904 vs 727

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gipperco

gipperco

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My Dad is building a Bracket car, 1974 Duster, he bought a crate 360, 455 HP i believe, and was originally going to go 4 SPD but has now changed his mind as he wants more consistancy and dependablity. He is thinking that he wants to go with a 904 ranther than a 727 for weight issues. Is there enough weight savings to justify this decision? Is there any performance loss or gain by doing this. He has been pricing a 3000 stall for the 904 and new they are 500.00+ from Hughes. I know that they are not that much for a 727. Can someone shed some light on this for me? Do I need to convince him that the 727 is the better way to go?
 
Well like about 35 lbs more. Yes the unspun weight of the parts etc takes a little more HP to, they do make lite weitgh sun shells etc. I know you can build some tuff 904s. But if it were me I would do a 727 and be done with it. Go with a decent manual valve body and one that applies the low-reverse band, and billet pistons, 4.2 lever etc.

good luck!
 
I echo Dave's comments. If he's running a 455 Hp engine a 727 with just a good manual VB will do the trick and last a long time. The 904 does weigh quite a bit less and use slightly less hp but won't hold up to that much hp in a bracket car without some higher quality parts than stock. It's no problem building them to take that much HP but will cost more in the long run. As far as the price difference of torque converters I don't think there's much difference between the 2 trans.
 
904 will be fine.. just make sure who builds it knows what they are doing and uses quality parts.... the 904 will run 1 to 2 tenths faster then the 727.. a good converter is gonna cost you that with either a 904 or a 727... that 904 won't hold up stuff is just old school thinking.. there are so many cars out there running in the 10's and 11's with 904's in them and there really isn't anything exotic in them... just good clutches,4.2 leavers, either owner built or over the counter shift kits... yea yea yea back in the day a 727 was the better choice but now the new materials out there in the clutches and things like that have come a long way....


do the 904 and don't look back...



heck the next big block i do is getting a 904..
 
Being you are bracket racing and the extra tenth or two doesn't matter I would use the 727 because it can be used as is with new valve body and convertor and you will never have any problems with it. If you were going to class race then I would use the 904 because you would need every tenth of performance you can get. If you use the 904 you will need better stuff in it to live in your application though. The 727 will be cheaper overall to put in the car.


Chuck
 
I agree with Joe on the 904....I beat the snot out of my 904 and I have no problems with iteven with nitrous launches. I run a CRT RMVB and an ACC performance converter. I used a CRT rebuild kit with Kollen steels and Alto Red clutches and I got the 4 pinion steel planetarys out or a lock-up 904 to replave the 3 pinion stock ones.
 
i never had a problem with 904's... i know a few guys that have basic stock rebuilds , with good soft parts, living well in 11 sec small blocks, one has over 1000 runs on it...

what tranny can be expected to live forever?

i'd say go with a 904 no doubt about it.
 
one more thing... converters cost about the same... dynamics are about 5-600 for 727 or 904, its not like a 904 converter is more money, but you get what you pay for...
 
crate 360, 455 HP
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did you guys read the original post??? 455 hp. come on.. a 904 will handle it with out even working up a sweat... some of you sound like you think its making 800 hp...



If you use the 904 you will need better stuff in it to live in your application though. The 727 will be cheaper overall to put in the car.
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that is not really true...you don't need anything really special in either trans to get them to last... quality parts yes but no matter what trans you use you want that right?

the only work done in my 904 is and extra clutch (i would have that done in a 727 also) my builder does his own shift kit and quality bands and clutches.. nothing exotic... with the converters i'll say it again.. the 904 and 727 are gonna be close in price.. you go cheap you get junk. spend the money on a quality piece....


you know i used to think the same way years ago because the stupid magazines used to feed everyone that garbage about a 904 not holding up.. my trans guy used to bust them for me because he knew better.. well after a couple years of not listening i finally let him do a 904 for me... guess what.. he was right... keep those big heavy bulky 727's (heck i have a few collecting dust in the shed..) . i'm sticking with a 904.....
 
You wouldn't need to add the other clutch in the 727. I have a bone stock 727 out of a Dodge pickup with just a valve body change in my drag car. I wouldn't have put a bone stock 904 in my car, I would have had to go thru it first to upgrade it which would make it cost more. This is the basis of my statement.

If you are talking about having cores and having to go thru both of them then there would be no advantage to building the 727 over the 904. I wish I had the money at the time to go thru a 904 because I had to modify the tunnel to get the 727 in the car. (Before anyone says that they fit fine with out modifying the tunnel it was not true in my case the trans would not go high enough in the tunnel to get the crossmember in.)

I guess it is just a matter of how you want to justify something is better.

Chuck
 
I had every intention of keeping my 904 after a rebuild (worn out). But I just aquired a nice cheap 518 to stuff in.

I know it's gonna sap a bit exta power...but now I can offset that with steaper gears. :evil2:
 
I would use the 904, I even used one in a 4100 lb. 5TH Avenue that ran 14.80's. I put about 80k on that car before I sold it. I had one in my 11.00 drag car with a 340, ran it for 10 years. I now have one in my street & strip Dart Sport, it ran 12.70's last year, now running 11.80's. You just need someone who knows how to build them & use good parts! My current 904 has 9 1/2 Dynamic covertor, Tubo Action manual valve body, 4.2 lever, & a 2.74 low gear.
 
superdart said:
I had every intention of keeping my 904 after a rebuild (worn out). But I just aquired a nice cheap 518 to stuff in.

