any comments on using Low Range w/ hubs locked out, while pulling heavy cargo on pavement through the hills? (I wish auto tranny - OD would work in low range...)

I have heard rumor this activity could be BAD

any comments ???
tugging 20,000# + CTD = 28,000 GCVW

(of course the most obvious... I need a bigger truck..., looking at a 1965 Autocar, twin screw, flatbed w/dump, 335Cum + 13 spd w/ 4spd brownie (52 spd...)

 

why do you need low range? Pull a combined weight of 22-25K lbs with my dads 2002 all the time down the highway.

As far as doing it in low range for some reason if you go fast for quite a while it could heat up the gears in the tcase. Not sure if it would damage it or not though.

 

If you just need to use low range for the low gearing then I dont see the need to lock the hubs, which would make it easier for street driving. I also dont see any problem with extended low range use.

 

Right - if you do it, do not lock the hubs. If you lock the hubs and you're on dry pavement, that's asking for something to go , especially when you're loaded heavy. If the hubs are locked, the T-case is in 4WD, and the tires can't slip, then something else has to give...

 

If you need low range for extended use on the road, you probably shouldn't be towing that load.

I have used low range with the hubs out regularly in all of my vehicles. Mainly just in the yard or driveway, sometimes offroad to idle over a rough section where high range would go too fast and beat you to death. I have also used it as gear reduction when going down a steep hill offroad to save brakes. It allows me to take off without slipping the clutch and idle at a low speed where 1st gear high range would be a faster start than what I care for.

On that same note, I know a guy who bought a mobile home. Instead of paying someone $500 to move it, he borrowed his Dad's half ton and hauled it about 10 miles. The last leg was over a mountain with lots of 7 to 9% grades (from Bells Creek WV to Mammoth over Pond Gap). He did it in low range 2wd. He cooked the tranny and destroyed the rear differential before he got to the top.

 

Mechanically speaking, I honestly don't think you'll hurt anything. The only problem would be if you're really rolling on the power...just keep a raw egg between your foot and the go pedal! Remember...you're applying tremendous torque to the drive train! Drive shaft, u-joints, differential, and axles could all suffer. For extended use...hmmm...I don't think you'll get overheating, etc.

 

I heard that a hub can turn itself in when you drive with the front end turning and leave the hubs unlocked. Supposedly if it happens and doesn't go all the way in, it could blow that hub.

I don't know if any of that is true, but i did read it in a 4wd magazine long ago when it was more common to see 4wd's with locking hubs.

Robert

 

very possible, The warning not to do this, was from instructions on a set of WARN HD hubs for a 1 gen

1) I'm not in Kansas (mountians, switchbacks, ~10% grades sometimes very long)
2) I don't have the torque or hp of your 2002, ...not even close

btw, it does fine on hilly interstate grades @ 65mph, pulling 28,000#; but... these country backroads are another story, and that is where the work is.

 

why not add some power to the truck? what upgrades do you have to the truck? you could get up to the power of a stock 02 without spending a whole lot. i was told they are at 245hp/505tq that's definately doable.

 

I think that I am getting a slightly better idea of what you are trying to do.

You have an automatic transmission, and you are trying to pull your equipment trailer around on steep secondary roads, right?

I am guessing that you are having trouble because your transmission temperatures are getting out of hand, and you have to slow down. If this is the scenario, running in low range will just shift your heat problem from the automatic transmission to the transfer case.

If, on the other hand, you are in first gear all the time, running close to the torque converter's stall speed, then running in 4-low would help you -- but you shouldn't go any faster.

I say this because I think the transfer case is limited both in the amount of torque that it can transmit AND the HP that it can transmit continuously in low range. Torque, for all intents and purposes, either breaks a transmission or not. HP, on the other hand, causes things to go through stress cycles, and generates heat.

Torque determines will the truck move or not -- hp determines how fast the truck will move.

Aparently you have not exceeded the drive-train's torque capacity hauling these loads, and whether you use hi or low range shouldn't change that. However, running in lo will increase your transmission's hp capacity, while drastically reducing your transfercase's hp capacity.

I hope this all made some sense.

 

correct

Tranny temp is well under control w/ underbed cooler, it cycles fine and keeps tranny pretty cool I will check Transfer case heat next trip (Saturday)

I don't like the thought of running out of gears on a steep hill, direct in 1st pulls down pretty slow, below 10mph(full throttle) BUT...in low range, I rarely use first, usually 2nd (below 20 mph) and 3rd (above 20 mph) Then I feel I always have first if the going gets tough

thx for comprehensive reply, and I will have to sleep on the HP vs Torque comments. Are you saying high RPM (1st in Direct) is better for Convertor to transmit power? I can control RPM much easier in Low Range... but I do see a potential problem with heat in Transfer Case.

I wonder if a governor spring would help my convertor (stall speed woe's) I of course would like to improve convertor, BUT, DTT says that would just break my tranny (they recommend a '93 / '96 Hybrid for stouter gears)

I can do all kinds of power and tranny mods, but will still have issues with drivetrain and brakes. The $$ spent might buy a more appropriate truck (that won't break)

 

"I can do all kinds of power and tranny mods, but will still have issues with drivetrain and brakes. The $$ spent might buy a more appropriate truck (that won't break)"

i can definately agree with that. that tranny wouldn't be cheap. if you could find a 5-speed with 4.10 it'd help a lot. your brake problem would still be there though.

 

Here is my opinion FWIW:

As long as you are a gentle operator, and don't take unnecessary risks, you can stick with the set-up that you have.

As long as you are careful and slow going down long grades, the truck has plenty of brakes to stop 10,000 lbs. The trailer brakes, assuming the trailer is rated for 20,000 lbs., had better be in tip-top shape, but if they are, they should be enough to stop the whole rig, loaded, by themselves, and can certainly take care of the 20,000 lbs. not on the truck.

I would keep the transfer case in hi range as much as possible, but know that if you need a little more grunt/low speed control you can always stop and shift down into low range. I would not run out of first gear in low range, though. 2nd in low is about the same gear ratio as first in hi, so in that case you are just heating up the transfer case unecessarily. (you can obviously bend these "rules")

It all comes down to how fast you need to go. If you are willing to creep, you should be fine. Remeber all those gyppos who hauled 20 foot logs 6 feet in diameter behind Ford TT's . . .

If you are really nervous, you can put a temp guage in your transfer case and rear end. Synthetic oil never hurts, either.

And, yes, a governor spring would help. Personally, I would just set the max governed speed up to 2800 + rpm with the stock spring, which should keep you pulling up to 2600+. If you can't set it to pull full power through 2600 rpm, then definitely change the spring.

Take it easy,

Alec

 

I dont see why you would have any problems using low range. Id say put it in low, with the hubs unlocked, and pull the hills like that. I cant really see how it would hurt anything or heat up the transfer case. The governor spring would also help. I helped my buddies truck a LOT. But then you will probably be watching EGT's more, and will be working your tranny harder(of course that wouldnt stop me ). Good luck

Eric