904: should I switch to 727?

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Please refer to post #19 by that one guy that comes in here running his mouth all the time like a damn know-it-all.
 
My 727 behind my 360 has done very well. Only concern in the back of my mind is the front drum which some have had it explode. I just street drive no racing so i guess that keeps it safe? Some burnouts have been done in the past though.
 
You have to blow the sprag to spin the front drum fast enough to explode. It's when something like a driveshaft lets go while under power. The rpms jump and somehow the drum spins triple engine rpm. If you can burn out in second, then the drum can't spin cuz the band is holding it stationary.
 
I had a 904 (998 / 999?) from an 85 Fifth Avenue in my car behind 300-ish HP for around 15 years. It was rebuilt with good quality stock internals and still had the lockup converter. I beat the living hell out of that transmission on the street and never broke it. Then I put installed an earlier non-lockup 904 and had it rebuilt with good quality stock internals, and I beat the hell out of that for 5 years before pulling it in favor of a 46rh.

Keep in mind I wasn't really racing the car and only driving it around 3000 miles a year.
 
volaredon said:
I've burnt out more 904s in stock daily driving than I can shake a stick at. I've never had a "race" car, put mild cams and 4 bbls on a few but that's about it.
I've swapped 727s in place of 904s whenever there was a 727 available. Problems solved.
318, 2bbl, 2.xx gears even.... And I have not had much luck with 904s. ..
I'd be interested in what you guys mean by "built right" 904. .. most of mine have been assembly line stock.
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Not all that useful experience to mention, you said yourself "assembly line stock". I agree in that form they're weak and burn up easily. Fried my original stock one behind a 318 that probably didn't even make 250 HP. If they were truly junk transmissions though I don't think Chrysler would have bothered to continue using the design for decades; the later beefed-up versions (998, 999, 32RH etc.) held up well in lighter-duty trucks and SUVs behind the 318.

I went back and looked up the thread about swapping the valve body in mine, @CudaFactHackJob was the one who guided me through the process and I couldn't be happier with how it turned out. Listen to him, he knows his sh*t. Here's the thread if you're curious: 904 giving up the ghost?
 
run the 904. If it starts to slip rebuild a 727 when you're going to spend $$$ anyway. For the 904 - put in a shift kit, or buy a beefed up valve body (A&A is my preference). This will increase the pressure behind the clutches and make it last longer especially under stress. You can do either of those without even removing the trans.
 
If you are gonna spend money on something like a valve body scrap the 904 and go 727 instead. You'll be money ahead
 
There is a "torque limiter" which protects the transmission, which is when the rear tires slip. I would expect that if using typical street tires, with no downforce like from a trailer tongue load, the tires would always slip before transmission parts break, even in 3rd gear at low speed. People who break transmissions and differentials, plus twist driveshafts are usually drag racers using wide sticky tires.
 
75Chimera said:
Well, crap, forgot to put more pertinent info! I haven't gone through the engine yet, but will likely run a mild cam, and have the cylinders bored to the next size as needed. I have NO idea about final horsepower. I think stock was what, like 270-275? I'd like to increase that a bit just for bragging rights, but nothing crazy. I currently have the 3.91 third member, but I'm considering something a little shorter so I get a bit better mileage, more in town / longer drives drivability. If that makes sense.
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Keep the 904. They are a good transmission. Biggest problem was selecting rev with the choke fast idle on. Break the rev band. All the transmission shops on what seemed every corner years ago relied on the General's slush boxes. If they had all been built like the Mopar autos, there would have been far fewer. Try to find a trans shop now. I would look to 3.23 gears for a mainly street vehicle. Then down the road and you want even better fuel economy, you could install an O/D auto with the police/taxi shift kit. Durability w/o the neck snapping hard shifts. A 3.55 gear common in Dakota 8.25 rear ends would work also. Just find one with a good posi.
 
volaredon said:
If you are gonna spend money on something like a valve body scrap the 904 and go 727 instead. You'll be money ahead
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I would suggest a shift kit or valve body upgrade for ALL transmissions. I put manual valve bodies in all my trans, 904 and 727. The TA RMVB in my 904 would swap right into a 727 if I were to choose to. If the 904 in my Duster fails, I will rebuild it or the other 904 in my garage. How would I be "money ahead" by purchasing a SB 727 along with the proper slip yoke rather than just slightly beefing up the 904 I have ?
 
