rockies or smokey's

Edd505 wrote:

garyp4951 wrote:
I never use cruise towing in the mountains, and wonder why some do. I'm in no hurry, and its also hard on the power train.

Not so in the newer diesels with the exhaust brakes. The ECM/TCM will hold the set speed & downshift as necessary & the CM's will not let the motor self destruct. As posted tap the brakes on occasion to slow & hit resume.

Sorry I should have said going uphill, and I always use tow haul with full exhaust brake.

PUt it in TOW MODE (usually on the end of your shift lever)...let the truck do the rest. No Cruise over mountains.

The TOW MODE will do engine/trans braking going down hills, and keeps it out of OD, and keeps gears longer...better towing experience, IMHO, over mountains.

I like cruise and use it a lot. But, it is a dumb robot and it cannot think ahead. On secondary roads, that are twisty turny, that I have driven for years, I know what is coming next. Why let cruise top a mountain at 55, just so I can stand on the brakes for the 25 mph turn on the far side? Those big, long multi mile grades out west, cruise is great. Appropriate Technology for the task at hand. Now, if cruise could be slaved to GPS, and interpolate elevation change, and the customer could do a little programing, yes, then we could almost use it all the time. Might as well get self driving too!!!

garyp4951 wrote:
I never use cruise towing in the mountains, and wonder why some do. I'm in no hurry, and its also hard on the power train.

Not so in the newer diesels with the exhaust brakes. The ECM/TCM will hold the set speed & downshift as necessary & the CM's will not let the motor self destruct. As posted tap the brakes on occasion to slow & hit resume.

I prefer to let the transmission do the downshift. I believe this is better for the transmission with less wear and tear for the driveline. If you just pull the lever sure it will just shift immediately and on my truck it can be a bit harsh at higher rpm and near full throttle. If I let the computer decide then the shift is much smoother.

However once the downshift is made I do tend to pull the lever and hold the gear to the top to avoid unneeded hunting up and down causing more wear.

For a fairly long and steady hill I will often set the cruise to a certain RPM (3500 maybe) and let it run to the top with transmission held.

Ok mine is an old 4 speed. For those with 6, 8, 10 speeds it might be just as easy to set the cruise and let it do its thing in automatic. Just let it run unless it starts to hunt then pull the lever at the next downshift. OK to reduce the CC speed a bit on a longer sustained climb. Don't make a race out of it and you will be fine.

I'm always in manual mode in the mountains.

The information starts on page 9-59
It appears that you can use the cruise control to your benefit. If you don't want to go fast, and turn 8,000 RPM, (it won't do that anyway) just set it to the speed you want.

Depends on where you are crossing them. Some of the lower/flatter crossings, it doesn't really matter.

On the steeper/twistier crossings, I prefer to keep control

Without the Allison tranny, it is a whole different game. Even the older GMs with Duramax/Allison (like mine) handle grades differently.

Your Owner's Manual is your friend.

I never use cruise towing in the mountains, and wonder why some do. I'm in no hurry, and its also hard on the power train.