66rfe Rating

[57Ram]

Can anyone tell me what the 66rfe is rated to handle power wise? Looking at doing a 5.7 based 392 stoker kit for more low end and mid range torque. I just don’t know if the tranny can handle it.


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[U&A]

I have searched high and low before and could never find anything concrete. Hopefully somebody can help you as I would be interested in knowing as well.


Sent while firmly grasping my redline lubed RAM [emoji231]

 

[57Ram]

Same here I cannot find anything anywhere just estimates.


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[mtofell]

My completely stock truck has burned mine up twice under normal driving conditions. Probably not the info you're looking for but well may relevant.

 

[57Ram]

My completely stock truck has burned mine up twice under normal driving conditions. Probably not the info you're looking for but well may relevant.

Did you ever get a reason of why it failed?


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[mtofell]

Did you ever get a reason of why it failed?


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First time the valve body blew part and sent metal through the whole tanny - that was at 38K miles under zero load, just sitting in stop/go traffic. Dealer rebuilt it under warranty.

It never felt right after the rebuild but good luck convincing the Ram dealer that.

Second time is happening right now - 93K miles and it started slipping bad and going into limp mode. It's at the dealer now and I'm waiting on info. I have the lifetime Maxcare warranty so this one is covered as well.

Even on its best day the 66rfe tranny is kind of a pile of crap - terrible gear spacing, lots of reports of poor shifting. It would be my last choice of something to have in a project truck.

Here's the thread I have going on the current problem that I'll update once I hear something:

https://www.ramforum.com/threads/failed-tranny-2-0.154655/

 

[57Ram]

The other question would be how do you beef up this tranny? Is anyone reputable making options to make them better?


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[U&A]

The other question would be how do you beef up this tranny? Is anyone reputable making options to make them better?


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Yes,

There is a good upgrade for reliability

I think these guys have the answer. I THINK it works with the 66rfe. If not there is another company that sells the gasket kit or new valve body for the 66.




Sent while firmly grasping my redline lubed RAM [emoji231]

 

[U&A]

@Burla
@Hemi395


Sent while firmly grasping my redline lubed RAM [emoji231]

 

[Hemi395]

The torque rating on any of the RFE trans is very hard to find. I've read from unofficial sources that the 65RFE can handle up to 410ft/lbs which means its maxed out with a stock 5.7. I find that kinda hard to believe since theres guys running nitrous on stock 545/65RFE with no issues.

The 66RFE is a variation of the 68RFE the Cummins trucks use. I would say you could comfortably throw 450+ft/lbs at it as long as its kept cool with fresh fluid. Again, this is just a guess.

https://www.allpar.com/mopar/transmissions/68RFE.html

 

[Burla]

The other question would be how do you beef up this tranny? Is anyone reputable making options to make them better?


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[57Ram]

The torque rating on any of the RFE trans is very hard to find. I've read from unofficial sources that the 65RFE can handle up to 410ft/lbs which means its maxed out with a stock 5.7. I find that kinda hard to believe since theres guys running nitrous on stock 545/65RFE with no issues.

The 66RFE is a variation of the 68RFE the Cummins trucks use. I would say you could comfortably throw 450+ft/lbs at it as long as its kept cool with fresh fluid. Again, this is just a guess.

https://www.allpar.com/mopar/transmissions/68RFE.html

Based off of what the shop is telling me with the 392 stroker kit I would be 500 plus hp and torque at the crank. So I don’t know how long it would last especially pulling my camper up a mountain pass.


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[mtofell]

Member "Southtexan" knows a bunch about the 68rfe and I believe he burned up his stock one and was working on a built up replacement a while back. You might search his posts or there is a good chance he'll find this thread and chime in. From all he has posted about the 68rfe I'd guess he knows a lot about the 66 as well.

 

[Nickx86]

I would plan accordingly w your 392 stroker and get a built transmission to handle the extra power. Since your taking the engine out, just go ahead and take trans out. That way your not having the truck down twice. I’ve never had an issue w my 66rfe except the dumb grinding from park to reverse on a negative incline. My ford 6r80 was a POS though on my previous truck

 

[Hemi395]

I would plan accordingly w your 392 stroker and get a built transmission to handle the extra power. Since your taking the engine out, just go ahead and take trans out. That way your not having the truck down twice. I’ve never had an issue w my 66rfe except the dumb grinding from park to reverse on a negative incline. My ford 6r80 was a POS though on my previous truck

Yup I agree. 500ftlbs is a lot for a stock 66...

 

[57Ram]

Any other suggestions than ATS I have more negatives than positives with them.


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