66RFE strange shifts, anybody experienced these symptoms?

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

BlueMule

Junior Member
Joined
May 29, 2018
Posts
10
Reaction score
2
Location
Maryland
Ram Year
2017
Engine
6.4L
2017 2500 bought new with 6.4L and 66RFE, 98k miles. Leveled with 37's, factory 4.10 gears swapped out at tire upgrade to 4.88's. Regular oil changes with synthetic, one spark plug change, no other fluids changed yet. No towing, only hauling some firewood occasionally. About 2-3k miles ago it would downshift violently from 5th to 4th during gradual/easy deceleration due to coasting or gentle braking all the time (to the point it was predictable). Regular downshift during rapid deceleration due to hard braking and it shifted fine. During rapid acceleration (from dead stop, passing, etc) it would have a pause and then a violent upshift. I don't beat on it much, so this happened a fraction of the time compared to the deceleration shifts. I schedule a dealer check up and before it goes in, the shift issues clear up. Dealer can't find anything. I put somewhere around 1000 miles on it and it's back to the shifting issues again.

I see the 66RFE posts on here with the valve body issues. Are these the symptoms indicative of VB issues?
 

ScubaSteve178

Member
Joined
Jun 19, 2021
Posts
31
Reaction score
21
Location
Kansas City
Ram Year
2016
Engine
6.4L Hemi
2017 2500 bought new with 6.4L and 66RFE, 98k miles. Leveled with 37's, factory 4.10 gears swapped out at tire upgrade to 4.88's. Regular oil changes with synthetic, one spark plug change, no other fluids changed yet. No towing, only hauling some firewood occasionally. About 2-3k miles ago it would downshift violently from 5th to 4th during gradual/easy deceleration due to coasting or gentle braking all the time (to the point it was predictable). Regular downshift during rapid deceleration due to hard braking and it shifted fine. During rapid acceleration (from dead stop, passing, etc) it would have a pause and then a violent upshift. I don't beat on it much, so this happened a fraction of the time compared to the deceleration shifts. I schedule a dealer check up and before it goes in, the shift issues clear up. Dealer can't find anything. I put somewhere around 1000 miles on it and it's back to the shifting issues again.

I see the 66RFE posts on here with the valve body issues. Are these the symptoms indicative of VB issues?

Sounds like it probably is a result of the valve body. The VB controls all of the shifting actions, and it definitely is not programmed to downshift violently for no reason. The VB's have a myriad of little things wrong with them, but the big one is cross leakage in the channel plate which creates inconsistent shifting and clutch dragging.
 

buckeyexx

Senior Member
Joined
Jan 25, 2015
Posts
677
Reaction score
704
Location
Ohio
Ram Year
2016 Power Wagon
Engine
6.4 Hemi
Yep I get the violent down shifts from 6-5-5-4. If I put my truck in 4th manually it is smooth from there on down. I am currently looking for an aftermarket valvebody for this issue. Going to swap this out and the solenoid pack. It’s not a big job to do yourself as I have helped a buddy do it on his Cummins with the 68rfe. They are basically the same set up with the valvebody. Just havent pulled the trigger on one yet and also we are limited on the 66rfe. The 68 is easier to find from what I have found.
It will upshift through the gears just fine with no issues and also if I put a trailer or some weight in the bed of the truck it seems to smooth out. One thing I have noticed is if I put it in tow haul it seems to help a little but not much. It has done this since the day I bought it two years ago and hasn’t got any worse or better. Does your do it when the trans is cold or when warmed up? Mine doesn’t seem to do it when cold.
 
OP
OP
B

BlueMule

Junior Member
Joined
May 29, 2018
Posts
10
Reaction score
2
Location
Maryland
Ram Year
2017
Engine
6.4L
Never noticed when it's cold which means it probably doesn't do it til it's warmed up. Does the trans need to be removed to service the valve body?
 

huntergreen

Senior Member
Military
Joined
Jan 5, 2011
Posts
12,186
Reaction score
25,926
Ram Year
2016
Engine
hemi 5.7
I’m thinking the line speed sensor. Same symptoms on a 545rfe. IIRC, the sensor was on the side of the trans.
 

