66RFE performance builds

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ksonnen1

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Has anyone built a 66RFE to withhold 600RWH or have any good suggestions on builders?
 

Burla

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Sharadon is a good name, although don just retired, look into them. Sun Coast does rfe's up to 950hp, but mainly the 68rfe or anything hanging off a cummins.
 
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ksonnen1

ksonnen1

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Sharadon is a good name, although don just retired, look into them. Sun Coast does rfe's up to 950hp, but mainly the 68rfe or anything hanging off a cummins.
thx.. I did call suncoast disel and they only sell the rebuild kits for 66RFE and not the actual builds. 68RFE they do builds
 
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Burla

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thx.. I did call suncoast disel and they only sell the rebuild kits and not the actual builds.
? That's crazy, here is their product line. Seams like the entire world took a dump and nobody feels like doing anything. If you can talk them into it - it would likely be 10 grand for the 66. I'd try begging :)
 

Wild one

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Has anyone built a 66RFE to withhold 600RWH or have any good suggestions on builders?
Nobody has a reliable RFE,no matter how much money they spend. Check out High Performance Rams and Tuned Rams on facebook and ask about building a reliable RFE on those pages. The higher power guys usually keep a stock of used ones on hand,or else swap to the 8 speed/Turbo 400 or 4L80 (GM trannies) and some guys are swapping in 727 or 518's (Chrysler trannies). The RFE was originally designed for the early low horsepower 4.7. Lay in a stock of used ones,get good at swapping them,and learn how to drive to keep the tranny alive,and they're usually good for a few months behind a semi high horsepower engine. Do not do wide open downshifts (like passing on a 2 lane highway),get in the habit of manually down shifting it prior to going wide open,and no high speed runs in high gear.The transmissions will last as long as you drive them to keep them alive.They're okay from a dig ,but not good from a roll
 
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2012RAM1500RT

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I don't have a race truck or high horse power engine but I have 2, 2012 Rams. One is a 1500 5.7 Hemi with the 65RFE with 137,000 miles and one is a 2500 5.7 Hemi with the 66RFE with 216,000 miles. Personally I prefer the 66RFE over the 65RFE because the difference between 2nd and 3rd gear on the 65RFE is a joke. I drive both of them just like anything I've ever owned, I push them to their limit a lot. "Knock on wood" I guess I'm one of the lucky ones but so far both of them has been flawless. Has so far given me no reason to feel like they won't go many more miles. They could go out tomorrow who knows. I've always preferred manual transmissions anyway cause I've always experienced the weakest link in a drivetrain "for me" is an automatic transmission.
 
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Bigskyroadglide

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I have adopted the practices that Wild One indicates. On my 2011, I manually downshift with the shifter lever before passing and on high speed runs, I know there's a possibility of damage so I try to stay under 120 mph.

My 11 has been serviced routinely ever 30k and at 150k. It's primarily a tow vehicle, for my 7x14 trailer.
 

jambbii

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Anyone that builds the 68 should be able to help you....There are a fair amount of diesel builders out there. The 66 shares a ton with the 68. I plan to build mine eventually when I start making some power. Might try reaching out to Sonnax and see if they have any builders they recommend in your area.
 

RLJ10X

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Its best to do as W1 advises and just not beat on the 5/6 speed.

Just my humble opinion, but these trucks come out geared too tall for that transmission. Tall gears are extra stress on an already marginal transmission. Guys like big tires; more stress. With the big tires, the truck gets sluggish, so then Headers, CAI, and tuner are added for more power. A bad situation just got worse. Throw on a little "spirited" driving, and you know the rest.

Give me 3 petals and a stick, please.
 

2012RAM1500RT

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Its best to do as W1 advises and just not beat on the 5/6 speed.

Just my humble opinion, but these trucks come out geared too tall for that transmission. Tall gears are extra stress on an already marginal transmission. Guys like big tires; more stress. With the big tires, the truck gets sluggish, so then Headers, CAI, and tuner are added for more power. A bad situation just got worse. Throw on a little "spirited" driving, and you know the rest.

