Too much slip in LSD ?

[Marius]

Please take a look at this picture:

 

http://137.226.73.44/~alex/webpics/20030607/20030607_061.jpg

 

We had some traction problems at Hockenheim under heavy acceleration out of bends, the inner wheel always started to loose grip to early for a LSD.

 

LSD is ZF type, 40%. The Diff is brand-new so my guess is that the rear suspension set-up might cause this problem. The car is not as low as it could be, has Vauxhall race dampers (200lb springs rear) and the Freesytle adjustabel ARB.

 

Is my Diff not working properly or might the suspension play tricks on me ?

 

Marius

 

[R2D2]

The LSD doesn't necessarily stop an individual wheel from losing grip. The idea is that the overall traction of the car improves. The amount of grip an individual wheel will develop will depend on the wheel loading, tyre pressure and surface plus a few other detailed variables such as type of tyre etc.

 

A conventional diff, which shares torque equally to the rear wheels means that if one wheel spins (approximately zero torque) then the other wheel will see the same torque and stop driving.

 

The LSD means that both wheels will drive until the difference in torque between them exceeds the pre-set value. In practice even when one wheel spins the other will drive.

 

It is normal in a front engined rear wheel drive car for the inside rear to be the first to lose traction as weight will usually transfer to the outer rear wheel when cornering so the inner wheel is unloading.

 

You can change these characteristics by adjusting the rear spring rate or increasing the rear roll stiffness, I guess the compromise is up to you.

[stevefoster]

If the diff is ok then you will get more grip with a softer rear end.

I can tell the difference between a couple of clicks on my dampers softer giving more traction in situations like this.

 

I am not convinced that a very stiff rear end is the way to go. You may have found a particular circuit and corner where 200lb stiff is not the right thing.

 

I run 150lb rear springs and no ARB and am getting faster with it.

 

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[JCM]

I was using 180/200lb on rear and have now increased to 320lb due to running lots more torque on new engine. With the lower rate springs on under hard acceleration out of fast corners it was trying to sit down to much and squirm around. Now it will still break traction but it is alot more controlled and smoother...

 

Any help?

[JCM]

 

 

Edited by - jcm on 10 Jun 2003 23:00:01

[EFA]

I run a soft rear like Steves 😳 but I also use the 5/16 ARB on a soft setting.

 

JCM - 220lbs is very stiff for a Di DIon rear end and causes massive loss of traction and the rear becomes very hard to slide around with any degree of prediction. What on earth is 320lbs like??? It must be terrible!

 

Fat Arn

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[NoLimits]

I can vouch for the un predictability of an over sprung rear end. Just look at the pictures in Low Flying this month.

 

Having returned to softer springs for a day at Pembrey it has returned the car to a some what understeery vessel but just soooooo predictable.

 

MY 51VEN - SLR

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