LSD a disadvantage on the track????

[grecomfs]

Am contemplating an Exige S for track/DE events. I'm being told that LSD option is good for autocross but is a disadvantage on the track. Can anyone here confirm/refute/explain? Thanks in advance and thanks for the great forum!!

[carl]

It's BS. carl

[ace10]

welcome grecomfs-

there are a number of decent threads on the subject. here's a sampling:
http://www.elisetalk.com/forums/showthread.php?t=32106
http://www.elisetalk.com/forums/showthread.php?t=29517
http://www.elisetalk.com/forums/showthread.php?t=27049
http://www.elisetalk.com/forums/showthread.php?t=18906
http://www.elisetalk.com/forums/showthread.php?t=16581

there are dozens more, but these represent the highest volume of posts.

btw- no lsd here, and i disable the TC on the track. i don't get much wheelspin once out onto the track.

[Rat27]

Unless you are good at adjusting the suspension it is a disadvantage.

[fzust]

Originally Posted by Rat27

Unless you are good at adjusting the suspension it is a disadvantage.

Care to explain, wise one? Because don't understand this.

More traction is faster. Spinning the inside tire coming out of a corner w/o LSD is slower. However, with LSD it is possible to break both wheels loose under power. I am guessing Lotus prefers no LSD to minimize people wadding up the car under street & track conditions. It is a must-have for auto-x.

[Ram]

Originally Posted by fzust

Care to explain, wise one? Because don't understand this.

More traction is faster. Spinning the inside tire coming out of a corner w/o LSD is slower. However, with LSD it is possible to break both wheels loose under power. I am guessing Lotus prefers no LSD to minimize people wadding up the car under street & track conditions. It is a must-have for auto-x.

I think he is referring to LSD's tendency to cause understeer.

[fzust]

It causes understeer because you actually have traction at the back. Under acceleration this causes the weight to transfer backward(because you are actually moving forward rather than just spinning the inside tire) and thus unloads the front. When you get on the gas out of a corner, you MUST uncrank the wheel as you get on the gas.

[macfly]

It seems odd that there is even any discussion about this when the guys at the factory who belt these things round all day says they don't like it and it isn't as good - now really who are we to argue?

Originally Posted by Nick Adams, Vehicle Development Manager for the Fed. Elise On Limited Slip Differential

The Elise was always designed from the outset to work without an LSD. We have recently started to offer an LSD as an option on the Toyota engined cars, primarily in response to market demand from the Autocross enthusists in the USA, who need one to be competitive when accelerating away at full throttle from very slow, tight corners in first or second gear.

In this type of competition they do not tend to run high speed (100mph +) corners and therefore the increase in understeer on this type of corner which you get with an LSD is of little negative consequence to them and they therefore are better off with an LSD.

In our experience an Elise or Exige equipped with an LSD is at a disadvantage to one without an LSD on a typical European race track. On top of that the LSD bluntens the steering feel and repsonse of the car which we don't like.

If you want an LSD then by all means fit one, but please understand that there are negative as well as positive effects. In the instance you describe, instead of spinning the inside wheel as you accelerate away at full throttle (which can be easily fixed by modulating the throttle! Very Happy ) a car with a 2:1 LSD like the obne we supply will provide twice the torque to the outside wheel as it does to the inside one. This will increase the slip angle of the outside wheel and the car will tend to oversteer heavily on corner exit, requiring a reduction in throttle if you are not to spin.... It isn't much quicker, honest.
The optional diff we supply is a Torsen unit, the aftermarket unit supplied by Motorsport is a plate diff, with a similar 2:1 bias and no preload so in terms of action it mimics the Torsen closely.

[codymac]

Originally Posted by macfly

It seems odd that there is even any discussion about this when the guys at the factory who belt these things round all day says they don't like it and it isn't as good - now really who are we to argue?

OTOH...

He told me it was impossible for my car to have been delivered with nearly 4° of rear toe in - he quietly tipped up his pint when a friend asked, "You want to see the alignment printout?"

Just because the factory says it doesn't mean this driver will blindly take it as gospel. I'd give it weighty consideration, but I'd still come to my own conclusion.

[charliex]

He told me the same thing, remember how much i hated that orange exige when i first got it?

[Thomasio]

> "LSD a disadvantage on the track???"

Wouldn't LSD in theory lower one's reaction time, and therefore be a disadvantage?

Besides, just say no to drugs.

T.

[Chris Mackey]

Yeah, LSD is fine at the park, the rave or at work. At the track, I prefer methamphetamines, cocaine or even Starbucks Hi-Test.

[codymac]

Originally Posted by charliex

He told me the same thing, remember how much i hated that orange exige when i first got it?

Yup - you were one of the few others that had experienced the same issue before I did.

[Randy Chase]

Originally Posted by codymac

OTOH...

He told me it was impossible for my car to have been delivered with nearly 4° of rear toe in - he quietly tipped up his pint when a friend asked, "You want to see the alignment printout?"

Just because the factory says it doesn't mean this driver will blindly take it as gospel. I'd give it weighty consideration, but I'd still come to my own conclusion.

And not everyone that worked for Lotus were singing the same tune. Some of the drivers liked the LSD.

[macfly]

Ahh, interesting, so should I take it from this that Nick Adams is some what of a pompous arse with a bad attitude and mediocre driving ability?

[codymac]

Originally Posted by macfly

Ahh, interesting, so should I take it from this that Nick Adams is some what of a pompous arse with a bad attitude and mediocre driving ability?

That's not what I'm saying, despite the factory guys getting passed by the locals on our home track and him being bested by a Lotus PR guy at the autocross at LOG last year.


I'm just saying that everyone should draw their own conclusions.

Just because he works at Lotus doesn't mean his word should be carved in stone tablets and brought down from the mountain. He's just as human as the rest of us.

[tonykomo]

The factory guys prefer the car without LSD because it's more fun to power slide it. FACT.

I raced my Elise pre fitting LSD and post fitting LSD. My laptime improved by over a second because of the ability to take the ultra tight turns with no inside wheelspin.

[maz]

Nick Adams is a good guy, and he forgets more about driving every day than you will ever know. Go be quicker than a local at a new track and then say something. As for the autocross, well, lets face it, going 40 in a mall parking lot isn't what lotus has in mind when they design these cars, is it?

[cgomez]

Nick Adams is obviously correct. Under an ideal scenario of the perfect high speed turn, the LSD offers no advantage.
But in many other situations, including non ideal ones like powersliding, saving an oversteer moment and basically have more rear-steering control, it provides a great advantage over the open diff; and that's why almost ALL racecars and track oriented sportscars have one.

For example, I don't think I would have saved this one having had my open diff Elise instead of my LSD Exige. Once that rear wheel is up in the air (A bit too much rebound) there's no power or push to keep the car from spinning into the Armco.

(save as) http://homepage.mac.com/c.gomez/.Mov...lOversteer.mov

[codymac]

Originally Posted by maz

Nick Adams is a good guy, and he forgets more about driving every day than you will ever know. Go be quicker than a local at a new track and then say something. As for the autocross, well, lets face it, going 40 in a mall parking lot isn't what lotus has in mind when they design these cars, is it?

I'm thirsty, please pass the Kool-Aid.

I suppose if he told you guys that the car would be quicker if it were painted pink, there'd be a run on pink paint?
Hooey.


Listen to everyone, think for yourselves.


cgomez - nice catch!