66RFE Experience

After reading many posts and taking away so much great information from the Ram forum, I decided to share my RFE experience to maybe help someone else, and/or get some advice. First post, have a 2017 2500, 6.4.

My transmission went into limp mode while pulling our ORV 21DBS camper in January 2022. Pulled to the shoulder and turned the truck off, waited, then back on, and for the rest of the trip it didn’t happen again. I took it to the dealer when we returned. They rebuilt the transmission at 64K miles under extended warranty. From invoice, dealer repair included:

-Valve Body pkg
-Plate pkg-planetary thrust
-Converter-torque
-Bearing-needle roller
-Pump Kit-Transmission oil
-Clip-power distribution center
-Gskt pkg-transmission
-Cooler-transmission
-Nut-U
-Transline oil cooler lines bundle
-Screw-hex flange head
-Filter pkg
-4x4 filter
-ATF+4

From dealer invoice:
“…teardown using group a and b, replace transmission bearing and shim…perform overhaul, replace all clutches…clean, inspect, and test all bearings, gears, pistons, and seals, reassemble transmission…replaced trans cooler line bundle…replaced transmission cooler, filled, quick learn, retested…”

That started my RFE research on this Ram forum. I was lucky to find a warm day in February 2023 to do the job with truck at 88K miles. Parts I used to replace OEM:

-Royal Purple 10-2867 (paint removed)
-Mag Hytec RFE45
-ATS thermal bypass
-Lubelocker gasket
-Sonnax CH146
-Redline C+
-Revmax steel fitting (for screw on filter)
-Mopar Sump filter

Unfortunately, after 5 days of easy driving my roundtrip commute of 40 miles, while exiting to home, truck shuddered for a second and went into 4th. The next day dropped the pan, thinking a filter got loose, everything looked good and tight. ALFAOBD codes: P0731, P1521, P1776, P2706. Currently, truck sits at a transmission shop.

Mine's failed twice - once @ 38K, once @ 90K and been rebuilt both times. First was under factory warranty, second under Maxcare Lifetime Warranty. Does all that aftermarket stuff you did now void your warranty? I've always kept mine bone stock for that reason.

Mine just failed at 97k miles. Never had been over 172 deg F. Doing a billet upgrade with lifetime warranty now

Transmissions have numerous components, and major component groups.

It isn't helpful to members to just say "it failed". What failed?
Torque converter, clutches, gears, solenoids, valve body, oil varnishing, planetaries.

RFE valve bodies are known poor design, solenoid, shift pistons, sealing. O.D. clutches umderdesigned and slip. Cooler thermostat too small and fail closed overheating oil and varnishing oil passages closed.

The planetary gear packs and torque converter seems ok. For me, the key was to get that oil temp down, use superior oil, and not dog the overdrives when loaded.

HEMIMANN said:

Transmissions have numerous components, and major component groups.

It isn't helpful to members to just say "it failed". What failed?
Torque converter, clutches, gears, solenoids, valve body, oil varnishing, planetaries.

RFE valve bodies are known poor design, solenoid, shift pistons, sealing. O.D. clutches umderdesigned and slip. Cooler thermostat too small and fail closed overheating oil and varnishing oil passages closed.

The planetary gear packs and torque converter seems ok. For me, the key was to get that oil temp down, use superior oil, and not dog the overdrives when loaded.

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One of the beautiful parts of having a Lifetime Warranty is I don't know or care why it failed.... for all I know the squirrels inside got tired and needed to be fed Just kidding... of course I care and am interested.

I know after the second rebuild it was still going into limp mode so they replaced the valve body. I'm not sure why they didn't start with that since it seems that is one of the many weak points.

First failure the "valve body accumulator plate" failed and shot metal all through the tranny and cooler. It was totally tore up by the time I drove it off the freeway and got to a safe place. From reading the invoice all the inside clutches and steels were replaced along with the cooler.

Funny aside.... I have a Jeep Cherokee as one of my company delivery vehicles and got a call from my employee today that the engine was revving up and down and the vehicle was barely moving. Got him to limp it to the dealer and I went and met him. 61K miles, 2 years old and the tranny is toast. These FCA trannies sure aren't like to the old Maytag Man I guess they built it just good enough to get past the 60K powertrain warranty. Luckily I bought another extended warranty.

