What's new
By:
5thGenRams Forums

Register a free account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members through your own private inbox!

3.21. vs 3.92 gear

The other thread was about heavy duty engine cooling...but that also includes the transmission cooler...standard on all 5.7l Hemi trucks
 
devildodge said:
The other thread was about heavy duty engine cooling...but that also includes the transmission cooler...standard on all 5.7l Hemi trucks
Click to expand...
Do you have a link that shows that Heavy-duty engine cooling includes transmission cooling?
 
Yes, it is. It is standard. I can not find anything that spells it out completely to satisfy his question.

5.7l Hemi V8 comes standard with Heavy duty engine cooling and transmission oil cooler

That is stated everywhere...but I can not find a guide that specifically call out the transmission oil cooler.

I can show that the max tow package does not list a transmission cooler as it is standard.

I can guarentee beyond a shadow of a doubt it is standard, but i can not find the exact wording to prove this per say.

Lots of articles state it and personal experience proves it...but I cannot find a feature guide that calls it out specifically
 
devildodge said:
Yes, it is. It is standard. I can not find anything that spells it out completely to satisfy his question.

5.7l Hemi V8 comes standard with Heavy duty engine cooling and transmission oil cooler

That is stated everywhere...but I can not find a guide that specifically call out the transmission oil cooler.

I can show that the max tow package does not list a transmission cooler as it is standard.

I can guarentee beyond a shadow of a doubt it is standard, but i can not find the exact wording to prove this per say.

Lots of articles state it and personal experience proves it...but I cannot find a feature guide that calls it out specifically
Click to expand...
Personally, I've been frustrated at the level of digging required to get into detailed specifications and design characteristics of the HEMI engine and the "upgraded" TorqueFlite 8HP75. Part of my background is engineering, and I'm curious...
 
Mike97 said:
I’m looking to place an order and I’m not sure of which gear ratio to order. 95% of the time I will be driving the truck empty. Gas mileage is important to me so I’m ordering the e-torque engine. I tow a small trailer that weighs 4000 lbs and only do it 6-8 weekends a year.

My concern is that the 3.92 gear is going to kill the gas mileage. The 3.21 just seems a bit low for a truck of this size.

Looking for the mpg difference between the two in every day driving.

Thanks
Click to expand...

I have not had mine long enough to do any road trips without towing something but my son has '17 with 5.7 and 3.92 gears and he gets 20-21 on the highway
 
https://www.prnewswire.com/news-rel...lity-technology-and-efficiency-300582322.html

Today's Ram 1500 employs a production-first thermal management system that taps into heated engine coolant to speed up the warmup of automatic transmission fluid and engine oil to maximize the fuel saving benefits of those fluids.
Click to expand...
The 2019 Ram 1500 continues to use the thermal management system to bring the transmission fluid and engine oil to operating temperature quickly. The system also serves a cooling function under high load/high ambient temperature conditions to ensure the transmission fluid temperature is controlled.
Click to expand...
 
All trims. It's standard. It's a heat exchanger connected to the cooling circuit.

The thermal axle is only available on 4x2 Max Tow configs.
 
Last edited:
http://media.fcanorthamerica.com/pdf.do?id=18758
Thermal management
The Ram 1500 employs a thermal management system that taps into heated engine coolant to speed up the warmup of the automatic transmission fluid and engine oil to maximize the fuel-saving benefits of those fluids.

The engine control unit manages a three-way valve in the engine cooling circuit. Heating the truck cabin always takes priority, based on the HVAC temperature setting. The 2019 Ram 1500 uses the thermal management system to bring the transmission fluid and engine oil to operating temperature quickly. The system also serves a cooling function under high-load/high-ambient temperature conditions to ensure the transmission fluid temperature is controlled.
Click to expand...

Thermal Management System is around 6:33. You can also see the plumbing at the transmission.
 
Last edited:
Chris said:
I disagree; current reviews already show that the tranny runs at the high end of its temp range under load, so to increase that load I think you would need to pair that 6.4l to a higher gear or a heavier duty tranny.
Click to expand...

My understanding is the transmission are the same?
 
SpeedyV said:
Between which vehicles? The V6 uses a different transmission than the HEMI in the DT, and the HEMI transmission (8HP75) has been revised for the DT.
Click to expand...
The 5.7 in the hd 2500 and 5,7 in the 1500 to my understanding is same transmissions cooled the exact same way.
 
