ZF 8HP70 replacement

[zlaja7892000]

I need to replace transmission on 2014 Ram 1500 sport 4x4, "4WD auto" on gear selector, 3.21 ratio. Can i buy used one 8HP70 from a truck that has 3.92 ratio and NO "4WD auto" option?
Will it work on my truck and retain 4WD auto?

 

[crash68]

The 4X4 Auto is done in the transfer case which is separate from the transmission, you would use the one off your truck.

 

[BenWade]

The trans in my '14 sport has the shudder 160,000 miles. I plan to drive it until it fails then swap in a used one. How many miles on yours and where did you find the used one??

 

[crazykid1994]

The trans in my '14 sport has the shudder 160,000 miles. I plan to drive it until it fails then swap in a used one. How many miles on yours and where did you find the used one??

Did you ever have it serviced? I would try having the fluid swapped and a new filter installed.

I need to replace transmission on 2014 Ram 1500 sport 4x4, "4WD auto" on gear selector, 3.21 ratio. Can i buy used one 8HP70 from a truck that has 3.92 ratio and NO "4WD auto" option?
Will it work on my truck and retain 4WD auto?

Yes. As crash said. The 4auto is not related to the transmission. You can use any 8hp70 out of a ram 1500 as long as it’s 4wd and you will be fine.

 

[crash68]

How many miles on yours and where did you find the used one??

Check: www.car-part.com

 

[zlaja7892000]

Do i have to find one from 3.21 ratio or i can take transmission from 3.92 ratio truck. Auto wreckers guy said that transmissions on 2014 4x4 8 speed 8HP70 are all same?

 

[BenWade]

Did you ever have it serviced? I would try having the fluid swapped and a new filter installed.

Yes. As crash said. The 4auto is not related to the transmission. You can use any 8hp70 out of a ram 1500 as long as it’s 4wd and you will be fine.

I had it serviced at 100k with Mobil1 fluid. Never had any problems until the shudder began @135k. I did a BG flush at that time and it improved. It has since returned and is getting worse. I might try the shudder fix that is mentioned in other threads about the shudder issue but it is all just temporary. I think these ZF trans are built for light cars and sedans, not heavy, hard working trucks that haul and tow.

 

[crazykid1994]

I had it serviced at 100k with Mobil1 fluid. Never had any problems until the shudder began @135k. I did a BG flush at that time and it improved. It has since returned and is getting worse. I might try the shudder fix that is mentioned in other threads about the shudder issue but it is all just temporary. I think these ZF trans are built for light cars and sedans, not heavy, hard working trucks that haul and tow.

Plenty of ecodiesel guys who tow heavy with well over 2-300,000 miles and still going strong. @VernDiesel is one of those guys. With The 8 speed you should have never used Mobil 1 oil in it. That may have been your demise. Lifeguard or factory mopar oil are the only recommended otherwise I think amsoil is the only other known oil to work in the 8 speed long term without fail. The transmission is very particular about what oil to use.

Do i have to find one from 3.21 ratio or i can take transmission from 3.92 ratio truck. Auto wreckers guy said that transmissions on 2014 4x4 8 speed 8HP70 are all same?

No. The gear ratio does not matter as that is in the rear axle.

 

[zlaja7892000]

Hi guys.
Just follow up, wrapping this story, i feel like i owe you...
My mechanic swapped my 2014 ZF 8HP70 3.21 (250 000km bad torque converter) for 2017 ZF 3.92 (70 000km).
Its like different truck, running great, smooth shifting..Mission accomplished..
Only downside is lost gear+ gear - functionality and i have filling like transmission is going into higher rpm before shift to next gear, like a little bit lazy...
My mechanic did reset on TCM, so after researching this forum it looks like i need to use alphaobd and rewrite my original VIN into TCM on my new(used, but new to me) transmission?
If someone can confirm?
Thanks

 

[Wild one]

Hi guys.
Just follow up, wrapping this story, i feel like i owe you...
My mechanic swapped my 2014 ZF 8HP70 3.21 (250 000km bad torque converter) for 2017 ZF 3.92 (70 000km).
Its like different truck, running great, smooth shifting..Mission accomplished..
Only downside is lost gear+ gear - functionality and i have filling like transmission is going into higher rpm before shift to next gear, like a little bit lazy...
My mechanic did reset on TCM, so after researching this forum it looks like i need to use alphaobd and rewrite my original VIN into TCM on my new(used, but new to me) transmission?
If someone can confirm?
Thanks

The TCM on the 13's and 14's is a bit differant then the 2015+ tcm,but i think you should be able to rewrite the Vin into your new TCM,if not you can swap your 14's TCM into your new 2017 transmission