Death wobble question.

[oldrusty]

Ok I'm looking for anybodys input here...... I have a 89 longbed 4x4 that has developed death wobble out of nowhere in th past couple months. The truck has about a 3 inch lift with stock control arms. I drive about 70 miles a day to and from work on some 2 lane and 4 lane roads. The truck has driven great about a year and a half until just recently at all speeds up to about 75 or 80. I have checked all the steering components and none of them are loose. The tracbar is a new stock one I installed about 1 year ago. I checked both ends of the tracbar and the frame mount and everything is tight there as well. All the ball joints are tight and well greased. The only problem ive had this summer is a broken stud on one front shock. All was well untill about six weeks ago when i switched from my summer aluminum rims to my steel winter rims and tires. I took the tires off and bubble balanced them and they are all good. The wobble comes in from 50 to 60 mph but goes away at speeds above that. If you accelerate quickly to about 65 it doesnt wobble from 50 to 60.Now here's where it gets really crazy. I took it out today for the first time with the 6 foot meyers plow on the front and had very little wobble what so ever. :???: :???: :???: Any body have any ideas why adding weight to the front made the wobble bearable?

[Eagle]

All was well untill about six weeks ago when i switched from my summer aluminum rims to my steel winter rims and tires. I took the tires off and bubble balanced them and they are all good. The wobble comes in from 50 to 60 mph but goes away at speeds above that. If you accelerate quickly to about 65 it doesnt wobble from 50 to 60.Now here's where it gets really crazy. I took it out today for the first time with the 6 foot meyers plow on the front and had very little wobble what so ever. :???: :???: :???: Any body have any ideas why adding weight to the front made the wobble bearable?

You do NOT have death wobble. You have tire shimmy. Read other threads on death wobble. You do NOT accelerate through death wobble to see if it'll go away at 62-1/2 MPH. When death wobble strikes -- you hold on for dear life, stomp on the brakes, and pray to the deity of your choice that you can control the vehicle long enough to get it stopped.

 

No, that is NOT an exaggeration.

 

Your clue is two-fold: (1) it began when you changed tires; (2) it kicks in at 50 MPH and it stops at 60 MPH. Classic symptoms of wheel IMbalance. The reason the plow stops it is that the plow puts a lot more weight on the front wheels, so there's a lot more resistance to wobbling. It's just about impossible to bubble balance larger, wider tires. Heck, when you get into larger LT sizes, most shops can't even get 'em balanced right on their fancy, high-tech computerized spin balancers.

 

Balance your tires correctly and you won't have any more problems.

[Comanchero87]

bias ply tires also will make a truck do a shimmy during the right conditions. My Friends 77 gmc short box would do this after he installed a set of baja claws. Never knew what caused it until he sold me the tires and i put them on my 78 blazer and all of a sudden i had the same problem.

[bigd44889]

i had same type of probem bent rim not disagreing with what thay said just that is what mine was :bowdown:

[oldrusty]

I should have mentioned before this also occurs at any speed above 50 mph if I hit a bump with the left front tire. I have also swapped out the wheels and tires with the wifes xj and while it was better from 50 to 60 but it still shook after hitting a bump just not as bad.

[Pete M]

How old are your shocks?

[oldrusty]

Just replaced the front shocks this morning as a matter of fact. I am now able to run up to about 58 mph before it starts to shake. Once it starts though I have to slow back down below 40 to calm it down. I'm gonna take the tires and wheels and have them spin balanced just to make sure I don't have a bent rim. I really can't believe its the tires and or wheels. I ran these tires last winter with no problem. Just seems funny that this all started as soon as I put them back on for this winter.

[carnuck]

Worn wheelbearings?

[oldrusty]

Both front wheel bearings are tight and smooth. Does anyone think that wear in the steering gear itself cuold cause this? Truck has 202,000 on it. I noticed yesterday that the steering in the wifes xj is alot tighter than what mine is. It doesnt seem to have much play in the wheel itself but the xj seems to steer alot quicker.

[jtdesigns]

The best way, I have experienced, to really test the track bar is to lift the front up by the axle and have someone turn the wheel lock to lock. Visually observe the the steering, it will causes the body to move in either direction if bad. I have real lose steering too. I think a new gear box will fix mine for sure, but going to have to wait on that one. The highspeed shimmy, I'd be willing to bet money on, is unbalanced wheels.. Do you think any water has gotten in the tires? I'm sure you'd be able to hear it sloshing around in there (if enough water to cause unbalance while spinning). Did you check to see if there any broken plys in the tires? If alinement is bad enough it will cause a shimmy, however, it will also pull to either side of the road really hard. My best advise is to have them road forced balanced then go with the steering box. The lose steering box still wouldn't cause the shimmy though. Which by the way, you can adjust, not sure which way you turn it, but if you look down on the box you will see the adjustment screw. It'll have a hex head set screw with a lock nut on it. I'm pretty sure it's been covered with-in the forum in the past. Good luck!

