904 transmission input shaft

[Barra_67]

Hi all,
I have a 904 transmission with code 2801534Y on the side.
From what I can tell this came with the 67 Barracuda that had a 273.
The input shaft is the 3/4" 18 spline version.

I am going to use the 273 steel crank in a 318 build which should make around 400HP.
Will the smaller 18 spline input shaft hold up?

What is required to change this to the later 7/8" 27 spline version? Just the shaft or will I need a drum or other parts?
I realise I will need a converter to match the 27 spline input shaft and the 273 crank pilot hole machined to 1.810".

Please see pictures attached.

Forgot to add that the transmission has been rebuilt. Prior to me purchasing it.

 

[Plymouth 65]

It's been a few years, but I believe you will just need the input shaft and later year clutch hub. 65'

 

[AJ/FormS]

>All 67 up A904s fit all 67 up LA-convertors, and have the larger TC pilot
>66 and down A904's, have the smaller stuff, and require the matching crank, or conversion.
> For a streeter, the 273 A904 will be just fine behind an HO318. In my youth, I put one behind a 340 2bbl, and ran thechit out of it for some two years before it broke.
----------------------
>To get to 400hpNA, with a true 318, is gonna take a lotta effort and, on the street, can hardly hurt a fresh A904 cuz you will rarely get the rpm up, to where the power is, unless you have race-gears in the back. And with a low to modest stall, the much smaller torque numbers make much smaller horsepower.
For instance;
300 @2500 is 143hp, the torque is now building,
315 @3500 is 210hp, the torque soon peaking
330 @4500 is 283hp, at the peak
325 @5500 is 340hp, the torque now declining.
320 @6500 is 396hp
>The biggest tires that you can install INTO the rear tubs of a 67 is either a 275/60-15, or a 295/50-15, and they only come, in one kind of street rubber, namely slippery as heck, so, unless you modify your rear suspension for better traction, they just spin with even a modest power application.
Because of these points listed, I would use that freshened trans of yours in a heartbeat.
However, I would have normal-use replacement parts in stock. Cuz you never know the weak points on the first install....... lol.
But honestly;
With a 400hp 318, that combo is gonna want steep rear gears and/or a higher stall, both of which, in Australia, sorta point to an A500.... in the longrun.

 

[mvh]

I think the break is between 1967 and 1968, so the previous post should read "1968 and up". When I swapped a 1968 engine into my 1967 Barracuda, I had to use an adapter for the torque converter on the 904.

 

[Barra_67]

Thanks for your replies. The issue is also limited converter selection with the smaller input shaft. Converters to suit the 27 spline input shaft are common. I did a quick google and couldn’t see any for the smaller 18 spline input shaft.

 

[Barra_67]

>All 67 up A904s fit all 67 up LA-convertors, and have the larger TC pilot
>66 and down A904's, have the smaller stuff, and require the matching crank, or conversion.
> For a streeter, the 273 A904 will be just fine behind an HO318. In my youth, I put one behind a 340 2bbl, and ran thechit out of it for some two years before it broke.
----------------------
>To get to 400hpNA, with a true 318, is gonna take a lotta effort and, on the street, can hardly hurt a fresh A904 cuz you will rarely get the rpm up, to where the power is, unless you have race-gears in the back. And with a low to modest stall, the much smaller torque numbers make much smaller horsepower.
For instance;
300 @2500 is 143hp, the torque is now building,
315 @3500 is 210hp, the torque soon peaking
330 @4500 is 283hp, at the peak
325 @5500 is 340hp, the torque now declining.
320 @6500 is 396hp
>The biggest tires that you can install INTO the rear tubs of a 67 is either a 275/60-15, or a 295/50-15, and they only come, in one kind of street rubber, namely slippery as heck, so, unless you modify your rear suspension for better traction, they just spin with even a modest power application.
Because of these points listed, I would use that freshened trans of yours in a heartbeat.
However, I would have normal-use replacement parts in stock. Cuz you never know the weak points on the first install....... lol.
But honestly;
With a 400hp 318, that combo is gonna want steep rear gears and/or a higher stall, both of which, in Australia, sorta point to an A500.... in the longrun.

Thanks for the input. I did a quick search on fitting the A500 to a 67 Barracuda and it requires tunnel massaging and a different cross member which I really don't want to get into.

 

[AJ/FormS]

which I really don't want to get into

Which is too bad, cuz that's a dynomite combo.

The .69overdrive let's you run up to ~4.30s on the street, altho 3.91s are my favorite. But your 400 hp 318 won't like 3.91s much either, unless you run a hi-stall. The more gear that you run, the less stall you can get away with. and a LU convertor makes cruising, say with 4.10s and 27" tires to be;
65= about 2300, and 75=2650 your 400 hp 318 won't get very good fuel mileage at 2300, but it will be about as good as gets, cuz at least the cruise-timing can be made to be close to correct.
But if you never or rarely hit the hiway, then I guess this is a moot point.
FYI;
The A500 at WOT, functions like a 5 speed with the LU adding another half a gear. The extra gear comes from the convertor having a torque multiplier function inside of it that has a ratio range of about 1.1 to 1.8, or even higher. At Zero mph, the ratio will be around 1.8. As the car picks up speed, the ratio will diminish, eventually ending up nearer the 1.0 ratio. The multiplier also varies with torque input. Of course the convertor in the A904 has the same feature as do all convertors.
Because this combo can put down so much power so early, on the street, you really don't need anywhere near 400hp, to have major fun with, and that has the side-benefit of the 318 being waaay cheaper to build, and it will last a lot longer.
Furthermore;
The difference is that to run 65=2300 with a non LU A904 convertor,the rear gear will need to be about 2.76s for 65= 2300,slipping at 3%, and your HO318 is absolutely gonna hate that gear at take-off, no matter how much stall she gets.
But I understand, cutting and fabricating ain't for everyone.
But with a 400hp 318, I'd be willing to bet you a dollar, that before very much time goes by, yur gonna thing about that A500 again.......lol.

 

[Barra_67]

It's been a few years, but I believe you will just need the input shaft and later year clutch hub. 65'

Thanks. As the shafts are different diameter I believe I will need pump as well? Pretty much front assembly, pump, shaft and drum.