another shaky front end at 55 MPH question

96 XJ 4.0 AW4 3" RC lift 31x10.5 on TJ rims

I'm trying to track down a newly occurring moderate to heavy shaking between 50 and 60 MPH. Worse in turns at highway speed.

All the joints under the front end look tight and have been greased regularly.
Track bar looks tight - both ends and frame bracket
Steering box bolts tight
Control arm and sway bar bushings all look good
Brakes feel 100% smooth, no shake or pulsing.

The PO said the steering stabilizer was probably due for a change soon, that was 6,000 miles ago when I picked up this truck. (have not done it yet) Also, have put 6k on the Procomp MT's on the pavement.

This problem was almost non-existant 2 weeks ago and is getting worse fairly rapidly - also the steering was nice and tight at the begining of August and is now getting quite wandering

Q - Could the stabilizer and tire wear account for this and progress that quickly? I didn't think the stabilizer had this much effect.

Q2-I was going to put the rears on the front to check tires as the cause - posts also suggest pulling the front DS to eliminate it - but is the wandering pointing really strongly to a bad TRE even though I can't find one? I can't see a bad front DS joint make it feel loose, just shakey.

One more note - for the last week I have been towing a medium sized trailer while up in the north country on vacation. Added wear?

Side question - I know that wheel balance is often a problem. Can wheels with tires that are 50% worn be effectively re-balanced?

Is the wear on the tires uneven if so that's the first place to look. I would say you should swap the steering stabilizer its pretty important and inexpensive. Those 2 things right there have solved "Death Wobble" on my jeep before fist time was just the stabilizer and the second was unevenly worn tires. Also at the speed your saying it happens at that is generally when you would get wobble from an unbalanced tire.

And to your side question tires should be rebalanced every 3000 miles so yes even if they are 50% worn they can be rebalanced.

I am new to this Forum so I have been doing a lot of reading. Lots of great history and knowledge. I had a wobble from my old tires at around the same speed and it went away when I put on my new tires. I could have re balanced but the tires were about shot and I just put on the 3" lift so I could add 31" tires. My new 31" Duratracs came with a free rotate and balance every 6k miles and understand the re balance is highly recommended.

"Looks good" as in with the front wheels on the ground you crawled under the front end with a bright spotlight and had a second pair of hands slowly turn the steering wheel to the left and right while you observed the steering components for odd movements?

After checking the above, did you then jack up the front end, grab a tire at 12 and 6 o'clock and try to wiggle it to check the ball joint? Did you then grab the tire at 3 and 9 o'clock and try to wiggle it to check the unit bearing? Did you then do the same thing to the other front wheel?

Did you take a large pry bar and slip it in against the upper and lower control arms next to the bushings and see how much play there is? Unibody and axle ends for all four bushings?

A steering shimmy that appears at 50-60 and disappears if you speed up or slow down is a tire balance issue.

You still might need some steering/suspension maintenance to replace any worn parts or bushings. Just because a part "looks ok" does not mean that it is not in need of replacement.

Here is your diagnostic checklist

-Front tires out of balance
-Front alignment out of spec
-Loose track bar
-Worn track bar bushings
-Worn track bar end
-Needing an adjustable track bar
-Bad bushings/joints in control arms
-Worn/damaged steering stabilizer
-Worn/damaged shocks
-Worn/damaged tie rod end
-Bad U Joint
-Bad ball joint
-Loose frame mount
-Steering box looseness
-Drive shaft(s) not balanced
-Bad front hub assembly

Gave it a really good going over with an assistant moving the wheels - on the ground, then jacked up.

Could find no slop anywhere in the joints.

Tires look very even, but I know it doesn't take much.

I will go throught the list and report.

Is the Rancho Stabilizer a good choice?

Sounds like tire balance. Easiest thing would be rotate front to back and see what happens- that's assuming the rear tires are balanced. Stay on top of rotating them, 6000 miles on a mud terrain without rotation is too far. You can always balance a tire, but you can't make it round again. Cupping leads to belt shifting leads to out of round tires.

Tire rotation reduced shakiness by at least half, still quite noticable.

However, one of the rears that I brought forward has a nice 3" wide machined grove all the way around the the tire just out from the rim - result of the time the small leaf slipped out of the pack. Beautiful lathe work; very smooth.

I am going to add the Rancho stabilizer tonight and see if it helps.

New tires at some point soon I guess is an answer, but an expensive one.

BrokenSockets said:

Tire rotation reduced shakiness by at least half, still quite noticable. New tires at some point soon I guess is an answer, but an expensive one.

Click to expand...

Since moving the rear tires to the front has decreased the vibrations by half then for your next test; I would have the tires balanced to see if there is more of a change.

You need to go thru the front end (check alignment) thoroughly since worn front end parts will cause quicker tires wear quicker and cause the tire balance problems.

Tires can almost always be balanced; a bent rim is a lot more difficult.....

Charles

BrokenSockets said:

Tire rotation reduced shakiness by at least half, still quite noticable.

However, one of the rears that I brought forward has a nice 3" wide machined grove all the way around the the tire just out from the rim - result of the time the small leaf slipped out of the pack. Beautiful lathe work; very smooth.

I am going to add the Rancho stabilizer tonight and see if it helps.

New tires at some point soon I guess is an answer, but an expensive one.

Click to expand...

Heaven forbid that you actually follow the advice that has been given in this thread. The steering stabilizer will not fix your problem, but hey, it's your rig and your money.

I already had the new stabilizer, so there was no reason not to change it out. I could move the old one in and out with practically no resistance so it was pretty much shot.

I agree with you and did not really expect any improvement but have not had a chance to get the tires balanced until this weekend.

I do take the advice given here. I have been reading as many posts and write ups as i can this week with alignment procedure tips and will follow them after the wheels get balanced tomorrow.

wow... 3000 mile rebalancing? belt shifting? where do you get this stuff.... uggghh

BrokenSockets said:

I already had the new stabilizer, so there was no reason not to change it out. I could move the old one in and out with practically no resistance so it was pretty much shot.

I agree with you and did not really expect any improvement but have not had a chance to get the tires balanced until this weekend.

I do take the advice given here. I have been reading as many posts and write ups as i can this week with alignment procedure tips and will follow them after the wheels get balanced tomorrow.

Click to expand...

I had a vibe just like you described. Started @ highway speeds and increased when the wheel was turned (in my case) towards the right.

Turned out to be the steering gear adapter was shattered behind the steering box. Replaced it, vibe gone.

Sorry, didn't post after the tire balance in early September. Problem 95% gone. Did a small adjustment to the toe after taking some measurements - Shakiness all gone!

that's where I'm at. I have replaced everything in the driveline, steering and motor/tranny mounts. All needed. The shake from 55-65 is still there after a balance and pep boys tech (read, can't do crap if the machine doesn't tell him to) aligned it. The only thing making a difference in the shake is where the toe is set. Slight out is higher speed wobble, slight in lower speed.