[Scubadude]

What additional wear would be incurred by keeping to 4H instead of 2H?

I can think of tyres,additional traction leads to more wear,if I'm correct,maybe even wear between front and rear?

Would any other part of the drivetrain be adversly affected?

I recall Andrew St Pierre White made a tenuous argument in his "Complete Guide to 4WD" that on a part time 4WD using 4H only has advantages over 2H, no disadvantages.

Driving all four wheels offers better all round safety, handling
and improved tyre life on anything but a perfect road surface.

Safety - check
Handling - check
Improved tyre life - no check
Later on he also mentioned a 5% reduction in fuel consumption - another no check

Sorry to diappoint you, Andrew, but engineernig (see it's true we can't spell) problems always involve tradeoffs. In fairness he did say "anything but a perfect road surface" ....

His advice re. Super Select does make perfect sence though:

‘Super-Select’ 4-wheel drive (Mitsubishi Shogun/Pajero)
Engage 4-wheel drive centre diff unlocked in ALL conditions other
than smooth dry tarmac. Lock the centre diff if there is any danger
that any of the vehicle’s four wheels may lose traction and spin.

[tonton]

His (Andrew St Pierre White's) advice re. Super Select does make perfect sense though:

‘Super-Select’ 4-wheel drive (Mitsubishi Shogun/Pajero)
Engage 4-wheel drive centre diff unlocked in ALL conditions other than smooth dry tarmac. Lock the centre diff if there is any danger that any of the vehicle’s four wheels may lose traction and spin.

I agree with this wholeheartedly.

Obviously the subjectivity about it is: at what stage do you have the risk of a spin, and at what stage is a spin a risk?. Unless you actually have the spin, the locked centre difflock (CDL) will have no benefit. If you did have the spin, CDL may have contributed to avert it. You will have to drive rather hard in 4H (CDL not engaged) to spin, but once it happens, it is too late to engage CDL.

Ant then... nothing will stop a roll-over when you go too fast, and / or you have a blow-out or hit something or encounter some emergency... But the best defense may reduce the risk from an accident to a "close shave"!

Anton

[JonnyD]

After reading Gerrit's explanation, my memories of ASPW's DVD where he insists that you engage "true" 4x4 (4HLc) and various members' preference of either 4H or 4HLc only one question remains in my mind.

Why did the Mitsubishi engineers develop the Super Select System that includes both 4H and 4HLc if they are the same (almost)? (For the moment I ignore the possible advantages and disadvantages it might have workig together with traction control/stability control)

[4ePikanini]

After reading Gerrit's explanation, my memories of ASPW's DVD where he insists that you engage "true" 4x4 (4HLc) and various members' preference of either 4H or 4HLc only one question remains in my mind.

Why did the Mitsubishi engineers develop the Super Select System that includes both 4H and 4HLc if they are the same (almost)? (For the moment I ignore the possible advantages and disadvantages it might have workig together with traction control/stability control)

super select allows RWD, AWD, Traditional 4x4, and tradiotional 4x4 Low Range.

[Gerrit Loubser]

When considering the advice of 4x4 industry experts, bear in mind that not all of them are really familiar with the Mitsu Super Select system.

What holds true for a typical part time 4x4 vehicle (e.g. most bakkies) or for a fulltime 4x4 with lockable open center diff (e.g. Land Rover Defender or Land Cruiser 100 GX) is not necessarily fact in the case of a Paj with selectable 4wd, but with a viscous limited slip center diff that can also be locked.

[tonton]

I picked this clip (48MB) up from 4xforum http://www.4xforum.com/video-samples:

http://www.4xforum.com/wp-content/uploa ... age4x4.mp4

Where he refers to "permanent 4x4, it refers to 4H in "super select" terms.

I think the clip explains it well.

(While youre there, check out the other clips.)

Anton

[Gerrit Loubser]

Hi Anton,

Thanks for the link. I will have a look at some of the other clips too.

Where he refers to "permanent 4x4, it refers to 4H in "super select" terms.

No. I believe he has vehicles like the Land Cruiser 100 GX or Land Rover Defender in mind. These have fulltime four wheel drive drivetrains, but have lockable open center differentials. The Super Select system in the Paj is different, because it has that clever viscous coupler attached to the center differential, that turns it into a viscous limited slip differential. The Paj's center differential is never an open diff, and the viscous coupler does a good job of preventing total spin-out. This is why you don't necessarily need to lock the center diff in a Paj the moment you set a tire on a dirt road (remember the Evo/Scooby rally cars). To paraphrase Andrew St Pierre White: You paid a lot of money for your Paj with Super Select. Now use it properly. Use all the modes.

The clip is certainly quite interesting and Andrew St Pierre White does quite a good job of getting his message across. He does not cover all possible driveline configurations, though.

It would actually be very interesting to repeat the skid pan demonstration, but this time using a Paj with Super Select instead of a part time 4x4 bakkie and repeating the test in 2H, 4H and 4HLc. Anyone with Gerotek contacts?

[tonton]

Note the Pajero he uses to show the difference. I bet he had the CDL on there?
Anton

[Gerrit Loubser]

That is quite possible, Anton, but remember that he was using the Paj to illustrate the difference between two wheel drive and four wheel drive on a dirt road, not between running with the center diff locked or unlocked. He could have illustrated his point by running in 4H or 4HLc on the Paj.

It clearly is much better to run in 4wd on dirt roads than in 2wd. In part time 4x4s, this means selecting a configuration identical to 4HLc, but the Paj is more sophisticated and has a mode that is perfect for dirt roads. That mode is called 4H...

[SimonB]

I have just returned from a weekend in the Cederberg. Now anyone who knows the Nieuwoudt Pass and the Uitkyk Pass will know that is is quite steep, pretty twisty and often quite corrugated.

This thread, specifically Gerrit and Roelf's quite logical observations on the fact that there should be little or no difference between 4H and 4Hlc, made me think I was imagining things about the handling of my vehicle.

So I did some experiments switching between the two. in various conditions. Under most conditions I could not detect a difference, BUT there was a significant difference between the two when one was on a steepish climb when one has to apply power out of the turn to maintain momentum and the same gear. In 4H the rear is very prone to stepping out which required correction (especially if the bend is corrugated). In 4Hlc, this almost never happened. Now one could argue (if Marius's statements are anything to go by) I am inexperienced and don't quite know how to deal with oversteer but I don't think so.

This is just my observation... I will stay with 4Hlc because this is what I am comfortable with.