Community Forums

GottagoChris · 05-10-2021, 11:15 PM

I'll be traveling coast to coast with an F-250, bumper towing a 31' trailer. When would I be expected to use 4 wheel hi and/ or 4 wheel low during my trip? Example: When I'm on an interstate highway and its bumper to bumper traffic, would I use 4 WD high or low to negotiate the constant stop-and-go to reduce the strain on the 2 WD system or am I overthinking this? What other situations would I face to justify using 4 WD?

mtofell · 05-10-2021, 11:39 PM

You're definitely overthinking it..... no need at all for 4WD of any kind unless you're on snow/ice/mud. Standard towing just leave the transfer case alone. And in most cases when 4WD is called for, just 4WD HI is all that's needed. 4WD LOW sets a large gear reduction (sorry if I'm butchering the terms) so you can only go about 5MPH in 1st, 15 in 2nd, etc. In low range you'll have insane pulling power for things like getting a stump out of the ground. But this is nothing you'll need for towing your TT. Really, the only times I use Low range is when we have snow/ice and I want to roll down hills in 1st gear at 2mph without hitting the brakes. Or, when moving a trailer full of gravel on a slippery surface. Again, nothing to do with your RV adventures.... hopefully!

YC1 · 05-11-2021, 01:16 AM

4wd is only needed on slippery surfaces and I try to avoid those if possible.

Of course, I have pulled I80 in a light snow storm and did use 4wd low but I am quite experienced and do not recommend that if you can avoid it.

4wd low is for grunt pulling up a steep hill which you should not encounter with a tt.

Of course, rough dirt roads where you need to crawl along the low range can be useful to keep the speed down.

I generalize a lot but you need to get slowed way down if you need 4wd towing. Good way to have the trailer come around and kiss your front end if you make a mistake.

TXTiger · 05-11-2021, 02:41 AM

I only use 4 wheel drive (hi or low) when I am off road. Never on the highway, unless traveling in deep snow and going very slow, 5 to 15 MPH. You should not be towi g if in these conditions.

tuffr2 · 05-11-2021, 03:54 AM

You are over thinking this. 4x4 is only used on snow or ice. There is no wearing out the 2WD system. Only wearing out the 4 x 4 system.

Also you do realize if you get stuck you only will have one front tire and one rear tire that will spin. The two tires with the least traction. So if you pull off the road onto wet grass with the two right side tires in the wet grass and two left tires on the road concrete - the two tires in the wet grass are likely to spin.

In the Ford 4 x 4 world unless you have a locking rear axle only the 2 tires with the least traction will spin.

FX-4 - you can get 3 tires to spin with 4x4 with a locking rear axle.

Tremor - you can get 3 tires to spin with 4x4 plus a locking rear axle. The front tire, if spinning will send power to the other tire. So this is called a limited slip front axle.

Bobby F · 05-11-2021, 04:05 AM

Don't ever use 4wd on dry pavement. Your wheels need to skid as you turn so as to not bind up the drive train. If you hear a big bang and coast to a stop while in 4wd, you will be reminded of this. Painfully. Expensively.

sirtate · 05-11-2021, 06:06 AM

Quote:

Originally Posted by Bobby F

Don't ever use 4wd on dry pavement. Your wheels need to skid as you turn so as to not bind up the drive train. If you hear a big bang and coast to a stop while in 4wd, you will be reminded of this. Painfully. Expensively.

Not even in turns!
There's enough difference in rotational speeds between the front and rear axles to bind up the 4x4 transfer case on dry pavement.

will stevens · 05-11-2021, 06:29 AM

I love 4 lo when backing a trailer that's heavy or uphill. Takes the strain off the transmission.

runamuck · 05-11-2021, 06:58 AM

I have had 4wd on every vehicle since the 80's and never had a problem from being in 4H or auto when on pavement..dont know where that comes from..maybe different between gm which I have always had and other makes..dont know. many a time I have come out of the mountains after a ski trip and didnt remember till the next fuel stop to switch out of 4 wheel. I dont make it a habit to drive in 4wd just saying I have done it without any trouble so it's nothing I worry about.

mikeyk101 · 05-11-2021, 07:00 AM

You should never drive in 4hi or 4lo on dry pavement. You will end up with a very expensive repair and find out why the hard way. Just because some have done it with with minimal problems doesn't make it right. The only exceptions to this is if you have auto 4wd which will sense when 4 wheel drive is needed. But using this mode will decrease your gas mileage and really should only be engaged if you think you might experience slippery surfaces. AWD would also be an exception as there usually is no why to deactivate this and works just like 4 auto all the time.

https://4wheeldriveguide.com/driving...amage-control/

**hamm2018** · 05-11-2021, 09:07 AM

Do not use 4WD on dry pavement, as said before. General rule of thumb.

Dave Pelletier · 05-11-2021, 09:29 AM

Quote:

Originally Posted by Bobby F

Don't ever use 4wd on dry pavement. Your wheels need to skid as you turn so as to not bind up the drive train. If you hear a big bang and coast to a stop while in 4wd, you will be reminded of this. Painfully. Expensively.

This.

Dave

LETMGROW · 05-11-2021, 09:56 AM

Quote:

Originally Posted by hamm2018

Do not use 4WD on dry pavement, as said before. General rule of thumb.

Right! When in 4 WD everything in the drivetrain wants to turn the same speed. On any pavement if you make a turn your front wheels are going to want to turn faster than the rear and the outside wheels will want to turn faster than the inner wheels This is all due to the arc of the turn. Dry pavement does not allow wheels to slip like they could on an ice, snow or mud surface which can allow for some slippage.
There are a lot of moving parts involved including driveshafts, differentials, U-Joints and the transfer case. A failure of any of these will without a doubt be cause to call a tow truck and a good credit score.

Dave Pelletier · 05-11-2021, 10:32 AM

From the link Mikey provided:

Driving on dry pavement or highways with a part-time 4-wheel drive while the center diff-lock is engaged should be AVOIDED AT ALL COSTS. The reason for this rule is, the drivetrain design of a part-time 4-wheel drive is not intended for high-traction surfaces such as dry pavements but rather for slippery, low traction off-road terrain where traction is limited. Drivetrain binding will result if a part-time 4WD is driven for many miles on twisty highways.

Transmission windup occurs due to the front and rear drive-shafts not being designed to rotate at dissimilar speeds while the vehicle is turning. Full-time 4WD’s and AWD’s that incorporate viscous couplings or multi-plate clutch systems are able to safely drive on dry pavements and highways.

the last part was bolded by me. FWIW, GM's use a CV joint rather than a U joint in thier front ends which allows for some rotational differences....downside is the cost, amintenance and complexity compared to a straight axle using U joints but I'd still avoid using them on dry pavement

Dave