I can't imagine the bean counters that price those warranties are too happy with me. I'm +/- $3500 paid for mine on two vehicles and will be well over 20K in benefit. I suppose my experience is not typical but I'm sure glad I bought them.

mtofell said:

One of the beautiful parts of having a Lifetime Warranty is I don't know or care why it failed.... for all I know the squirrels inside got tired and needed to be fed Just kidding... of course I care and am interested.

I know after the second rebuild it was still going into limp mode so they replaced the valve body. I'm not sure why they didn't start with that since it seems that is one of the many weak points.

First failure the "valve body accumulator plate" failed and shot metal all through the tranny and cooler. It was totally tore up by the time I drove it off the freeway and got to a safe place. From reading the invoice all the inside clutches and steels were replaced along with the cooler.

Funny aside.... I have a Jeep Cherokee as one of my company delivery vehicles and got a call from my employee today that the engine was revving up and down and the vehicle was barely moving. Got him to limp it to the dealer and I went and met him. 61K miles, 2 years old and the tranny is toast. These FCA trannies sure aren't like to the old Maytag Man I guess they built it just good enough to get past the 60K powertrain warranty. Luckily I bought another extended warranty.

I can't imagine the bean counters that price those warranties are too happy with me. I'm +/- $3500 paid for mine on two vehicles and will be well over 20K in benefit. I suppose my experience is not typical but I'm sure glad I bought them.

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Yep. The good 'ol valve body. Make a good driveline then install an umderdesigned valve body.

Sign of no Chief Engineer watching over the system design, and/or bean counter cost dictation.

Also sign of compartmentalized functional profit centers = bad executive management. Members have had good success with upgraded valve bodies from Sonnax, available at Rock Auto and Summit Racing. Built correctly.
It requires a PCM clear and relearn, though. I already tuned my truck, otherwise I would have made this mod for sure.

I put a valve body in my 68RFE, just over a year ago. I bought a brand new Mopar VB, added the Sonnax accumulators,plate, & solenoid switch valve, bonded separator plate, & DNJ billet lower half. Essentially one of the fancy ones but (at the time) about $600 cheaper.

Now that valve body when I bought it came with the solenoid pack and was just over $500, last I checked they’re up to $1500.

Regarding the aftermarket parts, I had to weigh the benefit of having a stout RFE transmission that hopefully will be reliable versus having the RFE breakdown again. For me, the benefit of having, hopefully, better parts to help avoid a future breakdown, outweighed having another visit to the dealership covered by warranty with stock parts. This forum convinced me that a cooler transmission and a better valve body are important to staying on the road. Our camping trips tend to have departures after work, into remote areas, and have night time arrivals.

Picked my truck up late Friday from the transmission shop. The bill was $5200 for a rebuilt transmission: $3090 in parts and $2110 for labor. The shop was referred by a buddy who owns an auto repair shop, so I decided to trust their work. I am not a mechanic, so I put my trust with the shop. They supported the use of the thermal bypass and a better valve body. The work entailed “completely disassemble the transmission: thoroughly clean and inspect all internal and external parts including case and housing.” The list of items is long, and included a new torque converter.

The transmission shop said, the RFE had 2 of 5 bolts loose on the stater, which is attached to the pump, and that is why the RFE failed. Most likely, last year at the dealership, they would not have detected the loose stater. I was able to wiggle the stater on the pump.

The Sonnax valve body was removed, and they installed an OEM VB with a heavier duty accumulator plate and another part, I have since forgotten the name. This is a job that they perform on other RFEs when a Revmax is not used. They recommended Revmax over Sonnax. The Sonnax VB was removed because the transmission range sensor was not correct for the 66RFE. Their VB mechanic pointed to the flat manual portion of the slot at the end of the diagonal. He felt the slot was too short and was from an earlier RFE. Looking at my Sonnax VB, it has a triangle above the manual slot. Looking at images online, it looks like there is another sensor with possibly a longer slot. Perhaps this part is also called a cam plate?

Perhaps the forum can clarify the effects of the differences with the transmission range sensors. Moreover, would this have caused some of the codes? The VB mechanic said that the shorter length may have caused the solenoid to not function properly and as I looked them up, most of my codes seemed to do with the solenoid.

