1955 Rear Universal Joint ID

C

cpcooper

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Mar 17, 2022
Thunderbird Year
1955
I'm pretty new to Thunderbirds, mostly an Austin Healey guy, but volunteered to help a friend get his '55 that arrived in boxes running. I'm close, but have run into a problem with the rear U joint. The one we have has an unusual way of attaching to the rear yoke; not a problem EXCEPT the caps are too small for the rear driveshaft yoke. It does fit the yoke on the differential. The driveshaft wants caps about 1-1/16 in diameter and the ones on our U joint are about an inch. Does anyone know if the type of U joint pictured comes in a larger size, or should we be looking to change the yoke on the diff?

Thanks,

CraigU Joint.jpg
 

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cpcooper said:
I'm pretty new to Thunderbirds, mostly an Austin Healey guy, but volunteered to help a friend get his '55 that arrived in boxes running. I'm close, but have run into a problem with the rear U joint. The one we have has an unusual way of attaching to the rear yoke; not a problem EXCEPT the caps are too small for the rear driveshaft yoke. It does fit the yoke on the differential. The driveshaft wants caps about 1-1/16 in diameter and the ones on our U joint are about an inch. Does anyone know if the type of U joint pictured comes in a larger size, or should we be looking to change the yoke on the diff?

Thanks,

CraigView attachment 21143
Click to expand...
Your car should use 5-1200X Spicer ujoints with Inside snap rings. Bearing diameter should be 1.062+/-.001" The kit above is not original and has 2 Low Wing Drilled caps that is for a non OEM yoke. If your driveshaft has O/S snap rings, part # 2-7-29 is the part. The inside snap rings are 2-7-99. The ubolt part # is 2-94-28X. Hope that helps.
 
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Sure does, thanks. Sounds like we have the wrong yoke on the third member. Any advice on source/part number for the correct one?

Craig
 
cpcooper said:
Sure does, thanks. Sounds like we have the wrong yoke on the third member. Any advice on source/part number for the correct one?

Craig
Click to expand...
Well, I need to make a correction! I went out and looked on my '55 and it DOES have the low wing threaded caps on two trunions and snap rings on the other 2 like your ujoint in the picture. So, the Spicer catalog was incorrect. Seems you do have the correct ujoint. Look in the Casco catalog and they have an exploded drawing and their part #'s for the ujoints. They do NOT have the yoke part #. You should be able to match up your ujoints at a local driveline shop too. Hope this helps. Sorry about the 1st post being somewhat inaccurate. Good luck this time.....
 
CP, it sounds like either your rear axle/ring & pinion gears have been swapped, which would explain why the OEM-spec. u-joint doesn't fit the yoke. I swapped out my 55 OEM Dana 44 3.31 gears for 2.72 gears from an 80s Corvette. The pinion gear did not have the same number of splines as the OEM, so I had to replace the yoke and get a combination u-joint that fit both driveshaft and replacement yoke.
 
I had this issue on a 64. I got a replacement third member and the yoke on it used the larger ujoint cap size than my original third member had. What I did was buy two u-joints, one with the small caps and one with the large caps. Turns out the diameter of the cross "pins" the needle bearings ride on is the same on both, all that's different is the wall thickness of the cap, at least for the ones I bought. So I just swapped two of the caps from one to the other and bolted it all up.
 
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