I towed with my new-to-me '08 for the 3rd time and being stock it leaves something to be desired compared to my old truck, but I am very disappointed in how the transmission was always shifting when climbing hills. Isn't there anyway to lock it out of 5th gear??

I was running 2-lane highways that have a lot of ups and downs; on the down side it'd be in 5th gear, on up the up side it'd drop to (I think) 3rd gear, after slowing down 5 mph or better. Once it crested the hill it'd get back to 5th gear. I'd love to lock it in 4th and let it climb the hills in 4th and use it to help hold it back on the down side. But I don't see anyway to do that, the manual has nothing about that.

I tried towing in both tow/haul mode and "regular", almost thought the regular was quicker to downshift to keep speed.

Any help or ways to fix this? I am in the process of getting Spartan tunes, will that help with the shifting? I know more power always helps, but I don't like the way it's always jumping gears.

 

what trailer are you towing? with my 7000lb enclosed car hauler I don't see ANY shifting, except extreme hills (like tennessee mountains)
all stock, 08, DRW. always use T/H, and cruise control.

the 6.4 trucks do not have any gear control.. that is only available in manual mode on the 11's

Sam

 

It's a 30' flatbed, weighs about 7500lbs empty. It was worse with a load.
These are pretty good, sharp hills, just up and down. Even though I had the power with my '99, I'd still lock it out of overdrive because it's a hard enough pull it did it much easier in 3rd.

I used cruise control, and tried giving it a "running start" at the bottom of the hill, didn't really help. I had the pedal floored and it still wouldn't downshift as it was loosing speed.

I sure hope with a little power behind it the '08 will improve. There was something in the manual about clearing the memory in the PCM to learn my shift strategy, or something like that. How would that help? I'll probably try it.

When is someone going to offer a manual shift like the '11 for these trucks?? I'd be willing to do some testing for it!!

 

disconnect both batteries for 20 minutes to unlearn and reset..

if no-one has created a manual shift control for these automatics by now, I doubt it would ever happen..

Sam

 

I'll give the reset a try, hopefully that makes some improvements.

I'm still learning these new trucks, the T/H mode doesn't lock it out of 5th gear from what I see, why wouldn't it?? If it'd do that, I don't think I'd be so upset. I just hate seeing it jumping gears all the time.

 

I use tow/haul and set the cruise control at 65 and leave it alone. Generally works pretty good except the steepest hills.

 

Correct t/h does not do gear lockout.

Nothing on the 6.4's

Sam

 

You didn't mention what speed you were running.

With my 4.10 gears I can run from OKC to Arkansas on I-40 pulling my fifth wheel (+14K) at 70 MPH and not downshift on the hills; if I run 60 it will downshift on some of the hills. If I am pulling the RV solo I tend to run 60 MPH; but generally when travelling with others I'm following them at 70 MPH.

With the 04 and 06 6.0L (3.73 ratio) and a lighter travel trailer running 70 would downshift on many of the hills; and all the steeper hills running 60 MPH. Son-in-law pointed out that with his 04 at the time that if he ran 75 it did not downshift. Too fast for me with the ST tires on my travel trailer at the time.

There is a sweet spot with respect to the torque and HP curves.

Bob

 

I'm running 60mph, 3.73 gears with 20" wheels.

This is running county roads, they don't move dirt to make them level, you just drive up and down the hills. I know you guys that run interstates don't have problems, but that's a whole different scenario than what I'm doing. I could pull those kind of hills all day long with my old truck; but these hills put a hurting on it, just steep and short, get over the crest and roll down to the bottom to do it again.

I'm probably right at the non-sweet spot for towing. When it downshifts, it goes from 1500rpm to 3000rpm. Just seems extreme to always be jumping gears.