Another 63-82 Trailing Arm Myth

[Michael H.]

Another item of contention I have is with the bushing/sleeve design. The twin bushings are secured in place by friction to the trailing arm, and therefore cannot move in relation to the trailing arm. The inner sleeve is flared so it can't move around the bushing. The ONLY WAY the trailing arm can rotate is for the inner sleeve to move freely around the bolt, like a door hinge on a pin. The bushings act as dampers only, they do not affect rotation. The design of the trailing arm bushings is very different from control arm bushings.

[Duke W.]

Re: Another 63-82 Trailing Arm Myth

I completely disagree. The outside bushing sleeves are an interference fit in the trailing arm. The inside sleeve and retainer plates are "locked" by being pinched between the frame sides when the bushing bolt is torqued.

Thus, the only allowable relative motion is in the rubber itself. There are no metal components siding against each other as the trailing arm moves up and down. Just as is the case with the front control arm bushings, all motion is
strain in the rubber sleeve.

If there was relative motion between the bushing bolt and innner sleeve they wouldn't last very long!

Duke

[Michael H.]

Re: Another 63-82 Trailing Arm Myth

Thanks Duke, I was just about to reply and say the same thing that you did. I think a cutaway picture of the bushing would help clarify things for everyone but I can't find one.

[Duke W.]

Re: Another 63-82 Trailing Arm Myth

There's a good longitudinal section drawing of this bushing assembly in
the '63 Corvette Shop Manual, and it's pretty clear from inspection how it
works. I also know from removing and overhauling the complete trailing arm assemblies on my SWC, which included me replacing the trailing arm bushings, overhauling the bearing packs, and reinstalling the trailing arms.

Duke

[Joe L.]

Re: Another 63-82 Trailing Arm Myth

Duke-----

I agree; that's exactly how it is.

[Michael H.]

Re: Another 63-82 Trailing Arm Myth

If this is true why is it that when you release the leaf spring & shock absorber the trailing arm falls like a brick? I think that this is one of those cases where design and practice differ.

[Duke W.]

Re: Another 63-82 Trailing Arm Myth

The rubber offers very little torsional resistance, and the complete trailing arm assembly is about 30 pounds of stuff with a 1.5 foot lever arm. That's why it drops like a rock it it's not supported.

If you install a front control arm or rear trailing arm (without all the drive and brake hardware), then tighten the bushing bolts at approximate normal height you can easily move them up and down several inches with one hand.

Duke

[John H.]

Re: Another 63-82 Trailing Arm Myth

There's an excellent cross-section of the trailing arm bushing (as installed in the arm) on page 4-23 of the 1967 Chassis Service Manual that makes it pretty obvious that there is no relative motion anywhere except within the rubber portion of the bushing, just like the front upper and lower control arm bushings.