need advice on u joint removal on aa

[birdacre]

question, does anyone know the best procedure for removing the short shaft from a 4 speed transmission back to the torque tube. i thought that if i unbolted it from the transmission and pulled the engine and transmission forward a few inches i could pull it forward out of u joint. does the rear end have to be pulled back too. if so what is the easiest, no pun intended, way to pull it back. final question? will this 4 speed shaft when removed slide into a 28 aa torque tube. my truck originally had a 3 speed and want to upgrade to a four speed. once i get the tube off the donor truck will it mate up to the 28 torque tube. thank you in advance, any photos or cross sections appreciated. kevin in ct.

[Neil Wilson]

Kevin,
There was a service coupling shaft released in 1932 which can be removed with out pulling back the rear axle. The stock coupling shaft requires that the rear axle be moved back enough to let the torque tube drop down so that the coupling shaft assembly can be removed out the back side of the #3 cross member.

It does not help to move the engine forward.

The u-joint from the 1930-1931 chassis is required to connect the coupling and drive shaft.

The frame must be jacked up to allow the rear axle to be rolled back.

Anyone - other thoughts?

[birdacre]

thank you neil, this is what i thought, just wanted to get a second opinion. i will remove as you described and then do the same to my 28 to remove the 3 speed intermediate shaft. i understand from what you said that i will then be able to reconnect my drivetrain as long as i have a good u joint from the 30 truck. sound correct, thank you for your help. kevin p.s. this is why the old farmer i got the truck from brazed the 3 speed u joint cover on the back of transmission. i am going to switch out the transmission case too.

[1crosscut]

Is there any advantage to putting in a 4 speed other than getting an extra low first gear. Perhaps my thinking is off but isn't a 4 speed just as fast in high gear as a 3 speed?

[BrianT]

It would be an advantage if 2nd and 3rd gear had a closer ratio than 1st and second that the 3 speed has, however there would be no difference in 4th, If I am reading birdacre correctly he does not have a Hi - Low unit in his express and would need the low first gear possibly for heavy loads.
The upside for me is I use the Hi-Lo unit as a gear splitter when confronted with a hill that's getting the better of her 2 ton weight, that gives me 3rd gear low, not used so much now with the 5.5 cylinder head and twin updraft carbs.

[tiredtruckrestorer]

Isn't the length of the 4-speed with bell housing assembly about an inch or so longer than the 3-speed with the bell housing? This would require you to use the complete coupling shaft and outer tube assembly from a 4-speed truck instead of mixing the parts of the two styles.

Keith

[BrianT]

I believe the u-joint that comes with the 4 speed intermediate shaft has slightly larger splines than the driveshaft, I have the front u-joint that came with the bolt together shaft and they are larger, its possible that the 2 halves of the rear joint could be coupled together providing the cross will fit.

[Bob C]

I would think if you used the parts listed in the 7-8-31 Service Letters for
installing the 4-speed in a Model A car it should fit using the 28-29 coupling shaft.

Bob

[birdacre]

today i am going to pull the rear end back on my 28 aa. i have the intermediate shaft from my junk truck, 1930. i could not believe all u joint bolts came free with not even any heat. these trucks have not been on road since 60's. i know neal posted that my u joint from the 30 is needed to connect to drive shaft on my 28. i have it in hand and hope it matches right up. one thing i fear is that the two different style rear ends might have had different diameter drive shafts. any one have any ideas on this. hope this is not the case. not trying to second guess anyone, just paranoid. thanks in advance, kevin