New Car Help

[Profpointy]

That's correct, but not desirable. With AWD you're only ever powering the front or rear, never both properly simultaneously. With 4wd you're spreading the drive load evenly across the axles, making it less likely that one will slip, and if one did you're still better off because the o the is already engaged and already has grip.

Indeed, the 110 is pretty elderly and as standard came only with centre diff lock. While that's very effective, newer stuff from the last decade also has cross axle locking, or simulation thereof.

is there a typo or some nuance above?

Awd = 4wd in my understanding. (well assuming only 4 wheels not a stalwart in which case awd = 6wd)

 

[Drago]

Awd is not the same as 4wd. My expansive, and rather boring, post prior to this explains the differences.

 

[Profpointy]

Awd is not the same as 4wd. My expansive, and rather boring, post prior to this explains the differences.

I understand the distiction (sort of) but I though the awd (all-wheel-drive) term considerably pre-dated the electronic trickery you describe - i think thers the awd club for instance which is (mainly land-rover) enthusiasts for off-roading - that's been around for yonks.

Anyhow - doesn't hugely matter

 

[Drago]

The Torsen diff has been around since the early post war era, and is completely devoid of electronics, yet is all that's needed to provide an AWD set up.

The terms over the year have been used largely interchangeably by an uninformed public, but even people who should know better will do so. The situation isn't help by manufacturers applying the 4wd or 4x4 labels to vehicles that strictly speaking are not.

Nevertheless, in automotive engineering terms the distinction does exist between the two, even if it is widely misunderstood.

 

[Pale Rider]

Harry Ferguson of tractor fame started working on his four wheel drive design for the road not long after Second World War.

The system eventually found its way onto a Grand Prix car and a road car, the Jensen Interceptor FF - Ferguson Formula.

When Audi came along with the Quattro in the 80s, everyone thought how innovative and exciting.

Well, everyone except those of us who could remember Ferguson.

http://www.uniquecarsandparts.com.au/how_it_works_ferguson_four_wheel_drive.php

 

[KneesUp]

Very good question my friend, especially about the tyres, and one you'll regret having asked!

A true 4wd system is either permanently locked, or can be manually selected to lock all 4 wheels, so each wheel receives constant power from the engine. On off road oriented vehicles it's usually a 50:50 distribution, but in sporty road cars it may be biased to the rear.

Some cars, like modern Defenders, have a centre diff so are left in 4wd all the time. Others, like my mighty Kia of Manliness, do not have a centre diff so you would only engage it when off road.

A true 4wd will almost certainly have diff locks, or electronic simulation of diff locks - again, my Kia has the electronic faux sort. Some full on 4wd vehicles will also have a low range.

Now here is where it gets interesting...

Awd systems normally only power the front wheels, engaging the rears only when the front loses grip. This mechanically simple, requiring only a TorSen diff or Haldex unit somewhere in the centre of the drive train.

But there's a big problem - you only get power to the rear when the fronts have lost their grip, and even on moderate off road such as a slimy unpaved track that is too late.

Now, you mention the thorny issue of tyres. On a 4wd car you will indeed vastly improve off road performance with specialist rubber. I run Yokohama ATS IIs on mine, which are also fairly civilised on the road.

However, on an AWD vehicle such as a Yeti or a NedFlander this doesn't work. You rely on the front wheels losing grip to engage the rear axle, but AT or MT tyres means the fronts won't slip and you never get drive to the rear wheels. So beefy tyres do nothing to improve an AWD cars chances off road, and may even make things worse. This is why Freelanders are crap off road, yet a quiet and unassuming Subaru Forester are little monsters off the beaten track.

So if it says AWD on the tin then it doesn't matter how meaty or rugged it looks, or what plastic faux lower body protection it sports, it inappropriate for anything but road use. The situation doesn't help that a lot of manufacturer s label such offerings as "4x4", when in the strictest technical sense they are not. AWD doesn't even help much on the snow, although with clever electronic management - such as in the XC 90 - it can be made to work well on the snow, but the systems required to do so cost money and tend to end up in the more expensive motors.

AWD and 4WD are not used consistently - Subaru describe their cars as AWD, for example.

And as has already been pointed out, in a 'normally FWD but 4WD when traction is lost' car, if the fronts don't lose traction, it doesn't matter. The Panda 4x4 (which has a viscous clutch in the new version I think - so is normally FWD) is reputedly excellent off road, probably partly because it is comparatively light. I suspect it's lardiness that is part of the problem for other cars.

