Alright i have a 1977 f250 highboy. I've had the truck for about a year now and have had a problem with the shaft inbetween the trans and t case. The shaft just eats up u joints like crazy. I think ive gone through 4 or 5 joints this year. It doesnt look like the shaft is missing any weights. Any ideas?

 

It doesn't "look" like it? Take the thing off and check it for balance.

 

Has anyone done any modifications such as dropping the case down for a lift? If so, it could be too steep an angle, or if the case is moved around at all, then it can cause wear on the joints.

 

really easy fix. Go to the junkyard, buy a married trans/t-case and the driveline to it. Stubby drivelines are one of the worst design flaws ever in my opinion. Tho if thats out of the budget, check the transfer case mount for any issues.. bent, broke, rotted. Could be causing it to bind. Also, if youre doing the joints yourself make sure theyre the right joints. And make sure the joint is centered and moves freely before you install the driveline in the vehicle.

 

Why in the woorld would dropping the transfer case help anything? Dropping a divorced case would create a problem with the angle of the shaft between the trans and case. The divorced case is already si far back that driveline angle issues are seldom a problem.

Now, there has to be a problem with either the slip joint os something in the shaft itself. I dont know why this thing could eat joints. The only thing I could imagine is that the joint is being installed incorrectly.
Is it the same joint that is going bad?
How much torque are you putting on the u bolts? If you tighten the u bolts too tight, you turn the bearing into a bushing, and this would eat a joint in no time? Are you greasing the joint before use? That packing grease is no good and they need real grease in them before real use.

Its virtually impossible to have a severe angle on this shaft, and even a compound angle may only lead to a vibration and not a torn up joint. Some other variable is present, and I believe that the u bolts are too tight.

 

I fyou look at many of the old school monster trucks, they used to relocate the transfer case to improve the angle of the driveshafts to the axles, trying to balance it out. never said it was a good idea, just that some would do that...

 

I believe that the OP was having problems with the driveshaft from the trans to the transfer case. This is the shortest driveshaft of the three total that this truck has. This driveshaft has very little angle at all and relocating the transfer case would create an angle where it is not necessary. The OP was not refereing to the angle of the output driveshafts for the front or the rear. Divorced transfer cases generally do not have angle problems. That front shaft is pretty long, and lifting these trucks to the moon typically does not create a problem.
Clocking, or reindexing transfer cases will only change the front angle, since the input and ooutput revolve around a common shaft.
These trucks have been running around for years without tearing up joints, and the angles are kept at a minumum by design, so there has to be a problem that will not require such a modification.

 

It was a suggestion to check, for crying out loud! I am not an idiot, I do know how these are put together, had one myself in the past, and I also never had a problem with the center drive shaft, but he is, and it was merely a suggestion, sheesh! I never told him to do it, never suggested it was a good idea, so get off it already! Perhaps the caps are getting too tight, that does sound plausible, but there are those out there that will do such as I suggested, so it is possible, chill out already! Can noone have a suggestion that might not be what you think? Do you really think I don't know that he was talking about the intermediate shaft, or do you think everyone else doesn't know as much? I do know there are three shafts, and I do know that the front drive shaft is long, but guess what, the rear isn't as long as a result. there is a reason why the rear shaft has a cardan joint, and it isn't because it has a nice angle. Save the know it all attitude for someone else.

I also was not referring to rotating, or clocking the transfer case, but rather, lowering it from the frame. The transfer case mounts can be lowered down, such that the lift would not interfere with the output angles. That would put an angle on the inter=mediate shaft that was not there before, but would take some angle out from the front and rear shafts. That is the idea behind what i mention that may or may not be a good thing, but it has and can be done. People do things to these trucks over the years, and it is possible to have had a PO that did such, so it is a possibility to consider. So rather than jump all over me, just leave it be already.

 

Take it easy turbo. I was not jumping all over you. I am afraid you may have taken this the wrong way. It is possible that a previous owner has changed the truck around and moved the transfer case, but I highly doubt this is the case. Of course this is all speculation.
If the case has been changed around or moved, the compound angle would probbably cause a vibrations and might not necessarilly cause the joint to fail. Though anything is possible, so who really knows right?
Perhaps after a joint failure, the end of the yoke is no longer round, and the cap is being deformed.
Perhaps the angle is the problem.

Also not real sure about the reason a double cardan on the rear shaft is used. My divorced 205's have single joints. (1350's and 1410's). I dont think they are necessary in the rear. I dont have a vibration problem or any chatter.