40 Ford p/u drivetrain question

[mnwildpunk]

I have revells 40 ford p/u I have a quick question about the rear end. Is it a torque tube design or is it an open driveshaft

[Art Anderson]

I have revells 40 ford p/u I have a quick question about the rear end. Is it a torque tube design or is it an open driveshaft

Torque tube.

Art

[Ace-Garageguy]

Yup.

[CrazyGirl]

ok i need to learn something ,,,,,,, whats the difference between the two

[mnwildpunk]

A live axle or driveshaft has two u joints at each end and you can visually see it turning a torque is shaft that is enclosed in a tube that runs from the transmission all the way to the rearend. That is putting it simply.

[Ace-Garageguy]

This is a '40 Ford rear axle assembly, and the driveshaft tube ("torque-tube"...the actual driveshaft is solid and runs inside the tube, and has only one universal joint on the front, at the transmission) is bolted rigidly to the axle. This basic design was used in Ford passenger cars through 1948.

This axle design works with a transverse leaf-spring (which runs side to side, across the top of the axle...shown installed on a similar axle in next photo), and the torque-tube and the radius rods on the sides are what control axle movement and alignment, and also transmit the driving force to the rest of the vehicle. This torque-tube setup is also called a 'closed driveshaft'.

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Torque-tube axle setup above, open-driveshaft axle below

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In 1949, Ford went to parallel leaf-springs in the rear, with an 'open driveshaft'.The springs are important, as they became the means of keeping the rear axle in correct alignment, and transmitting the driving force to the vehicle. Because of the different movement of the axle with this setup, the torque-tube was eliminated, and a hollow driveshaft (like most folks are familiar with today) was substituted, with a universal joint necessary on both ends.

There are many variations on this basic theme, and when you're doing engine / trans swaps, you have to know what you're working with to be accurate.

Edited March 21, 2013 by Ace-Garageguy

[mnwildpunk]

I knew I should've waited a bit longer because ace would have a detailed answer. Anne if you ever have a question 99.9% of the time ace has the answer aand it will be detailed. He is the man!

[CrazyGirl]

hey thanks guys !!!

[mnwildpunk]

How long did GM use the torque tube? I know they still had them in trucks til at least 51 because my old 51 had the torque tube. Did they switch out the torque tube when they changed design in 54?

[Ace-Garageguy]

How long did GM use the torque tube? I know they still had them in trucks til at least 51 because my old 51 had the torque tube. Did they switch out the torque tube when they changed design in 54?

I honestly don't know. One thing as far as function though...a torque tube driveshaft can work in a parallel leaf-spring application as long as there's a sliding, splined joint at the trans end (which there is NOT on a transverse-sprung rear, usually) as well as the universal joint.

Here's a good rear-suspension article. Pretty much covers all of it for hot-rods.

http://www.rodandcustommagazine.com/techarticles/0801rc_rear_suspension_and_chassis_tuning/viewall.html

[Longbox55]

Chevrolet used torque tubes on cars and 1/2 ton trucks to '54. 3/4 ton trucks had a hybrid driveline, using a "torque tube" from the transmission to the carrier bearing, then open driveline to the differential. All Chevrolets went to open driveline in '55.

I won't speak for Cadillac/Olds/Pontiac, but I do know that Buick was the last holdout from GM, using torque tube drivelines until 1960.

[mnwildpunk]

Ya wait didn't the pontiac tempests have a torque tube for a couple yrs?

[Ace-Garageguy]

Ya wait didn't the pontiac tempests have a torque tube for a couple yrs?

Yes, but they had a transaxle in the rear rather like a Porsche 924 / 944, and independent swing-arm rear suspension.

Edited March 21, 2013 by Ace-Garageguy

[Longbox55]

Yes, the early Tempest did have a torque tube.

[mnwildpunk]

That os what I love about 1:1 car's amd model lits each one has their own nuances

[blunc]

ah, the Tempest, built with 1/2 of a 389.

[Ace-Garageguy]

Thanks for the input on the Chevette, Derick. That's one I didn't know about.

[Art Anderson]

Yes, but they had a transaxle in the rear rather like a Porsche 924 / 944, and independent swing-arm rear suspension.

Actually, the '61-'63 Pontiac Tempest setup is NOT a torque tube arrangement! The first series Tempest used the same transaxle and rear suspension setup as the 1961-63 Corvair, swing axle independent suspension. The square, tubular unit supported a flexible driveshaft. Notice that this "tube" actually curves down and then back up at the rear. That was a system to reduce the driveshaft "hump" in the floor in the rear seat area. The driveshaft was supported by a series of bearings to hold it in a bend while rotating.

There may be some misunderstanding as to just what a torque tube does: It's purpose is to "locate" the rear axle housing and secure it from trying to "react" to the torque in the rear axle shafts themselves--very much like traction bars installed on muscle cars. On Fords from 1905 through 1948, the transverse rear spring could not resist the axle housing from rotating, so the torque tube was absolutely essential (Ford front axles in that era used a "wishbone" radius rod setup that not only kept the front axle firmly located at 90-degrees to the center line of the frame, but also served to keep the front axle from twisting the transverse front spring upon braking. Many cars equipped with parallel leaf springs also used torque tubes to keep the rear axle from trying to "wrap up" the rear leaf springs, or in the case of the late 30's Oldsmobiles (which were among the very first cars equipped with coil springs in the rear) to keep the rear axle housing from trying to wrap those around the axle under acceleration and braking. Oldsmobile and the rest of the GM lineup went to traling arms for that purpose when GM Divisions abandoned torque tubes and used coil springs in the rear. Those trailing arms also functioned as radius rods when used with rear coil springs (think 1958-64 Chevrolet and Cadillac in this regard, along with 1960-66 Chevy/GMC pickup trucks.

Fords equipped with transverse springs and torque tube drive used radius rods to firmly tie the rear axle and torque tube precisely, while cars using parallel leaf springs and "Hotchkiss" drive (Hotchkiss was the name of the French engineer who first came up with the open driveshaft with U-joints at each end) could rely on the parallel leaf springs to function as radius rods.

Art

[Ace-Garageguy]

Yes, you're absolutely correct that the Tempest design is not a true torque-tube, which should be pretty obvious with a cursory examination of the rear suspension. It IS however routinely referred to as a torque-tube in the literature about the Tempest.

Thank you for clarifying that point and for providing more in-depth information.

There is also a popular mis-conception that the Corvair transaxle is the same as the Tempest, when in fact almost nothing interchanges.

Edited March 22, 2013 by Ace-Garageguy

[Craig Irwin]

We always refered to the Tempest set up as a "speedometer cable drive" or "rope drive".

[Ace-Garageguy]

We always refered to the Tempest set up as a "speedometer cable drive" or "rope drive".

Now that you mention it, I remember the rope-drive jokes. Man, you have a good memory.

I think Mickey Thompson had the best mod for those...taking the whole mess out and swapping in a big V8 with a conventional driveshaft and axle.