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alias23

Why No Lsd?

9 posts in this topic

Eagerly waiting on the arrival of my Exige V6 and curious... Why did Lotus decide to not install a mechanical LSD into such a track orientated car? Seems as though both the S and Cup don't have one....

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Cost, pure and simple.

 

This is what I suspected. They probably think the electronic stability system is enough given that they aren't racecars and aren't therefore chasing ultimate laptime.

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All this nonsense about 'the car was never designed with one so it doesn't need one' makes me laugh.

 

People base that argument on the fact that the original S1 was never available with one and neglect to acknowledge the fact that the rover powertrain wasn't available with one at the time and that 118hp wasn't really enough to trouble the tyres.

 

Anything with more than the standard power needs one in my opinion, it absolutely makes the car....but what do I know!

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I have heard and seen written several times by the lotus development engineers that they think they negatively affect handling for many situations (they can cause understeer).

 

I really don't think cost is the reason, they aren't that expensive. For example with the evora they were already taking the gear box apart to change the gear ratios. The other cost problem is that some lsd's need servicing and adds a potential expensive serviceable item on high mileage cars.

 

The new v6 cars (evora and exige) also come with a sort of e-diff system as part of the DPM. They say this gives most of the benefits of a LSD but not the understeer. The engineer that was at an event I was at was also asked about the full ZF ediff systems like the jag xkr/xfr use and he said they tried several of the systems and they weren't happy with the performance of systems given the added weight they carried.

 

From a personal point of view, unless you're trying to do donuts or get the car sideways drifting on purpose or repeated trying to get full power from tight corners I've never felt the need for an LSD.

 

Edit: dan is one that likes to drive his car sideways more than forwards!

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I don't only drive sideways, I can also drive fast and smooth and still find the LSD a benefit, but I do have far more power than grip.

 

I've heard the argument before that certain engineers have talked about negative effects and I can understand in certain situations this can be the case, but it has to be taken in context. Were they talking about plated diffs or torque biasing diffs as the two are very different entirely.

 

Having said that I bet if you asked a lotus engineer why the elise doesn't have a rear anti roll bar they would say it doesn't need one, however I know for a fact it was originally developed with one but it was removed to cut costs.

 

Any serious sports car (with the obvious exception of the mclaren 12c!) has an LSD. Every single race car has one (including the mclaren 12c!) and any serious driver will want one....for me its as important as a steering wheel or seats, but I can fully appreciate that not everyone wants one!

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You don't need an lsd in these cars its a nice option but I can't say I've ever driven any derivative including 250 bhp supercharged ones and felt it would have particularly benefited from having one for road driving or track tbh. What would be the purpose? On a race car you will save a bit of time in a slide and possibly get a tiny bit more power down on a corner sure but real world Road car benefits?

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with the (electronically assisted) corner braking on the V6 you don't need one we have driven with Matin Donnelly a few times now and when I asked him he said the LSD was not necessary

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