HD Guys, Is The 66RFE A Good Transmission Unlike The 65/545/45??

[Drunken Hamster]

Reason I'm asking is because if I do a trans swap in my 3rd gen as a part of a performance build, I WANT a TRUE 6-speed with decent ratios and the ability to hold some good power.

From all of my reading and deductions thereof, a 66RFE seems like a good choice.

Good gear spread, true 6 speed, diesel strength internals[68RFE], same case as my existing 545 trans, should be a similar controller...

It just seems like a good deal.

But I can't find it having been done anywhere and don't know if there's aftermarket support {manual valve bodies, shift kits, converters, finned deepwell aluminum trans fluid pans, etc.} for it or if it's even any good or if it suffers the same problems as the horrendous 65/545/45RFE transmissions.

So, I'd like to know from you HD guys, does it hold power, does it break, will it last, etc.

Thanks, guys!

 

[HemiLonestar]

How are you going to control it lol?

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[Drunken Hamster]

How are you going to control it lol?

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Dunno, it's a hypothetical at this point. I haven't even really STARTED modding my truck aside from a few BS things like a double muffler delete and my "split level" which I'm thinking of partially undoing[the front spacers part].

But, speaking theoretically, couldn't it be controlled by a fully manual VB and floor shifter? Or an electronic VB and a dial+paddles with a standalone TCM? Or just a standalone TCM in general?

 

[HemiLonestar]

Theoretically, but no one has figured out how to do so; if anyone had it would've already been a gamechanger.

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[Drunken Hamster]

Theoretically, but no one has figured out how to do so; if anyone had it would've already been a gamechanger.

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I see... Are there any 6-speed swap options for our 3rd gens? Particularly those that don't involve a 3rd pedal and are TRUE 6-speeds with decent ratio spreads and evenness?

 

[HemiLonestar]

I see... Are there any 6-speed swap options for our 3rd gens? Particularly those that don't involve a 3rd pedal and are TRUE 6-speeds with decent ratio spreads and evenness?

Contact TCI and see if that 4L80 based 6sp they have will work in a Ram.

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[Drunken Hamster]

Contact TCI and see if that 4L80 based 6sp they have will work in a Ram.

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Taking a quick look on summit, and that's not a deep enough OD for 4.56's while at the same time not a tall enough 1st for less than 4.56's or so... :/

Guess there's kinda no option until someone does something new, huh?

 

[HemiLonestar]

Taking a quick look on summit, and that's not a deep enough OD for 4.56's while at the same time not a tall enough 1st for less than 4.56's or so... :/

Guess there's kinda no option until someone does something new, huh?

If you want that many gears lol

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[Drunken Hamster]

If you want that many gears lol

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Well, if ya wanna get specific....

I want 4th gear 1:1, even spacing[that isn't wide as **** like the normal RFE's], and to be able to cruise at 65-70MPH at 2000rpm in the last gear on a 31"-32" tire.

 

[Drunken Hamster]

If you want that many gears lol

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Actually... If I stuck with 3.92's, the TCI 6x would cut that cruise speed RPM on a 32" tire according to this gearing calculator I'm using. Think is, with a 2.97 first, is 3.92 really deep enough to move out a 5k lb truck as good as an RFE on 4.56's? {{It DOES have much shorter gearing than the RFE, maybe it would make it up there??}}

 

[NewBlackDak]

2nd gear is **** on the 66. Go read the 6.4 thread, and you’ll see all the complaints.


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[Drunken Hamster]

2nd gear is **** on the 66. Go read the 6.4 thread, and you’ll see all the complaints.


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The durability, the ratio, or both? Lol.

 

[NewBlackDak]

The durability, the ratio, or both? Lol.

The ratio and 2/3 spacing sucks. I’ve had rear tires break loose on a 2nd downshift. It’s scary with a trailer or on a wet on ramp.


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[RoadRamblerNJ]

Absolutely correct, said the 2500 HD havin' guy. This trans in my '17 2500 couldn't be more wrong as far as gear spacing, shift points etc. I'm under the impression it was basically designed for a Diesel. Not sure about that, but it ain't right for a 6.4 gasser.

2nd gear is **** on the 66. Go read the 6.4 thread, and you’ll see all the complaints.


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[RoadRamblerNJ]

It likes to short shift the 1-2 at about 4500 rpm with the pedal mashed. Then 2nd lugs until you get it up into the sweet spot (4000 rpm +), 2nd revs all the way to 5500 rpm, shifts to 3rd and revs drop off too far to win any races here. By the time you get to 4th, you're approaching triple digits. And I have 4.10:1 gears. Can't imagine what the guys with 3.73s and 3.55s are seeing. There are no 3.92s in HD land.
As wrong as the trans is re: gear spacing, it has never seemed weak or unwilling to take a flogging. And the 392 just keeps pulling (pushing?) no matter what gear you're in. As soon as I save enough scheckles, I'm putting 5.13s in. I'm a little nuts that way. [My last dirt bike had a 74 tooth back sprocket (thats 28 more than stock)] It climbed trees.
Good luck Hamster Man! Ed.

 

[SYKRAMMAN]

Holy ****! A 72 tooth rear sprocket on a dirt bike! That must be nuts riding it huh?

 

[SYKRAMMAN]

It likes to short shift the 1-2 at about 4500 rpm with the pedal mashed. Then 2nd lugs until you get it up into the sweet spot (4000 rpm +), 2nd revs all the way to 5500 rpm, shifts to 3rd and revs drop off too far to win any races here. By the time you get to 4th, you're approaching triple digits. And I have 4.10:1 gears. Can't imagine what the guys with 3.73s and 3.55s are seeing. There are no 3.92s in HD land.
As wrong as the trans is re: gear spacing, it has never seemed weak or unwilling to take a flogging. And the 392 just keeps pulling (pushing?) no matter what gear you're in. As soon as I save enough scheckles, I'm putting 5.13s in. I'm a little nuts that way. [My last dirt bike had a 74 tooth back sprocket (thats 28 more than stock)] It climbed trees.
Good luck Hamster Man! Ed.

 

[zeddy]

Is there a fix for the spacing, shift points? Only thing I hate about my 2500.

 

[tjfdesmo]

The 66RFE basically ruins he capabilities of the 6.4, IMHO. It is a "parts bin special" using gearing for the Cummins, which could not be more wrong for a small block gas motor.

 

[theviking]

Certainly it's better suited to the Cummins, but the 66RFE gearing is actually better than any gas engine 6-speed Ram has offered prior. Ram has confirmed a new trans is in the works for HD models and it can't come soon enough. But gas mileage aside, I suspect re-gearing would resolve most people's complaints. Everyone that's done it seem to love it.