L 71 half shaft and ujoints

[Hector G.]

Removed the half shafts on my 67 L71 in order to remove paint and rust. Here are some photos of the project. Lots of labor and naval jelly. Wanted to preserve as much of the shot-peened finish on the shafts and locate any markings. The numbers on the axel side flange are 3843018 and what I believe is the GM logo and some additional numbers. On the actual shaft's flanges there are several numbers. I believe one set of numbers are 3707775.
DSC08194.jpgDSC08195.jpgDSC08209.jpgDSC08263.jpg

In regard to the u joints, I beleive they are original to the car. But not sure. I've included photos. One side of the u joint has what I believe to be a four digit number, 8617. On the other side it has, GM 90R? It also has what appears to be a seven digit number. Can't make it out. Does anyone know whether these ujoints would be original for a 67 Corvette?
DSC08252.jpgDSC08253.jpg
Thanks for your help

[Joe L.]

Re: L 71 half shaft and ujoints

Removed the half shafts on my 67 L71 in order to remove paint and rust. Here are some photos of the project. Lots of labor and naval jelly. Wanted to preserve as much of the shot-peened finish on the shafts and locate any markings. The numbers on the axel side flange are 3843018 and what I believe is the GM logo and some additional numbers. On the actual shaft's flanges there are several numbers. I believe one set of numbers are 3707775.
[ATTACH=CONFIG]65267[/ATTACH][ATTACH=CONFIG]65268[/ATTACH][ATTACH=CONFIG]65269[/ATTACH][ATTACH=CONFIG]65270[/ATTACH]

In regard to the u joints, I beleive they are original to the car. But not sure. I've included photos. One side of the u joint has what I believe to be a four digit number, 8617. On the other side it has, GM 90R? It also has what appears to be a seven digit number. Can't make it out. Does anyone know whether these ujoints would be original for a 67 Corvette?
[ATTACH=CONFIG]65271[/ATTACH][ATTACH=CONFIG]65272[/ATTACH]
Thanks for your help

Hector------


Your half shafts and flanges are original or, at least, exactly the same as original (if a part is identical to the part originally installed on a car no one could say if it's original to the car, or not).

The u-joints may be original. However, it's an academic point since it's HIGHLY unlikely they'll be re-uasble and your chances of finding identical NOS u-joints is about as great as the people in hell getting ice water.

You need to remove the caps and inspect the bearing surfaces. If there exists ANY brinneling ("indenting") on ANY of the 4 bearing surfaces, the u-joints are unfit for re-use and are scrap metal. What are your chances of finding 4 perfect bearing surfaces? About the same as above.

[Hector G.]

Re: L 71 half shaft and ujoints

Thanks Joe for your input. Here are a couple of photos of the u-joint with the cap removed.DSC08257.jpgDSC08258.jpg I C
Cleaned the grease off the bearing surface. Could not see any "brinneling" until I held it up to the light and then only at a certain angle. It was almost unnoticeable Is "brinneling' a function of use and age? The car has just over 15 thousand miles on it. Would hate to replace the u-joints if not necessary. Thanks again for your input.

[Joe L.]

Re: L 71 half shaft and ujoints

Thanks Joe for your input. Here are a couple of photos of the u-joint with the cap removed.[ATTACH=CONFIG]65276[/ATTACH][ATTACH=CONFIG]65277[/ATTACH] I C
Cleaned the grease off the bearing surface. Could not see any "brinneling" until I held it up to the light and then only at a certain angle. It was almost unnoticeable Is "brinneling' a function of use and age? The car has just over 15 thousand miles on it. Would hate to replace the u-joints if not necessary. Thanks again for your input.

Hector------


From what I can see of it, this trunnion looks OK. Are all 4 on each u-joint the same?

[Hector G.]

Re: L 71 half shaft and ujoints

Joe: I have not removed the u-joints from the half shafts therefore I could only examine 4 of the 16. Those 4 were all identical to the one pictured above. I am cautious of removing the u-joints since I've heard that removing them would prevent them from being used again. I'm going to have to look into this some more. I would like to re-pack them. For now I'm going to go along with the adage, "Leave well enough alone". Had Duke Williams drop by the other day and look at them. He was of the same opinion. Leave them alone. They all move very smoothly, not to loose, not to tight. Wouldn't be putting much mileage on the car, maybe 500 mile a year. That's way more than the approximate 450 miles that was put on it for the 30 years before I purchased the car.



Here is a close up of the shot-peened surface of one of the half-shafts DSC08276.jpg In past posts, some folks had wondered what it looked like. I'll be working on the drive shaft next and will post photos of the u-joints. The u-joints on the drive shaft appear to be original to the car. Thanks again for your help.

[Duke W.]

Re: L 71 half shaft and ujoints

I've personally inspected Hector's halfshafts. The u-joints turn very smoothly without any perceptible play or notchiness. This car has very low miles, and given its condition and Hector's plan it will likely only accumulate miles at a very low rate in the future.

I mentioned to Hector that there was a problem with the early u-joint seal design that allowed water intrusion as outlined in Dave McClellan's book. Indeed, the left inboard u-joint on my SWC was severely worn at about 60K miles and five years of Seattles's rain, however, I would be willing to bet that this car has never been on a wet road - at least not intentionally.

My opinion is that removing the u-joints from the axle yokes and companion flanges for a complete inspection is not worth the risk of doing harm, and the halfshafts should be reinstalled upon completion of the surface finish restoration.

U-joints fail by the same mechanism as ball and roller bearings. Even with proper lubrication and no foreign matter entry they fail via a fatigue mechanism. As the balls and rollers move relative to the bearing surfaces, the material is loaded an unloaded, which eventually results in fatigue and tiny particles break away from the surfaces resulting is small pits, which can usually be seen with magnifying glass. Of course, these particles further abrade the wear surfaces, which results in rapid failure. However, most early u-joint failures were due to seal failure that allowed water intrusion that washed away the grease and corroded the wear surfaces, which combined to cause rapid wear. Otherwise these u-joints should last well over 100K miles of normal road service.

The wear that I experienced eventually caused a "clunk" in the driveline. and when I inspected the driveshaft and halfshaft u-joints by grabbing the shafts and trying to wiggle them the play in the worn u-joint was obvious. All the remaining original u-joints remained serviceable until I replaced them all at 115K miles in the process of a complete rear suspension and axle overhaul.

Duke