Unlike the RWD GT2 or GT3, the 996tt comes with an open rear differential. A factory LSD (albeit a weak one) was offered as an option the last year of 996tt production. So, if you remove the FWD system, you end up with a high horsepower car that is putting down power in a straight line to the two rear wheels via an open diff. As soon as you loose traction on one of the rear wheels (dirt, gravel, inside wheel unweighed in a turn) all your power will be transmitted to the wheel with no traction and you will get a lot of tire squeal and very little forward propulsion. Additionally, under very hard braking you will get a slight tail wiggle with an open diff as there is nothing locking the two rear wheels together. This is not generally an issue on a street car but will be noticeable at the track. This is usually a way to tell that your LSD is starting to go and is not locking anymore.

Unless you are strictly a stop light racer, a proper LSD is one of the best performance mods you can do to these cars and a virtual necessity if you like to drive the car aggressively in the twisties or at the track. An LSD combined with RWD will absolutely transform a 996tt. Most people have an obsession with huge turbos and bragging rights of a gizzilion horsepower but forget that you somehow need to put this power to the ground. At the track there is absolutely no comparison running against another tt that has an open diff even if they have much more power. An LSD will allow you to put the power down and launch out of corners much harder than a car with 800hp spinning it's inside tire.

Here is a detailed description of my Guard LSD review:
https://www.6speedonline.com/forums/...sd-review.html

 

Sorry to revive an old thread, but I think I'm going to do this today. Basically to avoid the problem in the post above you would just take out the FRONT CV's? That way you don't get the weight savings but you aren't turning your car into a 1 wheel drive vehicle?

 

Whether you remove just the CV axles or the whole front diff, the result is the same as described above with the only difference being a 65lb saving if you remove the whole diff. The front diff has no function if it's not connected to the front wheels. It's just dead weight at that point.

 

Well, I guess I will look into LSD's. Because I took everything out tonight. I am officially 1 wheel drive I guess.................

 

Call Matt at Guard. His products are awesome. The Guard Club LSD is one of the best performance mods you can do. I have over 30 track days on mine with zero issues.

 

With that same logic, the Porsche isn't really an awd car then, it's a 1 front 1 rear wheel drive with 80% of the engine output only going to one rear wheel from the getgo. Since the car can only send a limited amount to the front wheel, you're really have the same problem as a factory car.

An LSD would be killer on a 911turbo and be a huge difference, but most of the same problem exists whether awd or rwd, that being the open rear diff is where majority of the power will always be sent.

 

Yep. That's very true. Porsche uses PSM as a poor mans version of an LSD to keep the inside wheel from spinning but it does not contribute to forward progress. The only Porsche cars that come with an LSD are the real drivers cars, GT2/3s and Cups. That's why I said a good LSD is one of the best performance mods you can do to the TT. The fwd helps a little but no way will it equal the traction of a TT with an LSD. I tracked both a TT with AWD (open diff) and one with both AWD/LSD and RWD/LSD and it's not even a comparison especially on circuits that have fairly tight turns. If you drive the car at 7/10s it's okay but if you push it past that your traction will disappear through the inside wheel.

 

Yea, so I don't think anyone questions if a good LSD is the solution. But I don't know that I'd necessarily say that "with a RWD conversion, a LSD is an absolute must" as some have said. I think it'd be better to say a proper LSD is a general must on the 996tt due to the poor differential setup.

That said, the power adders put a bigger smile on my face and I'll be doing an LSD after all those are done, sorry =/


Based on that same example, a stock tune 996tt with rwd conversion would have roughly the same traction as a tuned awd 996tt i.e. ~15-20% more power means that much more is going to the rear wheel. And that example can go onward.

 

What is the reasoning behind the rwd conversion?

 

It is perceived that the 996 AWD system is less than impressive, so the complete removal of the system results in a savings of 70lbs and a more GT2/930 feel. In most cases it isn't working anyway and you would never know, using valuable HP trying to turn all that crap for nothing...

 

So how did the car with AWD and LSD respond vs just LSD?

 

It was a very subtle difference because the FWD transfers only a fairly limited amount of power to the front. I like the RWD feel better as it makes the steering a bit more communicative and the 70lb loss is a big plus. Another huge plus is the fact that with RWD you can run what ever tire sizes you want.

 

Is there any noticeable performance difference for straight ahead acceleration?

I've been tempted to do this conversion but rarely track the car. Most of my fun is stoplight to stoplight these days.

 

I am doing the full RWD mod next week on my 996TT. I will post the pictures once ready. I cannot wait...

 

removing almost 70lbs and rotating mass from the car is noticable.