904 or 727 ?

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pettybludart said:
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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Pro trans did that. There are a bunch of machined parts for them. SS/AH cars used 904 internals in 727 cases. They aren't cheap... :)

In this guys case, I'll still take a 904 over a 727 since I won't have the potential issue of a front drum coming through the floor.

Anyone can take a situation and make a case, let keep it in context to what the OP has 500/500. Not an issue for a 904.
 
abodyjoe said:
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
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I agree...back in the day we put 727's in cuz they were cheap stock. The 904 is more bang for the buck now. Find a good trans guy that knows mopar or do it yourself. I won't let anyone in my trans. except me. If there's anything more unforgiving than a f'd up trans I don't know what it is...(ex wives maybe:evil:)
 
Ok guys what about the converter issue with a 904? You know I'm not a 904 basher at all, in fact I promote them a lot, but when you start throwing a lot of torque and hp at them I've seen a lot of 904 TC's with cracked necks unless their a billet converter that costs 300-400 hundred bucks more. That puts a hurt on the build price. And how many drums have you guys actually seen blow in a 500 hp street driven 727? I have not even seen one. Yes, if it's a race car with no low band apply you definetly need a good drum but I'm not so sure about a 500 hp street car.

I have crunched the #'s of building a 904 vs. a 727 and the 727 always comes out cheaper by about $300. Now if the car already had a 904, changing to a 727 would necessitate a new driveshaft that would eliminate the diff. in build price and possibly even put it higher than a 904 so I'd stay with a 904 in that case.

And as for the claims that a 904 is a whole bunch faster than a 727 I'd like to see proof. Faster yes I agree their faster. A whole bunch faster I really doubt. And if it's not a race car why does a tenth or even 2 tenths matter that much? I have a buddy that has a mid 10 sec. 67 Cuda and he smoked his 904 mid season and didn't have the money to do it up good and put in a 727 that he borrowed and raced the season out. There was right at .1 difference between the 2. In a heads up track race it's important, but in a street car... JMHO :toothy10:
 
abodyjoe said:
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
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Hey Joe is the drum actually blown in that 727? Looks to me like something broke the case but the drum is ok, but I can't see it real good cause the pic is so small
 
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
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Where do I find the 24 spring kit?
 
I will be able to tell you how a built automatic shifting 904 does behind a 500+ HP stroker in a little while. PTC is building one for me now, as well as a 3500-3800 converter. The engine/conv/tranny combo will be shaken down in a lightweight drag Demon and ultimately wind up in a 68 street fish.
 
200r4 light, handles power, and an overdrive to boot.
 
This is the pic that Tracy posted but blown up.

And a 700R4 can't handle that power as a stock unit, it would also have to be beefed up plus all the other changes needed to use it.

Also notice which direction all that steel goes when they explode, straight up through the floor.
 

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Is there a big difference in physical size between the 2? I got a real nice 727 core that I was going to build for my 65 dart but if a 904 is a bit slimmer ill go that route just because of exhaust clearance etc. if not ill just build the 727.
 
fishy68 said:
Ok guys what about the converter issue with a 904? You know I'm not a 904 basher at all, in fact I promote them a lot, but when you start throwing a lot of torque and hp at them I've seen a lot of 904 TC's with cracked necks unless their a billet converter that costs 300-400 hundred bucks more. That puts a hurt on the build price. And how many drums have you guys actually seen blow in a 500 hp street driven 727? I have not even seen one. Yes, if it's a race car with no low band apply you definetly need a good drum but I'm not so sure about a 500 hp street car.

I have crunched the #'s of building a 904 vs. a 727 and the 727 always comes out cheaper by about $300. Now if the car already had a 904, changing to a 727 would necessitate a new driveshaft that would eliminate the diff. in build price and possibly even put it higher than a 904 so I'd stay with a 904 in that case.

And as for the claims that a 904 is a whole bunch faster than a 727 I'd like to see proof. Faster yes I agree their faster. A whole bunch faster I really doubt. And if it's not a race car why does a tenth or even 2 tenths matter that much? I have a buddy that has a mid 10 sec. 67 Cuda and he smoked his 904 mid season and didn't have the money to do it up good and put in a 727 that he borrowed and raced the season out. There was right at .1 difference between the 2. In a heads up track race it's important, but in a street car... JMHO :toothy10:
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I ran a 904 for 5 years in my Dart it ran high tens in a 3440 pounds street car. I had a 450 hp small block with a 200hp N2O kit on it pushing the button right out of the hole. It held up just fine. I did break the snout of the converter once and it was due to my bell housing not being perfectly aligned. Pro Trans in Lancaster Ca has done my transmissions for years and his expertise is second to none. His prices are exceptionally resonable as well.

