U-joint full circle alternative - thoughts?
 

I understand that a full circle conversion greatly reduces the probability of popping a cap however I am thinking about just tack welding the caps to hold them in place rather than grinding down material and installing the full circle clips. my thought is when it comes time to replace a u-joint I can just grind down those tacks and then replace the joint itself. My reasoning behind this is I have a second complete Axel and if I do break something I just swap out the whole thing at once. If I didn't have the second set then I would probably do the full circle conversion. Thoughts, opinions?

Tack welding the u joints caps is a pretty common practice.

X2, very common.

People do tend to go back and forth on this topic because to get a good tack requires you put a relatively large amount of heat into a small local area which likely bakes the grease under the cap. How bad is that really? I don't have the answer to that. Furthermore, I've seen a fair amount of pictures where the tack welds are broken, likely because the weld did not get enough penetration.

I've also seen people do a makeshift "almost alloy" kit by welding large washers over the u-joint caps. This is probably the route I'd go. Sure, that would take more effort to remove in the event of changing a u-joint, but if you already have the grinder out, how much more is it, really? This idea is nice because the ear of the shaft is reinforced to prevent the hole from becoming oblong under stress. On the other hand, there is a concern of welding affecting the material properties in the shaft. I'm not sure what alloy steel the factory shafts are made of and how they are heat treated, but I'm willing to bet welding to that area is not the best for the toughness of the material.

I'm not sure if preventing the cap from walking is important or if the idea is just to retain the cap into the axle. With full circle clips, the u-joint cap still has the ability to rotate in the ear of the axle shaft. Tacking the caps prevents this rotation. An almost alloy kit could either prevent or allow the rotation, depending on if you weld to the cap or not. I supposed one could do full circle clips and peen the shaft/cap to prevent rotation.

Does anybody with more information/experience on this have a justification for welding to the axle shafts to prevent the u-joint cap from rotating rather than doing full circle clips to just retain the cap?

Great suggestion, I never thought about using a washer to hold it in place, which would increase the strength of the ears.

I have mine tacked with a locked D30 on 35s. No issues yet knock on wood.

I have one side with full circle & the other is welded.

I like the way you do science.

I have only owned my XJ for a few months, is popping steering U-joint caps a common thing? Seems to me that the only way this could happen is if the yoke gets deformed enough that it allows the cap to move. It is logical that the steering joint takes a lot more abuse than the driveshaft U-joints due to the extreme working angles coupled with random shock loads from the wheels. In that context, I can understand the advantage of welding the caps in place. I can see welding doing two things. 1. Lock the caps in place. 2. Create a structural reinforcement to the yoke by making the assembly one piece in effect.

It really isn't much of an issue until you have 33" tires or larger and a locker in the front axle. The yoke getting deformed is exactly what happens, then if the cap falls out it wobbles around in the hole and makes it worse.

Kinda. What tends to happen is the C-clips which hold the u-joint caps in the yoke become seized to the caps. Then, under heavy stress from wheelin, the yoke of the axle deforms, causing the hole to oblong slightly. This causes the u-joint cap to rotate in the hole, which rotates the C-clip with the cap. Eventually, the cap rotates enough that the C-clip butts up against a shoulder on the yoke and falls off as the u-joint cap rotates and the clip does not. Once the clip falls off the cap is free to work its way out.

People run full circle clips to prevent this from happening.