Finally! RAM gets a competitive transmission behind the Big C!
Welp, it’s finally happenin. The 8 speed Powerline slush boxes are rolling off the assembly line and gettin stocked up to go in the ‘25 model Ram diesels!!!
Forum Discussion
I agree that this ZF is great for Ram guys. What I am getting at with my previous post is that the additional gears alone don’t provide much in the way of fuel economy or speed up a hill. A 3.14 : 1 final drive behind this ZF would provide the same oomph to get a load moving as 4.10 gears behind the Aisin. So, Ram guys need to realize that to get a fuel efficiency benefit they need to select a much higher final drive to go along with the 8 speed.
As far as speed up the hill goes, the HO Cummins won’t benefit from more gears the way an engine like the Duramax does because he HO Cummins makes very similar HP at 2000 rpm as it does at 2800 rpm. Unless Cummins bumps its power rating up, a 4.10 equipped 6 speed behind the Cummins is going to pull a hill very similar to a 4.10 equipped 8 speed up that same hill.
At strictly freeway type speeds grades etc, IE under 3-5%grades, 50+mph, I agree with you prognoses.
Where the extra two gears will help, is literal starting omph, since it will have the potential for an overall lower 1st gear ratio. Having closer splits below, allows on to go faster on local grades. Example, grantedy 6.5td was not a powerhouse. When I went from direct to 3rd at 1.6-1, I 50mph shifting down on a grade, while I could go 45, I was close to redline. I ended up at 35 mph at 2600 rpm. The nv5600 gear below direct was raised to a 1.3. this would have allowed me to pull that same grade in the low to mid 40's at 2500 rpm. Gaining me speed!
My 7sp in my IHC allows the same gains. Gear splits are 700 rpm drops vs upward of 1400 for the Allison 4 sp I could have put in, 1200 for the spicer 5 sp, 900 for the fuller 6sp. All having 4.33 axle gears, direct drives, 1st went as tall as 5.5-1 to my spicer at 10-1.
The overall driving is better. I've noticed this going from my C2500 with a 255/355 350 with a 4l80e, 4.10 gears, vs my 1500 having a 6 sp, 3.42 gears with a 285/305 4.3 V6. It pulls the same trailers just as easy or easier than the previous truck at lower speeds, up grades in the 5-20+% realm. This is where the 8 SP will help the ram owners.
Marty
