Tranny Recommendations for 600 HP

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1BA1970Dart

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Hi everyone. I'm having my engine built now to 550 to 600 horse. I have a standard 727 tranny. Any recommendations on a rebuild, if I need it, or what I really need to get done to ensure it handles the extra horse. I was told I need a converter with 3000 stall based on my 3.91 gear set up. Any advice I can get on parts I need or suitable rebuild would be greatly appreciated!
 
What is your intent for the car? Drag only, street only, etc...
That said, personally I'd go with a 904. It takes less HP to power the tranny (I believe it has 15-20 HP while the 727 takes ~40). One other thing you might want to consider is the GM 200R4. It's all hyd o/d tranny that can take a LOT of HP when built and like 904 only takes ~20 HP to power it.
 
Depends on the use but and if your going to be racing it at all to avoid a Trans explosion I would do all of the below. If not racing all of below except the Billet Front Drum.

904 is cheaper to built for racing purpose cause their is no need for the billet front drum and it will handle your power fine.

I just bought all the parts for my 904... $480.00 for the kit and everything below except the valve body, billet front drum and sprag.

Billet front drum, red clutches, new steels, Kevlar bands, billet rear servo, HD band strut. bolt in roller sprag. Hd return spring module for front clutch pack, new pump gears, your choice of valve body & new billet band apply lever to match valve body.
 
Intent for the car is for street and maybe 1 run at the strip in its lifetime to prove the build. So primarily a fun street able car. ( if it makes a difference). This forum is great! Thanks for all the advice!
 
I'd go with an overdrive tranny if I were you.
 
Ok thanks. I will be removing the 727 this Friday and will look around for a 904 with overdrive. I'll have a look on here first for any for sale. Any tips on reputable shops to buy a complete 904 from? Thanks again!!!
 
An overdrive transmission will have its own set of issues on install and they will vary depending on the transmission you choose. You need to make sure of these issues before you jump.
 
1BA1970Dart said:
Ok thanks. I will be removing the 727 this Friday and will look around for a 904 with overdrive. I'll have a look on here first for any for sale. Any tips on reputable shops to buy a complete 904 from? Thanks again!!!
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Call Martin Saine of MSP or Rick at A&A
 
I love the idea of overdrive transmissions. I am not sure though, that it would be cost effective at your intended HP level to build one. The GM 200R4 is a great transmission, but it's gonna take some dough to make one live.....but you can certainly do it. Course the A518 would be a great choice, if you didn't have to rebuild the whole frikkin floorpan. That leaves the GM 700. Not the most optimal gear ratios, BUT it is more popular and that could save some coin in building for that power level. If it was me, I would just build a warmed over 727 and be done wif all dat. They'll hold up at that level with no sweat.
 
1BA1970Dart said:
Ok thanks. I will be removing the 727 this Friday and will look around for a 904 with overdrive. I'll have a look on here first for any for sale. Any tips on reputable shops to buy a complete 904 from? Thanks again!!!
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Cope racing transmissions. Just did my 904, awesome, not a problem. But, you being in Washington, freight might kill you. But John Cope knows the Mopars.
 
You're looking at ~$2000 minimum for a 2004r to fit your application, plus the costs to install it. Roughly $4k.

You could do a 904, they can be built it nice, or you could just build the 727. I don't think you could go wrong with either one if you go about it right.
 
Not to pick your build apart, because I love making the most HP and TQ for my money, but that HP range is gonna be real sketchy on the street. To build that kinda power your gonna need a radical cam, really good heads, a big carb, a tall set of final gears, and a high stall converter. By the time you get it all matched perfect your not gonna like it on the street. I have done this many a times thinking I could tame a high HP engine (over 500 hp) and make it streetable. Boy was I highly disappointed every time. I've come to the realization that usually around 450hp maybe 500hp is the most on a street only car. I wish you the best of luck though!

Oh ya on the tranny, the 904 maybe uses less power to turn but you'll be glad you built a 727 instead. The 727 is the strongest hydraulically controlled factory tranny Chrysler has ever produced. Do a little research and you'll prove out my statement. Also, who cares if it takes 15 extra HP to turn it when your engine is turning out over 500hp!

