OK, I want to build up a 904 for drag racing. Since I don't want to build up the one in my 65 Plymouth (doesn't have the slip yoke), I was wondering what would be the best year trans to look for. I have a 79 /6 trans but it is a lock-up converter transmission. So, what are the best years for the 904 trans?

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-MattMan
LEANED & MEAN

What's wrong with the lockup transmission? You can shim the spring that controls the lockup and make it never lock up.

I have heard to avoid the lock up converters for drag racing. They are heavier than regular converters plus, I want the option of putting a different stall speed converter in it as I may need something higher than stock, depending on the cam I go with.
I have heard that 72 and later trans are heavier duty than earlier ones. Just hoping for confirmation on this. I know of a police car (Diplomat) in a salvage yard that may have a 904 or 999 trans. The engine was pulled (318 4bbl) so I'll have access to the trans. I would get it for the heavy duty internal parts (put them in a /6 904 case). I have no problem with mixing parts to get a solid trans. If I am doing all this hard work, I may as well have a good base to start with.
What do my fellow drag racers do in the transmission department?

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-MattMan
LEANED & MEAN

Grab the cop car guts and put them in the slant six 79 trans, but keep the gears form the 79 trans. The Diplomat will have the wide ratio gears which is not good fro drag racing (top much RPM drop between gears). The Diplomat trans will have a four planetary gears as opposed to the 79 slant trans' three, but the planetary gears must be used with the wide ratio gears. If you can find a 70s or earlier v-8 transmission you can use the gears out of that rans to get the four planetary gears with the non-wide ratio gears.

Back in the day, one of my buddies demo derbied a 1981 Cop Car Dippy, and late a 1983 Cop Car Gran Fury....both had 318-4v and were equipped with A-727's... So when you are back out there check the pan shape to see if it is a 904 vs. a 727...

FYI...

True! For got that the M bodies could be had with a 727.

Well, I am hoping it is a 904, but if it isn't, I am pretty certain that they have something there with one. It would be great to get one of the heavy duty ones.

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-MattMan
LEANED & MEAN

FYI- all 1981-up slant six 904s are 904Ts. More clutches and four gear planetaries (better than older slant 904s), but all will be wide ratio gearsets (not desireable for drag racing).

Use you 79 trans, but get a V8 904 for the clutch packs and gears.

Mine is the wide ratio trans and works ok in my drag car,then again I shift at 6200.

Be aware that the pilot hole in the end of the crank, is smaller in the 67 and older engines, then the 68 and newer engines. If you have the early crank, you must use a special (custom) torque converter, if using the later trans.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Well, my 65 engine is FUBAR. Spun two rod bearings AND has a cracked block (not related to the crank problem). I am going with my 79 engine. It is cast crank but I don't think it will really matter for my use. I plan to use it with my 65 cable shift trans (using the pilot hole bushing for the crank). I am considering building a newer 904 if I can get all the right parts. I still have the 79 lock-up trans to work with.

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-MattMan
LEANED & MEAN

I would say any 68-76 904 non lockup is going to be fine.

If you are serious you can go to Rick at A&A transmission http://www.aandatrans.com/Departments/C ... Trans.aspx

they have all the small parts, advice and info you will ever need to build the trans you need.

I have the close ratio grearset in the ruster drag car now, going to a low gear first this winter with bunch of other trick parts from A&A.

if you want to lighten it(aluminum drums etc) and go with a full roller look to drop about $3200 -

I will be doing the install of all these goodies this winter.


Good Luck..

Greg

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http://www.youtube.com/hyperpack

What gear are you running in the 'Ruster'?
I was thinking the low gear set would be advantageous for a 1/8 -1/4 (dual purpose) drag car.
I will be running 3.55 (with a 3.91 in reserve).

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-MattMan
LEANED & MEAN

Unless you have a car like madmax, the low gear set is a waste of time. What you gain in the 60' you give back at the shift. Max has a very light car, lots of converter, and makes a lot of horsepower.

There are no free lunches.

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Official Cookie and Mater Tormentor.

Ouch!, what can I get for $200

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6