF-type LSDs really aren't essential for 911 cars unless their engines produce immense amounts of horsepower. So, if true, does this mean a car with a modest amount of horsepower do not need LSD, even for corner entry.

Bill Verburg

An lsd serves 2 functions
the first and most obvious is putting power to the wheel w/ grip as opposed to the an open diff where power goes to the wheel w/ the least amount of grip. This happens when the road has uneven friction say ice on the left and tarmac on the right and also on corner exit where the inner wheel is lightly loaded and thus has little grip.

the second is stabilizing the car under heavy braking, an lsd will help distribute braking loads to both rear wheels equally and helps immensely in the effort to slow the car down. note that gear type lsd like Quaiffe do not perform this second function, only a clutch type acts this way.

too much lsd action can make the car a bear to drive unless you have a lot of power and are always using it to the max, the ultimate of this is a spool drive. The usual clutch type will be either symmetric in action in both of the above functions, a stock street ZF is nominally called a 40/40, a race version 80/80. newer designs are far better choices these can be ant where from 10/1oo as used in the 964 Cups to a more reasonable street 20/40, the sweet spot is 40/60 withe racier versions going 50/80. These asymmetric designs have higher decel lock than accel because that's where it is needed more.

KevinGross

Agree with Bill. Will add that an LSD is definitely a benefit on track even for a low power car, for tight corners and wet driving situations. You don't need a ton of power to spin the inside rear in these situations.