4x4 diff lock

[Stuarted]

... I do like the term all weather vehicle, though you get that ability from the tyres more than the drivetrain Though the Octavia and Superb 4x4s are aimed more at being towcars I think. I certainly wouldn't try taking mine on harsh terrain.

Indeed. I would find an "all weather" tow car very useful - occasionally. Just a shame about the permanently higher fuel costs. Would have expected better from a "part time", automatic system like Haldex.

_ _ _ _

Regarding types of 4WD vehicles: maybe I should start a new thread. It would be an interesting debate - choosing names which make the distinction between:

Off-roader / soft-roader

All-terrain vehicle / all-weather vehicle

Rough terrain / smooth-but-slippery terrain

[Huskoda]

One thing I'd like to add if you're considering buying one is the gearing. Although mine has 6 gears, its more like 5 as the first is low range and when pulling out I shift to second before I have fully gone over the white line. It takes a bit of getting used to and infuriated me at first.

However, it works really well as a form of descent control when I crept down a steep hill in the snow, feet off the pedals and just steering.

[auroan]

Erm..... a tradtitonal diff lock as you would find on a proper off roader like a landy defender can not be repliacted by anything in the haldex world.

This switch that people are talking about is just to force the car into permanent AWD mode. Nothing to do with locking the diffs at all.

This explains proper AWD diff setup;

http://www.lcool.org...iffs/diffs.html

Haldex systems don't have the centre diff. They just have propshaft out of the front gearbox/diff and coupling with a hydro electric clutch in the rear diff.

[Stuarted]

It seems a bit daft to have any form of four-wheel drive and no form of limited-slip diff at all in either "axle". That would mean that, however good the Haldex system was at providing drive to both front and rear "axles" as needed, you'd only have to have one wheel slipping at either end of the car for there to be no drive at all. That would reduce it to a two-wheel-drive car.

Even my entirely conventional rear-wheel-drive Mazda MX-5 has both a mechanical limited slip diff in its rear "axle" and a traction control (as well as dynamic stability control) system.

[Huskoda]

It seems a bit daft to have any form of four-wheel drive and no form of limited-slip diff at all in either "axle". That would mean that, however good the Haldex system was at providing drive to both front and rear "axles" as needed, you'd only have to have one wheel slipping at either end of the car for there to be no drive at all. That would reduce it to a two-wheel-drive car.

That would be (nearly) true if the EDL wasn't working. As the coupling locks, you would need to have one wheel slipping on each axle to have zero traction without the EDL. The Haldex propshaft is connected to a power take off before the front differential so it does get power even if the front wheels have no traction. Its not as bad as some people think it is, especially those with proper lockable landies.

[Kiwibacon]

The latter. The diffs are completely open. The only thing that locks is the Haldex coupling.

If I remember it right, the CRV uses an entirely different system for its 4 wheel drive. Instead of using the ABS sensors to see what is spinning and activate the coupling, I think it uses a mechanical pump on each axle and the coupling links based on an imbalance in the pressures. Its as dumb as Haldex 1. This may just be older ones, though. The nicest system I know of is (and we agreed it between various members on here) the Subaru Outbacks, where if the vehicle is stationary, the center differential locks when the vehicle is stationary, so it always moves off in 4 wheel drive then releases it once its moving.

I do like the term all weather vehicle, though you get that ability from the tyres more than the drivetrain Though the Octavia and Superb 4x4s are aimed more at being towcars I think. I certainly wouldn't try taking mine on harsh terrain.

Haldex freelander 2's also lockup before takeoff. I'd expect any Haldex 4 vehicle to do the same.

Edited 11 May, 2013 by Kiwibacon

[rockhopper]

Haldex freelander 2's also lockup before takeoff. I'd expect any Haldex 4 vehicle to do the same.

Haldex 4 does indeed. It starts off in 4wd, which is great for traffic light GP. My Haldex equipped Yeti can be very quick off the mark as I don't get any wheel spin.

Once on the move it reverts to about 96% FWD.

The Haldex senses when a wheel is about to spin and the locks the wheel, sending the torque to where it is required.

Unlike a 'normal' 4x4, where if you get wheel spin you back off the throttle, it is the opposite with a Haldex equipped vehicle, as you need the front wheels to start to spin before the rears get any drive.

This is a Yeti, but the principle is the same:

Sent from my iPad using Tapatalk HD

[Kiwibacon]

The Haldex 2 can try to lock up on take-off as well, but lacking it's own seperate hydraulic pump it requires the driveshaft to start turning before it can develop hydraulic pressure and start pushing.

My pre-FL scout should be a Haldex 2. On slippery takeoffs the front wheel slip is imperceptible, rumoured to be about 1/7th of a revolution. Or maybe I got lucky and my car got a Haldex 4 early? Probably not, but it's too low to easily check.

[Huskoda]

If it has the facelift interior then it can have Haldex 4 too. The few times my Haldex 2 equipped 4x4 slipped its front wheels, it was only for a fraction of a second before I felt the kick from the rear, I certainly can't complain.

[pipsyp]

New Octavia will not have the rough road pack like the MK2 4x4 did, consequently it will not even be a soft roader. A Yeti or MK3 scout will be more competent.

Also a shame the MK3 can only be ordered in SE spec as a 4x4 and only as a 1.6 or 2.0 diesel, VAG orders or SUK missing a trick again no doubt.

[Huskoda]

Its SUK sucking again. You can get the rough road pack in other countries. Even on the standard Octavias. The engine choices are more likely to be VAG though.

[pipsyp]

Its SUK sucking again. You can get the rough road pack in other countries. Even on the standard Octavias. The engine choices are more likely to be VAG though.

Indeed. My suspicion is that the 1.8 TSi will come out, be 4x4 only and probably only available in Scout or Elegance trim, that'd be my gut feeling.

Without 4x4 the performance of a 2wd 1.8 TSi would encroach on vRS territory, so they'll probably do something to limit its appeal to the masses. May well be wrong though.