When and how to engage 4WD - Mercedes G 460 series

The statement about swapping ends is correct, braking stability is adversely affected. Also when you have locked the two axles together steering becomes even more vague.

So you need to determine the probability of losing traction and at what speed you will be travelling.

You mention dirt roads. If these are dry with good traction and you intend travelling at moderate speeds say up to 70Km/h then leave it in 2WD. Leaving it in 4WD just for the sake of it will unnecessarily stress components even on non-paved surfaces. As a comparator I find when driving through snow it’s sometimes best to leave it in 2WD. I’d rather have steering and brakes than traction sometimes! OK when it’s deep and slow I engage 4WD. All the above refers to 460’s / Series III LR’s etc. not 463’s Defenders etc.

As soon as conditions become difficult and your speed reduces significantly then yes engage 4WD. It’s all a matter of anticipation / experience, if necessary get out and walk the route. Leave it too late and you will lose traction and any momentum. Don’t read too much in to momentum bit. Momentum is definitely overstated by people with more power/money than sense!! OK if you have a trailer to take your G home on. Not what you are after I think. Remember if you have approached a situation slowly and do get stuck you should be able to engage 4WD and reverse out without actually breaking anything. Remember ANYTHING will break if you’re dumb enough!

Russ

When I owned my 460, I made a rule to engage/disengage 4WD and the front and rear diff locks from time to time, to prevent them seizing. Obviously I'd do all this at walking pace, on dirt surface and mainly with the steering almost straight. I think that it's a good policy if you want to keep your stuff in good nick. Now that I own a 463 I do the same with the diff locks.

Thanks for that info Bill, I have been incorrectly using my diff locks at standstill and I'll bet I'm not alone, they never light up till about 5 yards so I'm sure you're right (again), ever thought about writing a book?.

BRAKES and SWAPPING ends.
The statement above is incorrect as I will prove.
Unloaded and brakes properley adjusted the initial braking force on a G is distributed mostly to the front on about a 60/40 split but this depends on proper adjustment of your rear brake & load sensor. G suspension geometry is so designed as to prevent nose diving as well as rolling so when you brake you may have noticed your vehicle duck down, this loads the rear sensor and increases brake force to the rear wheels and reduces it to the front, its a sort of mechanical active suspension. when your G is fully loaded the situation is reversed maximum braking is to the rear imediatley and you will notice if your compensator is adjusted properly that your nose actually lifts thus reversing the process, active suspension mechanicaly linked to braking distribution and anti roll. something those boffins in Land Rover couldnt master, but then they have never built a racing car.

Bill Moss

Ok Russ I think our differences are converging.
When you brake, the suspension geometry is set such that the rear sinks at or about the same rate as the front, thus preventing nose dive activating the load sensor, ie loading it and transfering the braking force rearwards as braking progresses.also giving equal down force and acting almost like ABS, because as you slow down the force gets less, and the brake compensator resets itself.
This is a problem in Motor racing, bcause as down force decreases with speed, so brake force has to decrease to prevent lock up, drivers have to lieraly lift the brake foot off the deeper they get into the corner however keep speed to a maximum to maitain down force. toe and heel driving.
To prevent end swapping at speed on gravel or loose track,or even Silverstone, set up the compensator to initiate early, this is achieved by lengthening the actuating rod to the bell crank.
If you want to go the whole hog, make the compensator finitly adjustable by disconecting it from the axle drill a hole in the floor above the unit and pass a threaded rod down to the compensator. put a nut wheel on the rod and a securing device and you can easily adjust it to your needs, a better approach is to use a bowden cable with a trigger type adjuster in the cab, you can then alter adjustment as you drive, ala F1 F3 F3000 DTM WRC etc it's the one adjustment drivers won't allow to be electronic because its all about feeling it with your backside and your foot. Remeber tho no matter what, : if you brake or accelerate when going through a corner, or not in a straight line you will spin off, because our old friend G force takes over and you become a passenger on a pendulum. remember your physics, potential and kinetic energy.
Bill Moss. :D

Correct, and the more you load it,ie pax or cargo the sooner that happens.
This is why there is a fairly small load limit on the tow ball. not drag force but nose weight of trailer , over load and this totaly upsets the balance of brake compensators in conjunction with suspension geometry. ergo upside down caravans on motorways.
Couldnt agree more about lock up, if you are locked up you are out of control, Mr G force is driving your car your a passenger,and he aint very good.

How unkind of your instructor, couldnt he recall the day he had a lot of bottle but not much experience.

This sounds like you could be in high range 4WD.

Try pushing the lever to the left and then towards the back.

If you are in 4WD you need to resolve this quickly before you cause some damage.

The "key" could be some non standard modification?

Good Luck

Russ

Bill, the instructor was totally correct in his assessment!............but then thats how you learn. Hopefully without any actual pain to the wallet or physical!!

Hi Bushy. Yes this is an Idle control. Mine was siezed solid when I purchased my 300 GD but if you lever the plastic knob off with two screwdrivers and squirt some 3 in 1 oil into the mechanism, replace knob and work it back and forth it'll work fine. You can adjust it where it links on to throttle under the bonnet. It's handy on very cold mornings. :wink:

It might be what I suspect. you don't have a 460 as stated in your profile, or may be you do with a 463 transmission. easy way to check, what is your chassis number?

460s have selectable 4wd
463s have permanant 4wd

Are your diff locks operated by plungers on the tunnel console or by switches on yourdash?

It would seem that a previous owner has converted the truck to full time 4 wd by fitting a 463 transfer box, which is not a bad thing, some where you may have a switch for engaging the transfer box diff lock.
It is something I have considered doing to one of mine, now I know it can be done I will examing it very carefully.

