904 race trans

What are you using in your trans other than the normal parts? Does it hold up? Mine Will be behind a 340. Don’t need a pro trans. Thanks

I just used the typical upgrade parts when I built mine a few years ago. RMVB, Alto Red Eagle racing clutches, Kolene steels, thicker band strut, red lined bands, teflon rings and rear billet servo. I did upgrade to an oem 5 disc drum and Multi-Spring Pack with Billet Retainer.
No issues but my car is lite 2513 lbs.

What kind of HP

Car runs high 9s @133 so far so whatever hp that is..

Jay is running low 9’s with his 904

Mine runs mid tens at 3600lbs. Its got A&A red clutches, A&A spring pack, and a TA reverse valve body.

How often are they checked or inspected?

I don't have a lot of data with mine. I maybe put 40 or so passes and drag week(got it really hot once) on it in 2018. I tore it apart in 2019 and looked at it and it looked great. It just had stock clutches and steels in it so I changed it to the red clutches and kolene steels because I wasn't super pleased with the 2-3 shift and the upgrade took care of that. I will probably not inspect it again until I have an issue I feel needs attention.

I ran my 727 for close to 15 years on the same fluid and it still worked amazingly well. I made the move to 904 knowing I would go faster and maybe have to look it every season or two.

Same here with the 727, never had a 904 though, real world info from you guys

I have a great 904 for a 400hp small block.... DON’T TRY THIS AT HOME! I have 67 passes on my 904 off the trans brake at 4K converter flash to 6100. We go 1.21 to 1.25 60ft on good tracks, and have been running 9 teens/.20s. ALL stock components with the exception of the A&A front spring pack, A500 flat drive gears in the pump, and front band. Both clutch drums have been cross drilled for fluid relief. I talked with Darren at Pro Trans and he was like... “I’d run it!” I’m hoping to do some major upgrades to it over our ultra short winter break.

It’s a shame.... with the 727, small 598 intake, and 4150 carb it was a really consistent 9.5/.6 bracket machine! Sold the 727 and now I have to find homes for the converters

Car weighs 2970 race ready....

“I don’t need a Pro Trans”..... EVERYBODY needs a Pro Trans!!

Multi spring pack. Blue Plates and Kolene. Rollerize the output shaft support if you are going to be spinning any RPMs (or even if you aren't). Convert to the late model converter hub and pump with the flats, As much billet as you can afford. Servos, drums,

Thanks for all the input from everybody. Class-bracket-fun car, maybe high tens. 3190 to 3310 pounds A-body

The issue I had trying to run a 904, had nothing to do with the clutches, or bands. The issue I had was breaking the case where the low reverse roller clutch attaches. If you are going to run a 904, my advice is to get the best low reverse bolt in roller clutch available, and make sure you have a blow proof drum up front. I busted my 904 many years ago on the street with a 340 six pack. 904's can blow up just like 727's same power flow just smaller lighter parts.

What adapter are you guys using to bolt it to a big block?

http://tcsproducts.com/media/uploads/user-files/Drum_Tests_Jan_2017.pdf

Failure to 904 drum “possible” but I’m betting the rpms required to achieve this phenomenon are up there with the aftermarket 727 parts due to its smaller size basically putting it above a threshold that we’d seldom see. In my conversations with a couple of shops that have been in the game awhile neither have encountered this happening to a 904.

I’ve never seen/heard of an “adapter”.... just the pro-flight internals in a 727 case. On my friends the front band adjuster is relocated (welded) so it’s not a total “bolt in” deal. Not sure what else is required as far as machine work. We just flew through it quick to inspect after a broken gear.

I had one I built in a mid to high 10 second car that was basically a stock 4 disc 904 with a run of the mill kit, valve body and kickdown lever that was in the car for years with no problems.

Been running 904s for over 30 years only broke one and that was my fault due to a shifter adjustment gone wrong.. Good parts, Turbo Action manual reverse pattern valve body, 5 disc clutch , rollerized output shaft, etc. go thru it about every 5 years or so, I have two identical 904s one in car , one spare... 3150 lb. w/ driver 68 Dart 11.50s on a stop but capable of 10.60s

Well from what I’ve read so far is that front spring thing should be the first to buy, the rest added down the road as the $$$ comes along.

What moved me away from 904’s many many years ago was the weak converter hub issues. It’s the only thing I ever hurt back then. I moved on to running 727’s and never looked back. And now everything I race has a powerglide and I couldn’t be happier as it’s nice having a SAFE aftermarket case.

