turn on 4wd high

[HikeN2Mts]

Just a question when I'm towing on mountains roads uphill I slow down of course gas engine, just wondering when I drop to around 40 or less would it help to turn on the 4 wheel drive in high mode to have the front wheels help pull?

[4x4ord]

brulaz wrote:

Grit dog wrote:

...
Oh and you can drive most all newer part time 4x4 trucks in 4 high on dry pavement without the driveline binding up. Turning sharp is obviously difficult though. Still not reccomended.

You and 4x4Ord are saying this, but I drove my 2009 Tacoma about 25km in 4x4 on a paved, secondary road 80km/hr. And the front transfer case (I think) was cooking good and smelly at the end of it. It wasn't a high speed road, but 80km/hr is the speed limit with no reductions for curves that I recall.

The road was white, but it was only a dusting of snow that fell around the crushed rock in the asphalt. So not slippery at all, as I discovered afterwards.

Try driving that Tacoma on dry pavement at 50 mph in 2 wheel drive. Measure your fuel economy over a few miles. Shift into 4 hi and measure your fuel economy. If do this several times and consistently measure an increase in fuel consumption then you you can figure there is a measurable power loss. So I doubt that you will measure more than a 3% increase in fuel consumption which equates to 3% power being wasted throughout the driveline and tire to road surfaces. So say your using 65 HP at 50 mph in 2wheel drive....so 3% more is 67 hp in 4 wheel drive. That extra 2 hp is divided up among a transmission, two differentials, a transfer case and four tires. It is going to make a negligible difference to the temperature that your transfer case oil is running at....dry pavement vs slippery.

[lawnspecialties]

I'm surprised this thread was ever created.

I'm more surprised its still alive.

[brulaz]

Grit dog wrote:

...
Oh and you can drive most all newer part time 4x4 trucks in 4 high on dry pavement without the driveline binding up. Turning sharp is obviously difficult though. Still not reccomended.

You and 4x4Ord are saying this, but I drove my 2009 Tacoma about 25km in 4x4 on a paved, secondary road 80km/hr. And the front transfer case (I think) was cooking good and smelly at the end of it. It wasn't a high speed road, but 80km/hr is the speed limit with no reductions for curves that I recall.

The road was white, but it was only a dusting of snow that fell around the crushed rock in the asphalt. So not slippery at all, as I discovered afterwards.

[Grit_dog]

^ Correct. Auto lock is only with the elect shifter.

[fireman41]

Grit dog wrote:

valhalla360 wrote:

mkirsch wrote:
Only problem there is that most 1/2 ton trucks haven't had locking front hubs in over 20 years in some cases. Chevy quit in 1988, Dodge in 1998, and Ford in 1997, if I'm not mistaken.

Read my post, I said "if" you have them. My F250 has them and lots of folks switch them out aftermarket.

Better check your hubs, unless you have an old square body Ford. Super duties locking hubs also lock automatically when shifted in to 4h or 4lo. Unless the vacuum actuator is broke or have a vacuum leak. Not sure why ford chose this redundant system other than the auto lock system isn't totally reliable.
Either way, you can't get 2lo out of a newer ford without modifying it.


On the flip side, there has been some good (obvious) info for the extremely misguided op in this thread, and also a greater than average amount of mis information. Be ware.

Oh and you can drive most all newer part time 4x4 trucks in 4 high on dry pavement without the driveline binding up. Turning sharp is obviously difficult though.

Not true. My 2013 came from the factory with 100% manual hubs. Locked or free are the only options. But I still have a lever to shift with.

[Grit_dog]

valhalla360 wrote:

mkirsch wrote:
Only problem there is that most 1/2 ton trucks haven't had locking front hubs in over 20 years in some cases. Chevy quit in 1988, Dodge in 1998, and Ford in 1997, if I'm not mistaken.

Read my post, I said "if" you have them. My F250 has them and lots of folks switch them out aftermarket.

