ZF Powerline for 2025 RAM HD Diesel

[BigPapa]

You guys remember all the talk years ago about the development of a CVT transmission to go behind the Cummins?

 

[Diesel85]

You guys remember all the talk years ago about the development of a CVT transmission to go behind the Cummins?

That would've been horrible if it was designed anything like what Nissan's CVT was. CVT transmissions were a big flop. Reminds me the EV rage. It'll fizzle out eventually.

 

[Ozymandias]

CVTs are much better now. Their R&D is also moving on.

 

[AH64ID]

Can’t imaging a CVT in a HD pickup, but a diesel-electric setup would be pretty sweet.

The best way I can put it from driving both the AISIN and the 68RFE is that the ZF's 7 & 8 gears are really double overdrives. Not for pulling. Just straight up cruising gears for better fuel economy mainly when unloaded or very low torque input. The 1-6 gears in my opinion do all of the work just like if it were a 6 speed gear box. In fact, I think it holds a better 6th gear even unloaded than the AISIN or 68RFE does when giving it some more diesel juice.

The top two gears on both the 68RFE and AS69RC are also double overdrives, but they are just fine for pulling with. The difference isn’t the transmission, it’s the engine torque. The 8HP isn’t mated to anything with enough torque to pull as effectively in overdrive.

6th on the 8HP is the same ratio at 4th on the 68RFE and Aisin.

4-6 on the 68RFE and 6-8 on the Powerline are very similar.

1st on the Poweline is much lower, so 2-5 on the ZF does the work of 1-3 on the 68RFE. One extra gear to spread the acceleration load, like going from a NV4500 to an NV5600.

 

[BigPapa]

It was actually called an "Infinitely-Variable Transmission". This is the only thread I could find on it. It was in 2004. There's a link to the original thread and the companies website. The thread link doesn't work anymore and the website is no longer there, either. It was talked about at great length in the original thread and really sounded promising.

https://www.turbodieselregister.com/threads/infinitely-variable-transmissions.98622/

 

[BigPapa]

I found it! Here's the original thread. In post #78 on page four, the guy that was developing the IVT posted up.

https://www.turbodieselregister.com/threads/best-available-torque-converter.86758/page-4

Man, a lot of memories in that thread.

 

[Ozymandias]

Here we go again, why has an eighteen wheeler 16 Gears if 6 would do.
Seems to be a waste then.

 

[AH64ID]

Here we go again, why has an eighteen wheeler 16 Gears if 6 would do.
Seems to be a waste then.

Big displacement diesel power bands are much smaller so more gears are needed when you’re only working with an operating range of ~900 rpms.

That’s also why I think 10 speeds is too many. 8 seems like a good amount, enough for an ultra low 1st and enough slow speed gears for any hill scenario.

 

[bcbender]

I would probably not buy one if I had to have 10.. I specifically passed on the GMC and Ford offering for the reason.

 

[Diesel85]

I would probably not buy one if I had to have 10.. I specifically passed on the GMC and Ford offering for the reason.

I don't want a 10 speed behind a Cummins. I'd prefer a stout and fast shifting 6 or 8 speed ZF.

 

[Ozymandias]

Big displacement diesel power bands are much smaller so more gears are needed when you’re only working with an operating range of ~900 rpms.

That’s also why I think 10 speeds is too many. 8 seems like a good amount, enough for an ultra low 1st and enough slow speed gears for any hill scenario.

The reasonable powerband of our Cummins isn't much wider then that.
Around between 1500 and 2500. Myself I like it to keep it even narrower, 1700 to 2200 which 500rpm usable. Below it lugs, above it screams.

 

[AH64ID]

The reasonable powerband of our Cummins isn't much wider then that.
Around between 1500 and 2500. Myself I like it to keep it even narrower, 1700 to 2200 which 500rpm usable. Below it lugs, above it screams.

As engines have modernized the operational rpm range has greatly improved, it's a combination of better programing and variable geometry turbo's. The usable rpm range on my 6.7 is much larger than what my 5.9 was. My 5.9 was happiest 1800-2500, but would pull hard to 3000 without issue. My current 6.7 is happy above 1500, and even as low as 1300 depending on the elevation. I rarely need over 2500 rpms, but it breathes well up there and makes excellent power. I'd put the happy rpm range at 1000 rpms on the 6.7, bit closer to 1500 rpms of advertisable operational range.