ScubaSteve178

Member
Joined
Jun 19, 2021
Posts
31
Reaction score
21
Location
Kansas City
Ram Year
2016
Engine
6.4L Hemi
Never noticed when it's cold which means it probably doesn't do it til it's warmed up. Does the trans need to be removed to service the valve body?
No, the valve body can be removed from the trans just by dropping the pan which is a part of the regular fluid service. It makes sense that it could be a warm only condition due to the fact that temperature can affect the quality of the seal between channel plate, separator, and valve body, which is usually what causes issues- cross leakage.
 

buckeyexx

Senior Member
Joined
Jan 25, 2015
Posts
677
Reaction score
704
Location
Ohio
Ram Year
2016 Power Wagon
Engine
6.4 Hemi
As scuba Steve said it is easy access to the valvebody. Once you drop the pan you can see it hanging from the bottom of the trans. It’s not a hard thing to do but need to pay attention on the new one to the check valve balls in the way they are sitting if I remember correctly. Also need to pay special attention to the correct torque value on each bolt when reinstalled. If the 66 is like the 68 then it should be a fairly simple swap. When I do mine I’m going with oem filters and Amsoil signature series fluid. Just need to figure out the best place to get my valvebody and solenoid pack. I’ll do some more digging today.
 

buckeyexx

Senior Member
Joined
Jan 25, 2015
Posts
677
Reaction score
704
Location
Ohio
Ram Year
2016 Power Wagon
Engine
6.4 Hemi
I’ve contacted a transmission shop (what ever it takes) near me that specialize in rebuild parts. I found that sonnax makes a universal valvebody with solenoid pack for the RFE transmissions . Waiting to hear back from them on more info and a quote.
 

mtofell

Senior Member
Joined
Mar 18, 2014
Posts
2,631
Reaction score
2,269
Ram Year
2014
Engine
Hemi 6.4
I've been through 2 tranny rebuilds on my 2014 66rfe (both at the dealer under warranty, thankfully). On the second one for whatever reason they tried to not replace the VB and the tranny failed again about two weeks after the rebuild. What you describe is pretty much exactly what my truck did all the times it was failing (although maybe different gears). Just crazy/erratic shifting and slamming through gears. I'd say it's likely to be the valve body but I'd be hesitant to just throw parts at it unless you know for sure.
 

buckeyexx

Senior Member
Joined
Jan 25, 2015
Posts
677
Reaction score
704
Location
Ohio
Ram Year
2016 Power Wagon
Engine
6.4 Hemi
I can agree about not throwing parts at it but I think a lot people with the 66rfe know the valvebody is a problem area in these transmissions. It very well could be something different but the signs point at valve body. I’m hoping if nothing else to eliminate that problem from occurring down the road if this isn’t the issue now.
 

Danielm

Junior Member
Joined
Jan 19, 2022
Posts
3
Reaction score
0
Location
Modesto, California
Ram Year
2014
Engine
6.4
2017 2500 bought new with 6.4L and 66RFE, 98k miles. Leveled with 37's, factory 4.10 gears swapped out at tire upgrade to 4.88's. Regular oil changes with synthetic, one spark plug change, no other fluids changed yet. No towing, only hauling some firewood occasionally. About 2-3k miles ago it would downshift violently from 5th to 4th during gradual/easy deceleration due to coasting or gentle braking all the time (to the point it was predictable). Regular downshift during rapid deceleration due to hard braking and it shifted fine. During rapid acceleration (from dead stop, passing, etc) it would have a pause and then a violent upshift. I don't beat on it much, so this happened a fraction of the time compared to the deceleration shifts. I schedule a dealer check up and before it goes in, the shift issues clear up. Dealer can't find anything. I put somewhere around 1000 miles on it and it's back to the shifting issues again.

