GU4 4wd selection difficult

G'day mate,
There is NO WAY you will be able to change from 2wd into 4H "on the fly" unless you have manually locked up the front hubs with the spanner.....not even at low speeds.
Think about what is happening uner there for a minute........As you drive along (even at a modest speed of say 40k/h), the rear tail shaft is spinning at a considerable pace, whilst the front tailshaft hangs around doing sweet fanny adams. So then you reach down and want give the stubby lever a quick jerk to put her into 4x4. That little shaft is expected to go from zero rpm to umpteen rpm (to match the rear tailshaft speed) in a millisecond..........I DON'T THINK SOOOOOO.
The whole idea of the auto locking hubs is in case you find yourself unexpectedly stopped in a mud puddle and going no where.......don't wanna get out and get the old suede shoes all muddy, so (being already stopped totally), THEN you reach down for the stubby lever and rip her back to 4x4 (either 4H or 4L) and have a go at getting out of the shyte. Of course, if you KNOW that you are possibly going to need to get into 4x4 at some stage of a particular trip, it is wise (IMHO) to lock the hubs up and that way you can do it on the fly.
I know the advertising blurb is a bit misleading and they tend to forget to tell you that in order to avail of the shift on the fly feature you MUST have the hubs locked up before-hand.
I am very surprised you say you were able to do it once @ 40k/h.....I reckon your hubs must have been locked in at the time.
Cheers mate
Roachie

Rokkit,

The easy one first. My 2001 model Gu needs the demister on with A?C at the first hint of rain too, as did my wifes 2000 model SUbie. to solve this problem I simply moved from those horrible wet places near the coast and now live in Broken Hill where rain is not a problem (lack of rain is).

Now 4wd Selection. I don't know if you have ever had the front hubs apart on your GU, I am guessing not. On a normal free wheeling hub there are splines on the end of the drive axle which engage with the wheel when you lock the hub. When unlocked and driving along these splines are stationary and the driven part of the wheel is spinning. When you engage 4wd this drives these splines are then droven by the transfer case through the front diff. In my minds eye I see the driven part of the wheel and the splines on the drive axle spinning at different speeds and going crunch as the auto lock hub tries to engage. I would suggest that this is also what is making selecting 4H difficult. I find it is actually easiest to engage when I am almost but not quite stopped and I have my foot on the clutch. I think this is because it allows the splines to find a comfy fit without too much pushing and shoving

When you lock the hub manually you remove this from the equation. This is because with the hubs already locked, the front diff and drive shaft will already be spinning at the same speed as the rear and it is easier for the drive gear in the transfer case to mesh with the out put to the front which is also spinning at the same speed. On my GQ I did many miles with the front hubs locked and the transfer case in 2wd. This does have a cost in higher fuel consumption but when travelling over constantly changing ground made life easy. In 8 years of ownership the only time that car gave me grief from the hubs was just after they had been serviced, that's another story. On the old GQ I could happily change from 2wd to 4H at speeds of up to 100km/h all I ever had to do was lift my foot off the throttle for a moment and in she went. I have not tried this on the GU but from my basic understanding of how the system works (I am no mechanic either) I can't see it being a problem, provided the front hubs are locked manually before I try it. I do have difficulty occasionally engaging 4wd but it is usually when I am trying to rush things.

Hope this helps but if someone more qualified than me has an opinion I am happy to listen.

Duncs

Rokkit,

I have found you need to have your hubs locked in. There are 2 options: You can manually lock them in OR you can leave your hubs in AUTO and stop and select 4wd and take off again. Now that your hubs have been locked for the first time (in the AUTO mode) you can now select between 2H and 4H on the fly.
I also tried to change to 4H on the fly before the hubs were locked when I first purchased the Trol but just grinding noises came from the hubs!!

Leroy

i agree with bazza and exploder in that i change from 2wd to 4wd high range and back at up to 80 k no trouble with hubs in auto position,dont see why you cant roachie.

Rokkit,

Which club are you in? I'm going out with a western sydney club on sunday as a visitor, up near Yengo on the Putty Road.

My email is chumpion_at_tpg_dot_com_dot_au.

Chump

Hi Rokkitt,

I have a series 3 GU 4.8P auto and have exactly the same problem
First attempt to shift into 4WD high on the fly is near impossible. I actually did it last weekend for the first time but don't know how.
Normally have to stop to do the shift. Thereafter shifting to 4WD high on the fly is easy.
I just think it is another Nissan built in design fault like the heating system, cruise control, transmission backlash, air compressor bearings etc etc.

You should be able to do this Rokkit. Some people can and some can not. Like you I am one of the latter. I had been waiting for my linkages etc to free up rather than Nissan adjusting them but after 50K that seems to be not happening.

The Manual states you can shift from 2wd to 4wd with hubs unlocked in auto mode at up to 40kmh and if the hubs are locked it is up to something like 80-90kmh. I have tried but not been able to do it in auto except for one or two occassions. I have a mate with the exact same car who has no trouble doing it at any speed in auto. I find it very stiff at times to shift into 4wd with the hubs in auto even when stationary and hence my assumption that the linkages and gate are just stiff. Once hubs are engaged (manually or auto) then shifting is no problem at any speed depending upon accelerator and surface I am driving on.

There must be some synchro (friction) or sprag clutch (freewheel) type device that gets the propshaft up to speed or perhaps the hubs are used to accelerate it. It only takes a half a turn or so of the prop shaft to engage the hubs in auto mode.

Jamie Mac

Ask the dealer to show you how to do it if he can, alls good.

if he cant tell him to fix it

Hi Rokkitt,
At present I am on my second GQ auto ,It has auto locking hubs and have on many ocassions shifed from 2wd to 4H on the fly up to 100kph and run my hubs awaysin auto lock never had a bother and have travelled extensively in the dirt and sand ,
If you lift ya right foot briefly and pull the lever in quickly no problems
hope it helps you out ,
mechpete Shepp.

Success,

After a day in Lerderderg - Success, dissapointment at being shown the ropes by a prado.....lol.

Their is certainly a "technique" to it.

Many many thanks to all those that responded to this question.

Apply light pressure to the little stick, dethrottle and pop - in she goes, and out time and time again.

Nissan service techs advised this could not be done "without the hubs locked" I will take great pleasure in demonstrating what a special car mine is and offer them many thanks for the free extra! I can shift with the hubs in the auto position "on the fly"

Thanks again
Rokkitt

Despite my previous replies I have now I followed Kingsley's advice of not putting a downward force on the transfer lever and now it works like a charm. Slips straight into 4wd from auto hubs disengaged. Ther was a slight clunck as it goes in but all was good. Tried ait several times at various speeds up to the Nissan limit of 40kmh with no trouble (yes I reversed and disengaged the hubs before each go!)

Jamie Mac