904 / 727 Transmission Questions

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68DartProject

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I mentioned to a few guys local here that I wanted to build my 904 trans. Only for them to mention they wouldn't do it cause of the valve body or something having problems of clogging up. For me to go and get a small block 727. Problem one. There are no 727 small block trans that can be had in around my area even for rebuilds. "Two" these guys are from back in the day. So my question is with all the new tech out there today. Can I build a strong reliable 904 reverse valve body with a good stall to go behind about 400 to 450 horse. Plan on building a 318 / 392 Stroker.

Thanks
Michael
 
Oh yea, noooo problem.
We don't know for sure that you can do it yourself obviously, but hell ya a built 904 can do it.
Valve bodies are'nt Voodo, ya just have to clean a flush them well.
 
The two old school guys might not be up on the latest technology, but you can build a strong 904 that will handle 450 hp.
 
I was actually looking at this information today for my trans build. From what i read/noticed the 727 and 904 use the same valve body atleast thats how they sell the manual reverse valve bodies described to fit both. Also i read that people prefer the 904 for racing because it requires less horsepowet to operate. The only negatives i could find on building them was that once you need it to handle large amounts of power 500hp+ it gets very expensive to build and that they are weaker than the 727 but i dont think there would be any problems building a 904 to handle 400-450hp. In fact one of the kits from summit racing will rebuild the trans for street strip duty and convert your valve body to foward manual shifting for i think $300?

But back to the topic of the valve body clogging even if that were true if you were switching to a manual reverse pattern there should be no worry with an aftermarket unit. Take this simply as an opinion though because this only from research done today and not real world experience
 
I thought there was some new stuff to build a awesome 904. The reason I was leaning towards that is because I already have one that is behind the 318 I'm building. My knowledge of transmissions are very limited and I don't have the tools I need for the build myself. So it probably will go to Cooks Transmission in South Carolina.

Thanks,
Michael
 
Is this them ??.......If so tell them times have changed lol

That being said.. Make sure you get a good builder who's comfortable with performance building.
 

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Build the 904. Requires nothing special and are easy to build.

Another benefit of a 904... the front drums don't explode! It doesn't happen often with a 727. When it does, you won't forget it.
 
Yep that looks just like them lol. Like I said before. I have never broke one down so didn't know of any special tools to do it. But if it's basic air and hand tools. I got that. Also if I had a good manual I could probably read and talk my way through it.
 
A pump puller is nice, but you don't really need it.
Snap ring pliers are almost mandatory.
A clean place to do it and a good solvent tank helps a lot.
The little tricks,,,priceless.

A four gear planetary, bolt in sprag, 5 plate front clutch, kevler bands and boom good ta go for 450 horse. (about 300 into the trans)
There is a weak spot that I would need to do though.
Weld the planet shell to the sun gear, instead of the power going through 16 little teeth.

Sorry, mean weld the sun gear to the sun gear shell. Duh




dustinmoran91 said:
What tools are required to rebuild the 904/727's? Anything outside of basic hand tools?
Click to expand...
 
Wow! I could handle that! Lol if i can narrow my own rear axle without jiggs or guides i think i can do that with a good manual and some patience
 
Most of this pertains to a 904.

http://www.forabodiesonly.com/mopar/showthread.php?p=1831180

I believe you can put a 904 valve body on a 727 by reaming out one hole or some such, I've read the book, and don't remember. The point is, no worries about 904 bodies "plugging up."

You need the Carl Munroe book, and a Chrysler shop manual is helpful

If you are handy, you can make some of the "special" tools, and if you have a big 'ol C clamp type valve spring compressor, use it.
 
Easy enough. Thanks for all the info. That is some good info guys. Believe I will just stay with the 904 as planned. Any suggestions on to where to pick a good kit up at?

Thanks,
Michael
 
Those clowns you talked to don't have any clue about torqueflites or they'd know the valve bodies are virtually identical from a 904 to 727. Just minor changes to program them to shift correctly with the different size parts.
 
fishy68 said:
Those clowns you talked to don't have any clue about torqueflites or they'd know the valve bodies are virtually identical from a 904 to 727. Just minor changes to program them to shift correctly with the different size parts.
Click to expand...

