Transmissions - 845RE vs 850RE vs 8HP70 vs 8HP75

[Huliodude]

I was wondering if anyone knew the differences in these transmissions other than what I've already found out.

My 2019 RAM Classic V6 shows on the build sheet as having an 845RE transmission.
I checked a few 2022 RAM Classic V6 VIN's and their build sheet shows as having the 850RE trans.
I checked some 2022 RAM Classic V8 VIN's and their build sheet shows as having the 8HP70 trans.

I couldn't find all the specific differences in these transmissions: other than:

845RE is rated to 332ft lbs - Built by Chrysler licence from ZF
Gear Ratios: (1st - 4.69:1) (2nd - 3.13:1) (3rd - 2.10:1) (4th - 1.67:1) (5th - 1.29:1) (6th - 1:1) (7th - .84:1) (8th - .67:1) Gear Spread: 7.0714

850RE is rated to 369ft lbs - Built by Chrysler licence from ZF - Found on both 4th gen and 5th gen RAM's.
I could not find the gear ratios for this transmission, and I'm wondering if it's the same as the 8HP50

8HP50 is rated to 370ft lbs - Built by ZF
Gear Ratios: (1st - 5:1) (2nd - 3.2:1) (3rd - 2.14:1) (4th - 1.72:1) (5th - 1.31:1) (6th - 1:1) (7th - .82:1) (8th - .64:1) Gear Spread: 7.81

8HP70 is rated to 516ft lbs - Built by ZF - Found in RAM Classic Hemi RAM's (not sure about diesels) - Ratios are the same as the 8HP45
8HP75 is rated to 550ft lbs - Built by ZF - Found in 5th Gen RAM's - Ratios are the same as the 8HP50

From reading various sources, it looks like the Chrysler version of these transmissions have slightly different clutches and other variables depending on their application.

My point is, if the 8HP50 is basically the same transmission as the 850RE, which is a 2nd generation transmission succeeding the 845RE, then you are getting this newer transmission with a wider gear spread, higher torque rating, and lower NVH in the new 4th Gen Classic RAM's, exactly the same trans as the 5th Gen RAM's, if you opt for the Pentastar V6.

If you opt for the Classic 4th Gen V8 Hemi, you are getting the 1st gen 8HP70, (not the 8HP75 found in the 5th gens), which has a lower gear spread and therefore slightly lower efficiency.

Probably not a big difference, but something I thought interesting and wondered if anyone else had further info on the topic.

If you want to see your build sheet, I used "https://www.jeep.com/webselfservice/BuildSheetServlet?vin=" <-- add your VIN after the equal sign, and remove quotes of course.

A little off topic, I also noticed when physically looking under the hoods of new 4th Classic RAM Hemi's vs V6: The Hemi's no longer have the 3 way coolant valve meant to divert warm engine coolant to the trans for faster trans warm up. The V6 Pentastar however, still has the 3 way valve. I've heard these valve can be problematic over time, but the quick trans warm up could be appreciated in colder climates.

 

[TheEnder]

I was wondering if anyone knew the differences in these transmissions other than what I've already found out.

My 2019 RAM Classic V6 shows on the build sheet as having an 845RE transmission.
I checked a few 2022 RAM Classic V6 VIN's and their build sheet shows as having the 850RE trans.
I checked some 2022 RAM Classic V8 VIN's and their build sheet shows as having the 8HP70 trans.

