VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 39 Chevy truck u joint/ torque tube problem

Hello
I am working on a 39 Chevy truck. The u joint is coming up short and not engaging the prop shaft bushing. Unfortunately it was something I did not notice when I disassembled it. So I'm not sure if it was that way before. The Trans was pulled for a rebuild along with the clutch. I also installed a new "Oakie" along with a new u joint. I trying to figure out if it was wrong from the start. It is a 216 , 3 spd #591195 and the Diff #37707 Thanks Ryan [img:center][URL=http://s1379.photobucket.com/user/RoadtoGlory/media/16aadeeb-b8a0-4473-812d-77a60d6e6515_zps22669c74.png.html][IMG]http://i1379.photobucket.com/albums/ah149/RoadtoGlory/16aadeeb-b8a0-4473-812d-77a60d6e6515_zps22669c74.png[/IMG][/URL][/img]

trying to load picture but i cant get it to work

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Thanks Jack

RoadtoGlory,

Do you have any use for a NOS GM ring gear and pinion for that PU?

Hi Ryan,
Glad you got the picture posted.
We could probably do with a bit more information on your Truck.
It sounds like a JC series. is that correct.?

Is it possible you may have had the rear axle Ubolts off and relocated the axle more back of the former location when you put it back together? Just a thought.
Good Luck

Ryan,

Was this truck running and driveable before you disassembled it, or was it a basket case? If it's a 1/2 ton pickup, the 1937 and 1938 models used the same 377707 differential housing as the 1939, but the torque tube and propeller shaft were 1-1/2" shorter on the 37 and 38. If you're working with a basket case, maybe someone supplied a rear end/torque tube assembly from a 37 or 38, thinking it would work in the 39.

If you had released the rear axle housings from the leaf springs, on reassembly, it would be difficult to assemble them wrong because the leaf springs have a dowel pin on the top leaf that locates in a matching hole on the bottom of the spring perch on the axle housing.

If the truck was driveable before you disassembled it, I can't imagine what would prevent the torque tube/propeller shaft from mating back up properly to the transmission on reassembly.

I'll be interested in knowing how this mystery plays out.

Mark

A QUESTION - DO YOU HAVE A CAR OR TRUCK TRANSMISSION ? I AM THINKING A CAR TRANS WOULD BE SHORTER IN LENGTH , CAUSING YOUR PROBLEM . FRANK

the truck is a 39 !/2 ton. It came to the shop running, but had trans issue. Needed total rebuild. The trans is a #571195 which is a truck trans. I will post more pictures tonight. I also loosened the u bolts on the axle to see it it had moved. which it did not, amd really cant because of the centering pins. The old u joint has wear marks from the bushing so im lost. got myself alittle mystery going on

ARE TRUCK & CARS THE SAME AS PER THE YOKE LENGTH ? JUST TRYIN TO HELP. FRANK

Is the truck jacked up? Is their weight on the rear springs? Do things mate up if the truck is in normal weight bearing position?

When you installed the Oakie bushing , did you remove a front bushing and the rear bushing. The 1950 parts book lists a kit for 1937-1939 commercials with two bushings (front and rear) and packing,and 1934-1939 Utility with front and rear bushing and seal.
The universal joint is only passing through the front bushing ,and not the rear.

Ryan,

Just to be sure, measure the distance from the front face of the transmission to the rear face. If it is a truck transmission, the distance will be 11-1/2". If it is a passenger transmission, the distance will be 9-3/8".

If you sent the transmission to a repair shop, I suppose it is possible they may have supplied a rebuilt passenger transmission.

Mark

Hello
i rebuilt the trans, it is 11 1/2 long. Does anyone know the torque tube lentgh from the end to where it goes into the Dif. The one on this truck is 55 7/8. I will post more pictures when i have more time. Thanks for all the replies.

The tube on a 1939 1/2 ton is 57 19/64" long

The tube on a 1937-38 is 55 55/64 long.

interesting so I have a 37/38. So then the 37/38 trans is longer. I guess I will be looking for another rearend or trans. I think the engine is a 42 when i checked the numbers. so when who ever did the swap they didnt use the original trans.

I have a complete torque tube assembly out of a '40 car. I don't know the length off hand. I'll go out to the barn and measure it. If it'll work for you, you can have it but you'll have to come get it. It's been taking up space in my barn for too long.

Edit: No cigar. It's longer than the 37/38 but still too short, 56.75".

It is a lighter and different animal.

If the rear springs were removed, might they have been reinstalled backwards? The dowell is not always in the center of the stack.
If it was running and driving when it arrived, wrong parts should not be the problem./

Mike

The 1937 to 1939 3-speed truck transmissions are all the same length. In fact, I believe they were the same through 1946. The difference in the torque tube length between the 37/38 half ton vs. the 39 is that the 39 requires a longer torque tube because it has a 1-1/2" longer wheelbase than the 37/38.

Regarding the rear leaf springs, unless you replaced the spring eye bushings, you wouldn't be able to reverse them because the front eye has a smooth-bore bronze bushing, while the rear eye has a threaded steel bushing.

WHEN DRIVING IN THE OAKIE , COULD THE DRIVESHAFT TUBE HAVE BEEN DRIVEN BACK INTO THE REAR END HOUSING ? TIS A PUZZLER FER SURE .

I have a 38 3 speed and 39 4 speed. When comparing in the hope of using the 3 speed gearbox with the 4 speed rear I found the gearboxes are the same length from bell housing face to the face the tube ball mounts to is the same though the the tubes and inside shafts are different lengths quite possibley due to 1 being spiral bevel and the other being hypoid.
Both units came from 112" wheelbase trucks.
Tony

The 3 speed and 4 speed were the same length and bolt pattern. They were designed to be interchangeable in production or for later use.