Does adding an LSD induce understeer?

[spacecadet]

Was wondering how understeer-ish a viscous LSD makes a previously neutral handling car?

Whats the best way to dial this out again after fitting said LSD?

[Tim Reid]

Good question, I have been a little confused after recently fitting a LSD.

Before I did a 360 spin on a private bit of tarmac/concreate that I know of. After 360 one wheel spins and the other stops.... normal open diff experience.

Now, with an LSD tried the same thing but only managed a 180 before the front started to slide out from me    

My first reaction was that the road condition was wet instead of dry, new tyres and I had a large friend in the passenger seat but I don't know if this answers the question and the weather hasn't been good enough to give it another try.  

[Blatman]

A viscous or ATB type will be more forgiving than a plate type.

The biggest trouble with an LSD is that after fitting one, people drive differently so the car behaves differently.

In my experience of both viscous and ATB type diffs, neither induce much in the way of understeer *but* I wasn't trying to prove they worked after I fitted them, just use them for what they're designed for, which is better traction out of the corner, better braking in to a corner, and donuts

[gixermark]

best do a search on this - plenty of us have been through similar, and asked before..

my personal opinion is that it doesn't necessarily induce understeer - but becasue you are getting better traction through/out of the turn.. it feels like you are getting 'more' understeer than before..

It certainly improved my lap times a lot... and although i haven't totally dialed out understeer its close, and have enjoyed the process of 'tuning' the car/suspension - its an ongoin project though.. I've been testing/racing since Feb this year constantly changing small aspects to improve overal handling...

[Guest]

I cannot see why it would induce understeer unless it was fully locked.  With a limited slip diff, the variation in wheel rotation speed in a corner would not be sufficient to lock the diff if both wheels have traction.  So it would be no different from a normal diff.  It is only when one wheel spins up relative to the other that the diff locks, at which point it will try to drive the car in a straight line.  However since this is usually once the back has already started to slide, understeer is not an issue.

If you are planning donuts - with an LSD you have to have enough power to keep both wheels spinning, otherwise you will not be able to maintain the drift.

[V 8]

With a limited slip diff, the variation in wheel rotation speed in a corner would not be sufficient to lock the diff if both wheels have traction

Sorry to disagree, but the variation in wheel speed has nothing to do with the diff gripping. it is caused by overall speed of the viscous coupling in a viscous unit, differing torque or resistance to drive/braking across the wheels in a ATB and the resistance to either acceleration or decelleration across both wheels in a plate type.

If you are planning donuts - with an LSD you have to have enough power to keep both wheels spinning, otherwise you will not be able to maintain the drift.

Bang on

[hilux]

QUOTE

A viscous or ATB type will be more forgiving than a plate type.

The biggest trouble with an LSD is that after fitting one, people drive differently so the car behaves differently.

In my experience of both viscous and ATB type diffs, neither induce much in the way of understeer *but* I wasn't trying to prove they worked after I fitted them, just use them for what they're designed for, which is better traction out of the corner, better braking in to a corner, and donuts

A standard diff will transfer some 80% (I stand to be corrected?) of the power side to side dependent upon how effectively it is working so can cause quite vicious sideways snaking believe it or not on greasy roads where grip is partial. Therefore if you tend to race or track in an ideal world you would fit a diff that transferred less (say 40%) as you dont turn too tight too often.

Anything else is middling (obviously).

Thats what I think anyway from many recommendations I`ve received over the last coupla years.