I know it's gonna sap a bit exta power...but now I can offset that with steaper gears. :evil2:
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now your talking about an entire different area...lol overdrive baby!...:)
 
You wouldn't need to add the other clutch in the 727. I have a bone stock 727 out of a Dodge pickup with just a valve body change in my drag car. I wouldn't have put a bone stock 904 in my car, I would have had to go thru it first to upgrade it which would make it cost more. This is the basis of my statement.

If you are talking about having cores and having to go thru both of them then there would be no advantage to building the 727 over the 904.
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first off in any 904 or 727 that i have built i have an extra clutch put into it... it doesn't cost much to do so why not do it...


second i would never put any trrans into a drag car or street car for that matter without going through it.. its not worth the time if there is something wrong with it. but hey maybe thats just me...


like i said do what you want.. if you want that big, heavy, power robbing hulk in your car then go for it.. but just don't go throwing that garbage about a 904 not holing up just fine behind a 450 horse small block around as fact...
 
They will both work just fine and I have seen many 904s in 500hp and less rides that are under 3800lbs. Just need to beef them up. If you already have the 904 then go for it.

But if the issues is saving 40 lbs and saving some spun weight of the parts that maybe loose 7-10 hp over a 727, not worth it if you already have the 727.

Do a nice valve body manual shift reverse pattern with low band apply, beef it up billet low reverse servo piston and a 4.2 band lever with a HD 2nd gear strut and the 5 clutch pack.. OH and a bolt in sprag kit. Go with a solid intermediate band too.

Should hold up ok!
 
Joe, I think you mis-understanding what I am saying. I think the 904 is absolutly up to the task. I believe it is a better tranny than the turbo 400. All I am saying is right out of the box it is not a strong as the 727 but then that is obvious to all of us.

I never once threw garbage around about the 904.

Don't be so touchy.


Chuck
 
You want real world experience with a 904 come to the track and help me replace my output shaft next time it breaks. I'll give you a quick run down. My car is 2450lbs and has a 620 hp small block in it. Car will run mid 9's with ease if it gets off the line. The last output shaft in trans only lasted 20 passes, the one b4 that made it 200 passes, who knows how long on the next one. My trans was also built by Rick Allison at A+A trans, pretty much an expert in my eyes. I think it is just a fact of finding a happy medium. I would not think that a 2400 lbs car leaving at 4000 RPM on the transbrake should keep kicking output shafts. I'm keeping my fingers crossed that this one will last, but in the mean time I am having a 727 built. Oh yeah may not be fair because I also run an unnecessary 2.76 low gear. Lots of torque multiplication.
 
in all fairness trans brakes are hard on everything.
 
How true! That is why they make hardend input and output shafts... Hey we are all Mopar guys and both trannies are good, just one is bigger and tuffer out of the box. They both have their applications..

nuff said!
:icescrea:
 
I wish I could replace the 48RE in my Dodge Cummins with a 904.. I don't trust that thing, and when it goes $$$$$$$...
 
I have a 904 for my car. i ran it for a year in my Barracuda with a T/A valve body and 8" T/A converter. It also has a low 1st gear in it. Before I bought it , it was in a low 10 second Duster.
 
I dont mean to knock on anyone but for this I would just go for whatever you could find first. They both are great tranmissions and for only 455hp, neither would take much money to build to a point that you would never have a worry. Also never beat your transmission up, such as waiting till the last second to shift or just burning the tires in 1st with out shifting. Seen Fords Chevys and Mopar transmission blow due to that.
 
Lets talk specs on the 2. The clutch surface area for a 904 is approx. 6.69 sq. inches per clutch plate and approx. 8.25 sq. inches on a 727 per plate. That's a 23 % increase in clutch surface area per plate. In stock form that's quite a bit of holding power. Also the larger input and output shafts are another plus as are the beafier planetaries.

I read an article that tested both and the 904 consumed 44 hp and the 727 consumed 52 hp. That's not much difference really. Yes theirs about 35 lbs. of weight added also. Again not a huge diff. I'm only a weekend racer so take this opinion as you will but that don't sound like enough to get you an extra .1-.2 in the 1/4. .1 at most is just my guess.

Again don't mis-understand. I'm not bashing a 904 by any means. Yes there are plenty of 10 and 11 sec. guys out there running them but how many of them are running all stock internals in there 904's??? Not many I bet. Just showing that the extra weight and negligeable power consumption is well offset by it's durability. Really I'm just saying there is a time and place for everything. Which ever is easier to come by has alot to do with what you use.

Another consideration is will a trans brake be used?? AFTER ALL THIS IS A BRACKET CAR WERE TALKING ABOUT. Trans. brakes are very hard on parts as mentioned earlier. I believe the 727 will hold up to a trans brake better and when racing you sure don't want to break down any more than needed.
 
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