Pros and cons with Cali 4 motion (4WD)

[Sp0_0k]

Bet it is just UK with weird limitations. Like they never had a 4 motion Beach.

 

[TomSawyer]

We went with diff-lock because we have had many Audi Quattro cars over the years and while they are better than 2 wheel drive cars in snow there comes a point without diff lock where one wheel on each axle spins and you go nowhere. Diff lock just adds the cherry to your icing at that point.

Has to be said that this has tended to happen on the in-laws farm drive which is about 10% gradient.

Have yet to use it on the Cali but (in Cali terms) it's not expensive and you couldn't easily retrofit it if you wanted it in the future.

 

[bvddobb]

We went with diff-lock because [...] there comes a point without diff lock where one wheel on each axle spins and you go nowhere.

In that case the 4Motion system will use ABS to break the spinning wheel(s), so torque will be sent to the non-spinning wheels. A 4Motion feature, aka 'electronic diff lock' or 'EDL' (a bit of a misleading term, though, indeed).

See e.g. this snippet from the 4Motion manual (page 17):

 

[TomSawyer]

In that case the 4Motion system will use ABS to break the spinning wheel(s), so torque will be sent to the non-spinning wheels. A 4Motion feature, aka 'electronic diff lock' or 'EDL' (a bit of a misleading term, though, indeed).

See e.g. this snippet from the 4Motion manual (page 17):

View attachment 22108

Yup indeed. And if you look at the Audi Quattro system description, I'm sure it's the same but our various A6 Quattros have failed to climb the in-law's drive in snow most winters through spinning wheels.

What can I say: I'm a mechanical engineer so I know it should work. Or perhaps, because I'm a mechanical engineer, I prefer my diff-locks to be mechanical

 

[Loz]

The problem is the spinning wheel causes a loss of momentum so having a diff lock engaged first may help you keep up momentum, however in the snow having the diff lock i makes it harder to turn, but that another issue...

 

[B J G]

Yup indeed. And if you look at the Audi Quattro system description, I'm sure it's the same but our various A6 Quattros have failed to climb the in-law's drive in snow most winters through spinning wheels.

What can I say: I'm a mechanical engineer so I know it should work. Or perhaps, because I'm a mechanical engineer, I prefer my diff-locks to be mechanical

Possibly more of a tyre tread/pattern problem than the actual mechanics

 

[TomSawyer]

Possibly more of a tyre tread/pattern problem than the actual mechanics

Yeah, you're right. I was mistaken in what I said.

 

[briwy]

I think there's some confusion here.
If you have 4motion without the now optional diff lock then EDL will work front and rear.
If you have the optional diff lock then this is a mechanical lock which is operated electrically by solenoid.
When engaged both rear wheels will rotate at the same speed and EDL will not be operative on the rear.