We are looking to replace the aluminum front drum in our 904 trans with one that is more durable than the race only aluminum piece yet safer than the explosion prone stock drums. I cant seem to find the steel billet front drums for a 904, only 727s. Is there anyone that make such an animal? Or is it time to put a 727 in it and slow it down. With all things being equal, does anyone know what the differance E.T. wise a 727 vs. a 904 would be? We will be stepping up the 394" Edelbrock headed engine to a 411" Indy headed engine so we will be making considerably more power, we just want the trans to be a little more reliablewith less maintanence. Street driving a trans with an aluminum drum plays hell on the drum. Frequent trans oil changes is getting old as well.

Depending on a number of factors( and who you ask) a 904 is going to ET anywhere from 1 to 2 tenths quicker.

I think about 1.5 is probably more common than any other, that i have heard of.

A few years back i swapped out a basic 727 with stock internals, for a full roller unit with an aluminum drum, lightened sunshell, etc.

The new trans proved to be ultra reliable, but i saw nothing on the ET slip from the torrington bearings, lightened internals, etc.

Long stort short, no matter what is done to a 727, its in fact going to be a good bit slower than a 904.


might want to check with SMR regarding a billet steel 904 drum.

His site seems to imply he has them

you have a PM

SMR does carry them: http://smrtrans.tripod.com/smrtransmissionsintro/id20.html

Rickster

tcs makes one. #123800s $574.50 looks good!

John Cope told me he had some and so did A&A. I will be having one of them build me a throw down 904 soon.

The reason that the 904 billet drums aren't plentiful like the 727's is because the factory steel 904 drums aren't a problem. The diamater is so small, they don't have the mass/rotational inertia to pull themselves apart.

I continually ask, and I have NEVER seen or even heard of a 904 drum coming apart. They are just too small to do so...

I did a post on this 2 years ago for someone to give me any info if they ever seen one blow up or heard of one blowing up and I did not get one response. I have always run 904s with my smallblocks and never had that kind of a problem.

Since the clutches are smaller in the 904 there is less clutch area to absorb the torque. More clutches help as does more line pressure but some of the billet drums for the 904 offer a larger apply piston so there is more area on the apply so more clamp force for the same given pressure. I guess what I'm saying is although there may be little to no chance of the drum exploding due to a sprag failure like the 727, then the additional piston area may be a good reason to consider the aftermarket drum for the 904.

I have had the same 904 in use since 1993, the only failure I have had was the rear drum separated...kind of hard to explain...but it was just a perfect break in the drum...you had to see it to believe it...

In fact at MATS, the tech guy asked my daughter about a shield since the dart runs low 11s, and said something to the fact about running a TF without a shield was dumb...I told him it was a 904 not a 727 and he was confused.

TCS has the "blow-up" numbers on the 727 drums ....stock OEM, steel and alum ....

Do they also have #'s on the 904 ?

Never seen one blow up either.

Run them for years and know other who have too.

About a 904 not blowing up....The stock Eliminator 340 Duster that I owned had one blow up when the prior owner had the car. The floor board in that car was absolutely DESTROYED! It looked like it drove over a bomb in IRAQ. I asked if it was a 904 and not a 727 and the prior owner assured me it was a 904.
My brothers car is too nice to have that happen to the floor board. With my luck, the 904 that I would put in his car would be the 1 in a 1000 that would blow up. If it wasnt for me owning a car that had one tear up the floor, I too would say that I have never seen one or heard of one blow up.

I`ve ran 904s for over 25 years and have broken them but never blew one up. Most of them last about 4-5 years before we rebuild them even then they look pretty good inside. I have a CSI shield its a pain taking the trans in and out with it but if I ever do blow one up I`ll be glad I had it. I`ve been as fast as 10.40 with a 1.40 60ft with my present 904 set up.

Wow, that's perdy. Who's product is this?
DC

Thats Rons 904 built by ProTrans in Lancaster Calif.

If it's peace of mind that you are after then by all means put one in,,I have been running a stock drum for many years with no failures, 12 years in a low 11 second dart, and last three years running in the low 10's high 9's in that same car, I know it took some tran's company's years to even make a steel drum because of no/low demand.