8HP70 Swap

[JayDizzle]

2020 Ram 1500 Classic 5-lug 3.21 5.7 8HP70 2wd long bed 75k

Hello, I’m having a heck of a time finding information in regards to messing with the transmission in my truck. Long story short.. I bought this truck & didn’t catch its issues on the test drive so now I have to figure it out.

It vibrates/shudders at a specific RPM - right under 1500. Doesn’t matter what speed, although the faster I am going the worse the vibration is, it’s only always at about 1400 RPMs. Give it the juice, it powers through it, let off it fades. Only shudders with pedal applied, doesn’t shudder at coast.

I’ve had the driveshaft professionally rebuilt & balanced - all new joints & bearing. This helped by changing the vibration from a thudding when I first got it to a high frequency, quick shudder.

Opened rear end, checked backlash .007, replaced worn spider gears & wheel bearings. Helped some, didn’t fix the issue. Pinion bearing seems fine.

I noticed a small leak at the transmission output shaft seal, like it’s lightly leaking because the output shaft is what is vibrating possibly? Checked flange bolt, still in same spot from factory, doesn’t seem to be any back and forth play in the flange itself however there is a small amount of play in the output shaft.

So, I’m looking at a used transmission out of a 2019 2wd with 52k that’s totaled. My dilemma is.. the TCM. Is it programmable to my PCM or do I need to retrieve my TCM from my trans out of the Valvebody & install it on the donor trans? Is this even possible? I’ve read some things that say “one time lock” so I don’t know if it’s programmable? I don’t really want to swap the entire valvebody if mine is possibly full of shavings but putting my TCM in the donor trans & valvebody seems like a good plan in theory.

Is there any info out there on how to get just the TCM out of the valvebody?

Thank you,

JD

 

[18CrewDually]

Don't take offense, but are you sure you're not feeling a mis-fire from bad ignition or injector ect? I've had it in the past people telling me the trans is shuddering and it ends up being a bad coil pack.
Just have to ask.

 

[JayDizzle]

Good point.. I’m not 100% sure of anything but I can tell you that the vibration is from underneath/to the rear & there are no codes, engine idles fine & seems to be about the best attribute on the truck.

So no, I’m not positive but you’d think that would throw a code. It’s the weirdest vibration I’ve ever felt, very high frequency & faster than the vehicles actual speed that it’s traveling.

Edit: also, turning the eco mode or mds or whatever off by hitting the shift buttons does not change the vibration.

 

[JayDizzle]

Problem #8 - The Bushings

A babbitt material from the factory, the ZF 8-Speed transmission bushings are likely to degrade over time. This, coupled with OEM’s manipulating consumers to not perform proper fluid maintenance make the factory bushings a common wear point. Roughly 2 out of 3 ZF 8-Speed transmissions we remanufacture have at least one bad bushing.

When bushings wear, the transmission can shuffle or vibrate under certain conditions. Further, many bushings are “Oil Dams”, or areas that hold oil pressure in a certain fluid circuit. As they wear, the become a crossleak of their own. Knowing of this to problem, a new set of upgraded bushings is a standard feature on all Next Gen Drivetrain commissioned ZF 8-Speed transmissions.

Taken from:

ZF 8HP Transmission • Problems & Solutions

As one of the most common transmissions on the market today, there is no shortage ZF 8-Speed transmissions needing repair. Unfortunately, it’s extraordinary complication and intricacy discouraged the majority of transmission experts disinterested in repairing them. Become an expert on the ZF...

nextgendiesel.com

My guess is, it’s a bushing & that these bushings are probably the root of a lot of these vibrations, however I can’t know for sure without gutting the trans.

 

[JayDizzle]

Update for anyone who happens to stumble across this thread searching about their Ram vibrations:

I successfully swapped the 8HP70 out on my 2wd Ram. I did a little research on eBay & found one from a totaled 2wd 2019 Ram Classic with 52k. I put my transmission’s computer in to it to avoid flashing problems.

It was the transmission. The vibration is gone. I haven’t opened mine up to see what exactly failed, yet but here is my premature theory:

The long driveshaft on the 2wd Rams coupled with the design of the 2wd 8HP70’s tail shaft creates a problem when the crappy, square Ram carrier bearing for the driveshaft wears out. It causes a wobble & wears the tail shaft bearings, bushings or maybe even the shaft itself out. When I had my driveshaft rebuilt, they put a more robust carrier bearing on it as compared to the square factory one. Remember, my Ram had 75k. I shouldn’t have been dealing with a bad transmission.

But that was it, I could be wrong in my theory.. maybe it was the torque converter? Idk bc I swapped everything out but I have a feeling that 2-piece shaft caused issues with the 8HP70’s 2wd tail shaft. Hopefully someone in the future can find this useful!

 

[Wild one]

Update for anyone who happens to stumble across this thread searching about their Ram vibrations:

I successfully swapped the 8HP70 out on my 2wd Ram. I did a little research on eBay & found one from a totaled 2wd 2019 Ram Classic with 52k. I put my transmission’s computer in to it to avoid flashing problems.

