Is the Porsche LSD option a true Limited Slip Differential (lockup on acceleration and deceleration) or is it a Torque Biasing DIfferential (lockup on acceleration only)?

I believe some track junkies have been reporting that the factory 997.2 LSD is not strong enough for heavy tracking (mdrums?). That would probably point more to a TBD type in this case. I would look into that if I was looking at that factory option.

Guard transmission has a lot of info on their website regarding TBD/LSD options. It is a very interesting read one way or another. Nothing wrong with being informed.

http://www.guardtransmission.com/tech_faq.html

I am looking at adding a LSD to my car for the track so I would like to hear other people's opinions. To the people who went with Quaife, did you also look at Guard? If you did, why did you go that way?

Thanks,

T.

 

Stig's Garage in Vara would be one place that can install that for you. Or if you are in Denmark as listed in your profile, there's Schoneman Motorsports.

Figure 6-10 hours for installation.

 

The factory LSD is a clutch type LSD. Quiafe does not make an LSD, even though their own marketing tells you otherwise. They make a TBD (torque biasing differential), which actually has no limit to how much wheelspin they allow and act like an open differential in a zero traction situation, such as when you lift a wheel on a tight turn. Though I suspect from your post you already understand this, and mention it more of the benefit of other readers of this thread.

The factory unit is made by Aisin, which is different than every other Porsche gearbox in the last decade. All other Porsche gearboxes are made by either ZF or Getrag. This has pluses and minuses. If you make your way over to the GT3 forum you'll see a thread called LSD Buster talking about the problems people have with the LSD in the Getrag gearboxes (LSD actually made by GKN). The Aisin LSD in the 997 works pretty well from the feedback I get from my customers. For a street car that sees some DE use it's perfectly adequate.

However, I wouldn't really want to be using it in a racing environment. It's just not aggressive enough. Every 997 Carrera running in Grand Am has removed the factory LSD and replaced it with our unit. To my knowledge, none of them use a TBD because they don't lock on braking, as you mentioned. In PCA club racing there's a mix of our LSD, our TBD and the Quaife TBD. TBDs are ok for club racing but they will never be as fast as a true clutch type LSD for road racing.

Thanks for the compliments on the website. It's newly revised and still a work in progress. We've got more content we're going to be adding to it in the coming months but it had been non-functional for a while and we felt we had to get something back up to start generating google hits and providing information to our potential customers.

Regards,

Matt Monson
Guard Transmission LLC

 

Thanks Matt - also for the good info about the different types of diffs.
Have you sold the Guard diffs to Schonemann in Denmark (so that you know that they can work the stuff)

 

Yes, we sell quite a bit to Schonemann. In fact right now there's a full gear stack with our 3 piece motorsports mainshaft and our GT2 Pro chromoly LSD on it's way to them for a 993 Turbo racecar they are preparing. They know what they are doing when it comes to motorsports gearboxes.

 

That's assuming the factory LSD is good. Most aren't near as good as aftermarket.

I'm waiting for slipper clutches.

 

Thanks Matt.

I will contact them if I cannot live without a LSD or TBD