727 or 904 in Dart?

[ramcharger_440]

Hello all.

I will be running a 74 Dart Sport with what I hope will be a 450 horsepower (at the crank) 360. Strip only car with slicks (not sure what size) and probably a mini spool.

Will the 904 tranny in the car now handle the power? It looks kind of small.

I have a 727 but have no idea if it is good. I am willing to rebuild and use it.

Also, anybody know what these two transmissions weigh?

Thanks!

[Hot Cuda]

I'm running a 904 behind a 318 in a '68 Cuda which on a good day might make 350 crank HP in the rarified atmosphere of 5800 feet at Bandimere Raceway near Denver. No doubt that the 904 is smaller, lighter, and has less rotating mass to spin up, all of which might be worth a tenth of a second in ET in low powered light car. I have found that the weak point in the 904, once the HP starts going up, is the high gear clutch pack, which in the early 904s has only four friction discs and steels. Despite using good red discs and Kolene steels, a Cheeta manual valve body, and a new pump, after 30 or 40 WOT runs, 3rd gear would start slipping.

Your '74 904 might have the later, 5 disc high gear clutch drum, which should hold up better than my '68 did, but in stock form may not hold up against 450 HP. I finally tired of pulling the transmission (though I enjoyed doing the rebuilds) out of the car so often, and had Rick Allison at A&A Transmission build me a 904 from a later model case, with all the goodies which will hopefully make it a long lasting unit. What with a modified pump support and an A&A valve body, both of which increase the fluid pressure to the 3rd gear apply piston, plus the 5 disc clutch pack
with A&A's trick spring pack, it should be way stouter than my old unit. Only have about 10 runs on it so far, but I'm confident time will prove the solution.

I don't know what the weight difference is, but the 727 is physically bigger, and the 727 clutch surface area is almost 2x that of the 904 even with the 5-disc setup. If you can live with the weight and rotating mass of a 727, then a rebuild with good frictions, steels, pump and valve body should give you a long-lasting trouble free unit.

Pay your money and take your chances. All depends how you want it to run. I'm sticking with the 904.

[FARGO318]

With slicks/spool, those tires are probably going to be mighty sticky to the raod. A built 904 would prolly be safe with 450 hp, but mines well play it safe and get a 727, hardly a diff. in price and in stock form, will prolly take the engine

[FASTDARTCHESTER]

Hey Hot Cuda,

I rebuilt my 904 last winter and used the Raybestos blues from mancini. You can get 5 plates in a 4 plate high gear drum (they're basically the same thickness as low gears plates/frictions).

I also use a cheetah reverse manual, Kevlar lined bands, and other goodies.

I put out around 450 at the flywheel with Hoosier cheater slicks, 4.56 rear. With about 30 hard street runs I have no issues at all. It was kind of a test and tune type summer; still tryin to get to the track once this year.

I can speak highly of the Raybestos kit that Mancini sells. The manual valve body helps life too.

TD

[Hot Cuda]

FASTDARTCHESTER

I too have heard good things about the Raybestos blue discs. Thanks for the feedback. Will try them in the future.

We are running a 4.56 rear end, 9x26 Hoosier QT Pros, and a 2.74 low gear cluster.

On our first first rebuild of the 904 we installed a B&M shift kit in the original valve body. When high gear first started slipping, we then put in the Cheetah manual reverse VB, and high gear was good for another 20 or so hard runs, so it definitely puts more pressure to the apply piston in the high gear drum. Per Rick Allison @ A&A, his reverse VB has several more ports flowing fluid to the high gear apply than the Cheetah, which he claims delivers higher apply pressure. Can't be a bad thing.

[Hot Cuda]

FASTDARTCHESTER

I too have heard good things about the Raybestos blue discs. Thanks for the feedback. Will try them in the future.

We are running a 4.56 rear end, 9x26 Hoosier QT Pros, and a 2.74 low gear cluster.

On our first first rebuild of the 904 we installed a B&M shift kit in the original valve body. When high gear first started slipping, we then put in the Cheetah manual reverse VB, and high gear was good for another 20 or so hard runs, so it definitely puts more pressure to the apply piston in the high gear drum. Per Rick Allison @ A&A, his reverse VB has several more ports flowing fluid to the high gear apply than the Cheetah, which he claims delivers higher apply pressure. Can't be a bad thing.

[b-1ken]

If this is going to be a bracket racer, wouldn't it make sense to use the larger, more durable 727?

[Dart]

Hey HOTCUDA...

How long have you been in Longmont? I live in Loveland and used to live in Longtown until a few years ago. Did you make it to the Mopar/Bandimere deal in June?

[MAXAXE3]

without a doubt build the 904, whereas the 727 is stout, durable, and heavy duty. the 904 is all that and quicker to the tune of about 2 tenths over the 727. when properly put together and clearance to the tighter spec - it is unbeatable. if your not convinced, ask the super stock and stock racers what internal parts the have in their 727's. 904 internals of course.
of all the 904 i have put together for drag racing, the transmission has never broke - i had a few converters break, but never the transmission. and with pure stock clutches right from a stock overhaul kit - the secret is in proper clearance - a mistake many folks make. raybestos clutches and the other are great and i have heard great things from them, i might use them if i run out of what i have in stock clutches.
by the way the car ... 3200 lbs, 360, e.t. 10.02 all steel except hood

[Hot Cuda]

Hey DART:

We've been in Longmont about 15 years. Lived in FC and worked in Loveland '72 thru '79. Did a stint in California in the interim.

Yes, we were at Mopar at the Mountain in June. My son did the driving (he can cut a better light than I). We were playing with the line lock for the first time, using it to help heat the meats. Because of the rain, we only got in one test run, and weren't real sure how well the car was hooking and running. In the first round of eliminations, got a great light and shut down early just in case, so still didn't have a good baseline ET. Another good light in the 2nd round, but broke out... Oh well, that's racing.

[Dart]

Hot Cuda:

Last year I actually made it into the final four with my '70 Dart. That was a lot of fun. I was unable to make it this year as our third child was born on May 30th in Boulder. I have a ton of A-body stuff if you happen to need anything. I also have a '85 Ram pickup for sale that's fairly decent i fyou know anyone looking for a reliable truck.

[71RR]

If you have to rebuild one anyway, I'd go with the 727.

[FASTDARTCHESTER]

Hey DART,

I'm looking for a set of all 4 wheel opening mouldings for a '70 Swinger. Do you have anything?

I can't seem to find them anywhere (in good condition at least) and I won't buy repro's from China.

Tom

[Dart]

No luck on the wheel lip mouldings. Keep in touch though.

[Mister Fiberglass]

since you have a 727 - use that one.

BUT the 904 could be quicker and faster than the 727 by up to .200.

[NZ 440R/T]

If you are thinking of using the 727 eventually start rebuilding it. In the mean time I would keep the 904 in there and run it how you would with a 727 under there, the 904 will surprise you. If it decides to disagree with you which after a while is very possible slap the 727 in and go from there...............In other words It's in there so why not she how much it can take

[Hot Cuda]

FASTDARTCHESTER

Layson's Restorations lists those I believe, for around $300. I don't know if they are made in China, however. Pretty discusting price if they are...

[FASTDARTCHESTER]

Thanks,

I'll check that out. Prices seem darn high on new ones. It's nuts.

TD

[Twisted360]

I have a friend who rented our local track and ran his 70 dart 340 with a 727. We then swapped in a 904 with the same brand and stall speed convertor. With no other changes we dropped 2 10th's in the quarter. One word of caution, After installing a trans brake he cracked a few cases and ended up going back to a 727, for durability, a few years later.