904 or 727 ?

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cudamike13

cudamike13

cudamike13
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Hi all!
I'm getting to the point where I need to get my transmission beefed up for the 500 hp stroker I'm going to install.

My trans guy said I should go with a 727 as they are stronger and cost less to beef up than a 904.
He said 72 to 78 so I wouldn't get a lock up unit.

The car is a 67 Barracuda coupe. I think the 727 will fit with no problem.
Am I right in thinking this?
Any years to stay away from?

Thanks in advance for any help!

CudaMike13
 
I have a 727 in my 67 cuda, it fits with no problems. As for which would be better, I'd rather have a well built 904 for my combo. I think you're right about using the larger 727 with your car, although a well built 904 should work and they do have less power loss...
 
727 will fit the 67 barracuda with no problems.

727 is stronger,

a 904 will handle the 500 hp stroker and is faster..

cost...dont think a 727 is cheaper then a 904....

define beef up?
 
Yes a 727 will fit in your car just fine, as barracudas came with 727s ( 340 automatic equipped cars) your trans guy is correct the 727 is a beefier unit, but a 904 can be built to be strong as well, but it will cost a little more, as 904 have smaller weaker stock shafts and can break and explode under the higher stress ( torque loads) that race motors can produce. Look for a 727 from a truck/van if possible, as they usally have the bigger drums, and make great cores to build. both 727s and 904s have there weak parts, but both can be built to be great units. 904s are usally slightly quicker in a race car, due to less rotating mass, and lighter weight, so it basiclly boils down to personal preference.
 
Thanks guys for the quick replys!

I would define "beef up" as being modified to handle the 500 hp 498 tq my small block stroker pumps out.

I think I will go with a truck 727 as suggested, and use the savings difference to buy a torque conv w abt 23 to 2500 stall.

I'm not going to race this car, but it will see some full throttle runs!
 
can someone tell me why a 727 is cheaper?....

to be safe a 727 needs the front drum replaced with a billet one ($500)...904 does not..

to be safe a 727 needs a new bolt in sprag ..a 904 does not...
 
I'm building a 500/500 stroker right now myself. My engine builder recommended a modified 904 for my set up, but I already have a rebuilt 727 with a shift kit, so that is what I'm going to run. I'm looking at running a 3000 stall convertor for street use only.
 
cudamike13 said:
Thanks guys for the quick replys!

I would define "beef up" as being modified to handle the 500 hp 498 tq my small block stroker pumps out.

I think I will go with a truck 727 as suggested, and use the savings difference to buy a torque conv w abt 23 to 2500 stall.

I'm not going to race this car, but it will see some full throttle runs!
Click to expand...


beef up is new clutches and steels in 904...

are you going to put old clutches and steels in the 727....so the price is awash

one thing a 904 needs is the 24 spring kit for the front drum...100 dollars
 
I'm in the same boat. I've got a nice buildable 727 but I'm thinking about going the 904 route.
 
70aarcuda said:
beef up is new clutches and steels in 904...

are you going to put old clutches and steels in the 727....so the price is awash

one thing a 904 needs is the 24 spring kit for the front drum...100 dollars
Click to expand...

Please tell me more.
I would rather use the 904 I already have.
Maybe I need to find another trans builder who speaks Mopar!
This guy said it would be way more expensive to build the 904.
He said I would need a new larger input shaft and even then it may break. (his words)
 
Find a new trans guy...

904 needs nothing but decent replacement parts Tony mentions at this level.

The 24 spring kit is more of an RPM thing than a power deal isn't it Tony?

If you have some clean work space, learn to do them yourself. If Tony, myself and mopardude318 can do them... ANYBODY could! :)
 
crackedback said:
Find a new trans guy...

904 needs nothing but decent replacement parts Tony mentions at this level.

The 24 spring kit is more of an RPM thing than a power deal isn't it Tony?

If you have some clean work space, learn to do them yourself. If Tony, myself and mopardude318 can do them... ANYBODY could! :)
Click to expand...

