What did I get myself into

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fryedaddy11

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Canyon Texas
Ram Year
2018
Engine
Hemi 6.4
I recently bought a 2018 Ram 2500 with the 6.4 Hemi to tow my travel trailer. The truck has 78900 miles on it. Three weeks in and already in the transmission shop. Codes P0729,P0735 and P0871. The transmission shop said this is a common problem with Ram trucks. Is there a cure for this besides a new tranny every 100,000 miles?
BTW it was a fight but the dealer finally agreed to pay for the repairs.
 

CanuckRam1313

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Sorry for your situation!
Welcome to the Ram family!
These are great trucks, but yes, they come with some inherent issues, as I have also found out!
I would look deeper into this forums archives for information on how to move forward.
I do suggest to include a full transmission filter and fluid service, plus additional means in how to obtain additional cooling for the transmissions.
These are fantastic trucks, but we also need to know how to better the OEM designs to ensure we get a great longevity vehicle.
Do also look into the "Caulk04" 8spd transmission bypass vale mod to keep the transmission temps cooler, etc.
We have incredible trucks so don't be discouraged! We just need to go a tad deeper into how we we make the appropriate adjustments to ensure our truck experiences meet our expectations!
 

wgreggking

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rural Arizona
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2017 4x4 offroad
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Knock on wood my 2017 2500 6.4 has been flawless 96K except for the turn signal not turning off after a left turn. installed a thermal bypass ATS my trans temps never get above 200, most times it runs 160 or so while towing. fix the trans and cool that tranny down.
 

HEMIMANN

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2017 2500 Laramie Crew Cab
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6.4L HEMI
My 2017 2500 6.4 has also been flawless, but I only have 46,000 miles on it. One of the 1st things I did, thanks to the knowledgable and helpful folk here was get rid of the dumb pencil-diameter thermostat restriction they installed into the transmission oil cooler line.

I wasn't aware it was there, but wondered why my transmission oil temp was always so high. Well, this is the cause - they introduced an extremely restrictive orifice into the oil cooling lines, and some guys have had the little thermostat fail closed, cooking the transmission oil and transmission. All to save miniscule fuel amounts when the oil is cold. Unbelieavable.

Anyway, get rid of that crap and install a bypass flow block from RevMax or ATS. I changed my oil & filter immediately after I found out about this @ 36k miles. It was dirty and stunk, probably from excessive clutch wear debris and oxidation at such high temperatures.
 

crash68

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Is there a cure for this besides a new tranny every 100,000 miles?
You missed the model year by one, in 2019 they started putting the ZF 8 spd behind the 6.4L in the HD trucks. Not saying the RFE is a bad transmission, just the ZF is a lot better. If you tow a lot the gear stager is much more conducive for towing. In comparison second gear of the 8spd is about the same as first in the RFE, there's also a higher top gear ratio basically two overdrive gears.
 
OP
OP
fryedaddy11

fryedaddy11

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Location
Canyon Texas
Ram Year
2018
Engine
Hemi 6.4
Sorry for your situation!
Welcome to the Ram family!
These are great trucks, but yes, they come with some inherent issues, as I have also found out!
I would look deeper into this forums archives for information on how to move forward.
I do suggest to include a full transmission filter and fluid service, plus additional means in how to obtain additional cooling for the transmissions.
These are fantastic trucks, but we also need to know how to better the OEM designs to ensure we get a great longevity vehicle.
Do also look into the "Caulk04" 8spd transmission bypass vale mod to keep the transmission temps cooler, etc.
We have incredible trucks so don't be discouraged! We just need to go a tad deeper into how we we make the appropriate adjustments to ensure our truck experiences meet our expectations!
 
OP
OP
fryedaddy11

fryedaddy11

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Location
Canyon Texas
Ram Year
2018
Engine
Hemi 6.4
Thanks for the info. This is my first Ram (been a chevy man for a long time) Hopefully this was just a fluke and ill look into the bypass valve. Thanks
 
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fryedaddy11

fryedaddy11

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Hemi 6.4
Thanks for the info. This is my first Ram (been a chevy man for a long time) Hopefully rhis was just a fluke and ill look into the bypass valve. Thanks
 

Papa Red

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Hope you get it all worked out. These are great trucks and welcome to the forum.

