Thread: All wheel drive vs 4 wheel drive vs ?

What is the difference between the "New" system and the one used on the very first 80" Land Rovers between 48 and 51? I've tried to read all 7 pages of this thread but got more and more confused.
.W.

Originally Posted by scarry

So is it like old school,RWD,but FWD instead of operated by the driver with a lever,is operated by a clutch that is electric,signal coming from an ECU?
No center differential at all?

And driver cannot change from AWD to RWD,or visa versa,it is done automatically?
But driver can change different TR modes,and high and low range,that may determine when FWD occurs.

If by "FWD" you mean Four Wheel Drive rather than Front Wheel Drive, then yes that's pretty much how I see it.

Originally Posted by one_iota

I take it that this was from the downloadable Owners App.

Yep.

I note that there is no distinction between petrol and diesel versions in the iGuide.

The new 2022 brochure describes all versions as AWD without qualification or distinction between petrol and diesel vehicles. It also doesn't describe AWD in detail.

So my take is that the 2022 Defender both diesel and petrol will have the same AWD system as described in the iGuide.

Yikes! You could be right about that.

The footnote that I referred to in my opening post: "1 Permanent All-Wheel Drive is standard on Land Rover Defender except for those fitted with new D200, D250 and D300 6-cylinder Diesel engines" no longer exists in the sales documentation. In fact nowhere in any of the new documentation have I seen the term "permanent 4wd" used.

Buyers beware.

I'm baffled. At least there's still a locking rear diff option, and Terrain Response is still the best on the market. And maybe the new system is somehow amazing in a way I just haven't yet come to understand. A big batch of new ones is getting delivered to Aussie customers this week so I'm looking forward to some first-hand reports.

Originally Posted by B.S.F.

What is the difference between the "New" system and the one used on the very first 80" Land Rovers between 48 and 51? I've tried to read all 7 pages of this thread but got more and more confused.

That depends on what an "over-run freewheel unit" is. I can be sure it's not a computer-controlled clutch though.

Something purely mechanical that permits the front axle to be driven but also allows for that axle to spin faster than the rear during cornering almost sounds better than a clutch! The clunkiest option I can think of (literally) would be like a ratchet mechanism. Another would be a cam-based setup that increases friction in one direction but releases it in the other. Both of them would result in the the reverse gear being RWD only – is that what happens in those old LRs?

Originally Posted by TB

That depends on what an "over-run freewheel unit" is.

FWIW,the old man had a Rover 75 that had one of those,when initiated,it free wheels on overrun.No engine braking.

I was too young in those days to know how it worked,but it seemed to work well.

Originally Posted by TB

That depends on what an "over-run freewheel unit" is. I can be sure it's not a computer-controlled clutch though. Something purely mechanical that permits the front axle to be driven but also allows for that axle to spin faster than the rear during cornering almost sounds better than a clutch! The clunkiest option I can think of (literally) would be like a ratchet mechanism. Another would be a cam-based setup that increases friction in one direction but releases it in the other. Both of them would result in the the reverse gear being RWD only – is that what happens in those old LRs?

Yes, to reverse in four wheel drive you had to lock the two shafts together by pulling up a ring on the floor You described it pretty well. Funny how 70 years ago they managed to get a message across in a couple of sentences.
.W.

Originally Posted by rar110

So more similar to the drive system in a discovery sport than a D4.

Well, look on the bright side - you can now buy a Freelander 2 and hand on heart say that it's just like a Defender.

Originally Posted by TB

That depends on what an "over-run freewheel unit" is. I can be sure it's not a computer-controlled clutch though.

One of my tractors has a free-wheeling sprag clutch in its 2nd gbox low gear, which has rollers that only grip in 1 direction. In the tractor it allows smooth down-shift, only engaging once the input shaft is driving the output shaft.