1999 V10 auto trans 4x4 with manual TC lever and manual hubs. Had to back our trailer UP into a tight camping space this weekend. The starting point was at least a 10% grade, but was paved so I had enough traction in 2wd. Had to do some pretty significant wheel turning to get in so did not want to have 4wd engaged, just wanted lowest possible gear.
After careful consideration of what I understand the drive system to be in this truck, I left the hubs unlocked, shifted into 4 LO, and backed right in with no effort. No noise, no drama, just quietly eased right into the space.

Did I miss something when thinking about doing this? Is there something in the design that makes this an ill advised practice?

 

You will be fine doing it this way!

Just take it easy when you do because there is alot of torque going to the rearend when you are in low range.

 

That is the preferred and recommended way by many to back a trailer up an incline. Helps keep the tranny cooler, too!

 

It's PERFECTLY FINE to do it that way. I wouldn't run at high speeds for long that way, but backing up like that, it's PERFECT for doing that.

Like Monsta said, it's a good way to keep the tranny much cooler too.

 

Thank you, all.
From what I could tell, it was a "traditional" 4wd transfer case and front axle setup so I gave it a try. Good to hear others understand it is OK.

It sure works well for inching in. The trans temp gage didn't even twitch. I do have a couple extra coolers.

Now I just need to glue the **** onto the manual lever. It slides right off, raking the finger right over the burrs on the end of the lever. That wasn't pleasant! JB Weld time.

 

Just out of curiosity and for arguments sake, what is the reasoning for not wanting it in 4LO went doing a lot of tight turning. I'm guessing the obvious, I know the front end gets a little jumpy when in 4X4 and I assume that's the reason. But, if it's due to binding in the U-joints (or CV) I'd think you'd get that anyway, because when 4LO is engaged the front drive shaft still drives and the front axles still turn, just the wheels don't drive because they aren't locked to the axle.

 

For those curious about the ESOF system, you can disconnect the vacuum solenoid under the hood, and do the same thing.

The vacuum solenoid is on the passenger-side fenderwell, just trace the vacuum lines back from the hubs. Unplug the electrical connector, and then put it in 4x4HI, stop the truck, put your foot on the brake, shift to neutral and turn the switch to 4x4LOW.

You should have 2LO

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fivonut, you will get a slight knocking from the front u-joints without the hubs locked, but it will be WAY less than if the hubs were locked. If you're in a low-traction situation, it won't be too bad and you'll probably need 4x4 anyway, but on pavement or hard-packed dirt, tight turns in 4x4 are a big pain.

 

I do this all of the time with my 79 250 (lever actauted obviosly)for various reasons. May have to try what KREWAT said with a toggle switch for the '05.

 

Way back in 2002-2003, when I was just a lurker, people were talking about doing that, and that the GEM would flash the 4x4 light if the solenoid was disconnected. My '01 doesn't do that, but who knows... maybe it's smart enough to know the solenoid is not in the circuit? I doubt it, but... just putting it out there

 

Hmmmmm, thanks for the info. I'll have to do some thread searching.

 

The binding won't occur when the wheels are unlocked. The binding in the driveline is caused by differences in the wheel speeds between the front and rear. If the average speed of the two front wheels is higher or lower than the average speed of the rear wheels, torque will develop in drivelines. This can even remain as static torque after you stop.

If the front wheels are unlocked, there can be NO torque in the front driveline, thereby preventing the problem.

Another more subtle problem has to do with the u-joints in the front axles (an imperfect system; CVs would be ideal). When a u-joint has no angle, the speed on the output shaft is the same as the speed on the input shaft. However, when you start to put an angle on the joint, the speed of the output shaft begins to fluctuate faster and slower than the speed of the input shaft. I am pretty sure that this fluctuation is sinusoidal. You can demonstrate the effect using a u-joint socket adapter and a couple of extensions, it becomes clear when you see it with your own eyes.

Most of us have experienced the pulsing that occurs when making tight turns in 4wd. This pulsating torque also gets applied to the front driveline, if the front hubs are locked. However, if the hubs are unlocked, there is NO torque, and therefore no pulsing.

 

Well said, Kel!

I try to avoid using true 4wd on high traction surfaces, ESPECIALLY when tight turning is required as it does create a lot of opposing forces in the drive line. Not a big deal at all on low traction surfaces as one or more tires can do a little slippage to compensate. But when backing up hill with a trailer on good asphalt with good tires, there is a LOT of friction and traction on all 4 tires so it takes a tremendous amount of torque to get a tire to slip. This is a worst case scenario. That is when things are most likely to snap.

 

What's even funnier is, the needle bearings that dry up do NOT turn when you have the hubs locked.

So if anything, you are prolonging the life of those needle bearings by having the hubs locked for long periods.

 

Thanks! It was kind of late when I wrote it, so I was hoping it was cohesive.

Yes, that is curious. I remember you (I think) mentioning this in another thread, and I actually had to go look at my spare hub to remember how it all went together.

Not like the classic manual-locking hubs of old (like a Dana 44), am I right? I think in those, the needle bearings were only being used when the axle shafts were turning.

 

Exactly. The bushing (or needle bearing in later years) was stationary in the spindle.

Now, with the unitized bearing, the entire thing is rotating all the time.