Rear end - Half shaft rubbing axle at U-joint

[Donald H.]

I'm having an issue which I hope is easy to fix. I put my 66 restoration in process up on jack stands to adjust the parking brakes. The car is on my lift and hasn't been on the ground except to roll off a trailer and onto my lift. I have rolled it back and forth on the lift and all seemed fine.

However, with it on jack stands and the wheels hanging, the half shafts are rubbing the axles at the U-joints. The two pictures show what is happening.

The axles are original as far as I know. They came out of the diff when I rebuilt it, with lots of help from Gary Ramadei. The half shaft are the LIC replacements that are supposed to replicate originals, i.e. weld seams etc.

I don't think it happens when the wheels are on the ground. I don't recall it happening when I first got and drove the car with the original half shafts. I had it on jack stand a number of times like checking to see if the posi was working and also check revolutions to determine gear ratio, so I know I had rolled the rear tires more than a few times.

It rubs so much that it is wearing a spot on the axle and actually take quite a bit of force to rotate past the bind.

Any suggestion for how to solve this.

Thanks
Don

[Donald H.]

Re: Rear end - Half shaft rubbing axle at U-joint

Some more info:

I have not tightened the rear leaf spring bolts yet, including the long bolts at the ends of the springs so there is lots of positive camber. Could that be causing the issue?

Thanks,
Don

[Joe R.]

Re: Rear end - Half shaft rubbing axle at U-joint

Don,

That rubbing won't occur when the Corvette is on the ground and level. The first picture shows the c-clip not seated. That might cause more trouble than rubbing.

JR

[Richard M.]

Re: Rear end - Half shaft rubbing axle at U-joint

Don, This is normal with the Trailing Arms hanging down. I've often wondered why the design allows this, especially if at some time the car would go over a large hill at speed and the suspension were to spring downward. Ouch.

That U-Joint Clip appears seated to me, but it may be a good idea to give it a few hits with a hammer and a drift to make sure it's home. Whenever I replace U-Joints I like to do that.

Rich

[Duke W.]

Re: Rear end - Half shaft rubbing axle at U-joint

U-joint grounding is more common between the outboard joint and the axle drive flange, especially on '63s that have a thick section cast axle drive flange that was replaced with a forged part for '64 that has a thinner section.

Rebound travel is limited by shock absorber travel, and I don't know if all aftermarket shocks have OE length when fully extended.

I covered U-joint grounding in a functional/safety inspection seminar I conducted at our So Cal chapter meet a couple of weeks ago. With the rear suspension hanging at the rebound limit the wheels should turn smoothly all the way around without any areas of increased resistance that can mean u-joint grounding.

So check the fully extended shock length. I don't have a spec, but maybe someone else with OE shocks does.

Duke

[Donald H.]

Re: Rear end - Half shaft rubbing axle at U-joint

Pretty sure all the clips are seated, but I'll have another look.

I pulled the old half shafts out of storage and it looks like they also took quite a beating, picture attached.

[Donald H.]

Re: Rear end - Half shaft rubbing axle at U-joint

Hopefully someone has the specs for OEM shock fully extended. I used modern delco gas shocks. It would be nice to compare.

Thanks to all.

Don

[Richard M.]

Re: Rear end - Half shaft rubbing axle at U-joint

What Duke explained makes perfect sense. That must be the reason. I've restored many midyears and typically use the modern Delco replacements.

However, a recent restoration of a '67 L71 with F41, was equipped with restored original F41 shocks, and I did in fact notice the extended length on the rears was noticeably shorter than the replacement non-F41 shocks I typically use. THis was from memory.

Unfortunately I do not have any shocks here, originals or Delco replacements, so I can't compare.

Rich

[Michael W.]

Re: Rear end - Half shaft rubbing axle at U-joint

Most replacement shocks are 1/4" to 1/2" longer than originals.

[Joe L.]

Re: Rear end - Half shaft rubbing axle at U-joint

Pretty sure all the clips are seated, but I'll have another look.

I pulled the old half shafts out of storage and it looks like they also took quite a beating, picture attached.

Don------


The c-clip in your photo is not seated.

[Duke W.]

Re: Rear end - Half shaft rubbing axle at U-joint

That needs to be corrected, but it's not the cause of the U-joint grounding.

Duke

[Rich P.]

Re: Rear end - Half shaft rubbing axle at U-joint

The F-41 rear spring does not have as much of an arc as the standard 9 leaf spring, I only noticed the binding on standard springs.

[Donald H.]

Re: Rear end - Half shaft rubbing axle at U-joint

Don------


The c-clip in your photo is not seated.

I think it is the angle of the picture. I've check and the clips are in the grooves all the way on both half shafts. Gave them an extra whack and they will not budge

Thanks all

[Joe L.]

Re: Rear end - Half shaft rubbing axle at U-joint

That needs to be corrected, but it's not the cause of the U-joint grounding.

Duke

Duke------

Yes, it's got nothing to do with the yoke contact problem.

[Duke W.]

Re: Rear end - Half shaft rubbing axle at U-joint

The F-41 rear spring does not have as much of an arc as the standard 9 leaf spring, I only noticed the binding on standard springs.

Then you must have had different shocks installed. See post #5.

Duke