Torque tube suspension (sort of)

[BillyShope]

Here's a modern dragrace version of the old torque tube suspension.

See Page 41 of
http://www.racetec.cc/shope

[exwestracer]

Billy,
You mention that a diagonal brace is necessary in the system. I'd say that's an understatement! If you were to encounter a difference in traction from one tire to another, the rear axle would be free to yaw around the radius of the panhard bar. Scary!

Off-roaders are using a variation of this suspension (a lot like a NASCAR truck arm setup with both arms attaching to a single pivot), commonly referred to as a "graderball". Great for articulation, but your comments about the panhard bar needing to be strong are spot on... Nothing like looking out the window and seeing the rear axle swinging out beside you!

[BillyShope]

Corrected a couple of typos on Page 41. I had typed "torque" arm when I meant "truck" arm. Very different animals!



Billy,
If you were to encounter a difference in traction from one tire to another, the rear axle would be free to yaw around the radius of the panhard bar. Scary!

Not certain what you mean here. By a "difference in traction," I must assume you mean some situation which causes a complete failure of the arm and/or its attachment point.

I could have introduced this design without mentioning the torque tube suspension. I mentioned the torque tube and its dependability for the precise reason of assuaging the fears you've expressed. When you stop and think about it, that old torque tube design was downright scary! I'm certain there must have been some sensational failures, but I've never heard of them. Perhaps there's a forum user who's had a frightening experience.
http://www.racetec.cc/shope

[Bryce]

Awesome, I will read your new page. Thank you!

[David Pozzi]

I'm not familiar with other torque tube designs, but at age 15, one of my first car building experiences was with a 46 Chevy sedan which had a torque tube rear axle. The rear had two trailing links close or just below axle centerline, these received front to rear thrust, the "ball" had a sliding sleeve attachment to the torque tube and allowed some plunge travel, along with a conventional looking sliding yoke into the transmission. It did not use the ball for F/R thrust loads, but it did handle left right and up/down loads. A panhard bar was used.

I've seen similar setups used with great variation on sprint cars and super modifieds.

We eventually made a dune buggy out of the 46, and shortened the torque tube in our farm shop using a power hacksaw. It was quite a chore to weld the pieces back together, I did have the foresight to cut the outer tube back more than the inner tube allowing access to weld the inner back together. Our dads said it would break but it didn't! I mounted the rear axle solid to the frame, that was my first experience with oversteer!
David

[BillyShope]

It did not use the ball for F/R thrust loads....
David
Yes, my description was more for the Ford version, which used a transverse leaf spring.

I'm puzzled about the other links, though. Did the car have coil springs? The description I googled had parallel leafs, which would handle the X-axis loads. What you described would have been an early example of a torque arm suspension. For that matter, the parallel leaf Chevy would also have been a type of torque arm suspension.

It's fun...though more than a bit embarrassing...to recount our early experiments with cars. At about that same age...maybe a year younger..., I put dual exhausts on my dad's car, using flexible exhaust tubing. It banged around for a couple of weeks, but it eventually took a set and worked quite nicely.
http://www.racetec.cc/shope

[exwestracer]

Corrected a couple of typos on Page 41. I had typed "torque" arm when I meant "truck" arm. Very different animals!



Not certain what you mean here. By a "difference in traction," I must assume you mean some situation which causes a complete failure of the arm and/or its attachment point.


http://www.racetec.cc/shope

I re-read the description and realized I misunderstood what you meant by "diagonal bracing". I thought you were referring to a bar running from the arm over to the left side of the axle housing.

Assuming the arm is the only link to the chassis, what stops the thrust force from moving the LR tire forward in the wheelwell if the RR should encounter a slick spot or other loss of traction?

We use a variation of this setup on supermodifieds, where the torque arm locates the LR and provides anti-rotation, but is coupled with radius rods on the RR to take the drive thrust on that side. Just wondering if I've been missing something all along...

[BillyShope]

I re-read the description and realized I misunderstood what you meant by "diagonal bracing". I thought you were referring to a bar running from the arm over to the left side of the axle housing.
The schematic is functionally complete. Any additional bracing would serve to reduce the stresses at the juncture of the arm and axle housing. The early Ford had bracing running from points near the ball back to points at the extremes of the axle housing. Starting with my schematic, a brace could easily connect to the right end of the axle housing. To the left, any brace would have to either attach to the housing for the ring and pinion gears or somehow dodge around that housing and find its way to the axle housing.


Assuming the arm is the only link to the chassis, what stops the thrust force from moving the LR tire forward in the wheelwell if the RR should encounter a slick spot or other loss of traction?
As with the original torque tube suspension, the Panhard prevents the advance of one tire relative to another. In this derivation, however, the offset of the arm increases the Panhard loading.
http://www.racetec.cc/shope

[David Pozzi]

I was wrong on the 46 chevy, it did have leaf springs and not links, the leaf springs located the axle front to rear.