Well can't really call them clowns. As to my first post I mentioned valve body or something. It could have been proportion valve and or something else they may have been talking about. Can't remember and all I know is they said find a 727. And I had thought what could be really wrong with a 904, for them to suggest the other. So I did what any person would do. Ask around before deciding on just one thing. Ha

Thanks
68DP
 
Thats funny and those guys you talked to should check this out
I run a 904 behind my small block
I run the low gear pack,forward manual valve body with a 4000 stall converter with a spooled up 4:10 8 3/4 rear.
I have had this trans in here for over 4 years without a single issue.
I drive it hard on the street and beat it hard at the track.
 

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Now if we could teach about the overdrive on the a500,you would have a nice transmission for a street car!:glasses7:
 
BRONZEBEE said:
Now if we could teach about the overdrive on the a500,you would have a nice transmission for a street car!:glasses7:
Click to expand...

Well I invite you to teach away!!!

My understanding is that the only real issue is cutting up the floor
 
Look at the top of the page and you will see a a500 installed with no floor cutting.My pictures are in with the 42rh/a500 in a duster pics.gdonovan did the duster and i did the 70 dart.
There is no reason why you could not install a 518 in the same location,the overdrive housings are the same.
The forward bell housing size of the transmission is what makes the transmission.904-a500 bell housing are the same and 727 -a518 are the same.
I'm not saying that a 904-a500/727-a518 interchangeable but the out side dementions are the same they changed how the rear housing bolts on.
Depending where you read the internal parts of the overdrive housings are interchangeable.
Alot of the upgrades you are doing aka low first change is already in the a500 in stock form,many of the 904 upgrades can be done to the a500.Same for the 727 -a518.

I hope this helps to take some of the mystery or misinformation out of the the transmissions.Lots of parts available to make them better for higher hp applications.:burnout:
 
BronzeB I have never measured a 500 next to a 518, always just assumed there was the same diff. in length as there is with a 904 or 727. But you are right about the main housing dimensions being the same dimensions and a 727's main housing is only 1/8" longer than a 904 and since they use the same o.d. unit on both the 500 and 518 they should be within 1/8" of the same length. Not like the 727 and 904 where there is 2-1/2" difference. Good catch there.

Oh ya, contrary to what I've read not all 500's have the low gear set. I rebuilt one for a buddy out of his 91 Dakota and it didn't have the low gear set. Surprised me since it was a V6 truck I expected to see it in there.
 
Strange that you say the 91 didn't have the low gear,i have also a 91 a500 out of a dakota but it was a 318.
I would think they would use the low gear set in a v6,must have a high gear ratio in the diff to get it moving.
 
BRONZEBEE said:
Strange that you say the 91 didn't have the low gear,i have also a 91 a500 out of a dakota but it was a 318.
I would think they would use the low gear set in a v6,must have a high gear ratio in the diff to get it moving.
Click to expand...

sorry to horn in here, but, can an overdrive 727 ( is this calleda 518?)be made to take 670 h.p. ? w/ approx 660 ft lbs of torque?
the floor board is no problem, I`m getting ready to take the 4 speed hump out anyway. looking for some one that knows. I too am old school don`t know anything but 727`s------------------------- thanks, bob
 
I"m sure it can be done,the front of the 518 has most of the same part as the 727 and some interchange,as far as the overdrive part it sounds if you need a diesel overdrive set up.
If you just want overdrive and not have to worry about a custom stall for a lock up converter i would shoot for a 518 from 89-90.This unit did not use a lock up converter,so a 727 non lock up converter can be used.If your old school you might have a few laying around.
The way you can tell is there is a 2 prong connector(yellow in color) in the transmission case which has overdrive only no lock up.The input spline will look lust like a 727.
Keep in mind that this was the transmission that gave the 518 the bad name,but the o/d section was most of the problem.With the updates now you should be able to make a nice transmission.

Hope this helps
:D
 
BRONZEBEE said:
Strange that you say the 91 didn't have the low gear,i have also a 91 a500 out of a dakota but it was a 318.
I would think they would use the low gear set in a v6,must have a high gear ratio in the diff to get it moving.
Click to expand...

I thought it was strange too. Completely expected to see a low gear set since it was the original behind a V6 but it was the std. gear set. It had the std. 3.55 gear ratio which wasn't terrible with the somewhat short tires but it still wasn't much to brag about on take off, especially since it had nearly 200,000 miles and was kinda tired.
 
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