727 or 904

[swing69]

minor hp difference..major longevity difference

Incorrect. According to what my trans builder told me; Figure on 70HP to turn high gear in a 727 vs ~ 35HP for a 904.
Hmmmm. why throw 35hp away? its too hard to get back.

 

[stroked 340]

In an a-body??..904..mine has been holding up just fine after 4 seasons of wheel up launches:cheers::cheers:

 

[fishy68]

Incorrect. According to what my trans builder told me; Figure on 70HP to turn high gear in a 727 vs ~ 35HP for a 904.
Hmmmm. why throw 35hp away? its too hard to get back.

From the dyno report I saw comparing them it's not that much difference. The 904 consumed 34 hp and the 727 used 56 hp. Still 21 hp is nothing to sneeze at. But you'll pay quite a bit more to make the 904 as strong as a 727 so it's a give and take.

 

[Guitar Jones]

You guys have been brainwashed. The 904 is fine, with a 5 disc front clutch it will take anything you can throw at it. The 727 is a big block and a truck trans. The 904 would hold up to most any big block too if there was a case made for the BB bell housing pattern but there isn't.

Quit fooling yourselves and leaving horsepower and weight savings on the table. All the Ford guys run the C4 which is a 904 copy and the GM guys use TH 350's or powerslides. No one runs a TH 400 anymore, it's overkill, like the 727.

 

[turbodart68]

Yea yea yea, that's the ticket.

Even though the 904 is lighter, the pounds saved are minimal. They are only a 10th quicker if your racing them and properly built.

If it's in a everyday car/street hot rod, I would also look for a lock up just for the extra push in mileage. Then again, depending how much the engine is built up...LOL, who cares about mileage.

I respectfully disagree. Every car that I have done the 999 swap to (4 including putting one behind my 383 in my Roadrunner) picks up 4-5 tenths and 4-5 mph. Hands down the 904 is a lot faster.

 

[turbodart68]

The SS/AA Hemi cars (now SS/AH) were running 727 cases with 904 internals in them built by a company called ProTrans. They were good up to 850 HP. When the SS Hemi cars started exceeding this they went back to 727 internals.

The 904 is plenty strong enough for most racing and street car activities.

The 998 was used behind the 318 (4 front clutch discs)
The 999 was used behind the 360 (5 front clutch discs)
The 904 was used behind the bent 6 (most had 3 front clutches)

Dave Smith, the owner of Protrans has been building my 904s for years now and they still use 904ish internals in those 727s. I say ish since the parts are all custom billet stuff that he makes himself.

JW makes a bell housing that lets you put it behind a big block. I did it to my stock 68 Roadrunner that ran 13.77 at 101mph with a 727. After the swap to a 904 it went 13.39 at 106 mph. I am a true believer with my 10 second Swinger going 3 years and its still swingin'.

 

[fishy68]

Of course custom billet stuff is going to be stronger. That's like comparing apples to grapefruit.

 

[70aarcuda]

Got two 904 in use on the drag strip...71 Dart 360 runns low 11 in Las Vegas working on 4 season with same 904...

69 Barracuda 360 runs high 10s in Las Vegas, working 5 season since rebuilt...

and they are very high tech trans...since I did them...LOL..

converted both 904 to 5 disc front drums...used good disc and bands..

Oh..did i say they are both being launch with a Tranzact Pro Transbrake...

 

[omahamoparguy]

I like the 904 (actually 998/999) Always keep a spare around though. Reverse patt manual valvebody helps. 5 cluthes etc.... Easy to rebuild too....Light weight also.
cheap too...I paid $45 for one out of a low milage car at a swap meet, the 727 next to it was $220. 904's need some help to stay together but nothing drastic for any type of street use. IMHO

 

[RustyRatRod]

Anybody that's ever done a 727 to 904 swap (I've done several) can attest that the difference is night and frikkin day. It's like drivin a different car. With the 904 the car has so much more bottom end stomp RIGHT off the line it makes you wonder why the HELL Mopar ever put the 727 behind the 340. It really IS that big a difference. That difference is even greater with the 2.74 low gear A999. I have an A999 and an A904 but I'm gonna use a 4 speed overdrive in my car......but I'm keep them 904s. lol

 

[RustyRatRod]

Got two 904 in use on the drag strip...71 Dart 360 runns low 11 in Las Vegas working on 4 season with same 904...

69 Barracuda 360 runs high 10s in Las Vegas, working 5 season since rebuilt...

and they are very high tech trans...since I did them...LOL..

converted both 904 to 5 disc front drums...used good disc and bands..

Oh..did i say they are both being launch with a Tranzact Pro Transbrake...

Would love to see some video,Tony.

 

[RustyRatRod]

The 904 would hold up to most any big block too if there was a case made for the BB bell housing pattern but there isn't.

Don't tell that to Bucky Hess. He ran 904s behind the HEMI in his 68 SS/A Cuda for years. lol

 

[dustoff440]

Even though this thread is 11 months old, I am surprised no one has mentioned the HP difference it takes to run a 727 vs a 904. It may only be important in competition racing where you need to get all of it.

