The last item to be refurbished is the u-joint.
The current u-joint was last taken apart in 2017 when I rebuilt Lurch's engine. At that time, I swapped out the worn out three speed transmission with a psudo-rebuilt four speed tranny. I took the best parts from three 4-speed trannies and made one 'better' tranny for Lurch.
When putting this 'newer' tranny back in Lurch, the 1928 front yoke of the u-joint mated well with the rear yoke that was on Lurch's driveshaft. At least statically, they bolted together nicely (or so I thought).
BTW, before I took the front u-joint yoke off the back of the transmission, I pulled out the little speedometer driving gear and shaft that is driven by the spiral gear that is pressed onto front u-joint yoke. With the speedo gear out of the housing, the u-joint yoke can come out without damaging the speedo gear.
Now that I have those parts out and in the open again, I learned that the 1927 rear yoke (and its trunnions) were smaller than the 1928 front yoke and its trunnions.
In photo number 86, you can see the '28 trunnion clamped nicely in the u-joint. However, rotating the u-joint 90 degrees (photo 87) and you'll see the 1927 trunnion with a big gap around it in the clamp.
THE SMOKING GUN OF THE SQUEAL!If you zoom in on photo 88, you can see where the 1927 trunnions were spinning in the clamp and thus, make a squealing noise.
So the remedy is to find a good set of 1928 u-joint parts that fit the one ton truck. According to my parts book, the same u-joint part numbers were used for the 1928 1 ton truck through the 1930 1 1/2 ton truck.
The hunt begins! None of the regular vendors carry new parts for this. ;-( One vendor has a used 1928 u-joint (unknown condition) and he wants $350 for it. Ouch!
I reached out to the VCCA Technical Advisors and one of them (Bill Hulbert) had some parts that he sold me for $200. This included a '28 front yoke (with clamp and two trunnions) and a complete '30 u-joint. All used, but beggars can't be choosers. He told me that the '30 (model LR truck) had the speedometer coming out the driver's side of the tranny, which is the reverse side from Lurch's tranny. Evidently, the worm gear is pressed onto the front yoke, so it can be taken off and replaced with the correct speedo gear.
When the parts arrived from Bill, I noticed something beside the reverse speedo gear: the trunnions were not domed, but had a ridge around them. I don't know if these ridged trunnions (and clamp) were aftermarket parts or if Chevy switched to this design at some point in time. Either way, I can't use these ridged trunnions because one of them is really worn.
See photos 89 and 90 for a view of three trunnions ('27 domed on the far left, '28 domed in the middle, and '30 on the right). Notice pronounced bevel showing on the middle trunnion in photo 89. The trunnions must go onto the yoke with the bevel towards the center of the u-joint. The bevel provides some clearance for where the trunnion shaft meets the yoke body.
Luckily, the trunnion shafts on the rear 1930 yoke have the same diameter to fit up with the 1928 domed trunnions and I have a few of those. ;-)
I ended up using some of the parts I got from Bill ('28 front yoke, '28 trunnion clamp, and '30 rear yoke) and the best four domed trunnions from my stash. The trunnion-to-shaft clearance I ended up with was a range of .004" - .008" with the used parts that I'm putting together. At least they all fit in the clamp and are in WAY better shape than the parts I took out of Lurch. ;-)
With the u-joint parts settled, I'm one step closer to the final re-assembly and hopefully get Lurch back on the road without the ominous squeal.
Cheers, Dean