[oldrusty]

Gonna have the tires done monday( my next day off). Ive adjusted steering boxes before just not on this truck. I may look at that today if things are slow at work.

[Jacobs]

The best way, I have experienced, to really test the track bar is to lift the front up by the axle and have someone turn the wheel lock to lock. Visually observe the the steering, it will causes the body to move in either direction if bad.

 

That doesn't work nearly as well as leaving the weight of the truck on the ground. If the tires are in the air, there's not enough force to make the loose parts show deflection.

 

I agree on tires being the likely culprit. However it's possible that the control arm bushings have softened up just a little since the tires were last on, a bolt elsewhere has worked its way loose, etc.

[Sugarfoot]

My bet is Ball joints with that many miles on it. Previous owner over 60-70 years of age? If so that explains the vib at a lower speed than where it usually is at, which is around 65 mph on any high mileage vehicle. Basically a high mileage worn spot after hours and hours of highway miles at a continues set speed. You rack more time and miles at that speed than any other speed you drive. It's possible to have if you always drove at 30 mph max for 20 years. The plow is just shifting the load, keeping the front end weighted down. Does it go away at 75/80 mph? My bet is it does?

[Jacobs]

My bet is Ball joints with that many miles on it. Previous owner over 60-70 years of age? If so that explains the vib at a lower speed than where it usually is at, which is around 65 mph on any high mileage vehicle. Basically a high mileage worn spot after hours and hours of highway miles at a continues set speed. You rack more time and miles at that speed than any other speed you drive. It's possible to have if you always drove at 30 mph max for 20 years. The plow is just shifting the load, keeping the front end weighted down. Does it go away at 75/80 mph? My bet is it does?

 

So if the prior owner was 60-70 years old, the vibration occurs at 65 mph? So a 40-50 year old owner would develop a vibration at 45 mph? Interesting.

[Eagle]

My bet is Ball joints with that many miles on it. Previous owner over 60-70 years of age? If so that explains the vib at a lower speed than where it usually is at, which is around 65 mph on any high mileage vehicle. Basically a high mileage worn spot after hours and hours of highway miles at a continues set speed. You rack more time and miles at that speed than any other speed you drive. It's possible to have if you always drove at 30 mph max for 20 years. The plow is just shifting the load, keeping the front end weighted down. Does it go away at 75/80 mph? My bet is it does?

 

So if the prior owner was 60-70 years old, the vibration occurs at 65 mph? So a 40-50 year old owner would develop a vibration at 45 mph? Interesting.

Anecdotal.

 

My mother's new 1958 station wagon shimmied at 53 MPH in 1958. I was 14 then. My 1988 Cherokee shimmies at 54 MPH in 2008. I'm now 64 and the XJ has 280,000 miles on it. Somehow I fail to see any correlation, or reason for one, between the owner's or driver's age and the speed at which the shimmy occurs.

[oldrusty]

I finally gave in today and changed the wheels and tires out for another set I had in the garage. Took it for a little spin and gueww what....no more shaking. :cheers: It amazes me that tires and or a bad rim could make a vehicle shake that violently. I have always mounted and balanced my own tires, had a few shimmy from not getting the balance just right, even had a couple with broken belts. But I would have never believed that a tire or tires could make a truck almost undriveable. Thanks to everyone who chimed in. At least I know my front end parts are all in good shape....lol

[chicofuentes0224]

:clapping: :thumbsup:

[jtdesigns]

I'm sure theres some long drawn out formula that explains the relation of speed to the frequency of vibration. 53 +- 4 or 5 mph seems like the sweet spot for a bad set of tires. I bought a used set of Goodyears for my Rodeo and mounted them myself at a friends shop. I get a high frequency vibration right around 60 mph; it evens out around 65. I left the old weights on the rims, but havent had them balanced. I always think unbalanced tires when the speed is higher. I changed ever brake part on the front of a old Honda I had before I realized that I needed to change tires. That was just because I would get a pretty bad shimmy, and if I hit the brakes, it would intensify the shake until a certain lower speed was reached..