Read somewhere a while back that a 727 sucks 70 horsepower

 

[RustyRatRod]

Read somewhere a while back that a 727 sucks 70 horsepower

I've read similar stuff.....up to like 110 HP to drive one. Lots of variables from trans gearsets to rear end ratios, torque converters... how many fat women you're haulin around........................you name it. I've also read that the 904 only takes around 35 HP on average. That's a big difference.

 

[70aarcuda]

Power loss for various auto transmissions:
Please remember these are approximate values, and were provided by Car Craft Magazine.

Powerglide_____18 hp
TH-350________36 hp
TH-400________44 hp
Ford_C-6______55-60 hp
Ford_C-4______28 hp
Ford_FMX______25 hp
Chrysler_A904__25 hp
Chrysler_727___45 hp
__________________

 

[grassy]

A comment by an expert MOPAR racing stated in either Mopar Action or Muscle a month or two ago said an a727 would cost you less than .5 seconds at then end of the run..and will last a whole longer.....but this descussion has turned religious like mac/windows..

Go ahead, vote with your money... or are you only putting your oar in the water to stir up this topuc... If Ma MOPAR used the A727 then it is good enough for me..I only want to do the transmision job once..

Happy trails,
Ian.

 

[memike]

904 Strong, light and very buildable has been the word here in the south for many years

 

[crackedback]

40 years ago the 727 was a much tougher piece and that's the reason they were put behind 340/360's in Dusters/Challengers/etc. Now, with the improvement in parts, a well built 904 will hold up behind most any street small block.

30-40 years ago having a 600hp engine was an unruly beast to drive on the street, that's IF you really had one! Look at what rolls around now... you can fall out of bed and build a 600hp bb that isn't rough around the edges to street drive.

Why run a 904..... ever see a front drum explode on a 904 like the "much tougher" 727? I've NEVER seen one explode. 727's seen a bunch of them go BOOOOMMMMMM! No $400+ front drum required or LBA valve body for a 904. For under $400 you can have a kick *** 904 built using the multi-spring front drum kit.

I'll take a stout built, faster accelerating, miniscual chance of detonating 904 over a 727 in a street, street/strip, hot rod A body any day of the week. It will cost less, weigh less and be faster.

 

[RustyRatRod]

Indeed. Well said, Rob.

 

[ham_r_down01]

I didnt vote because i like 3 of the options. Id love to have a 4 speed, i built a 904 for my car. 727 is a very stout piece, I guess thats why they came in all my trucks. My 727 in my ramcharger is as built as it needs to be, bolt in sprag and a 4 clutch front drum. But, I dont spin it to 6600 rpm either. 6600 x 2.45= 16170 rpm

 

[brandon2701]

904

 

[green1]

Low band apply valve body; no BOOM. And you might get faster by .033 with the 904.

 

[shadango]

..I have both..the 727 seems to be king of the stip and seems to last forever..and it allows you to grow when you want w/o having to mess with the trans again..I hear it takes 5 or 10 more horse to push..with a V8..that is nada..why would you put in anything else ?? ..so 727 for me with the 2-3 shift kit..

BTW, I also have an 8 3/4 rear end even though I hear the 8 1/4 is OK..I hate doing the same job twice...


Grassy

:thumbrig:
Same here.....

My car (72 fish) had no tranny when I got it. Same cost to rebuild/freshen either a 904 or 727.....figured with a 727 I would be prepared for whatever I might end up doing later to the SB. Transgo shift kit with some upgrades inside. The kit allows me to downshift/upshift to 2/3 "anytime" or at least that is what the transgo kit claims....LOL :burnout:

Also went with a nodular iron 8 3/4 (3.55 trutrac) and CR MO shaft with the 1330 (?) joints....yeah, more than my current engine needs, but I like to abuse it a little.....LOL....so the extra beefiness is a little extra peace of mind for me.

 

[shadango]

A comment by an expert MOPAR racing stated in either Mopar Action or Muscle a month or two ago said an a727 would cost you less than .5 seconds at then end of the run..and will last a whole longer.....but this descussion has turned religious like mac/windows..

Go ahead, vote with your money... or are you only putting your oar in the water to stir up this topuc... If Ma MOPAR used the A727 then it is good enough for me..I only want to do the transmision job once..

Happy trails,
Ian.

....windows is better......LOL

(Actually, I think they BOTH suck to some degree and whichever one you prefer to work in is the "best one").....LOL

 

[Oldmanmopar]

For all you guys that voted 904 I would like to know how you are bolting them in to a V-8 car this is a Slant Six trans bell and all. If you were going to for for the baby unit your choice would be 998 or 999 but the internals are different between these two. I vote 727 for street performance. More durable for pulling hills and extra weight like the wife, cooler and chairs to the shows.

I was wrong 904 is also a V-8 trans