904 Upgrades • The Dodge Challenger Message Board

by **TX70Challenger** » 05 Apr 2004 23:26

Pretty self explanatory, what upgrades do you recommend for the 904 tranny? It seems that those B&M transkits are killer and easy to install, but what about the other internals and what not? Anything absolutely necessary to replace when considering to hook it up to a hot small block?

Any opinions/suggestions? Thanks fellas.

-Ross

by **insuranceguy** » 06 Apr 2004 3:49

When I took my car to the tranny shop (the final time...long story) I asked what I could do to keep the 904 happy @ 500 hp? He said "replace it with a 727"

That being said, I do know several guys’ who have set up their cars for racing only with the 904, as it is much lighter. Just my 2cents...

Todd

by **NZ440R/T** » 06 Apr 2004 4:03

What will your small block be putting out roughly? :?:

380hp - 400hp?

by **TX70Challenger** » 06 Apr 2004 5:18

I might be optimistic here but lets say I'm shooting for 400-450hp. The weight loss issue is a plus, along with less rotational mass in the drivetrain.
I know I could just end all discussion and get the beefier 727. BUT...I already have a 904, have a 904 length driveshaft. I don't mind spending some money, but I'd like to try to be able to use what I already have and maybe improve on it. :roll:

Thanks for the input so far fellas.

-Ross

by **NZ440R/T** » 06 Apr 2004 5:59

Good reply bud, fair enough. :wink:

I was just going to say the money you spend on beefing up the 904 to get it as strong as a stock 727 could be spent on other mods (Suspension/Chasis, Engine, Fuel useage etc) you'd gain that weight differnce back with performance, and then some and you'll know what you have underneath is the best bracket trans out, tough as nails!!

I'm by no means a trans expert so this will be a good thread to keep an eye on, who knows that 904 might hold up well, if not then grab a TF-727!!

by **dave-r** » 06 Apr 2004 7:53

I would find a good used 727 and rebuild that. A stock (but well rebuilt)727 will take that sort of power no problem. You would have to spend a lot of money on a 904 to make sure it was safe to operate at that sort of performance level.
A trans explosion is something you want to avoid at all costs.

by **TX70Challenger** » 06 Apr 2004 22:40

Thanks for all the fast responses fellas, I really appreciate it! Looks like the 727 is the best way to go in the long run, especially after what Dave said last - better to be safe than sorry! :shock:

by **NZ440R/T** » 07 Apr 2004 0:20

Good decision mate. :wink:

Yeah, I to have heard of some close calls with picecs of trans, probably 904 flying through the tunnel and into the drivers area. :shock:

There a re a few 727's around to......so finding one shouldn't be a problem, just putting to good use is the key!

by **dave-r** » 07 Apr 2004 8:40

Finding a small block 727 is not as easy. They have a different bellhouse bolt pattern to the big blocks.
I don't know if the bellhousing from the 904 will swap over or not? I would guess not.

You will need to build the 727 at least to Hemi spec. Most rebuild kits allow you to do that.

by **Christer** » 07 Apr 2004 21:05

Hi Ross! Maybe this article will give you some information:

by **transman** » 09 Apr 2004 16:15

As others have pointed out, the 727 is the better route to go. That being said, the 904 still offers a lot but will cost you a fair amount of money to get it to be as strong as the 727. The 904 was used mainly behind six cylinders engines, and small displacement, small horsepower V8's by the factory. In all the years I've been involved with the automatic transmission trade, I've yet to see a factory installed 904 behind any high performance V8.
Depending on your location, finding a small case 727 should not be very difficult as they where used in most 360 truck applications. Have or do a quality rebuild to the unit, install a valve body improver kit (your choice, although mine would be Transgo/Transco), match a high stall converter to your engine and drivetrain combination, and then drive it like you stole it.
Transman

by **insuranceguy** » 09 Apr 2004 16:49

If the Tranny's are near as good as the engines, try this!

http://www.raybarton.com/tra.html

by **TX70Challenger** » 10 Apr 2004 7:35

Thanks for all the replies and information fellas. The 727 seems the best way to go the first time around, I'd rather "do too much" than "do to little" if you know what I mean. Todd those Ray B trannys look pretty stout, any opinions on the Mancini or Cope Racing Transmissions? I've pretty much got the consensus that the TCI trannys are crap so I won't even bother asking anyone about them. Once again fellas thanks for all the help and insight, this board rocks! :twisted:

by **dave-r** » 10 Apr 2004 10:44

This book;

http://www.amazon.com/exec/obidos/tg/de ... ce&s=books

will give you a good idea of what to look for in a transmission and might even encourage you to build your own!

by **TX70Challenger** » 10 Apr 2004 20:19

Sweet Dave thanks. And it's cheap too! Does B&M make any supplemental books or manuals? I have the transpak for my 904 and the instructions included with it are awesome. I believe that either Dave or Von got the B&M transkit and said the instructions included with that one are pretty cherry too. I'll get that one on amazon for sure though.

-Ross

by **insuranceguy** » 10 Apr 2004 22:18

Mancini, Cope or Ray B is all good. Careful with Ray B, though. He'll talk you into putting 15k in front of the 727 :twisted:

Another bet is to go to a "local strip", and ask the mopar guys who builds their tranny's for them.

Or you can use my dumb sh&t way, and keep buying till one doesn't break :oops:

Todd

by **transman** » 13 Apr 2004 4:42

Ross.
The Ray Barton, Mancini, Cope Racing Transmissions from what I've seen and been told, are typically high dollar racing transmissions. I know this, as the company I work for has been selling aluminum drums for the 727/904 transmissions to these companies.
If its a balls to the wall racing type transmission you're looking for, then go to one of the above and I'm sure you won't go wrong, but your wallet can take a big hit.
Dave and others have told you to try and rebuild the transmission yourself, and if you're at all mechanically inclined, a torque flite transmission is not all that hard to rebuild yourself. There are a couple of areas that you should be aware of. KEEP EVERYTHING CLEAN. If you are going to replace any of the bushings in the transmission, have a transmission shop with the proper bushing drivers (NOT SOME ILL FITTING SOCKET OUT OF YOUR TOOL BOX), install them for you. If they aren't fitted properly, the end result can be costly. Go slowly and follow the instructions you get with whatever kit you purchase to the letter. Remember the builder of the kit spent a lot of time and $$ getting the kit to market, and knows a whole lot more about how to install it than some well intentioned but poorly informed soul that read something in a HOT ROD magazine or on the internet. I've said it before, and I'll say it again, if you or your friend are not transmission builders or hydraulic engineers, don't try to change what the kit builder tells you to do.
Have fun
Transman

by **TX70Challenger** » 13 Apr 2004 17:39

Thanks for all the replies fellas, sure do appreciate it! By all means I would be up for rebuilding a junkyard 727, it's just the the fact that its a sb-727 makes me think it would be a little bit more difficult to find...but I'm sure theres gotta be some around here!

I need to scope out that book Dave was recommending, sure looks like it might come in handy!
-Ross