68rfe

[warwagon98xj]

Looking at a leftover tradesman ccsb Cummins, is the 68rfe reliable if the engine is left stock?


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[G. Mcpherson]

It will be fine. Yes.

 

[TXCOMT]

Hey, OP, thanks to some wonderful guys on this forum (here's lookin' at you, @SyN), there are numerous tips on extending the life of your 68. I'm sure others will chime in shortly to tell you exactly, but I know things got kicked off on THE "Synthetic Oil" thread and grew from there.

TXCOMT

 

[SouthTexan]

On stock power levels, the 68RFE is likely to last hundreds of thousands of miles with routine maintenance. Even with mild power increases, it will last a long time with transmission tuning and driving it sensibly.

One thing I would recommend change if you live or tow in hot climates is a to replace the thermal bypass valve with an open design. They are about $100-130 online and takes less than 10 minutes to change. It will keep your trans temps much cooler than stock.

 

[TXCOMT]

Yep, that's the good thing about the 68 (versus the 8-speeds)...you can maintain and mod to your heart's desire!

TXCOMT

 

[theviking]

I wonder if the 66RFE uses anything similar. Good info on the bypass, thanks for sharing.

 

[lpfm1990]

I wonder if the 66RFE uses anything similar. Good info on the bypass, thanks for sharing.

66rfe and the 68rfe are the same trans, just different bell housing to fit the Cummins or hemi. So to be short. Yes


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[theviking]

Well my understanding is that it's a hybrid of sorts. So wouldn't just assume that the bypass would fit without some additional research.

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

 

[68PowerWagon]

Well my understanding is that it's a hybrid of sorts. So wouldn't just assume that the bypass would fit without some additional research.

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

That is what I thought I read somewhere too. And isn't the 68 a generic version of the Aisin?

 

[theviking]

That is what I thought I read somewhere too. And isn't the 68 a generic version of the Aisin?

I've heard that as well don't know if it was ever substantiated.

From Wikipedia regarding the 68RFE:

The basic design and operation is the same or similar to the 45 and 545RFE counterparts with the following exceptions:

• larger bellhousing with different bolt pattern and cutout to accommodate diesel engine
• modified internal components to handle increased torque of diesel engine
• revised gear ratios and Transmission Controller programming for larger application

 

[SouthTexan]

The thermal bypass valve is an external component on the 68RFE. It is on the cooler lines between the transmission and cooler. I am not sure if the 66RFE even has one or is the same.

 

[theviking]

Thanks ST, will take a look. Where on the 68RFE is it located?

 

[SouthTexan]

ATS 66RFE/68RFE Thermo Bypass Block Install

 

[Hemi395]

The 68 is a good trans along with the RFE trans as long as the fluid is changed more regularly than the manual states, do the cooler line thermostat valve bypass, and avoid WOT downshifts. As mentioned maintenance is a breeze compared to the ZF trans.

The 65RFE in my truck has towed my camper across the country and from MA to FL and back. All while Hemifever tuned. Shifts perfect and stays nice and cool even while towing.

The RFE trans gets a bad reputation because of a few bad units and from the guys that take their trucks to the track and break it. For the average person that keeps up with maintenance, they're good trans.

 

[Fitz-0518]

^^^^To add to what Hemi said. My independent tech is a out spoken Mopar expert. Born, educated and raised in the Dodge world. He tells me the same thing that Hemi said. When I ordered my 2018 2500 I had the trans option. He made it clear that the best choice was the 68RFE.
Side bar. I asked him to install the trans thermostat by pas valve and he refused. While he agreed, pumping hot water to the trans is not a great idea. He was not going to over ride the engineers that designed it. Been my guy for 35 years, but he can be PIA. His number two guy was glad to do it. And he got the 6 pack. Fitz

 

[warwagon98xj]

On stock power levels, the 68RFE is likely to last hundreds of thousands of miles with routine maintenance. Even with mild power increases, it will last a long time with transmission tuning and driving it sensibly.

One thing I would recommend change if you live or tow in hot climates is a to replace the thermal bypass valve with an open design. They are about $100-130 online and takes less than 10 minutes to change. It will keep your trans temps much cooler than stock.

I live where the temperature can range from -20 to 100 and humid


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[Jimmy07]

I wonder if the 66RFE uses anything similar. Good info on the bypass, thanks for sharing.

Yes, 66 also uses a TBV

I live where the temperature can range from -20 to 100 and humid


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Just a note on removing the thermal bypass and running open, for others that might come along and think “running cooler fluid must be a good thing”- This should ONLY be considered for those in consistent hot climates. The trans won’t shift past fourth and there will be no torque converter lockup until the fluid reaches about 55f. Without a bypass, this would take considerably longer in extremely cold temps.

 

[bigdodge]

66 does use the bypass and the trans is not the same as the 68.

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[Fitz-0518]

I would agree with Jimmy07 post #17. MY POV. Ram did two things when they saw a significant increase in sales in Canada. 0-40 oil and directing hot coolant to the trans for a faster warm up of the fluid. I can see in those colder winter climates and summers that never get to 90* or 100* how the trans could run too cold to shift properly. On the other side. Those in hard summer climates of 105*-115* and winters that never get colder than 40+F. Running cooler fluid makes sense. Just like some people have found that 5-40 or even 10-40 oil has been beneficial in their 6.4 engine. Fitz

 

[Hemi395]

FWIW my 1500 came from the factory without the TBV. I'm in New England and we get temps from -10F to 95F+. I've never had an issue with my trans shifting in the cold but I also run Redline C+ in it.

This winter I'll pay attention to what gear it in when it's cold out but I don't remember it not going into 5th until the fluid temp hit 55...