Hello folks.
This morning, as part of checking the poor old C3 over to be ready for a year of (I hope), heavy use, I decided to have a real good look at all the U Joints. I seem to remember reading, (probably here), that sometimes the straps will come loose. Plus, when I was coasting down the street to my garage a month ago, beside stone walls which reflect sound, there was a little squeak-squeak-squeak noise at about the right speed for a half shaft U Joint. The third time I came down the street, I started pulling up on the park brake lever and the sound changed, and when I pulled a little more, it stopped altogether. Ah-ha!
So, I decided to look at them anyway, and under the car I got, and after fiddling around with wrenches, a ratchet, 4 extensions and the correct sockets, I checked all the U bolts and straps on the half shafts and the driveshaft, for a total of sixteen. Believe it or not, 8 of them needed snugging up. I'm not saying they were ready to fall out, but they were definitely not tight. I think I'm going to do this now twice a year.
Also, my car has 129,000 miles on it, and as far as I can tell, both driveshaft joints have been replaced and one of the half shaft joints. I greased the replacements, and of course, the originals have no fittings. It looks like 3 of the half shaft joints are original. How long do these joints normally last? They all seem to be tight and in good shape.
My car is an L48 with an automatic, and I think most of the miles are highway, so the half shaft joints probably have never been under a lot of strain. And of course, they turn at 1/3 speed of the driveshaft.
Time now to start on the horns, they sound like a cow with a stomach ache.

 

I have not seen or heard of anyone that needed to tighten the U-Joint straps. I might double nut them or use a Lock-nut if they come loose. Is there any angle on your half-shafts?

The half shaft joints are prone to squeaking if they have dry needle bearings in them. Non-greasable joints are a PIA sometimes but I would replace them just to be safe at some point. I replaced all four half-shaft joints on my C3 when I first bought the car with ~70k miles.

My C3 has a 427 and a Four speed and the original half shaft u-joints were the grease-able U-joints. I took my C3 to a dealer to rebuild the differential and it returned with the wrong length bolts at the ends of the springs. This lead to angles for the half shafts and that lead to noise and wear. Once I put the correct bolts in the spring the Corvette was fine until I tried a pair of D.O.T. Drag radials and then I learned that the grease-able U-joints didn't have the same strength. I heard a bang and the cars stopped rolling forward, a nice L.E.O. came up and offered to Push my 1967 Fiberglass with his cruiser off the road. Then he made me clean up the parts of the old U-Joint so nobody would puncture a tire.....

I switched over to the Non-grease-able quality U-Joints and have had no more trouble. I did however buy a spare set of half-shafts for my C3 and C4 and they are all ready for action bagged in the garage.

 

Torque on those u bolts is very light. Only about 20ftlb.

too tight can deform the cap and toss your ujoints.

I use blue loctite and paint a line with whiteout from the nut to the bolt so if it ever backs off I can easily see it.

 

do not over tighten..
Great way to check noise i did same with concrete barrier..
my bet is as mine were …e brake hardware….u joints…wheel weights hitting..
highly unlikely straps were issue if not totally loose.