oddballracing

Hi all,

Trying to wrap my head around this after totally disproving my original theory after getting under my Jeep today.

Up around 80 km/h (sorry, up here in canuckistan we've got that euro metric garbage) i get a vibration in the driveline, and anything over 110km/h she rumbles like a paint shaker. I'm getting this in both 2wd and 4x4 (full-time), but directly coupled hubs, i doubt that has any bearing on it.

I had originally suspected the universal joints on the front axle shafts, but after crawling underneath and wiggling these around the best i could with a pry bar, there is no play on these. i checked the joints on the front drive shaft, the two at the transfer case have no play, and feel solid, but the one at the front (at the dana 30 pinion yoke) is not up to par. Fair enough, parts wear out, i get it no worries, i'll get a new one and put 'er in... That's where the fun begins.

Looking at the way this mounts I can't help but remember a u-joint replacement on a friend's 95 ZJ (rear joint at dana 35 in that case) quite a few years ago, where the u joint we replaced was clearly not sized properly, and there was a good 1/4 to 3/8 deficit in the cap to cap length, and it slid around back and forth between the "tabs" on the yoke like a hot dog in a hallway. by the time i saw this unit, the shaft had actually dropped, and the u-joint was absolutely destroyed.

That is what i am seeing here, again. The play is only about 1/8 to 3/16 on mine, but the same hot dog in a hallway description applies. Being that this is on the axis that mounts to the diff yoke and is retained by saddle caps, there are no recesses for snap rings, and i can only believe that this is the wrong undersized u joint. the cap diameter is correct, but the overall width is jsut too small. and the offset and play are leading to vibration and tearing up the u joint. This is what was in the vehicle when i purchased it, and I'm only noticing this now that the u joint has gone dry (installed backwards so i can't get to the grease nipple on the cross) and it has begun to tear itself apart. I removed the shaft to inspect and the machined surface on the cross is definitely noticeably worn. I had another joint with identical sized caps (too large of a cross, otherwise i would have just replaced) and put them in as a temporary measure. This is my only operation wheels at the moment as we have just received 15+ inches of snow in Calgary 3 days ago, and are getting more right now as i write this (I'm good with a white Christmas ). The 2wd cars are useless at the moment.

As an avid customer of rock auto, that is where my search began. Unfortunately only one u joint listed had a cap-to-cap measurement published , but was not noted to be for the "front driveshaft" "front joint" location, so i'm worried that i have to buy them all jsut to get the right one. I guess the previous owner that did this install had the same problem, but just went with it).

Has anyone else had this same problem with getting the right u-joint for their jeep? Does anyone have a confirmed list or method of correctly identifying the right u-joint for this application? I'm in a bit of a catch 22 because i can't take this into the parts store to compare (it's wrong anyway), because i need the 4x4 to get out of my driveway .

Any help is greatly appreciated.

Merry Christmas!