All that means, is that a few more gears wouldn't hurt even thou my AS69RC does what I ask without complaints. Really all I'd like is a gear that lets the torque converter lock around 10-15 mph, vs the 20-22 it takes now. I spend a decent amount of time towing up steep slow grades watching my trans temp since the torque converter isn't locked at 15.


Just for fun here is a quick comparison of the 3 transmissions at fixed rpms. Speed is in MPH, tire size is 275/70R18, axle ratio is 3.73, and it's assuming a locked torque converter (even if they won't lock in 1st).

 

[Turbo Terry]

Interesting stuff but can’t you lock your transmission in 3rd on the steering wheel. Would that lock the torque converter and keep the transmission cool and still have enough power to go uo a pretty good grade. Plenty of torque in the engine

 

[Turbo Terry]

Still probably to fast for what your trying to do

 

[AH64ID]

Interesting stuff but can’t you lock your transmission in 3rd on the steering wheel. Would that lock the torque converter and keep the transmission cool and still have enough power to go uo a pretty good grade. Plenty of torque in the engine

3rd gear won’t work that slow, too few of rpms. It’s too slow for 2nd to lock even.

You can use ERS to lock the trans into any of the 6 gears.

 

[06 Dodge]

The ZF 8 speed sounds good but will it be like the one in the 1500 that needs $30 qt ATF trans has to be leveled an requires a new trans pan when it comes time to service it, oh it also has no dip stick to check trans fluid and you refill trans from under the truck

 

[AH64ID]

The ZF 8 speed sounds good but will it be like the one in the 1500 that needs $30 qt ATF trans has to be leveled an requires a new trans pan when it comes time to service it, oh it also has no dip stick to check trans fluid and you refill trans from under the truck

$30 ATF from the dealership, there are other compatible fluids that are cheaper.

That style of transmission service, and long fluid life, was introduced a long time ago on other platforms. Toyota started using it in with the 2003 4Runner (in an Aisin), and people just don’t have issues with it. The fluid lasts much longer than “traditional” ATF fluids. It’s also hydroscopic, which is why the transmission doesn’t have a dipstick.

 

[bcbender]

The ZF 8 speed sounds good but will it be like the one in the 1500 that needs $30 qt ATF trans has to be leveled an requires a new trans pan when it comes time to service it, oh it also has no dip stick to check trans fluid and you refill trans from under the truck

All reasons I would not be interested in it.. I have a friend with a new Gladiator that he says is the same and he's thinking about ditching it since its such a PITA to maintain when it comes to serviceability.. Seems like they are trying to guarantee that service is done by the dealers. This fill for life I do not view in the same light as lube for life u joints and bearings.. totally different animals IMHO.

 

[AH64ID]

All reasons I would not be interested in it.. I have a friend with a new Gladiator that he says is the same and he's thinking about ditching it since its such a PITA to maintain when it comes to serviceability.. Seems like they are trying to guarantee that service is done by the dealers. This fill for life I do not view in the same light as lube for life u joints and bearings.. totally different animals IMHO.

The wife just bought a Gladiator and I’ve read about the 850RE fluid change. It’s nothing crazy and certainly not a reason to sell a rig, nor is any of the maintenance on it.


At the end of the day people just don’t like change and are often too lazy to learn new maintenance techniques, even if they aren’t any more difficult.

 

[06 Dodge]

$30 ATF from the dealership, there are other compatible fluids that are cheaper.

That style of transmission service, and long fluid life, was introduced a long time ago on other platforms. Toyota started using it in with the 2003 4Runner (in an Aisin), and people just don’t have issues with it. The fluid lasts much longer than “traditional” ATF fluids. It’s also hydroscopic, which is why the transmission doesn’t have a dipstick.

Someone on on another truck forum emailed ZF asking about the life of the ATF, iirc they said the trans should be service between 50-80K or 6 years... I've seen photos of ZF ATF with 80K and its black, my self I would trust the manufacture of when it needs to be serviced over Ram.