HELP ! what to use 904 - 727

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74 dustaar

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1974 duster, I am replacing my 318 with a 360. the 360 will be .040 over on the bores. ISKY 280- Mega Hyd. cam. I am running a 391 gear and here is my problem. I am running a 904 ( stock ) with a shift kit. Should I buy a 2500 stall for the 904 or go with a 727. 904 is in good shape and I am not on the drag strip but I love to do burn outs etc. Will the 904 hold up ? Thanks for any input B.C. BUY AMERICAN
 
If you like to do burnouts... 904....

Ever seen what happens to a 727 sprag failure in low gear? Google 727 transmission explosion.

A 904 is more than capable behind that engine.
 
No, I have never seen a sprag gear period LOL. I did read some of the other threads about this but wanted reassurance. Thanks for the reply
 
I vote for the 904 also - have 900 miles on mine behind a 400 hp 450 tq 360 and I have had no problems
 
O.K. see here we go Venomvpr900 your trans is a 998 with performance adders and I have figured out that a 998 has more clutch plates than a 904. Mine is a stock 904 with a shift kit no extras. Thats what scares me when I am told a 904 will work but I am not told about all the upgrades they had to do to it to make it work. Learning on a limited budget here
 
our 71 Dart ran 2 seasons with a "904" which only had 4 clutches in the front , at that time it was running in the low 12s, and it had a transbrake in it for one season.

now the 904 is a "999" since I installed 5 disc in the front drum...
 
Did you have to buy a new front drum to accept the extra plates or is it a matter of me just buying a kit. No I have never built a trans. But over the winter I would try, I can always take the box of parts to the trans guy LOL. I did buy a book and it tells of the 998,999 being behind the 360 block in the late 70's
 
Out of my 6 small block Mopars, four were running 904's and two had 727's - none of the transmissions had any modifications. The only trans failure I had was with one of the 727's. It was in a 71 Challenger with a lot of engine mods and had been driven really hard, so I wasn't surprised when it finally let go. I've asked the same 727 vs. 904 question myself and have been told by some very experienced and trusted members that the 904 is a strong little tranny that will take some abuse, and it has a slight weight advantage over the 727.
 
here is how i do it...

the standard front disc is .086 thick, there is .061 disc available...

by going to the thinner disc...you are saving .025 per disc...so 4 x .025= .100

you are adding a fifth disc and steel....you are adding .061 plus the steel of .068 which is .129 ....

the problem is now you are not going to have enough clutch clearance,,,,it will down around .050 plus or minus a few thousand..

by using different snap ring thickness which are available from A&A trans you can get the clearance you need which is around .070 with 5 clutches...

but i do it a little different..I take the pressure plate that goes in the clutch pac and have it ground down .020 to give me the clearance...

I have done 3 trans like this and have no problems....two are in race cars...

actually have another 904 almost ready to assemble...just need to get a few parts...PLUS it is HOT out in the garage now.

there are alto red clutches that are available for the 904....
 
Thanks, I should have my 360 built by next week so I am going to get me a new stall and run it. I like the way you did the 5 clutch pack and when I need to I am going to try the same by grinding the plate.
 
theres a 904 in this dont kno if its a 999 or 998 goin 10.38 at 120 some mph picture is too big but its a 69 amx doin a wheelie about 3 foot off the ground
 
I vote for the 904 also. I use one in my NHRA stocker and never had problems.

Ken
Edison, NJ
 
I Use A 904 You May Want To Install A Reverse Manual Valve Body And Do All Burn Outs Starting In 2nd And Then Shifting To 3rd. And Use A Stall Around 3000. It Will Be Ok For Street. Read The Article On Exploding TorquEfliTES Above Your Post It Explains A Lot Of The Pros And Cons .and Showes A Sprag Explosion. In A 727 And At End Of That Post You Can Read What Happend To Me. Good Luck Gary
 
O.K. if I mount a 727 in place of my 904 will the linkage from the 904 work ? Am I going to run into problems or will it bolt right in.
 
stock linkage? or aftermarket shifter linkage?

aftermarket shifter linkage will work fine

stock...i believe one rod is shorter on the 727 then the 904...the rod that fit on to the shifter lever.
 
stock linkage is what I have. I found a 727 with a stall and is supposed to be in good shape. Now I either buy a stall for my stock 904 or add a few $$$ and get this 727 but I don't want to be chasing parts and I know I will need a new drive shaft with the 727
 
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