Better check your hubs, unless you have an old square body Ford. Super duties locking hubs also lock automatically when shifted in to 4h or 4lo. Unless the vacuum actuator is broke or have a vacuum leak. Not sure why ford chose this redundant system other than the auto lock system isn't totally reliable.
Either way, you can't get 2lo out of a newer ford without modifying it.


On the flip side, there has been some good (obvious) info for the extremely misguided op in this thread, and also a greater than average amount of mis information. Be ware.

Oh and you can drive most all newer part time 4x4 trucks in 4 high on dry pavement without the driveline binding up. Turning sharp is obviously difficult though. Still not reccomended.

[4x4ord]

Although I agree that you don't want to run in 4 wheel drive on dry pavement I think everyone is making a much bigger fuss about it than is necessary. So long as you're not doing much turning the power loss, tire wear, drivetrain wear etc would be next to nothing. If you only did it on steep hills I wouldn't be surprised that there would be more to gain than loose.

[mkirsch]

valhalla360 wrote:

mkirsch wrote:
Only problem there is that most 1/2 ton trucks haven't had locking front hubs in over 20 years in some cases. Chevy quit in 1988, Dodge in 1998, and Ford in 1997, if I'm not mistaken.

Read my post, I said "if" you have them. My F250 has them and lots of folks switch them out aftermarket.

...and read my post, that "if" is far and few between these days.

[Fordlover]

Only when the available traction of the rear tires are exceeded. 4x4 will actually reduce the available power from the engine, not add to it.

[transferred]

nohurry wrote:
The answer to your question is no. Read your owners manual's 4 wheel drive section for help understanding. As has been said, 4x4 should only be used on gravel, ice, or snow. Never on dry pavement.

Rain too. Makes things far safer so long as you still drive at a sensible speed...and I've never f'd a driveline doing so in 30 years.

4WD is there for whenever traction is compromised, and this obviously goes for empty too as the rear ends are relatively light.

[valhalla360]

mkirsch wrote:
Only problem there is that most 1/2 ton trucks haven't had locking front hubs in over 20 years in some cases. Chevy quit in 1988, Dodge in 1998, and Ford in 1997, if I'm not mistaken.

Read my post, I said "if" you have them. My F250 has them and lots of folks switch them out aftermarket.

[Greentreena]

They only time I've considered 4wd (for non traction reasons): towing up the Grand Teton pass fully loaded in my old truck.... about 10 km/h thinking that if I stop, there is no way I'll get moving again on that hill. I thought, if I am forced to stopped, 4 low should get me to the top. Thankfully, I continued to SLOWLY crawl up that hill without resorting to extreme measures. The following year that truck was replaced with my current truck.

[mkirsch]

Only problem there is that most 1/2 ton trucks haven't had locking front hubs in over 20 years in some cases. Chevy quit in 1988, Dodge in 1998, and Ford in 1997, if I'm not mistaken.

[valhalla360]

mowermech wrote:

valhalla360 wrote:
4WD High - No as others have said. You are still running at the same gear ratio so your engine will struggle just as much but there are minor differences between the front and rear gear ratios ad they likely will damage your drivetrain on a dry road. On gravel or snow, the tires can slip a little to adjust for that minor difference.

One option if you have manual lockers on the front is 4WD Low if the truck simply comes to a stop and can't get up the hill. Set the front lockers to allow freewheel and drop into 4WD Low. You won't have a lot of speed but you will have an extra low gear and since the front wheels are no longer connected to the drive axle binding won't be an issue. Don't make a habit of it as the low gearing can put a lot of strain on the driveshaft and rear diff.

While that has been done, successfully, (I even did it myself once, by accident), it is not recommended by any vehicle manufacturer, AFAIK. There is a very good chance of twisting an axle or driveshaft into two pieces. You REALLY don't want to do that!

That's why I put a warning at the end but if I'm stuck in the middle of nowhere and the rig won't go forward in the normal gear, I would likely chance it. Assuming you are borderline making it up the hill, it's unlikely fail unless you really hammer it.