I couldn't find all the specific differences in these transmissions: other than:

845RE is rated to 332ft lbs - Built by Chrysler licence from ZF
Gear Ratios: (1st - 4.69:1) (2nd - 3.13:1) (3rd - 2.10:1) (4th - 1.67:1) (5th - 1.29:1) (6th - 1:1) (7th - .84:1) (8th - .67:1) Gear Spread: 7.0714

850RE is rated to 369ft lbs - Built by Chrysler licence from ZF - Found on both 4th gen and 5th gen RAM's.
I could not find the gear ratios for this transmission, and I'm wondering if it's the same as the 8HP50

8HP50 is rated to 370ft lbs - Built by ZF
Gear Ratios: (1st - 5:1) (2nd - 3.2:1) (3rd - 2.14:1) (4th - 1.72:1) (5th - 1.31:1) (6th - 1:1) (7th - .82:1) (8th - .64:1) Gear Spread: 7.81

8HP70 is rated to 516ft lbs - Built by ZF - Found in RAM Classic Hemi RAM's (not sure about diesels) - Ratios are the same as the 8HP45
8HP75 is rated to 550ft lbs - Built by ZF - Found in 5th Gen RAM's - Ratios are the same as the 8HP50

From reading various sources, it looks like the Chrysler version of these transmissions have slightly different clutches and other variables depending on their application.

My point is, if the 8HP50 is basically the same transmission as the 850RE, which is a 2nd generation transmission succeeding the 845RE, then you are getting this newer transmission with a wider gear spread, higher torque rating, and lower NVH in the new 4th Gen Classic RAM's, exactly the same trans as the 5th Gen RAM's, if you opt for the Pentastar V6.

If you opt for the Classic 4th Gen V8 Hemi, you are getting the 1st gen 8HP70, (not the 8HP75 found in the 5th gens), which has a lower gear spread and therefore slightly lower efficiency.

Probably not a big difference, but something I thought interesting and wondered if anyone else had further info on the topic.

If you want to see your build sheet, I used "https://www.jeep.com/webselfservice/BuildSheetServlet?vin=" <-- add your VIN after the equal sign, and remove quotes of course.

A little off topic, I also noticed when physically looking under the hoods of new 4th Classic RAM Hemi's vs V6: The Hemi's no longer have the 3 way coolant valve meant to divert warm engine coolant to the trans for faster trans warm up. The V6 Pentastar however, still has the 3 way valve. I've heard these valve can be problematic over time, but the quick trans warm up could be appreciated in colder climates.

The 8HP70 and 75 are geared the same in the rams. I think the 2500 has the 5:1 first that the 8HP75 uses which makes sense.

845 and 850RE are also the same, but obviously, the 850 has a better torque capacity. The 8HP45/8HP50 are not the same as the 845RE and 850RE, the Chrysler-built 845/850 has more friction plates than the 8HP. And a deeper oil pan in some applications.

 

[TheEnder]

The 845 and 850 also have the same ratios.

 

[Huliodude]

The 845 and 850 also have the same ratios.

Are you sure? The wiki page for the ZF8HP transmissions states the 2nd gen trans came out in 2014 and had a 7.8:1 ratio spread.

Then in 2018 the 3rd gen 8HP was released and had an 8.6:1 ratio spread. Those release dates seem to fall in line with the 845 and 850 from Chrysler/RAM as well.

 

[hunterdan]

Pretty sure the "classic" aka 4th gen trucks are still getting the 845 and the 8hp70. The 5th gens (new body style) are getting the updated transmissions.

 

[Huliodude]

Pretty sure the "classic" aka 4th gen trucks are still getting the 845 and the 8hp70. The 5th gens (new body style) are getting the updated transmissions.

Yes I thought so too. However my 2022 4th gen Classic v6 build sheet shows I have the 850, which is why I started this thread, as I too expected to find the 845 in there. However if you opt for the Hemi in the 4th gen, you’ll still find the older 8hp70 on the build sheet.

 

[TheEnder]

Are you sure? The wiki page for the ZF8HP transmissions states the 2nd gen trans came out in 2014 and had a 7.8:1 ratio spread.

Then in 2018 the 3rd gen 8HP was released and had an 8.6:1 ratio spread. Those release dates seem to fall in line with the 845 and 850 from Chrysler/RAM as well.

Yes, the 845/850 and HP70/HP75 share the same ratios.