Well you have convinced me!
I'm going to try it. You may have just saved me a lot of money!
Where is good place to buy the trans parts?

cudamike13
 
I have a built 904 behind my 410 sb stroker with almost 500 passes over 3 yrs.My torque converter cost more than the trans build cost.I just had it freshened up and a transbrake added for more race duty.
 
VB's from transact

Transtar deluxe kit from Northern Auto.
 
Currently running 904 in my 71 Dart 408. Probably in the 530 to 550 hp range with 3500 converter. Only running on the street at this time. Very, very happy with it! John Cope built the trans with manual reverse, nothing super exotic, just good parts. See my pictures and specs for more info. When I start racing it, I will probably pull it out and go with a low gear set, a brake and beef it up a little.
 
I'm a 904 fan. Know guys running in the 10's with a 904 and no exotic parts in it.

You can keep that boat anchor 727 stuff.
 
The only thing I see that wasn't mentioned here which is the most important. Would be the weight of your car. 318's were installed in alot of different body cars . The deciding factor at the factory was. The weight of the vehicle. Maybe why all triucks and C bodies had 727's. 904's will handle the HP its the weight of the car that it don't like. If you have a stripped drag car go 904. Any car with High HP and weighs in the area of 3400. you should have a 727.

Not including the gear differences. The 904 does not increase power it increases torque do to the lighter reciprocating mass, So everything is smaller including the output shaft. and the pump drive. PG's are good too but you wouldn't put one in a full weight street car.

So what it comes down to is you as a driver and the HP per weight ratio of the car its going in. I have a 727 in my street weight High HP Duster. The way I drive I would have killed two 904's already. My 727 is in for three years of severe street driving with alot of launches and tire torching . I shift at 8500. It has a 5500 stall with 456 gears and 29x14.5 Hoosiers. . I have 904's if needed. LOL. so this advice is doing nothing but keeping them here.

At the track the 904 is safe there is guard rails and safety people. I wouldn't want to break a 904 on a street lined with poles or trees. This was the result of a trans failure on the street
 

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Wonder why they weren't offered in a 340 car???? Or for that matter any high output mopar from the 60's - early 70's. The most strength for the dollar is 727. Eccept for a sprag and some other small parts most of your up grades can be taken from a used diesel trans. I never saw a 904 behind any big block. And I already snapped the front of the tail shaft on a launch with a stock 904 that had a converter and a valve body behind a stroker. It then exploded . They do make a ton of improvement parts for the 904 so it doesn't break. It just don't see them cost effective for a couple tenths on a bracket/street stroker car. But the small 727 is getting scarce. I guess i'll be keeping all of mine. But like I said guys that go with 904s usually don't have a 727 so they use what they have. Or they are looking for a little quicker ET. Otherwise it doesn't pay to take the chance.


abodyjoe said:
If a 904 doesn't hold up in a 3400 pound car you need a new trans builder...
Click to expand...
 
Maybe because it was freaking 40 years ago. Lol. They Didnt come with efi or od either. So whats the point. Technogly, materials and things change and improve over the years.


Run that big tank of a trans(727) if ya want. Ill keep buying them up cheap and selling them at a premium to the guys still stuck in 1970. :)

DDB605C7-C1FD-4F0F-9774-F5A6CD805EEF-5523-000002ED4BA9EFC8.jpg
 
They weren't offered in the 60's because the parts used in them (clutches/Plates) were not as stout as they are today. The factory didn't want warranty issues. Today parts are light years better than in the 60's and many of the alleged weaknesses have been addressed.

500hp/tq is not an issue for a 904. You start throwing 700+ at them and they won't live. The OP is asking about a 500/500 engine, not some 700+ deal.

904's drums don't detonate like 727's do either, that's one reason I stay away from them.

There is no reason to run a 727 in a 3500# car anymore. Build a decent 904 with a 24 spring kit, decent valve body and go.
 
I,ve heard/read that back in the late 60,s early 70,s,the Hemi racers were using 904 internals in 727,s.How true this is?I guess it,s all behind your builder.Regardless,anybody running upwards off 700HP plus should run a shield wether street or strip.Accidents happen.
 
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