I take your point though - the youtube videos produced by Subaru showing other AWD/4WD cars being tested on rollers are quite interesting.

 

[vickster]

I've got a downer in general on soft roader that are so soft they have no dirt ability at all. Qashqai AWD versions, Yeti AWD, that sort of thing. Not only do manufacturers have the gall to palm them off on a gullible public, but huge swathes of people clamour to buy them. Why?

The one I towed recently was at an SAR callout, another team member vehicle. A few cars had parked on a soft verge and sunk, but the Yeti was then only one that couldn't free itself. An old Pug 106, a Mondeo and a very tired looking Laguna all managed a few feet of off roading where the Yeti failed (and it was the AWD one, I asked) which begs the question as to why they bothered in the first place? The penalties of extra weight, poorer handling an higher running costs clearly aren't compensated for by Bear Grylls like wilderness ability, so I genuinely would like to know - what is the point?

My parents are in their 70s and live in a cul de sac in Surrey. The most off roading they have to do is crossing the dropped curb to park on their flat drive. They didn't buy it to go off road, although I'm sure the bigger tyres help with comfort on the potholed roads and speed humps that are everywhere

Most proper 4x4 seem to be fugly gas guzzlers, might be fine for farmers and folks who live in the wilds

 

[KneesUp]

My parents are in their 70s and live in a cul de sac in Surrey. The most off roading they have to do is crossing the dropped curb to park on their flat drive. They didn't buy it to go off road, although I'm sure the bigger tyres help with comfort on the potholed roads and speed humps that are everywhere

Most proper 4x4 seem to be fugly gas guzzlers, might be fine for farmers and folks who live in the wilds

Your parent's car will be using more fuel than the 2wd version though, simply because the rear wheels do get some of the power all of the time (usually 5%) and there is a loss in the drivetrain. Plus the hardware adds weight to the car. Seems a bit pointless to pay extra for something you don't use and makes your car less efficient?

 

[Profpointy]

The Torsen diff has been around since the early post war era, and is completely devoid of electronics, yet is all that's needed to provide an AWD set up.

The terms over the year have been used largely interchangeably by an uninformed public, but even people who should know better will do so. The situation isn't help by manufacturers applying the 4wd or 4x4 labels to vehicles that strictly speaking are not.

Nevertheless, in automotive engineering terms the distinction does exist between the two, even if it is widely misunderstood.

I know I'm kind of starting an internet argument - but how do you reckon if four wheels are driven (all the time, some of the time, with added trickery or not) then it doesn't count as four wheel drive? Ditto awd?

Isn't pulling a lever to lock the diff the same as the magic box pulling it for you? Or for that matter engaging 4wd like in the old landrovers (sans centre diff) same as what the yeti tricky box is doing?

 

[KneesUp]

I find 4wd it two-too-few


View: https://www.youtube.com/watch?v=n9Kr5RKej-Y

 

[vickster]

Your parent's car will be using more fuel than the 2wd version though, simply because the rear wheels do get some of the power all of the time (usually 5%) and there is a loss in the drivetrain. Plus the hardware adds weight to the car. Seems a bit pointless to pay extra for something you don't use and makes your car less efficient?

Except they have the 2WD version! The criticism was of all Yetis from what I could understand as a soft roader. Large 4x4s are hardly fuel efficient as I understand it

And given how few miles they do, I doubt they care if it uses a little more fuel. It's also an automatic DSG version which may or may not be more economical (as is my Fabia but I don't really care much either as I do under 5k miles a year, I care more about not having pain in my left knee)

 

[Piemaster]

How about this as a 4x4 vehicle. No diffs needed, each wheel driven independently

Think one of the hybrids has electric driven rear wheels? I can see it being a direction manufacturers could move in.

 

[Deleted member 1258]

How about this as a 4x4 vehicle. No diffs needed, each wheel driven independently

Think one of the hybrids has electric driven rear wheels? I can see it being a direction manufacturers could move in.

That looks like fun, a big boys toy.

 

[SteCenturion]

An estate like a VW Passat or Skoda Octavia/Superb seem to fit the bill.

Myself, I am still considering going down the contract hire route for an Octavia or Superb, now that a Coupe no longer suits my needs.

A friend who has had Golf's & now an Octavia reckons his garage claim Skoda's to be better made than VW.