The 904 is much smaller externally than a 727 as well.

The 904 is much cheaper than the 727 to build in my experience. I dont have proof other than first hand experience in 2 cars I have personally owned that have done extensive track time. My small block Dart picked up .4 and just over 4 mph and my big block Raod Runner with a stock 383 picked up .5 and 4 mph if my memory serves me. Both cars were consistent cars that had the transmissions and restested the next weekend.
 
a 904 is .15 quicker and about 2 mph faster,,,,,as I removed a 727 and replaced it with a 904 in a 11 flat car back in 1992....the 727 actually had a better converter then the 904 did at the time...

the 904 is about 35 lbs lighter then a 727 and most of that is internal rotating parts...

a 904 will not bolt up to a 383 without some kind of adapter....
 
turbodart68 said:
I ran a 904 for 5 years in my Dart it ran high tens in a 3440 pounds street car. I had a 450 hp small block with a 200hp N2O kit on it pushing the button right out of the hole. It held up just fine. I did break the snout of the converter once and it was due to my bell housing not being perfectly aligned. Pro Trans in Lancaster Ca has done my transmissions for years and his expertise is second to none. His prices are exceptionally resonable as well.

The 904 is much smaller externally than a 727 as well.

The 904 is much cheaper than the 727 to build in my experience. I dont have proof other than first hand experience in 2 cars I have personally owned that have done extensive track time. My small block Dart picked up .4 and just over 4 mph and my big block Raod Runner with a stock 383 picked up .5 and 4 mph if my memory serves me. Both cars were consistent cars that had the transmissions and restested the next weekend.
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I don't know everything obviously but I've been rebuilding them for over 30 yrs. (mostly 727's) and I pretty well know the best sources for parts and just can't seem to build a 904 for less than a 727, but I always figure in a converter with a billet neck which raises the price quite a bit. Maybe I'm overthinkg the converter issue, but I believe a lot of other guys also overthink the front drum issue with the 727. Is it necessary? In any race application, Yes. If your running a manual valve body with no low band apply, Yes. But in a 550 hp street car with a VB with low band apply I don't believe so. It is a saftey concern and a lot of guys get scared as soon as they see a picture of one blown apart. Funny thing is I keep seeing the same 3 or 4 pics of blown 727's. Not 100 or 1000. Not saying or trying to down play the issue, I just haven't seen proof that the problem is nearly as bad as it's made out to be.

I can understand a low torque engine could benefit far more from a 904 and if you have an early A-body a 904 is definetly the way to go.

This is just my back in 1970 opinion, LOL

BTW: How'd you get a 904 to bolt up to a big block?
 
70aarcuda said:
a 904 is .15 quicker and about 2 mph faster,,,,,as I removed a 727 and replaced it with a 904 in a 11 flat car back in 1992....the 727 actually had a better converter then the 904 did at the time...

the 904 is about 35 lbs lighter then a 727 and most of that is internal rotating parts...

a 904 will not bolt up to a 383 without some kind of adapter....
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Thanks for the real world #'s Tony.
 
gtmopar said:
Is there a big difference in physical size between the 2? I got a real nice 727 core that I was going to build for my 65 dart but if a 904 is a bit slimmer ill go that route just because of exhaust clearance etc. if not ill just build the 727.
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904's are quite a bit slimmer, and a few inches shorter. IMO you definetly want a 904 in an early A. There's not much room there anyway. Sticking a big ole 727 in it will make life a PITA when working on it.
 
These guys are the experts compared to me for sure and this is where I come for advice - they helped me a lot doing my first rebuild and as I work out the kinks. I just traded a stock low mile 727 to a guy for an old 904 and 50 bucks.

He was doing a stock 318 and was telling me how the 727 is better and more reliable, and stronger. "Why don't you want to use that 727?".

I was like yes, you're probably right, I just don't want to have to cut my driveshaft. lol
 
I have a built 904 for sale ready to go for 200.00 less than 3600 miles has all the beefed up parts already in it. Just need your converter and you are ready to go.
Rob
 
cudamike13 said:
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
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WITtrans has been very sweet to me, good prices, everything you need. Since were talking OD, 42RH all the way, take a look at the top sticky link. :D
 
Hey fishy68.
Just curious, how many horse was your pal running in the 67 Cuda that blew the 904 out? If I was running 500+ h.p. I'd run a 727. At mid 10s I'm assuming he was over that???

I have a buddy that has a mid 10 sec. 67 Cuda and he smoked his 904 mid season and didn't have the money to do it up good and put in a 727 that he borrowed and raced the season out.
 
pyrojim said:
Hey fishy68.
Just curious, how many horse was your pal running in the 67 Cuda that blew the 904 out? If I was running 500+ h.p. I'd run a 727. At mid 10s I'm assuming he was over that???

