2-Way LSD making whining noise – is it normal, or something else??

March 02, 2021

2-Way LSD making whining noise – is it normal, or something else??

You asked, we answer.

 

There are many concerns lately about 2-way LSD making noise during cornering, so we decided to clarify this topic. To explain all aspects, we have to explain some terms first.

What is preload?

Put simply, preloading provides a base level of locking across the diff, so that it is never running completely open. To overcome this initial preload, the torque difference between drive wheels has to be higher than the preload.  This is generally referred to as ’breakaway torque’, and can be measured as the force needed to rotate one wheel while the other is stationary.

While preloading the LSD provides a diff that reacts very quickly, as it is already partially locked it can create problems on turning. If the preload is higher than torque difference between wheels during cornering, than inner wheel will over spin and bounce making weird knocking. This is extreme example, like with welded diff. But if you have the situation that preload of the LSD is pretty close to torque difference between wheels, than you will still have noise, but it will be consistent like whining.

Conclusion

 

It is not 2-way LSD that necessarily makes the noise, it is too high preload that it does. There is no exact amount of preload as a limit for the noise. It depends on tyre size, friction coefficient between tyre and surface and such.

 

This is why the trend moves from high preload to much lower figures. But beware of NO preload setup. In that case, clutch plates spins freely which increases temperature in differential/transmission. Therefore, lifespan of clutch plates is much shorter.



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