It was the transmission. The vibration is gone. I haven’t opened mine up to see what exactly failed, yet but here is my premature theory:

The long driveshaft on the 2wd Rams coupled with the design of the 2wd 8HP70’s tail shaft creates a problem when the crappy, square Ram carrier bearing for the driveshaft wears out. It causes a wobble & wears the tail shaft bearings, bushings or maybe even the shaft itself out. When I had my driveshaft rebuilt, they put a more robust carrier bearing on it as compared to the square factory one. Remember, my Ram had 75k. I shouldn’t have been dealing with a bad transmission.

But that was it, I could be wrong in my theory.. maybe it was the torque converter? Idk bc I swapped everything out but I have a feeling that 2-piece shaft caused issues with the 8HP70’s 2wd tail shaft. Hopefully someone in the future can find this useful!

Jon Sipple puts an upgraded rear bearing in his built ZF transmissions,but as far as i know doesn't sell it seperately.
Supposedly the back bushing has a bit to do with the regular cab shortboxes destroying driveshafts,that's according to Matt Fikac at Moes.

 

[Sherman Bird]

2020 Ram 1500 Classic 5-lug 3.21 5.7 8HP70 2wd long bed 75k

Hello, I’m having a heck of a time finding information in regards to messing with the transmission in my truck. Long story short.. I bought this truck & didn’t catch its issues on the test drive so now I have to figure it out.

It vibrates/shudders at a specific RPM - right under 1500. Doesn’t matter what speed, although the faster I am going the worse the vibration is, it’s only always at about 1400 RPMs. Give it the juice, it powers through it, let off it fades. Only shudders with pedal applied, doesn’t shudder at coast.

I’ve had the driveshaft professionally rebuilt & balanced - all new joints & bearing. This helped by changing the vibration from a thudding when I first got it to a high frequency, quick shudder.

Opened rear end, checked backlash .007, replaced worn spider gears & wheel bearings. Helped some, didn’t fix the issue. Pinion bearing seems fine.

I noticed a small leak at the transmission output shaft seal, like it’s lightly leaking because the output shaft is what is vibrating possibly? Checked flange bolt, still in same spot from factory, doesn’t seem to be any back and forth play in the flange itself however there is a small amount of play in the output shaft.

So, I’m looking at a used transmission out of a 2019 2wd with 52k that’s totaled. My dilemma is.. the TCM. Is it programmable to my PCM or do I need to retrieve my TCM from my trans out of the Valvebody & install it on the donor trans? Is this even possible? I’ve read some things that say “one time lock” so I don’t know if it’s programmable? I don’t really want to swap the entire valvebody if mine is possibly full of shavings but putting my TCM in the donor trans & valvebody seems like a good plan in theory.

Is there any info out there on how to get just the TCM out of the valvebody?

Thank you,

JD

There is no way for anyone to give you a pinpoint accurate diagnosis on this forum.
As a 49 year professional veteran of the fine art of auto repair and diags at the professional level, I'll share with you...

BEFORE you go off doing anything to the transmission, have someone QUALIFIED to do a diagnostic panel on that truck and narrow it down as to where the problem lies.
EVERY service information source out there directs one to eliminate engine drivability concerns FIRST thing! Many's the time I fixed a supposed transmission problem with symptoms just like yours with a new ignition component.

Beyond that, IF you have a transmission concern and this vibration is in a gear, not upon a shift or a TCC lock/unlock event at steady cruise, or if it also does it just sitting in Park and rev the engine, then I'd suspect the torque converter first.

 

[JayDizzle]

Jon Sipple puts an upgraded rear bearing in his built ZF transmissions,but as far as i know doesn't sell it seperately.
Supposedly the back bushing has a bit to do with the regular cab shortboxes destroying driveshafts,that's according to Matt Fikac at Moes.

I am going to open it up, soon. Can’t screw it up, it’s already screwed up! Lol. Mine is the long bed so the driveshaft is huge. A more robust bearing is a great idea. What ZF really should’ve done, in my humble opinion, is fashion some sort of extension housing design on these so that it could take the brunt of the driveshaft abuse. But, hey.. I’m just a driveway mechanic what do I know.

 

[RamDiver]

What ZF really should’ve done, in my humble opinion, is fashion some sort of extension housing design on these so that it could take the brunt of the driveshaft abuse. But, hey.. I’m just a driveway mechanic what do I know.

But, where would they use that in an Audi, BMW, Mercedes or Jags?

Maybe FCA or Stellantis should have considered something like this.
Why should ZF care?

.

 

[Sherman Bird]

I am going to open it up, soon. Can’t screw it up, it’s already screwed up! Lol. Mine is the long bed so the driveshaft is huge. A more robust bearing is a great idea. What ZF really should’ve done, in my humble opinion, is fashion some sort of extension housing design on these so that it could take the brunt of the driveshaft abuse. But, hey.. I’m just a driveway mechanic what do I know.

You mean the design should have mirrored that of the 45 and 545 RFE's extension housing design with that robust ball bearing!

