68 Firebird Rear U-Joint
 

This topic has been discussed, but I have searched the forum and haven't come up with an answer. My driveline is stock, 400 with TH400. The rear u-joint has 1 1/8" cups on the driveshaft side, with snap ring retainers on the inside of the joint. On the pinion yoke side, the yoke accepts a 1 1/16" cup. There are threaded style u-bolts with nuts and washers retaining the caps to the yoke.

The u-joints specified pretty much everywhere (NAPA, Ames, etc., etc.) are correct in that the conversion joint is specified (1 1/8" x 1 1/16"). However, the yoke cups do not have a groove for an inside snap ring, instead they come with the snap rings that retain the caps from the outside of the cup. With the pinion yoke and u-bolt configuration I need the snap rings to be on the inside, i.e., in a groove in the cup.

I don't think my configuration is unusual at all, like I said, it is stock, so I would think the right u-joint would be more readily found. Regardless, can anyone point me to the part number for the correct conversion u-joint with inside snap rings all around?

Thanks all.

Doug

I had a similar u-joint issue with my 1967 Firebird. Found that the pinion side actually accepts a 1 1/8" cup. The correct u-joint is a GM 3-RL (S44) style with 1 1/8" caps and inside snap rings on both sides. Spicer part numbers are below:

5-795X (lifetime)
5-3147X (greaseable)

Thanks for the reply, KentGBR. Unfortunately, 1 1/8" caps do not fit at all. 1 1/16" caps do fit. Can anyone tell me how the 1 1/16" caps are retained in the pinion flange? Are there supposed to be tangs cast into the flange to keep the caps from sliding out? The area on the flange where the caps rest is completely smooth on mine. I did have the gearing changed from 2.56 to 3.08 but I assume (maybe a bad assumption) the pinion flange was not changed.

Thanks.

Doug I can look at my 67 Sprint tonight if you think it may help? Not sure of the exact U-Joints it has compared to a V8 car though.

camerjeff that would be great. Mainly see if there are any retainers other than the u-bolts holding the pinion side. Thanks.

Did you try a u-joint with 1 1/8" cups to determine they do not fit? I ask because a 1 1/16" cup with a 1 1/8" pinion/u-bolt can easily seem like it's correct.

Doug sorry I forgot to look at my 67's until tonight.

I don't think it will help you in has a U-joint with four 1 1/8" cups, and just uses the U-Bolts and inside C-Clips. It is a manual trans car.

Thank you both for getting back. A 1 1/8" cap definitely does not fit, see pic. After a ton of searching, I found a part that should work. The Spicer 5-3022-1X has 1 1/8' x 1 1/16" caps with grooves for inside c-clips on all caps. It arrives Tuesday, I will find out then. I am still perplexed as to what the stock configuration is/was. The combination/conversion joint is spec'd for my car, yet the the ones provided by the parts houses have no means for retention of the caps on the pinion flange beyond the u-bolts.

Thanks again,

Doug

The Spicer 5-3022 is a 'adapter' u-joint used to adapt a Pontiac to a chevy style usually.

I use that when I swapped a chevy 12 bolt into my Bird.
Usually Pontiac used a size (3R?) that is different from others.
So, possibly the rear flange is changed or driveshaft?


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