I have driven the truck about 200 miles since the rebuild and there is a noticeable improvement in performance. Hopefully the forum can weigh in to help others when considering the Sonnax VB. For me, the next VB will be a Revmax.

Kona3085 said:

After reading many posts and taking away so much great information from the Ram forum, I decided to share my RFE experience to maybe help someone else, and/or get some advice. First post, have a 2017 2500, 6.4.

My transmission went into limp mode while pulling our ORV 21DBS camper in January 2022. Pulled to the shoulder and turned the truck off, waited, then back on, and for the rest of the trip it didn’t happen again. I took it to the dealer when we returned. They rebuilt the transmission at 64K miles under extended warranty. From invoice, dealer repair included:

-Valve Body pkg
-Plate pkg-planetary thrust
-Converter-torque
-Bearing-needle roller
-Pump Kit-Transmission oil
-Clip-power distribution center
-Gskt pkg-transmission
-Cooler-transmission
-Nut-U
-Transline oil cooler lines bundle
-Screw-hex flange head
-Filter pkg
-4x4 filter
-ATF+4

From dealer invoice:
“…teardown using group a and b, replace transmission bearing and shim…perform overhaul, replace all clutches…clean, inspect, and test all bearings, gears, pistons, and seals, reassemble transmission…replaced trans cooler line bundle…replaced transmission cooler, filled, quick learn, retested…”

That started my RFE research on this Ram forum. I was lucky to find a warm day in February 2023 to do the job with truck at 88K miles. Parts I used to replace OEM:

-Royal Purple 10-2867 (paint removed)
-Mag Hytec RFE45
-ATS thermal bypass
-Lubelocker gasket
-Sonnax CH146
-Redline C+
-Revmax steel fitting (for screw on filter)
-Mopar Sump filter

Unfortunately, after 5 days of easy driving my roundtrip commute of 40 miles, while exiting to home, truck shuddered for a second and went into 4th. The next day dropped the pan, thinking a filter got loose, everything looked good and tight. ALFAOBD codes: P0731, P1521, P1776, P2706. Currently, truck sits at a transmission shop.

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So, can I ask a question? Since you spent all that money on a rebuild for alight transmission for pulling why didn't you look into a 68RFE instead and see if they would interchange with your setup. It is a little heavier I believe. I have over 600,000 miles on mine I change the fluid and filters every 75,000 miles and I pull a 34 Montana 5th wheel. Another question when your pulling do you use your tow and haul?

When I was looking at replacement valve bodies, I saw RevMax cost twice as much as Sonnax but still used Sonnax parts, so I figured why not use Sonnax?

I don't know if or why RevMax would be better.

I never did the change out because I'd already tuned and didn't want to redo the whole thing again as the new valve body requires a reset and relearn.

Just my thought's and experiences with transmissions.....

Prior to buying my current RAM I had a 97 F250 with the 7.3 TD. Go ahead and bush me for this fact if it makes you feel better . It was an amazing truck and one of, if not the best, vehicles that I have ever owned. According to all of the "internet scuttlebutt" that I read during the 20 years of my ownership, the transmission in that truck (E40D?? IIRC) was junk and prone to failure, primarily due to overheating. I don't really doubt this but I never had a problem with the transmission despite how I used the truck. It carried a very heavy camper 99% of it's life and also often towed a fairly light trailer (around 1,800#'s). I mostly drove it like I stole it and the LE was chasing me....

I changed the original trans fluid at around 28,000 miles to Amsoil ATF, despite the "advise" of the Ford Service Advisor. I continued to change the fluid with Amsoil about every 30,000 miles and in the end, I never had a problem with the transmission after well over 150,000 very hard miles. So while YMMV, my strategy is to just change the transmission fluid MUCH sooner than recommended and use a quality fluid of your choice.

Another point that I will put out here is that the daily driver vehicles that I own claim that the trans fluid is "lifetime" and the manufacturer does not recommend any change interval. Right. Personally, I do not believe in a lifetime fluid, unless you are satisfied with a short life. For me, as I keep my vehicles for 18-20 years, regular fluid changes are key for longevity and reliability.

Just my .02.

