OK, most here know, my son has a DUster with a 360 magnum. Its been 11 teens on motor now and the trans even though its fresh has flared up on the 2-3 shift. Now the trans is all stock other than a shift kit. Its got stock valve body, pan, etc. Kick down linkage is funtioning properly.
Now the builder says he can raise the line pressure to help the 2-3 shift, and we were going to put a cast deep pan on it.
WILL this trans handle another 200? HP because we are about to unleash a plate on it soon.
He is not opposed to a manual valve body, but what will this thing hanldle? Id like to see the car go in the 9's so it can be ran in 10.0 index etc. It does get street driven quite a bit

It will do it, but it will require regular maintenance. Don't expect it to stay in there for hundreds of runs. And it will require being upgraded to race specs, not street. Valve body, good parts, right parts, partial or complete rollerized. And a decent converter.

I think Jay has gone 9.30's 9.40's with his UPDATED 904. Make sure you update the convertor hub, a known weaklink.

it is flaring because the front band is released before the high clutch comes on try making the front band tighter turn it in snug and come out 1.5 turns, you could also try a lighter return spring in the front servo.try adjusting the band first hope this helps

True. I ran the old style. It would start to crack almost immediately. 45 or 50 runs, it would start to drip a little oil out the front seal and you knew it was time to fix it. How far you ran it past that was kind of a gamble. Never actually broke one. I prefer maintaining to breaking.

Rollerized output shaft is the next issue. Depending on RPM, it will jam the shaft in the support.

Basically stock except for RMVB, deep pan & 6000 stall (3000-lb + my 160 footbake car), about 640 HP on mine. Low 10s.
Went through the cracked converter hub experience once, too.

I seen a modified Baby 904 with a big turbo 4G63. Ran 10's in a RWD converted Talon

Thanks to the SS Hemi guys running 904 guts in their 727 cases, there are good parts available for the 904. Pro Trans & A&A do the most of it.

thanks we will check that out

I know a 10.5Wx33x15 heads up racer that use the Proflyte(904 based) from Pro Trans (661-940-7400)making over 1000 HP running in the 7. with a 2900 lb. car
A lot of the NHRA Comp racers use that tranny also

I'm sure ..I am on borrowed time (trans) ... but i have the same 904 since 2003, with a 8" ATI, 2 rebuilds and one tightening of the converter, so far my best is 9.95@ 133 with a 60' of 1.44.. (room for improvement) weighs 3920 with me, I'm 210. so I would say its exceeded all my expectations

You running standard shafts, planetaries, etc. ?

What trans to engine adapter are you using ?

I recently went back to a 904 from a 727. I did Drag week 2018 with what was a stock 904 with a cheetah RMVB and an A&A spring pack in the forward clutch. It worked well, but I wasn't real happy with the 2-3 shift. It was good it just wasn't what my 15 year old 727 was. I recently tore it down and it looked good but the 2-3 pack had some heat in it but not burned up. I moved to A&A red racing clutches and Kolene steels and I can tell a noticeable difference. I just have a few miles on it but the wide open 2-3 shift at 7000 is crisp and quick. My car makes 575-600HP and weighs 3550lbs.

I have also been down the cracked snout road. This time I moved to the A500 style snout and got pump gears from A&A.

.... John our “updated” 904 was built used behind the iron headed combo back in the early 90’s.... other than some internal mods and A&A spring pack, she’s stock as a rock. It had just been sitting around here for 20+ years and I always thought that “if” I lived closer when my dad had the Duster, it would have been 904 equipped even through our W5 years.... the 727 dump truck trans just seemed a better suit for a “set it and forget it” combo. So far I only have like 16 passes on it with the W8 combo. 1.2 60 times off the brake, best of 5.79. I’ve had the shaft conversation with quite a few people, and I’m definitely in the territory where I “should” probably have them.

Oh yeah.... I did have our old converter updated at Ultimate and had Lenny change the pump drive to the A500 style. 6200 stall

My SB duster has been 5.6s at 121+. It has lots of HD parts though. Decent life from clutches and bands.

I know its a later model 904 with a JW bellhousing drum machined for extra clutches, I didn't build the trans but I think he said something about the clutch bands are HD and green in color, Standard Shafts I believe and Planetaries.

I know Keith Long is doing 904's now with bb bellhousings on them. MoparJohn has one in his 9 second GTX. It is holding up well.