boaterman

While towing my 14,000# 5th wheel with the 6.7 6speed the transmission downshifts much more often than my old 04 5.9. It seams to shift at very slight rises. I have tried all of the options available and was wondering what helpful advice the heavy haulers might have. I use tow haul and have also tried using 4th gear and 5th at different speeds.

Any insight will be appreciated.

GMScott

The 68re has 2 OD's. Set the cruise and let it do it's thing. I only use the tow/haul taking off from a stop when I'm towing heavy. I do not leave it in tow/haul. Plus I don't like the way it bangs downshifting in tow/haul. You will probably hear a great debate about this practice. I've got 114k miles on the clock and plenty of "practice" trying various methods. This tranny seems to be made for towing and coupled with a 4:10 rear and a computer controlled 6.7L it handles the weight very nicely. If you're running in 4th & 5th gear down the highway, you're wasting/burning alot of fuel and keeping the r.p.m.'s up high unnecessarily.

1stGen545

With mine and a 16K man lift on a 24ft tandem dual I have not had any probs with it wanting to shift back and forth. If any thing I have had probs with it not down shifting soon enough if I am going really slow and hit a steep hill. but over all I am very happy with how it pulls. I have done it with and with out tow/haul and I like it on but I have 3.54 so its not as aggressive when it down shifts as 4.10's would be. Even with it off it still dose very well and I have been really surprised how much I can get on it with out it down shifting. Like GMScott said use it to take off because it delays the 5th and 6th gear shifts and then you can turn it off.

Apache1

I set the cruise, turn the exhaust brake on and drive the grades and mountain passes letting the computer figure it out.

I really like the deliberate and crisp down shifts. You really feel the truck load is being managed. With the Ebrake, 2 ODs' and all those gears working together, you sure don't feel anything slipping.

boaterman

I really appreciate all of the helpful advice from the true experts...

I will just leave it in "D" and let the computer do its job...

Not too many big hills here in mid Texas...

westexhunt

If I hook up to a trailer that is over 4k lbs, I use the tow haul and turn on the e/brake. Set the cruise at 65 and let it do it's thing. My towing mpg's are starting to get better with more miles on the odo, empty mpg's are unchanged.

HANDSOME

Does it hurt anything to downshift manually to slow down ? I see some guys do it to save there brakes but if it takes a toll on the tranny ... I would rather replace the brakes.

coolbreeze

The exhaust brake slows the rig, and its OK to downshift too. No harm to the transmission

Hounddog

1stgen545. 3.54gear? Are you refering to the 1st/2nd gen truck in your sig.?

Spooler

What gear set do you have in the truck. With 3.73 gears I would think it to be normal with that weight. 4.10 gears are setup for the weight you want to carry and would not downshift as quick.