727 vs 904
 

has anyone here used a built 904 as compared to a built 727? i never built up the 904 as compared to my built 727...but i hear of people using them...

RE: 727 vs 904
 

Don't know of anyone personally but I would suppose there would be some weight savings involved and I believe some of the internals interchange between the two such as clutch packs and some others? Don't quote me here it's been awhile since having one apart but this seems to be part of the info clogging my brain still!:D They are supposedly just as bulletproof as the 727 when done correctly. If my oldest boy ever decides to build his Duster up I'm going to research it just to see the cost differential and if they truly can be as reliable since it's a slant six with the 904 and he's wanting to drop in a 360 crate eventually.

RE: 727 vs 904
 

Hey, a good built 904 does a good job behind a built small block. The 904 is a little lighter than the 727 and a lot of the street racers are using them because small block 727's are hard to find. The Valvebody an the speedo pinion is the only things I know of that will interchange between the two IF They Are Both NON LOCKUP. Check at a local salvage yard for a 16 passanger van with a 360 and you might find a non lockup 727.

RE: 727 vs 904
 

my mirada came with a lockup 904, and it was a real pain on the track...it was basically shifting 1-2-4...[:@]

which is why we went with the 727, but if im not mistaken, the 904 has a lower gearing...

i "lucked out" with my sb 727, as when i bought my 340 block, the guy asked if i woudl take the tranny too...:)

RE: 727 vs 904
 

Correct me if I'm wrong, but the 727 was supposed to be the strongest of the Torque-Flite and was used with the 426 HEMI, right?

RE: 727 vs 904
 

i believe that you are correct. i am pretty sure that if equipped with an automatic, the 727 was the trans mated to the hemi...the 904 was a newer trans, and was used in cases like the mirada, with a low performance V8.

im sure there is lots more detail to the whole explanation than that, but i think that youre right.

RE: 727 vs 904
 

Okay that is what I thought. I heard the current 545RFE used in the trucks is supposed to be based off of the 727. If this is true I wonder if it has the torque capabilities as the 727. That 727 was one transmission that could be abused big time and still last from the things I have heard. Come to think about it aren't most of the rear-wheel drive transmissions based off of older the Torque-Flites with newer technology added to them (except the Mercedes A580 5-speed which is used in the LX platform)?

RE: 727 vs 904
 

There were a few derivatives between the 727 and the 545RFE.

Ma Mopar's first overdrive was the a-518 which was more closer to the 904 than the 727. If there were a choice between the 904 and the 727, the vote goes to the 727, hands down. The 904 was intended as the 'light-duty' transmission for the slant and the LA, and replacement to the 2 speed powerflite engines when it was introduced in 1962.

The Aluminum body 727 was introduced in 1960-61 to replace the A-466 Cast Iron TF. They were originally cable-shifted, and had a ball and trunnion connection to the driveshaft. The '60-'61 models had the emergency brake at the end of the tailshaft. The '62-'63 727s still had the ball and trunnion connection, but the E-brake was moved to the rear axle.
The cable-shift was changed in '65 to the linkage that we all know of now.

The horsepower ratings for the R/B series engines weren't as high in the late seventies and early eighties, and the 904 was reegineered with an overdrive as the A-518. The 727 was retinkered, and the small block bellhousing added to the trucks and vans, and I want to say it was called the 999. I remember my Grampa's '85 Dodge Van had that transmission...It looked like a 727, walked like a 727, quacked like a 727, but it was a 999.

As far as using the 904, the A-518 would be a better bet, as it is stronger and was designed with the 360 in mind.

As far as I know, the 545RFE has little or nothing in common with the 727, but I could be wrong...

RE: 727 vs 904
 

excellent information kelly...

RE: 727 vs 904
 

Thank you for the information. Now from what I have read the A999 was a A904 with wider ratios. From what I have read the A727 four-speed version was the A-518 for lighter duty useage, later renamed the 46RH then became the 46RE when they added electronics, and the A-618 for the heavier duty useage, later renamed the 47RH then became the 47RE when they added electronics.

I'm not sure where I heard that the 545RFE was based off of the A727. That transmission is very mysterious.