Why the Limited Slip Differential/Traction Control? LSD

[Surferjer]

Originally Posted by knucklehead

KingJester,

I had never autocrossed, tracked or even karted before buying my car. The car is such an amazing car that it'll change your interest. You've been warned

I added LSD after buying the car along with Penske shocks and a BWR front sway bar. I launch harder and exit turns harder with the LSD. I also feel the car is more predictable with the LSD during autocrosses.

Me too, word for word what Jacob said. Never visited a track or autox before the Elise. Now I'm a junkie.

[TimMullen]

Originally Posted by Uncle Sam

It would help you when you drive in snow.

Yes and no. Yes it might help you get moving if you are stuck. No, because it can cause the back end to get real squirrelly. As a reference, I have an R Package Miata (with a Torsen LSD). That car can be a real handful in the snow if I'm not very careful. I've done more than one spin out on the neighborhood streets when they were packed snow (icy). Just a tad too much power, and both rear tires start to slide...

Similar with my 4x4 pickup, but not nearly as bad. But in that case, the LSD does help to pull out others stuck in the snow banks...

Originally Posted by CleanLivin

wouldn't the LSD help considerably taking the everyday right turn hard and fast. From what I've read it would seem that much like in autocross LSD would allow you to lose less traction/power in this tight turn and be able to put the power back on sooner. Maybe I'm wrong. I'll leave it to the experts to tell me.

Not unless the average Joe has a habit of smoking his inside tire around tight turns. Really hard to do that unless you are immune to tickets for some reason...

Originally Posted by Chris Mackey

Autocross is NOTHING like street driving. <...>
Er...seriously, If you know if the difference while driving on the street, you are creating a hazard for the public.

+1

[kingjester]

so just as a summary, if it is just for the street the LSD is not a NEED. If I am going to track/Autocross it is NICE to have.

I used to have an M3 with traction control and I hated it because every turn I went into with power, the traction control would step in, take all the power away from the car until it was "stable" again and then bring the power back. It was a really unnatural feeling. That being said though, I'm sure it kept me out of the trees a couple of times.

Do you find that it is easy to "break" the back end on this car easily and get into "trouble" ie. hit things?

[Hello Kitty]

Originally Posted by kingjester

Do you find that it is easy to "break" the back end on this car easily and get into "trouble" ie. hit things?

I have a open diff, and I wish I had LSD. With LSD, the backend slides as you would expect. With open diff, you never know when the back will slide out. Its up to the outside tire, which has a heavy load, and NO POWER GOING TO IT. The inside tire spins out of control. Open diff is just stupid.

[fosley]

Either way, the tires start sliding when you push them too hard, and I've never had unpredictability with either LSD or open diff. The difference is that LSD is more prone to doing a circle in the middle of the road when it starts slipping, while an open diff is somewhat self-correcting; since the inside wheel has less load, it spins, creating a counter-steer-on-throttle effect that helps balance the car through the corner, kinda like electronic stability control works.

Obviously, both of them can be driven without spinning, and both can spin in a heartbeat; LSD is just a little more twitchy than open diff, in my experience.

One disadvantage to an open diff is if you actually *want* to get sideways, it can be very hard. The Elise gets sideways enough for my taste without LSD, so it doesn't bother me.

The other disadvantage is while racing, but unless you put a lot more power in the car, it's not going to terribly improve times, even at an autocross. Because we already have a lot of weight in the rear, the tires aren't as prone to breaking loose as an FF or FR setup, so it's pretty easy to modulate the power on the stock setup, and I didn't have any problems getting the car to power-on oversteer when I autocrossed it last month--nor did I have problems with major inside-wheelspin*.

Also, I've heard that OEM LSD units aren't as good as aftermarket units, and don't really help much with high-powered applications. However, I think this may only apply to the older, viscous units, such as in my Mk2 MR2s, so the better, helical units Toyota uses now may be perfectly fine. Just make sure you don't spend the money on an OEM LSD if you're just going to replace it 6 months down the road.

* Umm, other than the "I suck at life" factor of having never raced a Lotus before.

[knucklehead]

If your going to compete in SS it has to be the OEM LSD and you have to have the TC with it.