Transmission

[Ade]

How fussy is the Q4 transmission to differing speeds on the front and rear axles?

For example, could you run different sized tyres front and rear?
I know the Sierra system doesn't allow this, but some others do.

Also could you safely lock up the rear wheels with for example a hydraulic handbrake to initiate a drift in a Q4 without damaging the transmission?

[AlfaJack]

How fussy is the Q4 transmission to differing speeds on the front and rear axles?

For example, could you run different sized tyres front and rear?
I know the Sierra system doesn't allow this, but some others do.

Also could you safely lock up the rear wheels with for example a hydraulic handbrake to initiate a drift in a Q4 without damaging the transmission?

As copied from .org:

I know that a Q4 can not be towed unless all 4 wheels are on the ground and I believe the same size wheels and tyres should be used all round. I think otherwise the viscous coupling will wear out.

That said I don't know to what limit that premature wear will set it. I have tyres on the back with 8mm tread and one the front only about 3mm. I don't know if it would react to the smallest of differences like this.

[WhizzMan]

I wouldn't use a Q4 for drifting, the rear diff is a torsen and they don't appreciate that. You could put a dedra diff in (locks with lever) or a plate LSD if you want to do that kind of thing. I have no idea what will break first, after you do that. It could be the planetary gears, but also the visco center diff.

[SteveNZ]

How fussy is the Q4 transmission to differing speeds on the front and rear axles?

For example, could you run different sized tyres front and rear?
I know the Sierra system doesn't allow this, but some others do.

Also could you safely lock up the rear wheels with for example a hydraulic handbrake to initiate a drift in a Q4 without damaging the transmission?

The short answer is no.

Only transmissions with an open centre diff could be used like that.

[#84]

Well, I believe you could remove the visco-clutch, which is the main issue. Many 4WD cars have an open centre-diff and for tarmac use you will probably feel no difference. Then off course it is a matter of constant, instead of occasional, planetary rotation. It is not the purpose of the design, but a few percent rotational speed would probably be totally ok.