Towing in 4x4 LO

[Skylerker]

Can I tow in 4x4 lo. Recently coming down a mountain here in beautiful BC I could not gear down enough because of road condition and steep grade and switch backs. (gravel Forestry road) Even in tow mode and being in 4x4 high still left me using brakes more than I wanted. I have it in my head for whatever reason that one should not tow in 4 lo as it puts an awful lot of stress on your differential. Am I out too lunch on this, please tell me its okay to tow in 4 lo to provide engine braking when conditions warrant it.

[eric2500hd]

It would depend on the conditions. You said gravel road so that would help some. You would be limited to very very slow speeds in 4 low. Do you have the ability on your truck to lock it in a gear manually, like 2nd gear. On my Chevy I can put it in tow haul mode and manual shifting mode and then set my top gear, say 2nd or 3rd and it will stay in that gear to provide engine braking.
I would say since you are on a gravel road that is steep with switchbacks your speeds are going to be pretty slow and 4 low may work for you. You can always try it through a couple switchbacks to see how the truck reacts. If you need to shift back into 4 high you could stop in a switchback and do so.

[nylyon]

If you are currently using 4-high, then the only difference in using 4-low is the gear reduction in the transfer case. As with any part time 4wd, do not use it on pavement because the wheels NEED to slip. Since you're on dirt roads I would use 4-low.

[Seann45]

When using the transmission to slow you down keep an eagle eye on the tach so you dont over rev the motor.. going into 4low will increase your RPM's.. if you are worried about over heating your brakes stop every mile or 2 and let them cool...

[dmax_83]

Originally Posted by Seann45

When using the transmission to slow you down keep an eagle eye on the tach so you dont over rev the motor.. going into 4low will increase your RPM's.. if you are worried about over heating your brakes stop every mile or 2 and let them cool...

Good post, especially since the op didn't state gas or diesel. However, if it is a diesel, you can rev them pretty high if you aren't fueling them without causing any harm. In fact, GM removed the 'redline' indicator on the tach because people were freaking out during grade braking.

[Seann45]

Originally Posted by dmax_83

Good post, especially since the op didn't state gas or diesel. However, if it is a diesel, you can rev them pretty high if you aren't fueling them without causing any harm. In fact, GM removed the 'redline' indicator on the tach because people were freaking out during grade braking.

Hey thanks I did not know that.... I had always hard stabbed my brakes to keep it under redline...

[FPM III]

Originally Posted by dmax_83

Good post, especially since the op didn't state gas or diesel. However, if it is a diesel, you can rev them pretty high if you aren't fueling them without causing any harm. In fact, GM removed the 'redline' indicator on the tach because people were freaking out during grade braking.

I always thought there was no redline on the tach because the Allison will automatically upshift when the max rpms for the engine is reached. Even if you manually attempt to shift to a lower gear, the transmission will not downshift if the computer knows that by doing so it will over rev the engine.

Manual transmissions are another story as it is possible to over rev an engine. My 96 Ford PSD (with a 5 Sp manual) had a both a yellow and a redline on the tach and I kept close tabs on that tachometer it when decending grades.

[clutch]

On gravel roads it is no problem to use 4 lo. If you have a diesel, an exhaust brake is nice. You can also buy a kit to be able to use 2 lo. With that you don't have to worry about being in 4x4 on pavement.

[TexasA&M]

You won't hurt the truck by towing in 4Low. There isn't any additional stress (probably less stress in some cases) on any of the drivetrain. You'll just be limited to slow speeds (15-20mph).

[dmax_83]

I don't want to hijack this thread, but I just want to make sure that I clarify. You can definitely over rev a diesel, but there is a huge difference between an engine under load and an engine grade braking. In fact with the duramax the redline it is approximately 1,500 rpm higher.

To the OP, as others have mentioned, as long as your are not on dry pavement you'll be fine. I use 4 Low often when maneuvering in less that desirable traction.

[Skylerker]

thanks everyone, good to know that I can use 1st and 4x4 lo/tow mode when descending steep grade. Its was a gas, 2012 dodge 1500.

[Skylerker]

The truck and a pic off campsite.