willysmjeeps.com

I may be dreaming but I remember reading a topic that discussed timing the u joints or drive shafts when re installing them. I have searched the Tech. Kn. Base and can't find it and looked in the manuals about the drive shafts and u joints and can't find anything. Does any one remember such a discussion.
thnks
Ralph

The topic was indexing or phasing prop shafts. Prop shafts with three or more joints require this. A two joint shaft doesn't. The topic came up because someone had a driveline vibration. Someone suggested checking the phasing of their joints.

Although our jeep's shafts only have two joints they are not solid shafts. They have a separable spline end. If you have a Willys shaft that is keyed at the splines it is not an issue. If you have a shaft that is not keyed at the splines then you can screw up and get the joints out of phase. The yokes at the end of the short and long shaft pieces must have their ears in the same plane.

Thanks Wes.

The timing of the shaft is no joke. I had my CJ3A give me heck. Vibration and buzzing noise coming from either the transmission or rear end. I looked at the rear drive shaft and the u joints were in time, so I set it aside and got into bearings and differentials. Well, it never went away. A neighbor mechanic came in to help look for the noise and said: "Oh NO!". He pointed at the rear drive shaft. Someone had pryed the little ears and taken apart the slider . Then put it back together wrong with the ujoints in time, but the ears 90 degrees off. That was all it took to set up the vibration. This was a expensive lesson. A machinist once told me: Education is expensive! He was right. John

John,
I understand about the u joints being in the same plane. I am not sure I understand what your problem was. I thought if you pulled the splined drive shafts apart they would only go back one way. I guess when I get the body work completed and go to the drive chain I will take special care with the drive shafts until I understand how they need to go back together.

Some of the civvy shafts are not keyed. When using them they are not dummy proof. You must phase the ears yourself.

It's interesting that the cj3a shafts are that way. Before I wrote my post I looked through the Willys Civilian Manual and could find nothing about aligning the u joints.
I appreciate your responses John and Wes

I didn't say 3A I said some of the civvy shafts. These shafts have been mixed and matched for years. So one never knows which shaft they have except for the obvious difference between the military and civvy shafts which is the threaded seal retainer on the tube end of the long shaft. For all I know the few civvy shafts that are out there without a key spline may be aftermarket.

My particular shaft on the 3A had a slider cap with bendable retaining clips or high points that would hit the splined part of the shaft if pulled all the way apart. It surprised me that someone before me had taken the two pieces apart. Interestingly, there are allignment arrows that should point to each other on each side of the joint. You want the "ears"with the holes to be in allignment. Mine were 90 degrees apart. It was the noise!!!!!! The front shaft is usually the one that wears out first. Wes is correct on the threaded caps being military. Ryan Millers book on M38's shows all this info. Great book by the way! I've used it to solve allot of questions. John