I see the 66RFE posts on here with the valve body issues. Are these the symptoms indicative of VB issues?
It possible transfer case. I had similar issues.
 

HEMIMANN

Senior Member
Supporting Member
Military
Joined
Dec 7, 2020
Posts
6,799
Reaction score
17,080
Location
Minneapolis, MN
Ram Year
2017 2500 Laramie Crew Cab
Engine
6.4L HEMI
I’ve contacted a transmission shop (what ever it takes) near me that specialize in rebuild parts. I found that sonnax makes a universal valvebody with solenoid pack for the RFE transmissions . Waiting to hear back from them on more info and a quote.

Same here.
 

buckeyexx

Senior Member
Joined
Jan 25, 2015
Posts
677
Reaction score
704
Location
Ohio
Ram Year
2016 Power Wagon
Engine
6.4 Hemi
I talked to what ever it takes about the valvebody. So basically it is a remanufactured unit with sonnax upgraded springs, pistons, accumulator plate ,separator plate and gaskets. Comes with solenoid pack. It is 771.21 plus 75.00 core.
 
OP
OP
B

BlueMule

Junior Member
Joined
May 29, 2018
Posts
10
Reaction score
2
Location
Maryland
Ram Year
2017
Engine
6.4L
Ouch. Any idea what OEM unit cost is? Just for comparison sake. Did I read on these forums that Dodge can't get the OEM valve bodies and is telling people to pound sand?
 

buckeyexx

Senior Member
Joined
Jan 25, 2015
Posts
677
Reaction score
704
Location
Ohio
Ram Year
2016 Power Wagon
Engine
6.4 Hemi
Ouch. Any idea what OEM unit cost is? Just for comparison sake. Did I read on these forums that Dodge can't get the OEM valve bodies and is telling people to pound sand?
Yeah it pricey. Not sure about an oem unit. It has never come up in any of my searches. I think I would rather have something remanufactured with upgraded parts any way. Sonnax is a well known trans parts company so I believe it would have to be better than the failing oem unit.
 

buckeyexx

Senior Member
Joined
Jan 25, 2015
Posts
677
Reaction score
704
Location
Ohio
Ram Year
2016 Power Wagon
Engine
6.4 Hemi

GsRAM

Senior Member
Joined
Dec 9, 2016
Posts
2,929
Reaction score
2,743
Ram Year
2017 Dodge Ram 2500
Engine
Hemi, 6.4L
I'd be interested to hear if you do it, if it solves your shifting issues.

My 17 is still doing well, but only has 15,700 miles on it. It does occasionally get a bit clunky but nothing major or violent as you describe.

From what I understand, the key is to get the valve body replaced as soon as those issues start or the trans is toast.

I just serviced my 17s transmission, transfer case and both diffs this past fall, and drained and flushed the radiator and overflow tank, based on time, as she's was right near the 5yr mark already (over 5 now). I used OEM mopar filters and a lube locker trans pan gasket. All went well. The worst part was cleaning and wire wheeling all of the OEM rtv out of the grooves on the pan.

If you know what your doing and have a proper trans drain funnel its not that messy either even with no drain plug, but I've done it that way many times.

Good luck revolving your issue.
 

buckeyexx

Senior Member
Joined
Jan 25, 2015
Posts
677
Reaction score
704
Location
Ohio
Ram Year
2016 Power Wagon
Engine
6.4 Hemi
I’m about to do a major service to my drive line. I’ve ordered the remanufactured sonnax valvebody with solenoid pack included. Should be here Monday. Putting Amsoil signature series fluid and oem filters back in.
In addition to replacing those things
I’m also going to install a line pressure booster kit on it. It is plug and play and suppose to help with shifting also made by sonnax. That will be installed before anything else because I want to see if it helps by itself. Also while at it ordered amsoil front and rear differential fluid so I can get that done. Along with transfer case.
Hopefully with all of this it will solve my hard downshifts from 6-5-5-4.
 
Top