I agree that winter tires would be more important than limited slip...

a gen 2 final drive taken down.....i think thats why they call them limited slip. they dont look very strong nor long lasting. no one makes a locker ,spool or lower gears.i looked into it a few mos. ago when i was installing NOS .they seem rebuildable friction plates,floaters etc but more suited to a go cart. imo

Actually, I'm considering getting a Cayman S in about a year, and considering the locking differential option. From what research I've done, it seems the advantage of a clutch-type differential is that it works under braking and very low one-wheel traction situations, whereas the more esoteric types don't. Disadvantages seem to be: possible understeering effects during hard acceleration in corners, possible "fighting the PSM," and a lack of physical robustness of the unit. I doubt I'd be driving so hard as to abuse it. Also, I wonder if it's really "necessary" for a non-track driven car. Even with normal wear-and-tear, it might not be worth having in my case. As it's a relatively new option, there isn't that much out there in the way of conveyed direct experiences with it.



Edited 1 time(s). Last edit at 11/23/2010 12:22PM by Laz. (view changes)

the reality is that under the majority of circumstances, these cars wont spin wheels. Even on a dry, clean track, my (admittedly mighty 2.7) will rarely spin wheels - even on such spin-encouraging places as exiting Oak Tree, still turning right, in 2nd, at full throttle ( then again, i'm ALWAYS under full throttle!).

So you spin a little on dirt and gravel. Big whoop. Sometimes Big Whoop! in a good way.

Tail happy can be fun.

Now, its useful in the wet, and very useful in snow. But, i'll also say that in snow i'd rather have open diffs and snow tires (as i do) than an LSD and summers or even all seasons. Ideally both.

Now, why do you need an LSD under braking? To avoid wheel lock up? That's what ABS does. Very, very well. And the front >>> back.

i would avoid the units that will have durability issues. Torsens hold up.

Grant

My contention has always been that the suitability of the rubber meeting the road determines the relative necessity for other compensations. My open differential '66 912 with rear snows went everywhere, even though over a certain speed the front end would begin to swim.



Edited 1 time(s). Last edit at 11/23/2010 08:34PM by Laz. (view changes)

Then torsens are awesome. I've had them in a procession of Audis since they were introduced in 1991.

I do drive my open diff 2.7 with snows in snow, but only if i get caught (else i'm in the aforementioned audi with snows - aka tank).

So i've never driven at higher speeds in the white stuff. That said, it was amazingly good int he few snows i did get caught in, albeit partly due to low expectations.

Grant

LSD and for my driving (from the mundane to the spirited but no track) I don't miss LSD on my cars.

If one is agressive on the street, taking corners under heavier throttle that 'normal' LSD can minimize unequal tire wear between the right and left rear tires. Sans LSD the inner tire on a turn can spin as the outer tire transfers torque to the inner tire. I'm aware of this shortcoming of a non-LSD car though and avoid whenever possible using too much throttle thus avoiding excessive wear on the right rear tire. (For instance the Turbo's rear tires have just over 12K miles and are quite even in their wear from side to side.)

I think the LSD is robust enough though if one's hammering down on the car all the time and causing the LSD to be active this has to increase the wear/tear on the hardware. Also, I always treated my cars with LSD to more frequent diff fluid servicing. But I never had any problems from the LSD.

If you're an infrequent user of LSD you probably could get by with EBD (electronic braking differential -- IIRC ) where the drivetrain controller applies the brake at the spinning rear wheel to transfer some of its torque to the non-spinning wheel.

I'd be a bit bothered about excessive rear brake wear/tear relying upon this system too often and I don't think I'd like it at all on the track. And I'm not sure how well it works compared to hardware LSD under all conditions.

That said, playing around on Porsche's web site the other day I built both a Cayman S and a Cayman R and for both cars I opted to have LSD. It is a $960 option. Were I to go ahead and get new Cayman (base, S or even an R), or Boxster or ?, I'd spec the car with LSD.

Sincerely,

MarcW.