i recently found myself on a 150mi trip where the road conditions would keep changing from seemingly "dry" to very slick. I did not want to leave the truck in 4hi as i keep hearing about all the damage it can cause but it was imposable to know when it was going to be real slick and it did not take much, if anything for the back end to start sliding and the freeway was bumper to bumper traffic...

in short, the road conditions kept changing on me and i felt it was necessary (to stay in my own lane) that i keep my truck in 4hi for about 150 miles at speeds of 20-40 mph

could this have done damage to my drivetrain? if so what?
if its just the hubs i'm not too worried.

 

As long as you're not making any sharp turns and your tires are all the same size, I say you haven't hurt your truck in the least. I've been driving mine in those conditions for 3 winters now. I've even turned my 4x4 on while on dry pavement just to give it a bit of a run every now then, but I was always on a straight road and didn't make any turns with the steering wheel. My truck is still like new with 65k km's (40'ish k miles?) on the clock.

I know what you mean though. You'll hit snow and ice covered roads and then it turns into dry roads. That's what I like about the ease of use of the electronic 4x4 switch. It's a snap to go back and forth to 4x4 or 4x2.

 

i made no turns and all my tires are the same size.

i would have shifted back and forth between 2 and 4wd but the ice was a light glaze that was IMPOSABLE to see. the roads looked clean but the back end would randomly break loose and/or the brake pedal was useless. over 150 miles i was 3 pileups and 40-50 cars in the ditch and the roads "appeared" dry the whole way.

 

Realistically, it's impossible to not hit dry pavement while in 4x4 mode. You'll hit slick patches of snow/ice/sleet, and then suddenly you're on dry pavement, and back and forth. I'm sure the system is designed for this, as long as it's not prolonged driving on the dry pavement. If it wasn't designed for that, I think the dealerships would be seeing a lot more trucks in for driveline failures.

 

i know it's not good to make sharp turns on pavement with the truck in 4x4, but just wondering why? isn't this the job of the differential????

 

If you had a differential at the transfer case you could (like a Subaru). Keeps the system from binding by allowing the front shaft/rear shaft to turn at different speeds.

 

That was what I appreciated the most about driving a Subaru, was throwing it into 4x4 and not worrying about the drive wheels spinning out.

I'm still wondering what gets ruined when you turn a lot in 4x4 on dry pavement, and does that apply to rocky - sandy - gravely terrain?

Good point, but the numbers I heard is that 95% of 4x4 owners never put it in 4x4 even once, 2% put it in once just to see if it works. That puts us in the 3% who use it.

When you put a differential in the transfer case, (again like Subaru,) you'll fix the turning problem on dry pavement, but then you'll have less traction in the mud, deep snow, and uneven terrain. When one front wheel is off the ground the transfer case differential will send all power to that front wheel, resulting in that wheel spinning and the vehicle going nowhere.

 

For those living in Texas, or Florida, I agree. But for those living in Wisconsin, or Nebraska etc , or most of Canada, I believe there are enough 4x4 users in which driveline failures would tend to surface due to being used on dry pavement patches.
Like I mentioned, I've clicked mine into 4x4 many times on dry pavement while driving straight on a smooth road just to run the gears and get them up to temp. I have no doubts that when I need it, the 4x4 will work, like it always has, so far. I flip it in and out fairly often just to listen and feel, and knock on wood, it has always performed perfectly.

 

Those statistics are old, and I don't remember where I got them from, but I also remember that 25% of F-150s are sold in Texas.

 

There is no doubt that you will shorten the life of your transfer case by running the truck in 4x4 on dry pavement. In the long run it will stretch the chain and stress the lock up hub assembly as well as the planetary gear set. The question is by how much will you shorten the life..... I have no scientific data to back up how much it will shorten the life but I would bet that your truck will rot and rust out before the t-case gives up. I use mine at street lights in the rain for extra traction. It finally after over 140,000 miles decided to act up. I have a rule that I follow when driving on the street. If you can get by without 4x4 then don't use it.

Regards

Jean Marc Chartier