Red
 

Harley Harrold

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:party36: :welcome::party36: I had to replace my 545RFE transmission @ 72,900 miles, due to losing 4th gear, 4th gear clutches & overdrive clutches. I now have a Remanufactured performance 545RFE transmission with torque converter. I also installed a 4x4 transmission fluid pan on my rwd truck to add a quart more transmission fluid, & a 3500 model transmission fluid cooler, due to it being twice as large as the 1500 model transmission cooler.

2.JPG

IMG_0827.JPG
 

4xdad

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Makes you wonder why they thought that a minivan tranny would survive in a truck
 

trailram

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Birmingham, AL
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2016
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6.4 hemi
You missed the model year by one, in 2019 they started putting the ZF 8 spd behind the 6.4L in the HD trucks. Not saying the RFE is a bad transmission, just the ZF is a lot better. If you tow a lot the gear stager is much more conducive for towing. In comparison second gear of the 8spd is about the same as first in the RFE, there's also a higher top gear ratio basically two overdrive gears.
Is it possible to have a shop install the ZF8 in a 2016 Hemi 6.4? I've got similar codes P0735, P0729, P0882, P0871. I don't trust the local Aamco since they sold me a $700 TCM install after a couple weeks post transmission flush, a few months ago. and shifting issues were not remedied. 122k miles currently. truck doesn't hold 5th or 6th - strong in 4th, at highway speeds. (3000-3500 rpm - trans temp 150-160s) downshifting is funky - rolling less than 15mph won't really downshift into a 2nd or 1st at base of hill (must come to full stop to get in low gear) I've been reading Sonnax info... any way for me to identify if a valve body would remedy the performance issue? how can one differentiate between clutch plate wear - and the need to have those internals changed vs. the valve body only repaired?
 

A_mod_too_far

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I would say start by finding a transmission shop that doesnt suck. If they immediately recommend replacement just run. There is no need to replace a transmission that isnt physically snapped in half unless its warranty work. It could easily be rebuilt for half the cost.
The problem is lack of skilled shops and rebuilds are lower profit margin than swaps.
 

crash68

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Is it possible to have a shop install the ZF8 in a 2016 Hemi 6.4?
I know there's a company that deals with doing 8HP swaps into vehicles that don't have them. The 8 spd used behind the 6.4 is an 8HP75-LT, it's different from the 8HP70 and 8HP75 transmissions found in the 1/2 ton trucks. I know @Wild one knows the company that doing the conversion but I think I remember him saying they had not mastered the 8HP75 yet
 

HEMIMANN

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I know there's a company that deals with doing 8HP swaps into vehicles that don't have them. The 8 spd used behind the 6.4 is an 8HP75-LT, it's different from the 8HP70 and 8HP75 transmissions found in the 1/2 ton trucks. I know @Wild one knows the company that doing the conversion but I think I remember him saying they had not mastered the 8HP75 yet

That would be a cool upgrade. I'm gentle on my 66RFE, bypass kit installed, oil changes, no OD lugging etc. But, still...
 

Wild one

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Is it possible to have a shop install the ZF8 in a 2016 Hemi 6.4? I've got similar codes P0735, P0729, P0882, P0871. I don't trust the local Aamco since they sold me a $700 TCM install after a couple weeks post transmission flush, a few months ago. and shifting issues were not remedied. 122k miles currently. truck doesn't hold 5th or 6th - strong in 4th, at highway speeds. (3000-3500 rpm - trans temp 150-160s) downshifting is funky - rolling less than 15mph won't really downshift into a 2nd or 1st at base of hill (must come to full stop to get in low gear) I've been reading Sonnax info... any way for me to identify if a valve body would remedy the performance issue? how can one differentiate between clutch plate wear - and the need to have those internals changed vs. the valve body only repaired?
Russell at Sound German Automotive is the guy building the kits to put the 8 speeds in trucks that didn't originally have them.You'll want to ask him if you can put the HD HP75 in your truck. Hunt up Rick Tapp of Tapped Performance or Charles Barret of Hell Raiser for shops that'll install it for you. Phone numbers are listed on their sites,and that's probably the best way to talk to them



 
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