 

[JayDizzle]

Update:

It’s been a year now since I bought this truck.. I’ve done more stuff than I can even recall to remedy this vibration.

Anyway, it’s the torque converter. And apparently, it’s just a Dodge thing, their TC’s are pieces of crap. I just installed a brand new one from Mopar. It fixed the vibration, but because I’m “traumatized” by it, I can tell that even with this brand new one the vibration is ever so faintly there at higher speeds at 1400 rpm. But, if anybody else drove it right now, they’d say it’s perfectly fine.

 

[RamDiver]

Update:

It’s been a year now since I bought this truck.. I’ve done more stuff than I can even recall to remedy this vibration.

Anyway, it’s the torque converter. And apparently, it’s just a Dodge thing, their TC’s are pieces of crap. I just installed a brand new one from Mopar. It fixed the vibration, but because I’m “traumatized” by it, I can tell that even with this brand new one the vibration is ever so faintly there at higher speeds at 1400 rpm. But, if anybody else drove it right now, they’d say it’s perfectly fine.

My '07 Tundra Limited had a number of features that I preferred over the Warlock, but overall, I couldn't be much happier with the upgrade.

If anyone else would say your truck performs perfectly fine, it might be time to change your medication.

Install a set of beefy AT tires and move on already.
It's a heavy duty truck, not a caddy.

.

 

[runamuck]

my '19 laramie 4x4 ccsb 3.92 came with the 8HP75 for some reason..maybe because of the E-locker I dont know but I never had any trouble with it. having the 5.0 first gear was nice for towing my travel trailer.

 

[JayDizzle]

My '07 Tundra Limited had a number of features that I preferred over the Warlock, but overall, I couldn't be much happier with the upgrade.

If anyone else would say your truck performs perfectly fine, it might be time to change your medication.

Install a set of beefy AT tires and move on already.
It's a heavy duty truck, not a caddy.

.

I’m not trying to be rude to you & I hear what you’re saying, but this level of functionality was only achieved after a trans swap & 2 torque converter swaps. Plus a ton of other stuff that didn’t do anything to remedy the situation.

But yes, now that it’s normal enough, I’ll drive it until it’s out of negative equity lol.

 

[RamDiver]

I’m not trying to be rude to you & I hear what you’re saying, but this level of functionality was only achieved after a trans swap & 2 torque converter swaps. Plus a ton of other stuff that didn’t do anything to remedy the situation.

But yes, now that it’s normal enough, I’ll drive it until it’s out of negative equity lol.

I believe the new vehicle's build quality, on average, has become quite variable in recent years.
Sometimes, we get a Friday afternoon build that has an undesirable feature.

Or the bean-counter's epiphany that substituted with a foreign-made part, saved the OEM $15 and created aggravation for the end user.

Buying any vehicle has become more of a PITA, and buying a pre-enjoyed is far more challenging unless from a dealership that cares about their reputation.
There are likely a few of them in the States.

At least you have solved your dilemma.
Congrats on that and thanks for the update. This info might save another member.

.

 

[JayDizzle]

You

I believe the new vehicle's build quality, on average, has become quite variable in recent years.
Sometimes, we get a Friday afternoon build that has an undesirable feature.

Or the bean-counter's epiphany that substituted with a foreign-made part, saved the OEM $15 and created aggravation for the end user.

Buying any vehicle has become more of a PITA, and buying a pre-enjoyed is far more challenging unless from a dealership that cares about their reputation.
There are likely a few of them in the States.

At least you have solved your dilemma.
Congrats on that and thanks for the update. This info might save another member.

.

Yes, you’re right. I’m liable to buy something else & then deal with 17 problems that come with that!

I’m basically an expert on this thing now, might as well just keep fixing it.

 

[Sherman Bird]

Update:

It’s been a year now since I bought this truck.. I’ve done more stuff than I can even recall to remedy this vibration.

Anyway, it’s the torque converter. And apparently, it’s just a Dodge thing, their TC’s are pieces of crap. I just installed a brand new one from Mopar. It fixed the vibration, but because I’m “traumatized” by it, I can tell that even with this brand new one the vibration is ever so faintly there at higher speeds at 1400 rpm. But, if anybody else drove it right now, they’d say it’s perfectly fine.

Easy does it, Champ. If you are so dead set that the truck is "cursed", then, by all means get rid of it. I really doubt you have time for all the drama!

It's just a man made machine, a literal erector set full of nuts and bolts. Anything that can break, likely will. There are parts and skilled folks who can fix it.

 

[Wild one]

my '19 laramie 4x4 ccsb 3.92 came with the 8HP75 for some reason..maybe because of the E-locker I dont know but I never had any trouble with it. having the 5.0 first gear was nice for towing my travel trailer.

All Hemi 5th Gen 1500's get the upgraded 8HP75

 

[star_deceiver]

Quick solution: Put it in tow/haul. Keep it there. That should raise your rpm in normal driving to 1800-2000rpm and keep you out of the 1400rpm vibration zone that you’re overfixated on.