Hey Czechsix, thanks for the reply. Couple questions: What is the max cruising speed you feel comfortable at on the highway? What's your preferred cruising speed?
Given the gearbox is an automated manual, do you feel like you can crawl adequately without smoking the clutch? I watch this video:
https://www.youtube.com/watch?v=8KWZ9ID_SEc
and it makes me worried about crawl speed. I hope that isn't the minimum speed you can reasonably drive... What do you think?
Max cruising, if it's under 75 degrees or so, has been 75mph, up to 80mph or a bit more in spurts. Much depends on the tire temps, if it's a hot day I'll run slower. Preferred cruising speed is 65mph, truck is pretty happy there.
Forget about crawling with the Duonic, not going to happen. What will happen, in slow speed/high torque situations, is you'll get a nice transmission oil overheat indicator. At that point you have a couple of options: one, stop what you're doing. Which can be an issue if you're trying to get over something, or up a hill. Two, is floor it and if you can make it over/up and increase the revs in the next few seconds the transmission oil will cool down fine. As with all vehicles, getting in the proper gear is essential to making it over obstacles - and even more essential with these trucks.
When off road, the truck is always kept in the full manual option. Even with that, gear changes are slower than I'm able to do with a regular clutch. The Duonic system is definitely slower between gear changes. I don't care what they say about their fuzzy logic learning and optimizing the gear selections. It probably works fine for city driving (which, after all, is pretty much what these trucks are designed for), but for serious off road it's a big issue.
I still think that I'll wind up doing a few more things to it, one is working out a solution to the DPF system, two is possibly putting a two speed transfer into it ( I still have to check angles, space limitations, etc), and three is a total repower with a 12 valve Cummins and an Allison with a two speed transfer case. At that point it'll get a reworked suspension too.
What you saw in that video was Howard keeping his revs up over 2000, and he has the lower gearset too. "Idiosyncrasies of the vehicle design" etc etc.
If you foresee doing really slow speed crawling, opt for the older trucks, not the Duonic.
For my purposes, it works fine. I just want to be able to get into the back country, and if there's a snowfall, some mud in the way, sand - to be able to make my way in, and back out with minimal drama. Serious uphill/downhill ruts, ledges, rocks I have to avoid.
