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2025 Ram Heavy Duty To Get New ZF Powerline® 8-Speed

I’ve heard complaints about hard shifting. I never did experience that but also hooked to a trailer 99.8% of the time that’s why I love the transmission. It is a trailer pulling monster! as for the snapring issue. I also have heard about that I think they Had a supplier that dropped the ball if I remember correctly. from my experience when you’re happy with something and it works good for you, sometimes moving to something else leads to just disappointment. I hope I’m wrong. I will keep an eye on the form and see how things are turning out for you guys for my next go round.
 
I only brought up the snap ring failure for the previous poster to just illustrate that no transmission is trouble free, everything has its downsides. Agreed its not a common and was on a small run.

For a number of years I had twin turbo (sequential) BMW 335d (2011) which I later tuned, deleted, raced 1/4 mile in the 12s. It had unrelenting acceleration (turbine like) with no drop in power during shifts even in stock form. That was my bench mark for what diesel performance can be. On the other end I own a 7.3L powerstroke with 335K miles slow as crap. My stock HO is in between.

The RAM from a dead stop (full throttle max acceleration to me). I feel is response delay (lag, lag, lag) some power, then damn its shifting, wait, some power and well I long ago lost the stop light race to merge down to 1 lane. Even from a highway pull the cummins has noticeable delay in generating full power from a steady cruise. The slowness off the line makes pulling out in to traffic tricky as it just takes a while to build power. I recognize a lot of this is trans/engine tuning, possible torque limiting, and a big single turbo is not going to be as responsive as twin. I don't experience the feeling of response delay while towing, it seems much more consistent in output, but slower of course..

Yeah thats pretty typical you'd see some boost spikes (typical with throttles closing on gas cars), though I don't know on the Cummins how it handles this situation. diverter/blow off, etc, loss of exahust energy while shifting..
 
Empty trucks shift hard with this transmission, Most likely this is why they only offered it in the 3500 series trucks.
 
Cummins have always been work horses not race horses... But yeah the lag is quite aggressive at times... Every trustworthy source I know in the industry blames torque limited programming and honestly if you follow any of the high hp custom tune world it seems to ring true cause they all program it out.
 
Shifting issues from reading here is more of a 2019 HO problem, and it was bad before I had it updated with the current software. Ram issued a software update for later model years that addressed a lot of the trans bad behavior. Like my wife asking did I run over a curb or something when the trans shiffted (neck snapping in 4-low)....
Ostracize said:
Turbski spool between shifts is not a transmission shift speed thing.. It's a ecu defueling between shifts thing. Only highlighting the difference because the trans programming could be "perfect" but if the ram ecu programming is biased to conservative (to lessen strain on the whole driveline) the between gear feeling likely will be similar to current applications.
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Your right defueling matters, and Shift speed matters more than you might think. As when your shifting, the engine is "defueling" which reduces exhaust energy to spin the turbo and depending on the intake design, the turbo will slow down noticeably, then you have a delay when exhaust energy returns before the turbo will spin back to full speed. Some call this lag, the shorter the shift the less loss in turbine/compressor speed.
 
If the past few years are any indication, HD Rams tend to be available for ordering sometime around September-December, and start shipping sometime around November-February.
 
Nick said:
My 20 upshifts so smooth I have to really pay attention to even feel the shift .
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I agree 100%, my 23 2500 shifts a lot smoother then my 2015 2500.
Really pretty happy with my 23 so far anyway.

That said I am still very interested in learning more about these new 2025 models with the ZF8.

I am curious if all the models are getting the ZF8 including the cab and chassis 3500-5500 models.

I am thinking of ordering a 2025 dually and putting a Norstar bed on it. I know after owning an Aisin a year or two ago, never had any issues with it, just know I am not wanting another one, it just shifted rough and mileage was pretty poor too in that truck. I am waiting on the new ZF8 before buying another 3500 or 4500.
 
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cc1999 said:
I agree 100%, my 23 2500 shifts a lot smoother then my 2015 2500.
Really pretty happy with my 23 so far anyway.

That said I am still very interested in learning more about these new 2025 models with the ZF8.

I curious if all the models are getting the ZF8 including the cab and chassis 3500-5500 models.