Great question. I asked the shop about a new transmission versus my rebuild. As I stood in the shop, I had to consider the added time off the road to get a new tranny, the added cost, and possibly replacing with another RFE that might start me all over. In the end, decided to have them do the rebuild. Especially when I already started asking the shop about the cost to install a Revmax. Yes, I still have a Mopar warranty, and now, the shop 2 year warranty on the tranny.

My towing experience includes knowing my payload; multiple trips to a scale, tongue weight; own a tongue scale, measurements of sag, WDH; 1400 lbs bars, tires, tires, trailer TPMS, truck weighs>trailer, and lastly, transmission health. I drive over the Ike multiple times along with other mountain passes every camping season, along with a few trips to the west coast and upper-midwest. The 6.4 has done great, RPM's are a given, but with the crap we carry, I needed adequate payload, along with a truck for my DD. Tow/haul is a must in CO, so it is used whenever with our trailer, along with the manual gear selection.

I am still interested to hear, if the transmission range sensors makes a difference when considering the Sonnax VB. This information might help another owner have piece of mind when replacing the VB.

This forum has been instrumental with staying on the road. Hopefully, another newbie will benefit from this post, and I am looking forward to sharing more experiences in the future. I support regular fluid changes and love my 4th gen.

BLUKTY2 said:

I changed the original trans fluid at around 28,000 miles to Amsoil ATF, despite the "advise" of the Ford Service Advisor. I continued to change the fluid with Amsoil about every 30,000 miles and in the end, I never had a problem with the transmission after well over 150,000 very hard miles. So while YMMV, my strategy is to just change the transmission fluid MUCH sooner than recommended and use a quality fluid of your choice.

Another point that I will put out here is that the daily driver vehicles that I own claim that the trans fluid is "lifetime" and the manufacturer does not recommend any change interval. Right. Personally, I do not believe in a lifetime fluid, unless you are satisfied with a short life. For me, as I keep my vehicles for 18-20 years, regular fluid changes are key for longevity and reliability.

Just my .02.

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I would have to agree, i always changed my vehicles transmission fluids at 10k miles to get the break-in material out, and usually again at 40k. Never had a problem.

Mag-hytec pans allows me to change the transmission fluid easily. Currently my ATF mix is 7 quarts of redline and 5 older quarts of atf+4. The next time I drop the fluid the concentration of redline C+ will go up. The fresh fluid def helps tighten shifts up after 30k-40k miles on older fluid.

I had a 2006 545rfe get the same treatment and was strong at 160k miles before I got rid of it. I have a VW 09g tranny still going perfect at 160k miles with 4-5 transmission fluid changes in its lifetime. It’s laughable they say lifetime fluid.

Kona3085, I completely neglected to say "thanks" for posting your experience with your transmission. While I hope not to ever need to use it, great information!

I am currently working on a 1000 HP 66RFE build for my Procharged 2018 2500. As soon as we start the testing I will post more info.

Bettywhiteram said:

I am currently working on a 1000 HP 66RFE build for my Procharged 2018 2500. As soon as we start the testing I will post more info.

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Whatcha doing to it? Obviously torque converter and OD clutches (unless you remove entirely), hopefully a new valve body! What else?

It a complete custom trans, Hd and billet parts with all basic HD parts much like the large 68RFE builds, but We are building for us gas guys plus a trans brake.

1) I shouldn't have read this thread.

2) was the 66RFE limited to 12-15? Ram's website says my '18 has a 66RFE

ffx2018 said:

1) I shouldn't have read this thread.

2) was the 66RFE limited to 12-15? Ram's website says my '18 has a 66RFE

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I believe your 18 has the 66rfe. HD trucks didnt get the 8 speed until the new body style came out in 19 I believe.

Dont worry about it, properly maintain it with fluid changes every 30k and run it. Life is too short to worry about what its. Yours may never have an issue and if you do, deal with it then and move on.

That's what I do anyway. Absolutely use the great info here to your advantage and take steps to try to prevent failures (like removing the trans thermostat) but don't worry about it. Just my .02.

ffx2018 said:

1) I shouldn't have read this thread.

2) was the 66RFE limited to 12-15? Ram's website says my '18 has a 66RFE

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Your window sticker (Monroney Label) will also state the trans type FYI.