Why don't most performance cars have a LSD?

[cerb4.5lee]

I'm a very big fan of a LSD for the improved grip and the added fun factor, yet Lotus/Porsche/Mercedes don't seem to fit them as standard.

Also you only get a LSD on Bmw's full fat M cars, but I think the M140i/M240i would benefit from one, is it purely cost why manufacturers don't bother with them? Or the fact the most drivers maybe wouldn't even notice if one was fitted.

[krisdelta]

Increases costs and price point of the car and I would guess they assume most drivers won't notice or if they care will pay more to add it.

[Speed addicted]

They seem to have been dropped and replaced with traction control, which is obviously far less fun.

[Mike335i]

I imagine cost. Most if not all cars now come with a pretty sophisticated traction control and stability programme that does the job of keeping drivers safe enough. Add in e-diff systems that use the above to mimic an LSD and the average driver would not necessarily know the difference. If it is applied to all cars the same (bar some programming / calibration differences) then the manufacturing cost is going to be equal across the range.

Start adding bespoke components into the mix and you'll end up bumping up the cost for little gain, save for with the really enthusiastic drivers.

[Bill]

AIUI Lotus prefer the feel of their cars without.

[cerb4.5lee]

Yes and it does seem that traction control has took over and the LSD has gone out of fashion, McLaren don't bother with a LSD either, I've never really liked the feel of traction control because its either too intrusive or unpredictable.

[powerstroke]

cerb4.5lee said:

I'm a very big fan of a LSD for the improved grip and the added fun factor, yet Lotus/Porsche/Mercedes don't seem to fit them as standard.

Also you only get a LSD on Bmw's full fat M cars, but I think the M140i/M240i would benefit from one, is it purely cost why manufacturers don't bother with them? Or the fact the most drivers maybe wouldn't even notice if one was fitted.

Because most people can't drive !! cars have traction control ABS and other driver saving aids to keep 99% of numptys who rent these cars safe ..
your average driver will get in a mess with a LSD.. the rest of us have too much fun !!!

[xjay1337]

Cost. Pure and simple.

[liner33]

Bill said:

AIUI Lotus prefer the feel of their cars without.

As does Jaguar, a lsd makes a car less manoeuvrable so the Jag system keeps it open and only locks it when really needed

http://goodtobebad.kinja.com/how-jaguars-active-di...

[Oilchange]

I reckon it also has something to do with the way the back end is ‘lost’ with an lsd.
Someone once said that the inside wheel spinning up first (with an open diff) gave the car a little safety margin before the whole back end drifted or the car spun, whereas with an lsd the corner speeds are higher as the diff keeps both wheels gripping until the very last moment, then it lets go very quickly.
With road cars crashing and the extra cost, just leave it with an open diff and fit traction control.
Your average driver might push on (lsd) and not know how to react if it becomes unsettled.

[0ddball]

You are assuming that most performance cars are bought by driving enthusiasts. Of all the performance cars in my work car park, only 2 are driven by people who I would class as real petrol heads. And they have a mint but aged integra and s2000.

The others have simply bought whatever Audi, BMW or VW product is in fashion that year and are more interested in whether it's got electric memory seats than what the final drive ratio is.

[996TT02]

Many performance cars DO actually have an "LSD" but it's electronically controlled, not purely mechanical. And there is no physical LSD. The spinning wheel is braked by the ABS system so torque goes to the wheel with traction. You don't notice this. The net effect is the same as with an LSD, power to the road, rather than one wheel spinning like crazy.

[Yipper]

Cost, software, and fashion.

[J4CKO]

0ddball said:

You are assuming that most performance cars are bought by driving enthusiasts. Of all the performance cars in my work car park, only 2 are driven by people who I would class as real petrol heads. And they have a mint but aged integra and s2000.

The others have simply bought whatever Audi, BMW or VW product is in fashion that year and are more interested in whether it's got electric memory seats than what the final drive ratio is.

That is because they are normal, the car still does the same job, and 99 percent of the time, even an enthusiast wont notice in most scenarios.

[anonymous-user]

LSD by definition makes it harder for the driven wheels to rotate at different speeds, which is what they need to do to help you get round a corner. In other words, an LSD tends to promote understeer by pushing the car in a straight line when the driver's trying to make it turn.

[MDMA .]

Yipper said:

Cost, software, and fashion.

What software for an LSD?

[PhillipM]

As in it's easier to just simulate what you need in software with the ABS than fit an LSD.

Then you negate all that tyre scrub, economy loss, cost, etc.

[Rich_W]

rockin said:

LSD by definition makes it harder for the driven wheels to rotate at different speeds, which is what they need to do to help you get round a corner. In other words, an LSD tends to promote understeer by pushing the car in a straight line when the driver's trying to make it turn.

I think people are talking about RWD.

No powerful RWD I've had with a LSD suffered from Understeer

[Escy]

Bill said:

AIUI Lotus prefer the feel of their cars without.

Yeah, the MR2 Roadster uses an LSD as standard and the Elise with the same engine and gearbox doesn't.

[nickfrog]

Rich_W said:

No powerful RWD I've had with a LSD suffered from Understeer

You mean on the throttle I guess, not on on turn in. I don't know many road RWD cars that are not set up to understeer.

IME a LSD can actually promote push understeer more than an open diff as I guess the front end can easily become the weaker link in the traction zone.