2H to 4H While driving...Is it really possible?

[ra_01]

Hi All,

I have been to wild coast in December. During this trip I had to switch to 4H quite often and sometimes to 4L.

According to the manual, I can switch from 2H to 4H while driving. Not that I was doing 80k/h, but I couldn't even set to 4H when I am doing 40km/h. However, if I stop the car, then it works fine. Funny thing is once I am in 4H, I can switch between 2H and 4H without stopping the vehicle

Hubs was set to auto.

Has any one experienced this issue.

Thanks

[Peter Connan]

I am pretty sure it's due to the auto hubs.

My car has manuwl hubs, and I have engaged 4H on the move many many times.
I suspect if you lock the hubs you will easily be able to engage 4H on the move.

The reason is that with the hubs in auto, the front drive components are not rotating, thus the gears can't engage, but if they are locked the output shaft is turning at basically the same speed as the input.

[iandvl]

I imagine it was probably the fact that once the vehicle was set to 4H, the auto hubs locked, and this made it possible to shift easily between 4H and 2H.

However, please do not shift between 2H and 4H with hubs on auto. You will damage splines somewhere. If you attempt to do this with a window open, you will literally hear the splines battling to engage. The correct way to do this is to lock the front hubs. Before starying the part of your journey where you need to shift between the two. You can drive in 2H with the hubs locked - no issue. And then easily shift between 4H and 2H whilst on the go.

[ra_01]

Thank you guys. That makes perfect sense.. When the hubs are set to locked from auto, what happens exactly.
Can I still do highway speeds by towing a trailer etc..

[XenoBlitz]

When the hubs are set to locked from auto, what happens exactly.
Can I still do highway speeds by towing a trailer etc..

When the hubs are locked, your wheels will be engaged to your shaft permanently, so even if the transfer case isn't engaged in 4H, the shaft will still be turning (when the wheels are turning.) When set to auto, the shaft disengages from the wheels when there is no torque applied from the transfer case, so the shaft will be stationary even if the wheels are turning.

I drive a lot of dirt roads and practically leave my hubs locked in 4wd almost permanently and set from 2H to 4H on the fly regularly. A little more road noise when driving at 120 kph, but otherwise, no problems yet.

[ra_01]

I also found a similar discussion on the forum today.

Since I use my vehicles mostly on tar. I'd rather leave it on auto and stop the vehicle and set to 4H when needed. Would have been nice if I could do it on the fly. But I understand the mechanism now.

Thanks

[iandvl]

I also found a similar discussion on the forum today.

Since I use my vehicles mostly on tar. I'd rather leave it on auto and stop the vehicle and set to 4H when needed. Would have been nice if I could do it on the fly. But I understand the mechanism now.

Thanks

As I said, lock the hubs when you are doing trips where you will be shifting between 4H and 2H.

An example of this would be my recent trip to the West Coast and Nam (http://patrol4x4.co.za/viewtopic.php?f=57&t=8172).

I locked hubs when I refueled in Springbok, as I knew that we would be leaving the tar road at Garies and would be alternating between tar road, gravel and very soft sand tracks from then on for pretty much our entire trip until we were back at Kuruman. I unlocked the hubs again when we reached Red Sands, as the remainder of our trip home was tar road. And they have been unlocked since.

You can drive fine on tar with the front hubs locked - just keep the vehicle in 2H.

[Peter Connan]

Driving with the hubs locked on tar, even at highway speeds, is no problem.

In fact, the manual instructs that you drive with the hubs locked for at least 50km per month.
The reason is that the front diff does not get lubricated when the hubs are on auto and the car is used in 2wd.

The only drawback to driving with the hubs locked is a small penalty in fuel consumption.

[ra_01]

I also found a similar discussion on the forum today.

Since I use my vehicles mostly on tar. I'd rather leave it on auto and stop the vehicle and set to 4H when needed. Would have been nice if I could do it on the fly. But I understand the mechanism now.

Thanks

As I said, lock the hubs when you are doing trips where you will be shifting between 4H and 2H.

An example of this would be my recent trip to the West Coast and Nam (http://patrol4x4.co.za/viewtopic.php?f=57&t=8172).

I locked hubs when I refueled in Springbok, as I knew that we would be leaving the tar road at Garies and would be alternating between tar road, gravel and very soft sand tracks from then on for pretty much our entire trip until we were back at Kuruman. I unlocked the hubs again when we reached Red Sands, as the remainder of our trip home was tar road. And they have been unlocked since.

You can drive fine on tar with the front hubs locked - just keep the vehicle in 2H.

That was a nice read and looks an awesome trip.

Thanks for the suggestion. I will lock the hub when I get into this kind of situation or I would have done that if I knew while I was in wild coast.

[mvcoller]

I have never tried this in my Patrol, but on my many safaries in my TD27 Nissan Terrano I regularly changed between 2H an 4H with the autolocking hubs on auto mode with no problems. I have soft copies of service/user manuals and the autolocking hubs on the Terrano and the Patrol seems nearly identical in the way they work although the Patrol's have a different spline count to the Terrano and the Terrano has no manual locking mode. Sideshafts on the Patrol may be a mm or two thicker, but setup seems to be identical.

I have also watched an Ausiie video on youtube (I think it was called '10 things you did not know about a Patrol') where it states that you can change from 2H to 4H and back, at speeds of up to 80kph