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Assessment is now done and a catastrophic failure is clearly evident. (Lo Jodi`)

Damage was found to be more extensive than I thought or hoped. In my mind's eye, though the RPM's were somewhat accelerated, I cannot believe that in addition to the U-joint failing, I also see a hairline crack in the universal joint flange (yoke) as well. My inclination is that the old gal is going to be down for a while and I'm going to need a professional man or shop to replace the flange and then reset the internals surrounding the pinion ring and other components. This kind of repair is way above my pay grade and or skill set.

I am very interested in what Craig H, Randy B., Keith L., and Howard H., and others think. I just cannot believe that the manner in which I have driven this car would cause the flange to crack as seen. I've been told that other than this most recent mishap, I drive like an old man.

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Here is the start in Riki's original thread where jp decided he needed to source a different U joint for his 56. I didn't read thru the whole thing again for the reason his had to change. Being a 56 might be one reason. Possibly yours being a 55 Packard built unit maybe repros or NOS are still available.
https://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?post_id=126722#forumpost126722

Yes it will need a new yoke. Those caps look suspect. They look like cast caps. Sure to be a failure point. Something to check for the rest of us before failure. Mosd gm use a half strap forged ans secured with gr 8. The ford use a u bolt with nuts and lock was. Observe the spec if retro to that style as overtightening can distort the u joint caps and cause failure.

At this point i would say that the crack in the axle yoke is "just one of those things" that happens. How many miles have put on that axle yoke.??? Might be when u get the axle apart u'll find evidence of previous owner hot rodding abuse. Maybe bad from the factory.

Not related to this failure i will advise that after the new u-joint is pressed into the prop shaft to use a standaard mechanics hammer to strike the loop of the drive shaft around the circumfrence of the u-joint cup. This will help to center the cupps and relieve any binding.

Well Parnelli, if you are in to Hole-shots, it's rime for a Ford 9 Inch :) Otherwise, it's a pretty easy job to switch the yoke. Bearing pre-load is your only concern and should involve someone experienced. Any 4WD shop likely has an axle expert. I doubt that you damaged the drive shaft, just install a new u- joint. If you should develop a vibration, then I would explore damage to the Drive shaft.

wait a minute. Did u convert to some other transmission and thus used a cardin type front u joint????

In my experience, that failure is completely unexpected in a vehicle like yours "driven like an old man." I didn't see much of it in many years of NHRA-class drag racing, where you would expect it and did see things like that.

If the driveshaft/rear U-joint were off center before failure, then you would have experienced bad driveline vibration at freeway speeds, which you didn't complain about. Therefore, I don't think it was related to your tranny conversion.

Finding an experienced, competent rear end shop in Tucson should be interesting, but mandatory. But, that's the way to go to fix this and check everything else out. Given the failure pictured, it's not a simple matter of swapping out the yoke and rear U-joint if you want it done right.

Good luck and keep us informed.

Craig

The crack on the diff flange was probably caused by a real hard reverse sometime in the distant past. Notice it is on the left side, where power is applied in reverse. A little extra spread on that ear probably set you up for the joint failure as those Detroit joints are not prone to that failure.

Anyway, I do have an diff flange if you want it. Don't have any new joints but could probably pick you out a good used one and repack it.

As far as replacing the flange, just find some old timer to do it. It is soooooooo not worth pulling the axles out and using a torque spec to set the preload. When I was young I used to try that and found that you could not achieve the spec on a well run-in axle.

Now if I change flanges for some reason I just tighten the nut to oh, maybe 100 ft lb or so. The sleeve in between the bearings determines the spacing and after it has had its initial crush at assembly, we just need to bring the bearings back in firm contact with it.

I agree with Ross on the repair. You can do it at home we can give add. pointers. You do not want to "crush" the collar to add any additional preload. You may want a new nut or loctight. I used to mark the nut and pinion tip with paint . Then run it up to match the marks. First check fluid level, cond and spin the rear several times from the pinion to ensure on grinding, noise, roughness, or play in the rear.(no damage to rear). u may want to renew pinion seal while ur in there

Back on the road again. I acquired all the hard parts, seal and did repairs as you all suggested and guided. I am just done taking her out for a 10 mile drive. All looks, feels and sounds good. I also gave it a new fill of gear oil too. I'm lucky to have a 6' deep automotive pit here at the house in my garage. (I thank the prior homeowner whoever he was).

Feels good to be driving the 400 again.

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