Purpose of welding u-joint caps

[Capt. Nemo]

I've just upgraded and replaced my 297x's with the larger 760x's. This was my first time replacing u-joints, and it went without a hitch- very straightforward. In replacing the u-joints, there are clips on the bottom of the caps which keep them in place. I can't imagine that welding the caps is to keep them in place because these clips are there and serve that purpose. The only conclusion that I could come to as to why caps are welded is to eliminate the axle yoke from flexing and spreading apart. Am I on the right track? What is the real reason for welding the caps? I imagine that the tack weld on the cap (from what I've read it's only a tack weld) would probably break under a hard load, maybe acting as an indicator that you're about to have some problems??? Someone set me straight... because I'm about to weld my caps and want to know exactly why I'm doing it.

 

[woody]

Well, I've never welded my 297 caps on, but lots of folks here do, so I'll pass along the concept.

The factory clips are just pop-on "c"s that really are just a press/snap fit. IF the caps are snug in the yokes everything 'should be' tight & good.

When axleshaft yokes stretch (cap holes 'egg out') and the caps spin, then the OEM type c clips offer a slim margin of retention....usually popped out by cap rotation and/or bind (recall how you got the old joint's c-clips out? new ones haven't got the benefit of years of rust & funk to help keep em)

Some folks take a die-grinder & relieve the inner/back surface of the yokes to accept full-circle 'snap rings'...offering LOTS better retention than c-clips.

Better yet is to (in addition to the snap-ring mod) tack weld the caps to the yoke. I suppose the theory is to prevent the caps from spinning within the yoke and thus reducing/eliminating the potential for wallowing out the holes.

If the yoke ears are going to fail, it's usually because they spit a cap out of a loose hole, or their range-of-motion has been exceeded (IE your steering stops let you turn too far and the yokes bind up = :explosion: ) I don't think 'pure torque' is gonna do it... something mechanically faulty is usually the culprit. :dunno: YMMV

Since I haven't welded mine, I'll defer on tips besides this: try not to cook the grease inside

 

[BrettM]

welding is for the sole purpose of keeping the caps in place, the extra heat will actually negatively affect the yokes, but the caps are usually the first thing to go anyway. you can also get full-circle clips but they require grinding the stock shafts. the normal clips don't do a good enough job of holding the caps on.

the biggest concern when welding caps is to not melt the needle bearings. there are some joints that have a solid bushing to replace the needle bearins so that this isn't a problem

http://www.longfieldsuperaxles.com
http://www.sn-fab.com/retail.html