66RFE options

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tonycindylevi

Junior Member
Joined
Aug 15, 2022
Posts
2
Reaction score
1
Location
Middletown CT usa
Ram Year
2015
Engine
Hemi 6.4
Hello Ram owners. Looking for some guidance. I have a 2015 Ram 2500 6.4 tradesman with 103k miles. When towing a trailer with my family's dirt bikes bake from the trails in NH home to CT my truck went into the dreaded limp mode. I was 150 miles from home so I had little options but to press on.

When I got home I scanned it to reveal a P0871 code.
I replaced the valve body and solenoid with a Sonnax but I think the damage was done. Now I get a P0735 code and it slipped on the 4/5 shift. So the tranny is toast. So here are my options:

1) get a Mopar factory tranny and install it (I'm a bit concerned about they durability)
2) Have a highly rated tranny shop rebuild it. (Concerned about people doing it correctly)
3) Buying an aftermarket built proof tranny ( suggestions please) and installing it.
4} Anything else you suggest that I'm missing...
I've rebuilt an automatic (Ford aod-e) before but I just don't have the time/ambition to tackle it again. I really want my truck up and running soon.

Bonus question: if anyone in CT has had this happen and can recommend a quality rebuild shop I'm all ears.

Thanks in advance for your suggestions
Tony
 

drewboy455

Junior Member
Joined
Nov 16, 2021
Posts
1
Reaction score
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Location
MN
Ram Year
2015
Engine
6.4L
I started having the same issues back in Nov of last year. I did a lot of research on what is causing these issues and finally found that (like almost everyone else) the valve body was likely the cause of the OD clutch failure. My 15 Ram 2500 is in the shop now getting a full rebuild. I also ordered a "high performance 66rfe valve body" from Next Gen Diesel. I've called them 3 times, and every time, Nate (the CEO) has called me back. He's been unbelievably helpful and takes the time to make sure I understand what is happening. I will hopefully have my truck back later this week or early next week. I'll try to follow up and let you know how things went. I would highly recommend calling Next Gen Diesel. They will be more than happy to help, and guide you in the right direction.
Good Luck!!
 

Steve White

Junior Member
Joined
May 23, 2021
Posts
23
Reaction score
46
Location
52404
Ram Year
2014
Engine
5.7
66RFE transmissions have a horrible reputation for burning up the OD and UD clutch in the front input clutch assembly. Beings you have already replaced the valve body, you have gotten the root cause for of the problem. But unfortunately the damage was already done. The 66 is prone for scoring the valves in the valve body and when dirt gets in them they will not allow the proper pressures to get were they are needed in the input clutch. I cant remember which valve it is exactly but there is a valve in the 66 that once it sticks it will burn the input clutches out. I have rebuilt alot of them and these transmissions and along with the 68 RFE in the diesel only ever have problems in the input clutch section. They are a very simple transmission in itself and is equally as simple to overhaul as long as you have the special tools. I have an extra 66 sitting at home that is burned up and I will try and bring it into work within the next week to take a part and figure out which valve it is exactly. A reman transmission from Chrysler will have a 3 year 100,000 mile warranty on it. Overhauls are just as good just make sure to find a good shop. I would say bring it to me but I'm in NE Nebraska.
 

Jeepwalker

Senior Member
Joined
Sep 8, 2017
Posts
3,138
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3,331
Location
WI
Ram Year
2012 Reg Cab, 4x4
Engine
5.7 Hemi
Couple things:
1) double-check your vehicle grounds, the PCV system (I know ...sound unrelated but I've had issues that seemed to goof up the tranny shifting), and your throttle body (for a lot of deposits). These might lead to nothing, but since they take almost no time to inspect, I think it's worth it.

2) How long did you test drive it? Took one of my Chrysler vehicles a while for the tranny computer to re-learn new solenoid and start shifting better. It was a couple days as I recall.

3) If you have to replace it, I think either a new mopar (esp if they build them with the latest updates). Or, go interview some tranny shops. Often they will add in all the newest 'fixes' which overcome known weaknesses.
 
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