Drive Shaft U-Joint/Rear End Pinion Flange Problem
 

I need to resolve a problem that is causing a vibration under hard acceleration/high RPM. I’m not sure how to approach/resolve the problem.

When I purchased the car 10 years ago, the previous owner had installed some type of shim under the clamp on each side on the rear u-joints. When I did my resto work 4 years ago, I had new u-joints installed on the driveshaft. I was going to replace the rear end pinion flange, but was told not to do that myself do to the preload (I think) on the ring and pinion.

The problem is that is seems that the u-joints fit tightly in the rear end pinion flange, but after a short period of time I end up with side-to-side movement within the caps. The caps are not moving side-to-side within the yoke, but the part of the u-joint that the needle bearings are against inside the cap. The side-to-side movement is aprox. with caps in place is 1/8” to 3/16”. Does this make sense?

Before I purchase a new rear end pinion flange or question the new u-joint, does anybody know what the correct overall OD dimension of the required u-joint, or the ID of the “stops” on the rear end pinion flange? Or what else should I look for? Thanks

Re: Drive Shaft U-Joint/Rear End Pinion Flange Pro
 

does the ujoint have clips on it to retain it or does the yoke have little titties on it to retain the caps.

Re: Drive Shaft U-Joint/Rear End Pinion Flange Pro
 

The yoke has the stops that the caps sit between.

Re: Drive Shaft U-Joint/Rear End Pinion Flange Pro
 

Rob...I have the driveshaft out of my 70 Nova[same rear end as yours?] I can crawl under it and measure anything you want on the yoke. let me know what you need.

Re: Drive Shaft U-Joint/Rear End Pinion Flange Pro
 

Moroso part number 85810 is a "girdle" that might save the yoke if the little ears are the problem. Summit shows them for about 20 bucks. You don't even want to see what happens when a driveshaft comes loose. Had it happen on a 67 Caprice drag car. Had to beat the floors back down with a sledge hammer..... the trans was totally scrapped. Not a fun day. https://www.yenko.net/ubbthreads/images/graemlins/no.gif

Re: Drive Shaft U-Joint/Rear End Pinion Flange Pro
 

[ QUOTE ]
Rob...I have the driveshaft out of my 70 Nova[same rear end as yours?] I can crawl under it and measure anything you want on the yoke. let me know what you need.

[/ QUOTE ]

Tony, If you can measure both the ID between the ears or tabs on the yoke, and the OD of the caps on the u-joint.

John, I also looked at the "girdles" that Moroso makes. Thanks for the info.

Re: Drive Shaft U-Joint/Rear End Pinion Flange Pro
 

The measurement betwee the tabs is 3.220
The measurement, total length of the u joint, cap to cap, is 3.221, so it is a snug fit.
The OD of the cap is 1.065

Re: Drive Shaft U-Joint/Rear End Pinion Flange Pro
 

[ QUOTE ]
The measurement betwee the tabs is 3.220
The measurement, total length of the u joint, cap to cap, is 3.221, so it is a snug fit.
The OD of the cap is 1.065

[/ QUOTE ]

Thanks Tony

Re: Drive Shaft U-Joint/Rear End Pinion Flange Pro
 

You are welcome. I hope it helps.

Re: Drive Shaft U-Joint/Rear End Pinion Flange Pro
 

Change the pinion flange. It's common for the little tits that act as the 'stop' to wear and that allows the U-joint caps to move. It only needs to be slightly worn to cause a lot of vibration!! I would change the straps also.

Re: Drive Shaft U-Joint/Rear End Pinion Flange Pro
 

Ditto what PaulK says! The pinion flange on my '69 Yenko Camaro was only slightly worn, but changing it completely did away with my driveline vibration.

Re: Drive Shaft U-Joint/Rear End Pinion Flange Pro
 

Well it looks like the problem is that it is worn bewteen the stops, allowing the movement. The measurement is close to 3 5/16 between the stops.

The caps under rotation got "pushed" to the stops, allowing the side to side movement within the caps.

Would you change the pinion flange or buy the Moroso caps for now.?

Re: Drive Shaft U-Joint/Rear End Pinion Flange Pro
 

Rob, You have a P.M.