FTHESHACK

Quick XJ description:

Front D30 4:56 gears, detroit trutrac lsd's, 33" MTR's, USA Alloy manual locking hub conversion kit with new axles, bearings, and ujoints, tatton double cardan front drive shaft, rusty's adjustable upper and lower control arms, RC control arm drop kit, ball joints, adjustable track bar, & RC 6.5" lift. Just about everything under the front end is nearly new. All of the suspension/axle build work was done this summer and has about 7K miles on it. No bump steer issues, either. 127k in the XJ.


I am getting intermittent front end vibrations, like I am driving on rumble strips. Usually occurs between 30 & 40 mph. Drives great at highway speeds. I have a 25 mile drive to work and it will occur about 5 times each way. The vibration will go away if I slow down or speed up about 5mph. It is mostly induced by small bumps like manhole covers and shallow potholes, though sometimes it just starts on smooth road. 4wd works as it should and no vibes when in 4wd.

Here is what I have checked:

BJ's, TRE's, tightened track bar, checked torque on all the bolts under the frond end, checked alignment, balanced and rotated the tires, no wiggle in the tires side to side or top/bottom, checked brakes/rotors, hub bearings, all the u-joints (all new and greaseable), greased the spicer centering ball, checked the yoke for play, rechecked the pinion angle, checked all the bushings for wear, & drove the jeep with the front axle removed and still had the vibes. All of the above mentioned is in great condition and performing as it should.

Today I noticed that the front axles have a little bit of in/out play when the manual hubs are "free"/"unlocked". I would estimate the passenger side to move in/out about 1/8" to 3/16" and the drivers side felt like 1/4" (I didn't attempt an exact measurement). With both hubs manually locked (tc still in 2wd) the play on both axles seemed equally tight.

So, I decided to keep the hubs locked, keep th TC in 2wd, and drive the XJ to work that way. NOT a single vibration in 50 miles today. "Unlocked" the hubs and took the jeep for a quick drive when I got home...got the vibrations again. "Locked" the hubs and no vibes on the same stretch of road.

I am completely lost as to what might be causing the vibes and am hoping the expertise on this forum can help me resolve the issue. BTW, all this started about a month ago and I have methodically been hunting the issue as weather permits. I'm just out of ideas at this point and need some help, please. If you need more info from me, I will be happy to get it.

FTHESHACK

TTT

JerrytheJeep

Sounds like its that bit of slop with the hubs.

Can you clarify what you mean when you say "equally tight"?

FTHESHACK

When I lock the hubs and check the axles for play, both sides feel the same. I can rotate the wheels with no grinding or abnormal resistance.

robsgotit

Your experiencing "death wobble" it coul be happening for a number of reasons. Bad alignment (castor mostly) worn tires, control arm bushings, weak stabilizer etc. there's a lot to check

robsgotit

By what you described that slight play in the hubs when unlocked is what's setting it off

I ARE EL1TE

Does it shake the steering wheel?

FTHESHACK

There is no shaking in the steering wheel at all. The vibration seems isolated to a single wheel and generally lasts for only a few seconds at a time. It sounds like driving on a rumble strip or an out of balance tire. I have had the tires balanced and I have rotated the tires with no change to the vibration. I am thinking that it's possibly one of the axle bearings that is bad causing a vibration when the hub is unlocked. Locking the hub locks the axle in place and it rotates with the bearings and that is why the vibration isn't there when locked. What do y'all think of that possibility?

FTHESHACK

I had forgotten to update the thread with the solution. Took me a while to isolate the problem. I finally found that the passenger side spindle bearing was worn slightly, but just enough that small sharp bumps in the road would cause it to buzz/vibrate on the axle for a few a seconds at a time. It took a magnifying glass for me to see that the needle bearings had worn in the middle shaping them like hour glasses. When the hubs were unlocked, that slight bit of wear was just enough to unseat the bearing from the axle after a sharp bump and cause the intermittent vibrations. Easy repair (once found). About one hour start to finish.

DJeXeCute

Nice glad you got it fixed