Differential Preload

[silente]

Hi,

I know this topic was already discussed some time ago, but i couldn't find the thread, so i ask again here.

Working with a salisbury differential, with ramps and friction plates, what are the effects of preload on handling in your opinion?

I have noticed that having too much preload can lead to turn in understeer, but i would like to know your point of view on this. And what about mid corner and corner exit?

Thanks!

[graham bahr]

ultimately preload has no great effect the more preload the quicker the diff reacts

[tristancliffe]

Preload has more of an effect BETWEEN the phases. With no preload the differential will act like an open diff between power and coast, which could make the handling... interesting.

Adding preload ensures there is always some degree of limited slip even during the transision, although it's usually pretty small in comparison to the ramp angle locking. Some people suggest about 10lb.ft preload torque, others prefer 50lb.ft (whoops, nearly wrote lb/ft - who put the / near the . button!!).

Which you choose depends on driver preference, and how willing you are to keep dismantling and shimming the diff!

[Tim Falce]

Originally Posted by tristancliffe

Some people suggest about 10lb.ft preload torque, others prefer 50lb.ft (whoops, nearly wrote lb/ft - who put the / near the . button!!).

I'm sure we would understand what you meant, this isn't P***N H**ds you know.
If you don't have enough preload don't they just slip as one wheel unloads?

[GORDON STREETER]

Personally I've always shimmed mine to 50ft/lbs in the vice with a couple of old cut off halfshafts. At the end of a race as the diff and oil warms up there is hardly any resistance anyway !
In the "good old" cheapo days we all used welded diffs with the "narna skin"tyres and very rarely broke a half shaft, also you only had to turn the steering to park it on a hill

[Belatti]

Originally Posted by tristancliffe

Preload has more of an effect BETWEEN the phases. With no preload the differential will act like an open diff between power and coast, which could make the handling... interesting.

So what about the cars with no LSD? They are not that difficult to drive

[tristancliffe]

Probably because they are made with an open diff in mind. And most (if not all) would probably benefit from the use of a LSD except the most underpowered.