Vibration from 50 mph on up
 

Hi, my name is Brad S. and I'm from Holland, MI & new to the forum and new to XJ ownership...I hope you all can help me.

I have a 2000 Cherokee with stock 15" tires on it and stock steel wheels. All other items are stock as well with no lift kit. Auto trans, command-trac 4wd, 4.0L

Now for the problem that has been keeping me awake at nights!!

I have a vibration that starts at about 50-55 mph and gets a touch worse as I get up to 70 mph, but stays the same all the way to 100 mph (tried driving that fast just to see if there was a "window" that it wouldn't vibrate in). It doesn't seem like a tire balance as it doesn't vibrate the wheel side to side.

I have read all the vibration posts I can find hoping to not have to post a question.

I have taken both drive-shafts off completely and did not see any missing weights or dents in the drive shafts and they are clean and free of mud/dirt. I did have a bad lower u-joint (binding needle bearings in one of the caps) on the front DS which I changed out, but that didn't help. The rear drive shaft yoke is tight with no wobble or play and the trans shaft that the rear DS fits onto is tight. The front diff yoke is tight with no play/wobble and the companion flange on the transfer case is also good. There is very small (less than 1/16" of an inch side-to-side & up-and -down) play in the front DS where the cap/grease zerk fits over the smaller shaft.

I drove it in regular drive/OD and get the vibration at about 2100 rpms. I then shifted into 3rd gear and brought it up to 2100 rpms and the vibration is still there (that's what the Hayne's manual says to do to try and diagnose if it's in the driveshafts...I'm a newbie mechanic DIY'er too)

I also drove it w/out the front driveshaft in and the vibration was gone, so thinking it was that lower u-joint on the front DS I thought I had it figured out.

Also, when I drive it in 4 HI at 50-70mph the vibration is gone.

I put both DS's in by marking the orientation first when I took them out. I re-used the stock u-joint straps and all are tight.

Everything in the front end (tie rod, ball joints, control arms, steering stabilizer) "seems" tight, so I don't know where to go from here.

I have not:
*balanced tires (all wheel weights are present and tires were just replaced and have 12/32" of tread on them and have about 5k miles on them).

*done an alignment, b/c it goes straight down the road and doesn't pull/drift at all either way

*taken either front axle out to check the axle u-joints. Is there a way to check these w/out taking the axle out?? Please tell me there is!


Can anyone point me in the right direction? I'm fearing the worst and I'm very frustrated at this point.

Thanks!!

In would believe it is the front U-joint. Even if you replaced it there would still seem to me that there is something going on there. Especially if you take it out again and the vibs are gone.

50-70 mph in 4hi? Were you on a dirt road? I sure hope so as the Command Trac 4wd system is not meant to be driven on dry pavement.

The front driveline has 3 joints in it plus a centering ball in the H-yoke, did you do all of them? If not, you might want to give it a shot. It's a cheap experiment. If you just did the one on the axle and it didn't fix the problem, I would suspect one or both joints in the H-yoke, especially since the vibes are gone with the shaft out.

Hey guys thanks for replying so quick...

...on prerunners question:
I replaced the front u-joint on the front drive shaft (between the transfer case and the front diff).

And I drove straight at 50-70 mph, not turning, so it's ok to drive straight on pavement as long as you don't turn as I understand it.

I did not replace or check the front axle u-joints. Is there a way to check those w/out taking the wheel/hub/axle out??

Matteo: what is and where is the "centering ball and H-yoke." Have not seen that terminology before.

Thanks!

Look at your driveline where it comes off the t-case. You should see this. That's your h-yoke. It has two u-joints that you should be able to see, and a centering ball inside of it that will be more difficult to see. :) All of these can and will cause a vibration when they start to fail.

This is everything inside the h-yoke.

Hope this helps.

Matteo:

I know what you're talking about now...the other end of the front drive shaft where it connects to the transfer case.

No, I checked those and they are swiveled fine and there was no binding.

:D The "new to me" junkyard front driveline I just put in the rear of mine with my SYE swivels fine with no binding, too. I have a vibration. I'll be changing mine out soon.

So the H yoke and centering ball can be "bad" and you wouldn't know it if the DS was out in your hands, even if everything moved freely with no binding?

I hate to just start throwing parts at it (= $$) but I will replace the H yoke, u-joints there, and everything on that end of the DS and see where we go from there.

Do you or does anyone else think it could be a tire balance or axle u-joint? How do you test the front axle u-joints w/out pulling the axles?

Matteo and prerunner, I really appreciate your responses so far.

It can be. Remember, the h-yoke itself is a non-wear part, so leave that alone. Just change the joints and ball. Also keep in mind that in the Jeep, it's spinning far faster than you can move it with your hand, so what feels 'fine' may well not be. It could be a tire balance issue, so you might want to throw them on a balancer, but since you say the vibes go away with the driveline out, I'd lean towards that first.