Now if this was drag only car I would say go 904 cause you want to squeeze out every drop of power and put it to the ground. On a street driven car thats gonna see alot of stop and go driving, you want the beefier tranny.
 
I thought I read a couple of test reports stating the in drag racing, the difference in time with a 904 vs a 727 was something like a 1/16 of a second.

For the street, I like the 727 because it tends to be bullet proof..

Grassy
 
If you aren't after every last bit of ET, build a 727 with good sprag, low band apply valve body and other basic performance items and you should be fine.

Only real drawback to a 727 is potential front drum explosions. That can be minimized if you learn what to do and not do when running a 727.
 
Whew!

I'd do the 727 and not worry about the difference in power consumption.
 
Anything that will make a 727 explode will make a 904 explode too. Do burnouts in 2nd gear.

600 HP small block? Naturally aspirated?!? That's a pretty pissed-off motor! If you're looking to build "a beast" you're on the right track. But you're also on the right track thinking the high mileage stock 727 in the car now will go away pretty quick if left alone.

The 727 has been on race tracks for 50 years now, there is a pretty good knowledge base for what works, and what lasts. I'd call some of the usual suspects that build race car Torqueflites.

If you're looking for a "tranny guts in a box" type kit this should give you an idea what you'll spend http://smrtrans.tripod.com/smrtransmissionsintro/id51.html Figure at least half the transmission cost for a GOOD converter.
 
C130 Chief said:
Anything that will make a 727 explode will make a 904 explode too. Do burnouts in 2nd gear.

600 HP small block? Naturally aspirated?!? That's a pretty pissed-off motor! If you're looking to build "a beast" you're on the right track. But you're also on the right track thinking the high mileage stock 727 in the car now will go away pretty quick if left alone.

The 727 has been on race tracks for 50 years now, there is a pretty good knowledge base for what works, and what lasts. I'd call some of the usual suspects that build race car Torqueflites.

If you're looking for a "tranny guts in a box" type kit this should give you an idea what you'll spend http://smrtrans.tripod.com/smrtransmissionsintro/id51.html Figure at least half the transmission cost for a GOOD converter.
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That is not a True Statement. Please show us 1 example of a 904 exploding. 727 Yes 904 not the case. See the post below>>>

http://forabodiesonly.com/mopar/showthread.php?t=2167
 
3941670936_8f5151f26c_b.jpg


Kaboom
 
Found on another forum. behind a max wedge with a sub par aftermarket valve body. Sprag came apart and well the rest is history. Looks like some serious carnage. Hope there was a scatter shield........
 
71Scamper said:
Found on another forum. behind a max wedge with a sub par aftermarket valve body. Sprag came apart and well the rest is history. Looks like some serious carnage. Hope there was a scatter shield........
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Can you post a link? I am curious as all get out to read the whole story.

This is the very first case I have ever heard about. From what you are saying the VB was subpar so I wonder what else was subpar in this trans to make this happen?
 
I have run a 904 and 372 stroker for almost 7 years on the street. Motor dynoed at 540 and the 904 was built with all the above mentioned parts. This is in a 65 Valiant full interior street car with 4:30 gears and it is the tamest motor I have ever had with a solid roller cam. Reverse manual valve body 27" drag radials and car runs mid elevens through mufflers and on pump gas. Holley 750 with Victor intake and RPM ported heads. The 904 has been bullet proof and also weighs less than a 727. My mother could drive this car if I could teach her how to shift backwards. The 904 has never been opened up since it was built, 3000 stall. I would probably not build a 727 unless it was behind a big block with more torque than 500 and horses above 550 - 600.
 
PoisonDart74 said:
This is why you don't do 1st gear burnouts, always selected second!!!
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There are all kinds of reasons why that 904 could have came apart. At this point I am not sold on the idea that it rolled the Sprag making it happen. The driver would have had to keep his foot in it revving the engine into the 9k range to have enough RPM at the drum to have it explode. The drum would need to spin more than double the engine RPM for the Drum to be the reason it exploded. Correct me if I'm wrong but I thought a 904 drum can handle in the 20k RPM range before it exodes.
 
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