Ramit392 said:
The 5.7 in the hd 2500 and 5,7 in the 1500 to my understanding is same transmissions cooled the exact same way.
Click to expand...
I can’t speak for the cooling. And aside from more advanced programming (e.g. 40+ shift maps, etc.), I’d like to see more information on the “upgrades” to the transmission in the DT. If there have been no mechanical changes, then the two transmissions may be fundamentally the same. Otherwise, they’re two different generations.
 
SpeedyV said:
I can’t speak for the cooling. And aside from more advanced programming (e.g. 40+ shift maps, etc.), I’d like to see more information on the “upgrades” to the transmission in the DT. If there have been no mechanical changes, then the two transmissions may be fundamentally the same. Otherwise, they’re two different generations.
Click to expand...

great thoughts....not sure upgrades either on the DT if any.
 
Ramit392 said:
great thoughts....not sure upgrades either on the DT if any.
Click to expand...
It's a new transmission (8HP75 vs. 8HP70). But it took a lot of digging to understand what that last digit means...

Statements from Ram's own press releases:
  • New generation of TorqueFlite eight-speed automatic transmissions provide improved efficiency with more powerful control computers
  • The 5.7-liter HEMI V-8 uses an upgraded TorqueFlite 8HP75 transmission.
  • Both transmissions use a new generation of computer controllers that process data faster and coordinate transmission operation with the eTorque mild hybrid system. There are more than 40 individual shift maps to optimize shift changes and points for fuel economy, performance and drivability.
  • The 2019 Ram 1500 continues to use the thermal management system to bring the transmission fluid and engine oil to operating temperature quickly. The system also serves a cooling function under high load/high ambient temperature conditions to ensure the transmission fluid temperature is controlled.
  • 2019 Ram 1500 models employing the legendary 5.7L HEMI V8 utilize the new TorqueFlite 8HP75 transmission, with a torque capacity of 545 lb-ft.
More comments from other sources:
  • The eight-speed has been upgraded with weight reductions and durability upgrades (Allpar).
  • ...Ram has upgraded their 8-speed automatic for the 2019 Ram 1500. The truck will launch with the 5.7L HEMI V8 and the higher-rated 8-speed that backs it up. Ram updated some hardware and software to make the transmission handle higher loads and operate more smoothly...(TFLtruck).
  • Wikipedia shows the 8HP75 (2nd Generation) being used in the 2019+ Ram (DT) and rated for 750 N-m, whereas 2018 and earlier Rams (DS) use the 8HP70, rated at 700 N-m.
  • The 8HP75 is stronger than the 8HP70 and will hold 50 more N-m (553 lb-ft capacity on the 75 compared to 516 for the 70). It shifts faster and is supposedly more efficient too (less parasitic loss) (Ramforumz).
And maybe the best source of detailed information is from an obscure site:
  • The ZF 8HP75 transmission transfers power from the engine to the road through 4 planetary gearsets and 5 multi-plate clutch pack. To increase both operating and fuel efficiency, the ZF 8HP75 transmission is designed to only keep two of its five clutches (3 rotating and 2 brake) open at any given time. This significantly reduces spin losses, and the little springs between the clutch friction elements, help to keep the clutch completely open to improve both efficiency and the transmission’s coasting function. This ZF 8HP transmission can also immediately downshift from 8th to 2nd gear when maximum performance is required.
  • To provide compatibility with hybrid drivetrain components, the ZF 8HP75 transmission control unit has been upgraded to process commands significantly faster. Some applications will have as many as 40 individual shift maps, along with compatibility with thermal management systems. The ZF 8HP75 hydraulic impulse oil storage system (8HP75 HIS System) has been reengineered to provide much faster reaction when coupled with an engine start/stop system. Additionally, the 8HP75 transmission works with shift-by-wire setups, and the ZF 8HP75 transmission fluid is said to last a lifetime of the vehicle. However, it is highly recommended to perform a transmission fluid change at normal intervals (Transmission Repair Cost Guide).
 
Ramit392 said:
The 5.7 in the hd 2500 and 5,7 in the 1500 to my understanding is same transmissions cooled the exact same way.
Click to expand...

there may be similarities to cooling the transmissions, but the two platforms do not share the same transmissions. the 2500 engines are mated to a 6 speed tranny
 
You must log in or register to reply here.

Users who are viewing this thread

Total: 1 (members: 0, guests: 1)

Site Vendors

https://www.jasonlewisautomotive.com/

Members online

Total: 231 (members: 13, guests: 218)
Back
Top