I have a buddy that has a mid 10 sec. 67 Cuda and he smoked his 904 mid season and didn't have the money to do it up good and put in a 727 that he borrowed and raced the season out.
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I don't remember the exact # but it was right at 500, or just slightly above.
 
Are 10.60s and 10.70s mid tens? got 3 904s with years of racing on them with no problems with transbrakes..

one was last rebuilt in 2005 (69 barracuda)...another in 2006 (71 Dart)..and the last one was done in 2010 (71 Demon)..just put one together a couple of months ago for 71 duster...car has not left the garage yet.

each one has 24 spring kit in front drum...each one has a reinforced band strut ....two have stock disc and steels...barracuda has alto disc and kolene steels...all have kevlar bands...and all use tranzact Pro brake valve bodies....and my biggest speed secret is the type F fluid from wally world...

71 Duster 904 has stock disc/steels...24 spring kit, kevlar band..TA valve body..reinforced band strut

if you can not get more then a half season out of a 904,,,better find someone else to build them...cause i did not stay in a holiday inn ...ever,,,and I have rebuilt this 3...

yeah..probably not making 500 horses either...probably 450-475 hp

need to make sure you clutch pac clearance are right...remove and replace pump bushing, front drum bushing and rear tail shaft bushing...check thrust washers for wear and replace as necessary....if racing ..replace single wound spring with 24 spring kit (single wound spring comes unwound and lets front clutches drag at high rpm)....and reinforced band strut...and I am using 5.0 kickdown levers in all of them....that is about Beefed as a 904 I get..

as said before..pick your parts and spend your money....if 727 floats your boat..go with it...
 
Tony when I said he smoked it mid season I didn't mean, or say, it was the 1st season. I think it was his 3rd. I was just making the point that he swapped to a 727 and only saw .1 diff in perf.
 
fishy68 said:
I don't know everything obviously but I've been rebuilding them for over 30 yrs. (mostly 727's) and I pretty well know the best sources for parts and just can't seem to build a 904 for less than a 727, but I always figure in a converter with a billet neck which raises the price quite a bit. Maybe I'm overthinkg the converter issue, but I believe a lot of other guys also overthink the front drum issue with the 727. Is it necessary? In any race application, Yes. If your running a manual valve body with no low band apply, Yes. But in a 550 hp street car with a VB with low band apply I don't believe so. It is a saftey concern and a lot of guys get scared as soon as they see a picture of one blown apart. Funny thing is I keep seeing the same 3 or 4 pics of blown 727's. Not 100 or 1000. Not saying or trying to down play the issue, I just haven't seen proof that the problem is nearly as bad as it's made out to be.

I can understand a low torque engine could benefit far more from a 904 and if you have an early A-body a 904 is definetly the way to go.

This is just my back in 1970 opinion, LOL

BTW: How'd you get a 904 to bolt up to a big block?
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The numbers I came up with are from my own real world experience. I also always run the low gear set which helps in the e.t. department. At the time my cars were running low 13s so my results will be more dramatic.

I love the 727 but why not run a baby version. My 727 in turbo car took over 1000 hp with no complaints. I dont build my own transmissions I have Pro Trans do them and the 904 is always cheaper. Go figure. So I can't really comment on why they are cheaper.

To run a 904 behind a big block I cut off the bell housing in a mill and bought a bolt on bell from JW. Dave over at Pro Trans scolded me and said the JW Ultrabell actually makes the case weaker and would have rather seen an adapter kit used. Next time I will do just that.
 
turbodart68 said:
The numbers I came up with are from my own real world experience. I also always run the low gear set which helps in the e.t. department. At the time my cars were running low 13s so my results will be more dramatic.

I love the 727 but why not run a baby version. My 727 in turbo car took over 1000 hp with no complaints. I dont build my own transmissions I have Pro Trans do them and the 904 is always cheaper. Go figure. So I can't really comment on why they are cheaper.

To run a 904 behind a big block I cut off the bell housing in a mill and bought a bolt on bell from JW. Dave over at Pro Trans scolded me and said the JW Ultrabell actually makes the case weaker and would have rather seen an adapter kit used. Next time I will do just that.
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Ok. That explains the dramatic difference. in e.t.

A 727 capable of holding 1000 hp would cost a bunch more to build. Even if not building for 1000 hp cost always goes along with what parts you use.

If you re-read my posts (and numerous other posts I've made concerning 904's in different threads) you'll see I don't say not to run a 904. Each has their own application.
 
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