[Mvez]

+1 for Richbot and Dogbone, all good info.

I say this all the time....an LSD doesn't magically lower lap times, what it does is give you more options on how to drive (and rotate) the car more quickly. The handling dynamics are increased, because now you have lock on accel and decel. This allows for both confidence and the ability to better perform (and consistently) things such as trailbraking, threshold braking, and allows for better on-throttle modulation of the car's attitude.

Plus, when you want to be a hoon, it's just way easier to drift a car with a good locking LSD.

I run Giken in my miata and 987, and I can tell you without a doubt, I can do things in my 987 that would be damn near impossible with an open, or stock diff. Mid engine cars don't like to be sideways, that's just not their inherent trait, so my goal was to make it as progressive as possible. The Giken achieves it. Mid engine cars are pussy-cats until you get to 9-10/10ths, and then you better be up on the wheel....there's a reason you don't see mid-engine drift cars, they change direction way too fast. The Giken is superb in controlling it's change in direction, and allowing me to do so.

Giken is dynamite in the low powered miata as well. Again, gives me options on how to rotate the car. You can't go flat fast enough.

I ran a Guard 4-clutch (60/40 ramp) LSD in my RS, and the difference over the stock unit was night and day. Go to throttle sooner, better control off the corners, rock solid stability under braking, and the ability to lay down awesome stripes when you feel frisky.

Money well spent, but it's something you can't really appreciate until you get to a point with the car where you really are in tune with it. These M-diffs really aren't that bad, they do lock and are very reliable (very much like Torsens in that regard), but once you go to a really high performing unit, you get ruined, and typically don't go back.

IMO, based on the wear from both my Guard and Giken, and how they work (which is slightly different), it seems the Giken should offer a longer service life, which I like. What I learned is that at the highest levels (pros in Porsche world), some didn't like the Giken as much, simply because it was a bit more difficult to tune because of how it works, and the way it uses gear oil as part of it's locking factor, especially in transaxle applications (think Porsche 911 and Cayman).

For us DE and club race guys, I think it's a fantastic diff, with a more buy-it-and-forget-it use. Because they can use virtually zero pre-load, it also reduces heat and wear of the internals...a lot of other clutch-pack diffs use more pre-load as part of the equation. The more pre-load, the more the diff is still somewhat locked in off throttle (coasting) situation....basically at turn-in. It's all a tradeoff. For my RS diff, I specified low pre-load, so that car would be free-er off throttle and on turn-in, so less understeer, but the tradeoff with less pre-load is that when the diff locks, it locks faster as the ramps do their magic....and, pre-load always lessens over time, as the clutch plates wear...so it means the non-Giken type diffs lock even harder/faster. I can say certainly this was the case in my RS, thus requiring a rebuild at some point.

In a BMW or miata, for example, you don't have to worry about gear oil weight because it's not a transaxle, you run what is specified for the LSD, or how you want to Giken to lock. If you run lower weight than the specific Giken oil (80W250), the diff will lock faster and harder....which takes away from the progressive nature. We always use Giken fluid in our miatas, it just works better than anything else.

FWIW - I will very likely put a Giken in my E92, for these reasons. The Diffs online LSD's are great too, no doubt, but I value service life a lot, and this is where I think the Giken shines. This is where the progressiveness of locking is preserved, via the lack of internal clutch plate wear. Part of that voodoo, black box magic of the Giken I suppose. Just my .02.