LSD for a street driven 911SC - What's best?

[Porchdog]

I find myself starting a refresh of my drivetrain in my 81 SC sooner than I had planned.

The throw out bearing fork cracked. When I pulled the drivetrain I found a broken head stud. Suddenly, instead of hot rodding the motor "someday", I'm getting ready to do it now.

One issue with the 911 that has bothered me as long as I have had it is single wheel spin - either on launch or leaving a slow speed corner. On my rear wheel drive cars and truck that solution has always been simple - add an LSD or a locker.

Now that my transmission is going to get refreshed, an LSD is going in. The question is - which one?

I always figured the OEM friction plate style was the way to go - but I'm reluctant to get more oversteer in low-traction conditions. I will be driving in heavy rain, on snow and ice and on gravel. The Kaaz unit seems to offer improvement over the traditional unit for this. I have had lockers and they can be tricky, even in a pickup truck.

I have experience with gear type limited slip in my trucks and I really like it. the choices there seem to be the Quaife ATB, the Wavetrac and the Guard Torque Biasing.
Out of those, I'm leaning to the Guard.

Any experiences or advice?

Thanks Guys!

[David Inc.]

For street? Unless you're going with big horsepower I don't imagine you would need the LSD. My '82 is a little bit hotted up and I've never felt the lack of the LSD, even on track. Unless you're putting the car into a really upset condition there's just plenty of grip and not enough power.

[-Levi-]

For whatever it's worth, I just rebuilt my 3.6 to a well built 3.8. I did the transmission at the same time. For my transmission build I did nearly every upgrade offered including the internal Wevo gate shift kit, trans cooler, rsr spray bar, side plate... blah blah blah.

I kept with the factory lsd and had it rebuilt. The car is great at the track and on the street with sprinted driving.

[rdimarco]

I've been very happy with the Wavetrac. No bad behavior on the street.

[Porchdog]

David, - I think the car needs more traction. I expect increased power will increase that need.

Levi - If I had the factory LSD, I would get that rebuilt. Since I'm buying an LSD and there are at least 6 choices on the market for this trans I'm looking for feedback. I appreciate yours.

Rick - that sounds great - thanks!

[OldSpool87]

I have a 930 with factory LSD and an SC with Wavetrak. I don’t really notice either on the street. However, under heavy braking, the LSD in the 930 really keeps it planted. Wavetrak is not an LSD.

[Bill Verburg]

each has merits and minuses
factory ZF 40/40 clutch type;
reliable can be setup 80/80(nominal) if you wish, generally not intrusive,
for street use 40/40(nominal) is best it's nice coming out of a corner and under braking
not so nice if you hit a full lane width patch of ice or oily water
generates heat

gear type:
even less intrusive than a clutch type,
fixed setup
doesn't generate extra heat
has zero effect on during decel

asymmetric clutch type;
multiple setup options, 20/80, 20/60 40/60 etc, the smaller the first # the less intrusive on acceleration, the bigger the second the more effect on decel, These are all nominal figures

generates heat

[shoooo32]

I have a Wavetrac in my 3.2ss SC. It's a street car but I take it to the middle of nowhere and slide around in the gravel. It seems to have no downside - very predictable and as Bill pointed out, doesn't generate heat (which is the 915's Achilles heal). If I had to do it over again, I'd buy a Guard. The owner Matt is on Pelican, super helpful and stands behind his products.

[Matt Monson]

Thanks for the kind words, from those who commented. I do try to avoid selling here, and prefer to largely let folks chat among themselves, but do want to add one thing. I pulled out of the TBD market a handful of years back, and now we only make clutch type LSDs. That said, our LSDs are robust, reliable, and totally streetable, even though they are Motorsports grade. The usual internet generic lsd comments about noise or frequent service or twitchy handling aren’t something you’ll get from us.

Regards,

Matt Monson
Guard Transmission llc.

[Jeff Higgins]

I have been very happy with my Guard torque biasing unit. It's unnoticed in street driving, but a real asset on the track. It does nothing under braking, but it sure helps on corner exit. Completely unobtrusive otherwise.