Bill Moss

Torque Wind up, which means there is no centre diff, or your rear diff lock is engaged

Johann:

What you describe is very highly suspicious. I doubt that somebody has fitted a 463 transfer box to your car for two very good reasons: 1) is that it would not work without replacing both axles as well, since the 463 axles turn in the opposite direction to those of the 460. And 2) is that yours is quite an old G (no offence intended) so why would somebody fit a 463 transfer box in a car whose value is not that greater than the box itself?

It looks to me that either a) your 460-type transfer box is stuck in 4WD or b) your car does not have a 460 transfer box anymore (possibly not even a MB box at all).

To check this, go to your nearest MB garage armed with your car's VIN and politely request that they give you a print-out of your car's datacard. You'll see there the serial number of the transfer box which was fitted to your car in the factory.

The correct type for a 460 is VG080 and the serial number should start 750.60X. If it was a 463 transferbox, it should be type VG150 and model 750.650. Once this is checked go underneath your G and note the serial number stamped on the side of the transferbox and check that it is the same as the one in the data card. MB transfer boxes have serial numbers with 14 digits, for example 750609 10 032566 was the number of the one in my ex-G.

Come back to us with your findings. Good luck

Johann:

No W460 has central diff. That´s why is only part-time 4WD, to avoid transmission wind-up in hard surfaces. On these (on road) you would normally drive in the 2High position (rear-wheel drive only).

The two 4 High positins that you have in the gear lever are exactly the same. They connect the front axle, making the car have four-wheel drive. The fact that there´s no central diff, makes this position totally similar to that of a W463 with the central differential locked, i.e. both axles turn solidly together. This is why this position is only advisable off the road, so that the wheels slide over the ground to compensate for the differences in turning between the axles that the central differential would be otherwise there to compesate.

The 4 low position is virtually identical to the 4 high in every respect other than the fact that there is a reduction in the gearing.

New to all this , but I understood that 460 only had two difflocks , 1 in each axle ( cf. 463 which has 3 ie extra centre diff for permenant 4WD ) AND that 460 normally rear drive only , and that when 4WD drive is engaged in high range , or low range which is always 4WD that front axle then driven off transfer gearbox , no diff being involved , unless one chooses to lock up either or both axles.
Marcus

Just to add another, non-technical slant- I travel long distances on Australia's corrugated and loose outback gravel roads which necessitate an average 100-130 kph (60-75mph) just to lessen the vibration and keep the dental work intact.

I always engage 4wd as I get better grip at those speeds.

I have tested my 280GES @ 80-100kph in 2wd on soft, sandy gravel bends and it understeers badly-same speed in 4WD it just turns in normally and grips.

The braking effect is an issue but you drive to the conditions and leave plenty of safety room, bearing in mind that more than one car an hour is a traffic jam out there, three cars and people think it's a parade..

In fact a Ford Explorer nearly killed me by disengaging 4WD in the middle of a wide bend near Mt Isa - not going fast - but I went sideways into the scrub - why those death traps are still being sold is betond me.

Also I have a 460 so no ABS - I regard this as a bonus as it's hopeless on other ( Non Benz) 4wd's I have driven in the dirt.

Cheers.

Jimmy McEwan 8)

As a newcomer I am now :( very confused with S SA and diff locks etc has anyone got a picture or where can i get one of what is doing what for a 280 1978 G-wagen Thanks Gary

Thanks will have a go Gary

I know this is an old post, but I'd like to share my experience with 4WD engaging.

I have a 1983 300GD SWB Auto with STT Turbo conversion.

First of all, I've driven the car since I was 16 (now 35) , and I have had no issues with stability or "swapping ends" syndrome all this time.

I've driven it a lot off-road and also did 4 Cyprus-Rally events (part of WRC) as an opening car ("000" car).

I also found that engaging 4wd will not lock the wheels during hard braking on wet roads and it generally feels a lot more stable under wet/muddy conditions.

The only downside is vibration from the drive.

Hussein,

if you did not have problems with using SA on-road (yet) it is due to the strength of the G. But if you stress parts long enough - even the toughest will give up.

The fact that you don't notice how the car drives differently (worse) maybe due to your not so sensitive seat of the pants. Driving downhill on pavement with sharp bends (SA engaged) is plain stupid. By doing so you are overriding the rear brake pressure regulator. It might feel like "CLING LIKE A CAT" - but that's your feeling. Just a tad faster than you drove so far, just a tad more brake pressure than you applied so far and your rear will very suddenly move to the outside of the turn - no chance of recovery. I am not just quoting physics books - I have been there.
http://www.4x4abc.com/G-Class/flip.html

Here is why you either drive in 2WD on pavement with a part time 4WD car (460) and why full time 4WD cars (463) do not have that restriction:
http://www.4x4abc.com/4WD101/def_turn.html

But this like the discussion of wheels and gears - there are the laws of physics (and you can explain them until you are blue in the face), and then there are the 4WD users (most of them) who would rather listen to old husband tales.

your opinions alexis are the same as mine.i have hardly ever used SA here in the uk and never really needed it.but as you mentioned the terrain in cyprus is different.even the asphalt we drive on in the north is like glass,ok its quiet but boy does it slide in the wet :shock:

i think knowing your G's limits minimizes an accident and reading the the road ahead is very important.

i must say i have driven a G in cyprus for 12 years and always used the same philosophy and never had a problem,but i am alot more aware now of this so called stress that can be put on the transmission when using SA on non-slippery surfaces.

rgds hus.