Speed specific vibe (55-60) ideas?

Guys,

I've got a vibration on my 99 XJ 4.0 automatic that is finally bugging me enough for me to chase it. It's been there for quite about 30k but is now getting a little worse.

It is a "speed specific" vibration. It ONLY happens between 55-60 mph, never happens below those speeds and never happens above those speeds. It happens on acceleration and when coasting.

It is pretty noticeable in the steering wheel and heck, you can even see the passenger seat shake a bit when it happens.

HERE ARE THE THINGS IT IS NOT.....

It is NOT death wobble. I had that malady a while back and fixed it with replacing all the ball joints, steering stabilizer (not the root cause of DW but needed replacing) and an alignment. This vibe shares none of the extensive symptoms of death wobble.

It is also NOT wheel and or tire related. I have completely exhausted that possibility. Tires have recently been replaced and vibe continues. Wheels have been verified by the best of balancing equipment (twice).

Now that I've completely eliminated wheels/tires, I need to look elsewhere.

I've done a thorough inspection of all front end and steering components and everything is pretty tight but hard to know for sure with that. 140k on the vehicle.

I'm wondering if I shouldn't remove the front driveshaft for starters and see if that eliminates the vibe.

Anybody seen this on yours or have ideas on things to try/check?

Thanks guys......

I'm having the same issue on my 99. My vibration starts around 50 and only gets worse as I go faster. Everything is tight on the front end and my tires are new. I adjusted toe in to + 1/8" and that seems to have helped slightly. I'm thinking its my front DS, I noticed yesterday that there seems to be some lateral play in the slip joint, not sure if this is normal?

I'd start checking out for siezed up u-joints. Pull the driveshafts to see if the u-joints move freely and without play. Mark them at the flange connections first so that you can get them back the same way. Or maybe consider turning them 180 degrees to see if that runs smoother.

yup joints at the wheels and the double cardan on the front shaft by the transfer case are ur suspects. pull the front shaft and try it out. that will eliminate the shaft and point to the joints in the wheels if it still vibrates. check pinion bearing while u are at it. small possibility but it can happen

I would pull the front shaft and see what that gets you.

While you are under there check the driveshafts for any dings/dents, and see if there is any sign of a missing weight from either shaft.

Also, what is the condition of your steering dampener?

Another vote for removing the front driveshaft, mark it on both ends first. If the vibe is gone, put the shaft back in 180* from where it was when you removed it. Test again, depending on results, try each end 180*, testing each time.

I've been fighting a 89 XJ with vibes at 65 & +. Shaft out, it's fine. I had the shaft rebuilt and rebalanced. Spent many $, gave up, pulled a used one from the junk yard. Flipped it around until, viola no vibes. Marked it's installed position with a paint pen, it's a keeper.

I vote for the front driveshaft. Do the front, single u-joint, see if it's any better. The axle u-joints can also contribute to vibes, but these usually make themselves known when turning sharply, as when pulling into a parking space. They'll bind up, then let go, feeling as though you're in 4wd part time. If you decide to do the axle joints, the unit bearings will be out, so maybe it's time for those also.

Had a case of this two weeks ago. would get a bad vibration from 55-60, then it would go away. made doing 55 unbearable. Checked the front shaft and had play in the single u-joint, even though it had maybe 15k on it.

Steering dampener and axle joints have only a few thousand miles on them. Vibe was there before and after replacement of those items.

Guess it's time to inspect driveshaft(s) for missing weights, and not that much trouble to drop the front driveshaft and see if that leads me to the promised land of no vibes!

If it is driveshaft related, I suppose the suspects would be a bad ujoint, drive shaft balance and less likely... shaft angle?

Thanks for the tips so far.....keep em coming!

I just went through a time last fall where I was doing u-joints, had the rear one checked for balance, drove around without the front, turned out it was out of round tires. I've had this happen before, but each time the symptoms are different. Deffinitely pull the front DS, free and easy to do, and start from there.

winterbeater said:

I'd start checking out for siezed up u-joints. Pull the driveshafts to see if the u-joints move freely and without play. Mark them at the flange connections first so that you can get them back the same way. Or maybe consider turning them 180 degrees to see if that runs smoother.

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This. I'd also check the unit bearings... mine were exhibiting no real problems up till about the same speed you give, at which point they made my XJ sound like it was attempting to either take off or grind itself into oblivion.

I would check tire balance before doing anything else. My toe was slightly off and caused a wear pattern to knock the tires out of balance, which produced a shudder around 50 mph

Finally got around to chasing this vibe. I have a friend with a shop which makes things much easier!

We put it on the alignment rack and the alignment numbers were not good, especially the toe numbers. Realigned it and took it out for a test ride.

The problem is 95% better. There is still a very "slight" vibe at around 58 mph, but it is very, very slight and I can live with it. Disconnecting the front DS made no difference.

Bottom line is that I have had a vibe in this range for a very long time and there is likely something that is still contributing to this and if everything else (wheel balance, alignment, etc) isn't perfect, the vibe comes back to a certain degree.

With 140k on it, I can't be too anal about it and as mentioned, I'm fine the way it is. Have to keep some perspective about an 11 year old vehicle at this point.....