Blew up my 904 yesterday shifting into 2nd gear under power..Stroker SB, Nitrous, 3400lbs, transbrake with radials and caltracs. Was hoping the 904 would last the season and it went boom (inside the case thankfully...with no forward gears left, just reverse) but looks like it shat the bed first race of the season.

Wondering if its time to step up to a 727? The only part I have that I could re-use is my Tranzact non LBA transbrake valve body. What other parts are needed to make a 727 live up in a street/strip application in a car this weight with about 650-700hp? My 904 had a bunch of little tricks, extra clutches, etc, but wondering just how much of that is needed with the 727? Or should I just try and fix the 904 (dont know the damage yet) and go racing and roll the dice again?

if you are going as fast as you can go every time---904 puts more HP to the wheels---build it with 999 internals----but if you are running for consistency the built 727 lasts longer...

I broke the front planetary (4 pinion, if my memory is correct) on a 904 years ago, it made a nice boom when it broke. All forward gears were gone, but reverse worked fine. In my case the planetary was steel with a welded on "collar" with splines that engaged the output shaft, I'm guessing it was an OEM planetary. The weld had poor penetration and/or cracks formed and that's where it broke.

Member KOS has a killer sb 727 for sale. He's in Hamilton.

Not what I wanted to read Matt!!


If you part it out hit me up about the trans brake VB. Been thinking about one

you haven't even torn it down yet to see what's up! Not sure what shield you're running, but I had to cut the floor out to clear my CSR shield with our 727 in the Duster.... they'll clear with 904. ....and while my 727 is "ok", I'm pulling it and hauling it to Pro Trans. I've had a "good" 727, and this one aint it!

First thing I would do is lighten the car up some. Matts 1970 Duster weights slightly over 3000 pounds with cage, frames tied, factory bumpers and brackets, 2 front seats, rear seat, factory glass all around, factory wind up windows, factory carpet, 727, and all metal factory body parts except for his 6 pac hood. Next I would go with a powerglide as they are "super cheap" to build and maintain and parts are always available.

Another thing to consider is how much spray you are throwing at it. A 150 shot at 4,000 rpm must add about 200 ft lbs of torque. That is a lot on top of an already stroked small block. I think it is time for a 727, as I doubt you will retire the bottle.

I didn't have to cut the floor with my BB

Take the 904 apart and see what broke. There are good aftermarket parts available for them. A "good" 727 uses 904 internal components. The advantage of a small block is you don't have to spend the money to get it all in a 727 case.

Small block car I would (1st) stick with the 904, (2nd) Glide with a gear set, (last resort) 727.

Only reason ours has a 727 is that when my dad was wheeling the car I wanted something that was "set it, and forget it". I "should" also go 2 speed.

Once you do you will NEVER go back. I have had powerglides in 4 of my cars that I've raced and the 2 that I am building now will have powerglides too. 1000's of passes with these cars and never broke a stock 1.76 gearset. Never broke and input shaft, and never broke a drum, out-put shaft or any other part. I took my convertor out of my 572 Daytona after my wreck and put it behind my 9.90 running 408. Life is simple, life is great. It cost me under 250 dollars to rebuild my powerglides every 3-5 years.

Thanks for the input fellas! Your right, I haven't pulled the transmission yet, but I was eventually going to upgrade away from the 904...just wasnt planning on doing it now! lol

I am yanking the trans tomorrow. It has a stock steel 4 pinion front planet and stock aluminum rear...whatever it was that went, it made a nice boom/bang when it did and scared the crap outta me! First thing I did after shutting it down was look at the floor lol

The car is getting glass front and rear bumpers with lightweight brackets, a glass trunk, and already has a glass hood...Realistically I dont want to go spending a ton of money right now to lighten the car, or on anything car related for that matter, I just want to tune what I have and get it dialed as other priorities are calling right now (like buying a house).

Part of me is thinking I should fix the 904, throw the low gear set back in and find a nice high stall 8" vert to run it on motor and not stress the little 904 so bad anymore just for now, but part of me thinks time to go 727, or more so glide (although everyone tells me I will hate it in a street car and im too heavy for one).

I dont really know of any hard parts available for these things to make them stronger other then input and output shafts...unless I am just looking in the wrong places???

i have had the same 727 in my duster since 1994.i hear all the stories on both trans issues.i listened to a local trans guy whos car had a superstock record for a couple of months 426 maxwege auto car.
i played by his rules on the burn out and no dryhops. two seasons ago i got to see a car blow up the front drum. i had him put in a billet front.
it never broke. i get it blessed every couple of seasons.
the 727s are strong and if you do not brake the sprag in the water box they last.

I would update your 904, A&A or ProTrans have all the parts and pieces you need. Brett and Tory still run them in there 8 sec darts. I ran one for years only switched when input and output shafts were on back order and couldn't be found.

LOL! he already got "sticker shock" from Dave's 904 quote and decided it wasn't the route he wanted to go...... although we might not be having this post if he'd taken the plunge. While I do have some basic knowledge of torqueflights, I'm no Dave Smith or Chuck Lofgren. The 727 in the Mirada was a Chuck trans and I had Dave do some updates to it. That trans was lightning quick and worked ever so well. I miss it dearly and "IF" I stay with the 727, I'm heading west to have it done.

If it broke on the 1-2 shift........chances are above average it is the front planetary. I would have a hard time spending much money on a 904

From what I have been looking into, that seems to be the largest possibility...Curious to see how much of a mess inside there is.

A 904 is just not a transmission I really want to sink money into...I had sticker shock when I called Dave at Pro Trans since he recommended a trans with a 4k price tag to run 11's at the time, and my homebuilt unit that cost a 1/4 of that has withstood more then that even if it did finally break. I am going to try and get this thing fixed and running for this season, but this winter I will put my money into a transmission that is worth it to me to build for the long run....and for me, that is not the 904...to each their own.

The 727 in my Dart cost way less than $1000 and has ran high 6.50's in the 1/8 and a bunch of street miles without any problems.