904??

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BrazilMopars

BrazilMopars

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Hello!

I use Automatic transmission Torqueflite 727 in my Drag Racer Mopar, and I'm seeing that many people use the A-904! I believe the reason is that the 904 is lighter, and the engine ends up yielding more power because of smaller loss! There are kits Performance for the A-904 3-speed transmission for Drag Racing?? What is the advantage of 904 over the 727?


Thank's a lot!




God Bless America!
 
I believe for lightweight drag cars, GM powerguild uses the least hp, yeah it has only 2 speeds but with a race converter it doesn't hurt--in fact its quicker than a 3 speed, until the weight goes pass--not sure 2,800 lbs??
 
I've been using the 904 for about 20 years now. The 904 can be a quality race transmission! If your Mopar is 3000+ lbs, the three speed is what you want. Especially being a small block! There are many quality manufacture's of the 904 parts. May I suggest aluminum internal components. [drums/servo pistons and output shaft support assemblies.] A person can spend many $$$ on the 904, but reliability is impressive/very good! I know of many vehicles now running deep into the 9 second range with 904's! And a few of these vehicles weigh as much as 3400 to 3600 lbs! My combination is almost 650 hp with over 600 lbs/ft of torque! I have not had a transmission failure...period! I have installed new clutches, and a second gear band only because of wear NOT because of failure. All being told. the 904 is a "positive" move for one looking to improve on ET and MPH. I use one source and one source only, A & A transmission's parts/pieces to move my Dart down the 1320!
 
a 904 is usually .15 faster then a 727...lighter internal parts..
 
Thanks for the replies! My Dodge weighs about 2500 lbs! Use Small Block Stroker Engine 410-V8 with 727 transmission, but want to swap for a 904! Just need to know what changes I need to do to get the maximum performance and durability!

Thanks for the help guys!
 
Isnt the 904 about 4" shorter than the 727? If so you'll need another driveshaft and keep in mind the yoke is different for a 904 than a 727
 
Kernel Yes, I will need to make modifications to use the 904!

They would know tell me if I can buy a 904 ready to race in a store? And along with the transmission, already have to buy everything they'll need to install 904 in my Stroker 410-V8!!

Thanks again!
 
buy alto red clutches...kolene steels...replace the single wound spring in front drum with a 24 spring kit...

upgrade the front drum to 5 disc using thinner disc....set the clearance to .060 to .070

your will need a longer drive shaft...and new converter

at 2600 lbs you should not have any problems....with a 904.
 
70aarcuda said:
buy alto red clutches...kolene steels...replace the single wound spring in front drum with a 24 spring kit...

upgrade the front drum to 5 disc using thinner disc....set the clearance to .060 to .070

your will need a longer drive shaft...and new converter

at 2600 lbs you should not have any problems....with a 904.
Click to expand...

Exactly and great advice from a guy that builds his own 904's with transbrakes.

No reason to spend huge money on a 904 when you can do it yourself and spend about $100-200 total for a rebuild kit. 24 spring kit is about $110.
 
crackedback said:
Exactly and great advice from a guy that builds his own 904's with transbrakes.

No reason to spend huge money on a 904 when you can do it yourself and spend about $100-200 total for a rebuild kit. 24 spring kit is about $110.
Click to expand...

How hard is it to rebuild? Are any special tools needed?
 
64physhy said:
How hard is it to rebuild? Are any special tools needed?
Click to expand...

EASY!!!

Snap ring pliers and a home made clutch compressor are the only two things you really need to have. You don't need a slide hammer like most think to get the pump out. I have a video that shows how to rebuild 727's, 904's are just a smaller version, with a bunch of neat tricks and such.

A nice big, clean table is really helpful.
 
you need to remove and replace 3 bushing...pump...front drum and tail shaft bushing

you can take those 3 items with the new bushing to a trans shop and have them R&R them ....

there are bushing drivers available ..but unless you find them on a "deal" they are expensive for using only once or twice.
 
Thanks everyone!

EL5DEMON340, I contacted John (copiracingtrans.com). I spent all of my car to specifications and see if he can help me!

Again, thanks to all who are helping!
 
You can also use the direct drum from an A518 and use the standard width clutches. There's a seller on Evilbay who sells remans LOADED with new clutches for 20 bucks and 12 bucks shippin. Just search 904 drum and you'll find it.
 
StrokerScamp said:
You can also use the direct drum from an A518 and use the standard width clutches. There's a seller on Evilbay who sells remans LOADED with new clutches for 20 bucks and 12 bucks shippin. Just search 904 drum and you'll find it.
Click to expand...

you better check what year your trans is before you go buying A518 drums,,,,,the 518 is based on the 727...the A500 (42RH and 42RE) is based on the 904...some of those drums have two bushing...alot of the older 904 front drums have one bushing...

the 5 disc drums that i have both hit my pump and did not seat ...tried that last week...even posted pictures ....so buyer beware...


here is one of the pictures...you can see the drum on the right which is a 5 disc 904 drum how the inside is recess...the outer area hits the pump before that recess area seats on the pump....there are pumps that are available for those drums...dont mix and match parts unless you know what you are doing....
 

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70aarcuda,

Thanks for the pics! That makes it easier not to buy the wrong parts!

I'll see in detail the parts to buy the correct transmission!

Hugs to all and have a Happy New Year!
 
I am interested in this 5 clutch drum swap, as I am in the middle of a 904 rebuild...Currently I have all the parts to rebuild what I have. (a 4 clutch from drum) How do I exactly tell what year my tranny is? It came out of my 68 cuda, but who knows if it's the original because my car had like 8 previous owners, and I am trying to unhack everything! haha! What other parts will I need, or what else will need to be changed? Is it totally necessary to upgrade to a 5 clutch front drum? How much will you gain?
 
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