Give me 3 petals and a stick, please.
I agree with the 3 pedals and a stick 100%. I personally would never pick "any" automatic over a manual if given a choice! JMO!
 
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jambbii

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Randy's transmission, Firepunk, Tier one transmission.....like I said, anyone that does diesel stuff will be able to do a 66 since they share a ton of parts. I would find someone local by you that obviously knows what they are doing. The reason there is not very much info on this stuff is because it is not very common with HD gas trucks.

I have an 18 Wagon too. Once I start making some power I will probably pull mine and upgrade it as well but I am not looking for 600hp. I tow heavy in extreme conditions but I will be boosted as well on 37s.
 

quickster2

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I don't have a race truck or high horse power engine but I have 2, 2012 Rams. One is a 1500 5.7 Hemi with the 65RFE with 137,000 miles and one is a 2500 5.7 Hemi with the 66RFE with 216,000 miles. Personally I prefer the 66RFE over the 65RFE because the difference between 2nd and 3rd gear on the 65RFE is a joke. I drive both of them just like anything I've ever owned, I push them to their limit a lot. "Knock on wood" I guess I'm one of the lucky ones but so far both of them has been flawless. Has so far given me no reason to feel like they won't go many more miles. They could go out tomorrow who knows. I've always preferred manual transmissions anyway cause I've always experienced the weakest link in a drivetrain "for me" is an automatic transmission.
What maintenance if any did you perform please?
 
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ksonnen1

ksonnen1

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Randy's transmission, Firepunk, Tier one transmission.....like I said, anyone that does diesel stuff will be able to do a 66 since they share a ton of parts. I would find someone local by you that obviously knows what they are doing. The reason there is not very much info on this stuff is because it is not very common with HD gas trucks.

I have an 18 Wagon too. Once I start making some power I will probably pull mine and upgrade it as well but I am not looking for 600hp. I tow heavy in extreme conditions but I will be boosted as well on 37s.
I have been doing more and more research and found some choices and as you stated they do use mostly 68rfe internals and they have them withstanding massive torque and hp. I'm already FI with a procharger which does take these trucks to a new level of performance.
 

HEMIMANN

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Any of you guys swap the valve body for a more robust one? Tempted to replace with the Sonnax build ---> https://www.summitracing.com/parts/sox-chr146

If I do this, I need to call them to ask about tuning. They mention something about a PCM re-learn upgrade or something, and I have an in-line Diablosport Edge Pulsar tune ECM installed. Unsure what all this rigamrole is about.
 

2012RAM1500RT

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I personally don't mess with an automatic I've had if they don't do anything wrong. I've changed fluid and have had them to go out afterwards. To me they are the weak link in a drivetrain so I let them alone and if they go out I look to get something better or stronger then. Not saying it's the right thing to do but it's worked for me.
 

StickyLifter

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I bought a book and built the THM350 in my drag car, and it wasn't that hard to do. I put about $1200 in hard parts and clutches and guess that it should be good for about 750hp.

All automatics can be beefed quite heavily if you make certain the valve body seals to the case, crank the line pressure up, and add clutches. It's all about apply area and fluid pressure.

The 66RFE is just a set of 68RFE internals slid into a 65RFE case. The 68's planetaries have a much better gear spread than the 65's, but the 8HP70 slaughters them both. Anyone that can beef a 68 should be able to beef a 66.

Building automatic transmissions is not hard when you go by the book and do your homework. They are absolutely fascinating when you understand them.
 

jambbii

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I have been doing more and more research and found some choices and as you stated they do use mostly 68rfe internals and they have them withstanding massive torque and hp. I'm already FI with a procharger which does take these trucks to a new level of performance.


I know lots of people say different things about these transmission, they are not built for this or that etc bla bla bla. Everyone is repeating the same stuff on all the forums. They are still putting the 68 in Cummins trucks! If it can be built to hold 1000lft lbs of torque, it will hold anything a 6.4 will throw at it.
 
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