I am thinking of ordering a 2025 dually and putting a Norstar bed on it. I know after owning an Aisin a year or two ago, never had any issues with it, just know I am not wanting another one, it just shifted rough and mileage was pretty poor too in that truck. I am waiting on the new ZF8 before buying another 3500 or 4500.
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Mileage is poor because of the HO, not the Aisin. Lower compression, higher boost and fuel is never going to yield better fuel economy. ZF is touting up to a 10% fuel efficiency increase with this transmission, so at most we’re talking about roughly a 1 to 1.5mpg gain if it turns out to be true. While not earth-shattering, I’d gladly take it. That adds up on a dedicated tow rig.
 
mbarber84 said:
Mileage is poor because of the HO, not the Aisin. Lower compression, higher boost and fuel is never going to yield better fuel economy. ZF is touting up to a 10% fuel efficiency increase with this transmission, so at most we’re talking about roughly a 1 to 1.5mpg gain if it turns out to be true. While not earth-shattering, I’d gladly take it. That adds up on a dedicated tow rig.
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One has to wonder how much of that "up to 10%" is realized when you're not sitting at a stop light in neutral.
 
Brutal_HO said:
One has to wonder how much of that "up to 10%" is realized when you're not sitting at a stop light in neutral.
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Yeah for sure. Between neutral stop, skip shifting, and a faster gear change with better ratio spread, I’m sure it all works together. I’ll be really excited to see if it actually comes true.
 
Brutal_HO said:
One has to wonder how much of that "up to 10%" is realized when you're not sitting at a stop light in neutral.
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Or in steady state cruise..... The fuel economy gains from a transmission seem very heavily related to city driving.
 
AH64ID said:
Or in steady state cruise..... The fuel economy gains from a transmission seem very heavily related to city driving.
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Yes, but something to consider; parasitic drag. Pretty much everything in the transmission is spinning while driving. The type and number of clutchpacks, bearings, planetary gearsets, et cetera, can have a significant impact on parasitic drag...
 
johanh13 said:
Yes, but something to consider; parasitic drag. Pretty much everything in the transmission is spinning while driving. The type and number of clutchpacks, bearings, planetary gearsets, et cetera, can have a significant impact on parasitic drag...
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Absolutely, but the amount of reduction in drag to create a 10% increase in fuel economy would be substantially more than exists. We'd see much higher steady state trans temps, and much quicker empty trans fluid warmup if there were that much drag.
 
AH64ID said:
Absolutely, but the amount of reduction in drag to create a 10% increase in fuel economy would be substantially more than exists. We'd see much higher steady state trans temps, and much quicker empty trans fluid warmup if there were that much drag.
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I agree; just to put some numbers out there. Imagine it takes 100HP to go 75MPH on level interstate. The old transmission incurs 5HP of parasitic loss, while the new one incurs only 2.5HP, that should result in a 2.5% increase in fuel economy... 20 MPG becomes 20.5 MPG
 
johanh13 said:
I agree; just to put some numbers out there. Imagine it takes 100HP to go 75MPH on level interstate. The old transmission incurs 5HP of parasitic loss, while the new one incurs only 2.5HP, that should result in a 2.5% increase in fuel economy... 20 MPG becomes 20.5 MPG
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If 2.5% reduction in power results in a 2.5% decrease in fuel, but hp:fuel isn't linear.

Are those 5hp and 2.5hp published parasitic drag numbers or assumptions?
 
AH64ID said:
If 2.5% reduction in power results in a 2.5% decrease in fuel, but hp:fuel isn't linear.

Are those 5hp and 2.5hp published parasitic drag numbers or assumptions?
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Nope, I just made up those numbers. And, I do agree, the numbers may not be linear (lots of variables). In any case, I do like higher efficiency
 
johanh13 said:
Nope, I just made up those numbers. And, I do agree, the numbers may not be linear (lots of variables). In any case, I do like higher efficiency
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Oops still figuring this out.
I wanted to reply generally to this tread not specific to your post
For one I love the ZF gearboxes got lots of experience with them, not this specific gearbox because its not in our market yet. The first thing to ignore is its filled for life, service them according to your driving and towing duty's and only use the genuine oil. We implemented this proactive approach since the beginning of the modern filled for life ZF gearboxes and the longevity and reliability is amazing.
 
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