4x4 Questions...

black_knight · Dec 23rd, 2004, 05:48 PM

Well we had a pretty good snowfall here in the north texas/oklahoma area and I got to test out the new 4x4 on our way up to Tulsa to visit some relatives yesterday. I must say it is AWESOME!! There were some pretty hairy spots on HWY 69 where my former 2wd would have gotten sideways and started spinning the rears. When we pulled off at the only gas station the snow was pretty deep and I couldn't get back out across the highway along with many other people stuck spinning their tires, but I just slipped it into 4H and took off like it was dry pavement! (Sorry for the enthusiasm but this is my first 4x4 and i'm not used to having this much control in bad weather!) After using it though I have a few questions...

1. It says on the visor that to "unlock" the auto-lock front hubs you have to put the truck in 2Hi and drive in the opposite direction for 3 feet. So if I'm going 25 mph on these snow covered roads and I would slip the transfer case in and out of 4HI on Hills (to keep from sliding slideways), are the hubs not disengaging when I put it back in 2HI? will this affect gas mileage? It's kind of annoying to have to stop and back up 3 feet if I'm gonna put it back in 2Hi for a while.

2. What kind of gas mileage are you 4x4 Frontier owners getting? I'm hoping it's just the engine breaking in but I'm getting about 3 mpg difference in city and highway from my 03 2WD I used to have. Surely 4x4 doesn't make that big a difference (unless I'm driving around with the hubs locked and don't know it).

Sorry for the long post, Thanks.

Later,

jakeslouw · Dec 24th, 2004, 02:49 AM

Firstly: reversing to disengage the front hubs is mandatory. The Mitsubishi series uses a similar system, and I think now Toyota as well. The old Nissan DiffLoc system also needed this to be done.
Why do you need to do this? A thing called "diff wind up" that can cause your sideshafts to break at the worst, and at the best, will cause excessive tyre wear, as you are effectively driving with a solid front axle.
That's why I prefer the old manual lock hubs, even though it's a PITA getting in & out of the truck to do this.....

Secondly: a 4x4 will always have more gas consumption that a 4x2, as there is more drivetrain bits being rotated, even though half of them aren't engaged all the time.....extra drag on bearing & seals, yadda yadda yadda....
But I think your front diff is still locked.......;-<

werks2much · Dec 24th, 2004, 09:52 AM

Yeah Black_Knight, you have to run in reverse to get the front hubs to disengage. If you shift between 2HI & 4HI while you are running forward your front hubs will stay locked and your transfer case will either be powering just your rear axel or both axels depending on your selection. Your front drive train will rotate regardless until you back up.

I had a problem with my Automatic hubs not unlocking in extreme cold weather. I replaced them with the Warn Manual hubs. Now I have to get out but when they are locked they are locked and likewise when they are unlocked.

We got 15 inched here in southwest Ohio and man these Nissans rock in the snow! I have never had such a sure footed vehichle in the snow before. I am very pleased also.

black_knight · Dec 24th, 2004, 03:49 PM

so is there a way to tell when the front wheels are unlocked or locked? I would assume that after backing out of a driveway in 2HI (the next morning) they would unlock or is it a lengthy process you have to go through? right after driving in 4hi or 4Lo?

Later,

werks2much · Jan 1st, 2005, 08:41 PM

Quote:

Originally Posted by black_knight

so is there a way to tell when the front wheels are unlocked or locked? I would assume that after backing out of a driveway in 2HI (the next morning) they would unlock or is it a lengthy process you have to go through? right after driving in 4hi or 4Lo?

Later,

It should only take about 3 feet to disengage your hubs. Backing out of the drive way the next morning is fine but all the parts will be cold by then. I would disengage them before heading in for the evening.

**88pathoffroad** · Jan 2nd, 2005, 07:09 PM

Quote:

Originally Posted by jakeslouw

Firstly: reversing to disengage the front hubs is mandatory. The Mitsubishi series uses a similar system, and I think now Toyota as well. The old Nissan DiffLoc system also needed this to be done.
Why do you need to do this? A thing called "diff wind up" that can cause your sideshafts to break at the worst, and at the best, will cause excessive tyre wear, as you are effectively driving with a solid front axle.

Bullcrap. It's an open diff. One wheel will always be open to spin faster than the other in the case of the hubs staying locked. I've NEVER heard of a 4WD vehicle breaking a front axle from leaving the hubs locked on a open front diff and running it in 2WD at ANY speed. I've personally run my Pathfinder in 2WD at up to 50 MPH on the beach with the Warn front hubs locked. No damage or noises or problems whatsoever.

Quote:

Originally Posted by jakeslouw

Secondly: a 4x4 will always have more gas consumption that a 4x2, as there is more drivetrain bits being rotated, even though half of them aren't engaged all the time.....extra drag on bearing & seals, yadda yadda yadda....

Bullcrap again. On a vehicle with unlocked hubs on the front driveshafts/CV's, the front drivetrain does not spin at all. It's running in 2WD with only the rear drivetrain spinning, just as a 2WD only vehicle would be. The only differences are curb weight, center of gravity and sprung/unsprung weight.