What are the major differences between A904 and A727?

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Realest

Realest

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i am going to build up my /6 A904 to go behind my turbocharged /6.
been talking with a guy on the slant six board that successfully upgraded his A904 with a drum from an A999 to gain 5 clutches in the front and 4 in rear. along with other modifications. buddy told me that the torquefilite A727 transmission handbook by Carl H. Munroe helped him out a lot. So i purchased it. I've also downloaded the 727/904 pdf manual floating around.

my questions is in the title. what are the differences between the two models? or similarities? the 904 sure doesn't have the same information trail the 727 does for obvious reason. thanks in advance for your input
 
Their basically the same transmission except for the size of the parts. There are very few differences in them and they work exactly the same. The 727 was first introduced and then the time came that they needed a auto trans. for a 6 cyl. that didn't need to be as beefy so they made a little version of it known as the 904 or TF-6 as they were called in the old days. Later on they started using the 904 on small blocks.
 
well i am just starting to read that book so i guess i should save any questions i have for after i finish it. so far it tells me lots of parts or interchangeable between the 904 and 727 as they are in the same family. i assume it'll cover more in later chapters
 
Just in case it matters, the 727 sucks up 20 HP more than the 904 because of the larger rotating parts according to Car Craft dyno tests. The 904 can easily be built to handle over 300 HP with the current parts out in the market. I see no problems from my slant 6 experience with it handling what you want and would also benefit you as it weighs about 30 lbs less.

Lastly, they are a little more difficult to find, require a new driveline and linkages. Just more $$.

Just my $.02 worth.
 
For your purposes, the valve bodies interchange between the 904 and 727, but most other stuff does not. That 727 book is pretty useless for cross-compatibility or even working on a 904. It didn't help me much at least.

That tech download is a lot more useful, but obviously no good for beefing up your trans for performance use. I'd get with someone knowledgeable when it comes time to order parts. A&A or Cope Racing Transmissions are a good place to start.

The 904s don't seem to blow up like the 727 has a reputation for (probably due to the weight of the parts as the design is the same).

Good luck:

Steve
 
In stock form a 904 has no problem handling 300 hp and with just upgrades to the friction linings and the installation of a good shift improver kit will handle 400+ hp. The book you have is very informative on torqueflites whether a 904 or 727 since they work the same. Only exceptions are the clutch pack springs and way they take up the end play thrust. And as LX said the only thing that really interchanges is the valve body. Everything else looks the same but the 904 parts are smaller.

69Dartconv. has a good point on how much extra power it takes to spin a 727. That's why I always use a 904 until the HP power gets above the practical level of it's capabilities. You can change a bunch of parts to make it handle 600 hp but that gets expensive pretty quick.

LX guy the reason you don't see as many 904's blown up is probably due to them having a bolt in sprague from the factory. An upgrade necessary to the 727 when building a perf. trans.
 
A friends Father races an altered in NHRA Comp class. He's running a V6 making over 600 horse power and a 904 that handles it really well. It's a wicked combination and it looks like a great ride!
I under stand that the AA Hemi Super Stock guys use a 904 inside a 727 case when they wanna set records or feel they just HAVE to win an event. The trans will generally last a few passes at that horsepower level.
 
thanks guys this is great information. even if the 727 book doesn't provide me with parts interchangeability at the very least it can give me a good brush up on automatic transmission and general performance upgrades. i am a new truck and transport journeyman but don't deal with automatic transmission. the closest thing i come to is an automated manual transmission. i have torn down and put back together a couple allison transmission while in school which makes me believe i am more than capable of doing my own 904. however i am the furthest thing for an expert. thank for the info guys
 
Realest said:
i am going to build up my /6 A904 to go behind my turbocharged /6.
been talking with a guy on the slant six board that successfully upgraded his A904 with a drum from an A999 to gain 5 clutches in the front and 4 in rear. along with other modifications. buddy told me that the torquefilite A727 transmission handbook by Carl H. Munroe helped him out a lot. So i purchased it. I've also downloaded the 727/904 pdf manual floating around.

my questions is in the title. what are the differences between the two models? or similarities? the 904 sure doesn't have the same information trail the 727 does for obvious reason. thanks in advance for your input
Click to expand...

Where can I access the 904/727 pdf?
 
nothing interchanges between the two. i know, you can buy an after market valvebody that fits both but that has been modified. so as stock, no. they are different trannys.
 
727 a bigger bodie tti and dougs dont want to put in headers if u have a 727 they will if 904 in earley a bodies shift levers come in diff 904s lighter but technalogy gettn caught up lotta guys trading to them
 
uhh, this thread is 3 yrs. old. Silent thunder resurected it by asking a question.

Silent thunder if you look through the 1st page you'll find at least 1 thread that'll answer your question but it's really much better to start your own thread especially since your question has nothing in common at all with the original posters question. Asking an unrelated question in a thread can create confusion, another reason to start your own thread.
 
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