Never seen or heard of a stock 904 drum blowing up. However, that doesn't mean that normal precautions like making sure the roller clutch parts are in perfect condition, use of LBAVB where they should be, proper burnout and driving procedures, inspection of the trans after a driveline failure, etc., because they will fail and tear up parts and possibly the case.

~ 50 passes was the norm. When it started to drip a bit of oil on the trailer floor, it would get pulled and sent for repair. Got to be expensive.

Out of curiosity, I pulled a fresh one out with like 5 runs on it, just to look. The crack in the corner had already started. I haven't run one for awhile but the new style hub and pump gear is supposed to have fixed all that.

Anyone can jerk one apart and slap it back together. Getting clearances, end plays, oiling in the back with a manual VB, and all the other details dead nuts is the most important thing. The parts upgrades needed are mostly dictated by horsepower/RPM levels.

Agree on that. No need for a billet drum in a 904. If you want one, run it. Have seen them get distorted over time, never seen on explode like 727's do. Critical mass RPM is likely never seen with any bracket racer SB.

A billet drum or two have failed in 727's. Billet doesn't mean safe, just less likely.

Yep I just jerk em apart, ain’t that the way?

There’s actually an even cheaper alternative available too.... a reverse wound spring.

http://www.atiracing.com/products/trans/904/index.htm

Our 904 hadn’t been used since the mid 90s when my dad was racing the Duster with our iron head 360. Chuck Lofgren built it for him and his attention to detail is second to none. I’m certain he wouldn’t recommend this build for a low 9 goal, but I was just kind of curious. We too suffered a cracked converter drive once, but Dynamic changed the hub and it never happened again. Not wanting to test that converter, and it wasn’t trans brake friendly, I sent it to Lenny as he had data on our build and had it nailed down pretty good, I had him change the drive to the A500/flat style. A&A used to have the gears, but I don’t see them listed anymore.

Nothing personal. Just a general statement.

I just bought some from A&A last year. The A&A page is a little clunky and doesn't sort well off the search feature. But they are great to deal with on the phone so I just call them anymore.

[quote=cudaman1969 Don’t need a pro trans. Thanks [/quote] Does that really mean you don't want to pay for the good parts that Pro Trans uses in their race trannies?
If so you may need them and won't save money by not buying and using them now instead of buying them later
Mopar designed the 904 for low power use in 6 cylinders, 272 and 318 V8, not for high powered cars that would get beat on a lot under warrentty
Dave found out that by using some of those lighter weight parts and beefing them up to work well and live in drag cars was a good way to make those cars go faster without having to make more power with that combination, reduce drag and improve net power
Maybe you should think of buying and using one of his special race built Pro Flytes for your car

Does 500 HP and never going over that warrant a $6000+ trans? My opinion, no. Some people can tear up an anvil. I want an upgrade that will fit MY racing habits not Joe Blows who can’t do a burn out proper and no clue when the sprag is broke.

Just because the car moves, don't assume the roller clutch is OK.

Fellow has a street/strip car, A body with a fairly stout G3 Hemi with a 904. Broke some teeth off the ring gear or something. Fixed that and took the car out for a drive. Seemed ok except for a slight vibration. Check the driveshaft and all that and couldn't figure it out. He was about to say the heck with it and go to the track. I convinced him to pull the trans and bring it to me.

Half the springs in the roller clutch were smashed flat when it freewheeled. Half the rollers were just along for the ride and the other half were actually holding well enough to drive it. It would not have survived the first hit. The vibration was the inner race and reverse drum being forced to one side by the rollers that were still halfway working. Just not worth taking a chance.

Do I know people that have broken 904 input/output shafts running 10’s? Yes. Both were trans brake cars in the 3100lb range. On the flip side I know people who’ve run for years with no probs. Starting to sound like an 8.75 conversation.... only you can get parts to make the 904 live
.

Agree 100%

What I plan on doing to my 904…. I’m going to go billet shafts and I’m going to get it machined for roller bearings. I’m retaining the stock components unless convinced otherwise.

I have a new 904 on order, supposed to ship next week .. I will see how well it holds up

What’s the combo?

Nothing crazy, just a 530 hp small block

That will test it

Will be interesting to see the build sheet on that…. at least I know where a spare is if I need one over Labor Day weekend

Keith has a 904 behind the 499 in MoparJohn's GTX. So far all I know that has broken was an input shaft. Keith found a supplier for hardened ones I believe.

Who did you order the 904 from?

Cope .. he posted on Facebook , he was going to not take orders for more complete transmissions , worn out

already took them off his website too it appears

JW ultrabell. 904/big block

Pro Trans is in Waco now…. Not too awfully far from you.

and another option for the big block crowd….
https://smrtrans.tripod.com/smrtransmissionsintro/id9.html