Don't think you should give up the 904:

Screenshot_20200828-220947_Gallery.jpg


But those 727s sure are pretty:

20180620_181813.jpg


☆☆☆☆☆
 
Oldmanmopar said:
I am a 727 man. I'd destroy 904's with Horse power. Just think how long a 904 would last behind a 440 or a Hemi. Probably why they never offered any Big block 904's. If your lacking that much power to turn a 727 keep the 904 and rebuild it more often. Put a 7 1/4 in much lighter also.
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Well you said it there, destroy with HP. What you really mean is torque. The General and Ford trans models 4Lxx and 4Rxx, the 60, 65, 70 and 75 is the design torque, X10.
When the General came out with the TH 200, it was designed for I6 and 305 2V engines. Functioned fairly well. Then some deranged einstein decided they could save weight in the Impala and Caprice models with a 350 4V engine. The torque ate them.
Then they added O/D. When they put that trans in the Grand Nationals they got beefed up. Then the hot rodders tinkered with the engines and the trans companies designed upgraded internals. They will now take 800 ft lb of torque, not cheap though.
 
Here is the 1971 Challenger A-904 from post #44 above, that had the "4 Pack Clutch Set" not the standard 3 pack.

So yeah this particular '71 904 is the one to build.

20230204_161106.jpg


☆☆☆☆☆
 
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abodyjoe said:
nothing exotic... good parts, extra clutch, correct kickdown leaver, proper clearances everywhere and **** kit home made or quality bought...
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Yeah, the extra clutch that everyone overlooks like in the post #47.

Go Get Them . . .
 
Keep the 904.
Even better if you can find a 999 or 998 from the late 70's to early 90's (Basically a beefed up 904 the 1980's version had wide-ratio 1st & 2nd gears, 2.74/1.54/1.0 vs. the normal 2.45/1.45/.1.0 1st, 2nd and 3rd gears)
--A lot of the F, M & J platform cars in the late 70's & 80's had these as well as V6 magnum Dakotas and some vans etc. For Example mine came out of a *1988 Dodge Diplomat Police Cruiser. (Plymouth Gran Fury was the "corporate twin")
I've been daily driving a 10.2 compression 360 with it for nearly 60,000 miles. No issues. Done many 500+ and 1000+ mile trips, it has never let me down.
Mine was rebuilt using a deluxe HP rebuild kit Kevlar bands, kolene steels and red eagle clutches.
I also put in a stage 2 Cheetah valve body kit from Turbo Action.
The ole' transmission tech who helped me rebuild mine (he's been doing it for over 30 years) assures me that mine can easily handle the 450+ hp 408 stroker I'm building at the moment.
---> He did tell me to get rid of the 8 1/4 rear axle that have. (I also have an 8 3/4 that I'm assembling)
Don't get me wrong the 727 is a good transmission it's just heavy and soaks a bit more horsepower than the 904. (I read somewhere that it's like 45 hp vs. 24 hp)
There's a guy locally here in UT that I talked to years ago at a car show, he had a 490HP 3G Scat Pak Hemi bolted to a modified 904 and has no issues.
-- (yes the new 3G hemi's will bolt up to a SBM pattern transmission, they just don't utilize the 12 o'clock bolt and need a spacer due to crank offset)
This is not the exact site I used in the past but something similar: A904 HP Rebuild Kit A998 A999 Master Banner Overhaul Automatic Transmission Dodge Chrysler Jeep

*Those Diplomats & Gran Fury's were sure ugly but in a kind of a lovable way (like a warthog), but they do make great unassuming "Sleepers" (they do have a following with respect to the dippy.org goons)
Nothing like watching a some young guys face when his new Mustang GT gets left in the dust by some ugly 1980's Minecraft looking monstrosity of a car.
 
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