Technical Radius rod mounting location

Working on my 1928 AV8. I’m using a 1939 drivetrain, trans, rear, torque tubes and radius rods. I’ve shortened the torque tube to but before I shorted the radius rods I have a question about the mounting location on the torque tube.

How far forward should the radius rod mounting location be? I’ve left the mount in it’s stock location in relation to the front of the torque tube, but I have a feeling its to far forward. You can see it circled in the photos below.

 

Proper length is to be the same length as axle tube, thus no binding action be happening.

 

The torque tube, axle ***embly, and radius rods act as one solid unit therefore there wont be problems with binding. Longer rods are better than shorter.

 

I would think using the stock mount on the torque tube would be good?

 

That's mostly true with an open drive shaft, but a slip joint yoke will allow for a bit of length difference.

 

I would reattach to the stock mount.

 

The axle to torque tube with a radius rod is a rigid connection, there is no independent movement or chance of binding.

 

The 39 stock radius rod length should be short enough to use unmodified, so I would move the torque tube mount to
work with the stock rods.

 

The first thing I would do is make a tab like the stock one then bolt it between the ends of the radius rods. Push it up to the torque tube and tack weld it. Thats where it goes

 

The current mounting tab location will work ok.
Your torque tube cut location might give you trouble later on though. The problem being, getting the front and rear flanges parallel and on center line. Almost impossible with the cut location you have.
You should cut at the rear flange after machining a concentric "dial in" area on the OD of the tube just ahead of the flange.

 

I did not read everything! cederholm said: I have a question about the mounting location on the torque tube.
I thought that he was going to have the radius rod ends attached to tabs mounted outside on the frame.

 

29-AV8 diff with stock length '46-'48 radius rods that required a gentle heat and bend at the axle end to align with a donor torque tube eye relocated to match where it needed to align with the rod eyes.
In other words relocate the eye instead of shortening the radius rods.
.

 

I don't believe you could move the mount any further due to the taper; just shorten the rods to use the mount where it is. Cut the eyes off the wishbones, bolt them to the mount, and shorten the tubes to fit; probably will need to heat and bend the eyes a little to get a square match with the shortened 'bones.

 

That was one of my concerns.

 

I don't think from a strength or driving point it will make any difference if you shorten the rods or move the eye. I would go with whatever is easiest, which I think would be to move the mounting eye. Then as already said, bolt the rods and eye together to find out where to mount the eye, clamp the ***embly to the tube and weld it on.

 

Six of one and half of twelve for the other.

 

I'd move the mount and keep the radius rods the same length as original. If you shorten the radius rods you will also need to deal with the angle change due to the mount being closer to the axle tubes. Not a big deal, but leaving them the stock length and moving the mount eliminates a few steps.

If you keep them stock length all you need to do is move the mount.

If you shorten them, you need to cut each rod, and weld them back together at the new steeper angle at the rear axle. Now the front eyes of the rods will not be parallel with the rear mount of the radius rods, so they may both require some attention as well.

 

It doesn't really matter, the radius rods only job is to keep the torque tube perpendicular to the rear axle ***embly, do what takes the least amount of work to install them.

 

Not to disagree with the reasons stated to move the mount and leave them long; but I do have to say they would look pretty abnormal mounted way up on the taper.

 

Ebb is right shortening the rods doubles the amount of work and makes any replacement more difficult, add in the angle change and you have a no brain'r. move one point as long as it does not interfere.
Keep it far enough off the bell for ease of service would also be a concern. And no weld in a slip joint area as it will distort the joint.

 

^^^ Slip joint?

 

He must be a Chevy guy.

 

Very helpful all - thanks!

 

FYI...Henry's take on the torque tube.

 

i did like wideglide74 cutout the mount while shortrning the torque tube and used slightly rebend 46-48 radius rods
works great