Why don't most performance cars have a LSD?
Discussion
Nanook said:
Does it?
It distributes torque but it has no ability to limit slip. The car itself will have better traction, but the differential is only controlling the torque split across the axle, based on a multiple of the torque applied at the wheel with the least grip, it cannot lock up like a plate or viscous differential
4 times 0 is still 0.
No that means it is not a locking differential, it is still very much limited slip.It distributes torque but it has no ability to limit slip. The car itself will have better traction, but the differential is only controlling the torque split across the axle, based on a multiple of the torque applied at the wheel with the least grip, it cannot lock up like a plate or viscous differential
4 times 0 is still 0.
kambites said:
Nanook said:
300bhp/ton said:
Depends. This isn’t the case with an ATB.
An ATB isn't an LSD though. The clue is in the name.
It's a differential that limits slip... how is it not an LSD? https://en.m.wikipedia.org/wiki/Limited-slip_diffe...
https://en.m.wikipedia.org/wiki/Torsen
ging84 said:
Nanook said:
Does it?
It distributes torque but it has no ability to limit slip. The car itself will have better traction, but the differential is only controlling the torque split across the axle, based on a multiple of the torque applied at the wheel with the least grip, it cannot lock up like a plate or viscous differential
4 times 0 is still 0.
No that means it is not a locking differential, it is still very much limited slip.It distributes torque but it has no ability to limit slip. The car itself will have better traction, but the differential is only controlling the torque split across the axle, based on a multiple of the torque applied at the wheel with the least grip, it cannot lock up like a plate or viscous differential
4 times 0 is still 0.
said:
A limited-slip differential is a type of differential that allows its two output shafts to rotate at different speeds but limits the maximum difference between the two shafts.
Not even a plate type LSD does that though. They have a spec for maximum lockup percentage but they don’t hard ‘limit’ the difference in speed they only work to equalise it as per the ramps and lockup spec. If you want to be pedantic about it.I concur with the thought around the increasing in traction control and related electronics reducing the need for a mechanical LSD.
However, both my current personal vehicles have them.
My Proton track car uses an Evolution RS drivetrain and my current train station workhorse (R26 Megane) has one up front.
But, the Megane also has a lot electronics that kick in most if you let them.
Rich_W said:
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
Driving in a circle with neutral throttle, just under the limit of traction in a RWD car with LSD. The front end will have adjustability of where the car is pointing.
Put a bit more power down. The front will run wide... Understeer. Why? Both rear wheels are pushing the car forward.
Put even more power down. You start to break traction on the rear. Both rear wheels spin up and you have oversteer.
When I done an autotest in a rwd car with LSD, the front end would wash out on low speed turns very easily when applying power. It would then (quickly!) transition to oversteer when the power exceeded the rear tyres ability to grip.
Actually, in that situation an open differential might have given me a better time.
300bhp/ton said:
Jaguar is cost lead though. The 6.0 XJ12 (XJ40 shape) had an lsd. But no tcs. The x300 XJ12 variant got tcs as standard and ditched the lsd. This was the change over point.
The X300 XJR had an LSD as standard, it was an optional extra on the regular cars but unavailable on the XJ12 as you say. The traction control system on these cars was dire, it was a vacuum servo tugging at the throttle cable!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.
Why fit one as standard when you can put it on the optional extras list as part of the Performance Pack. 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.
ZX10R NIN said:
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.
Why fit one as standard when you can put it on the optional extras list as part of the Performance Pack. 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.
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