97 grand shimming at 50 with 31s on it

[austtill]

ok guys here is the problem i put 31 10.5 15s on my grand now it shimmys at 50 to 55 and it never done it before the tires have been balenced what gives i checked the suspension when i was under it everything was tight and looked ok please help thanks

[austtill]

come guys all you smart people and no one has any ideas

[JoshuaDHarp]

How old are the shocks? I had a shimmy in the front end and I replaced the shocks, it took care of part of it and then after I put on my new 31's and had them balanced it's completely gone. Mine was happening at 45 to 50 either slowing down or speeding up.

[austtill]

they are fairly new both stablizer links are broke could that do it.

[JoshuaDHarp]

What do you think?

[austtill]

i guess it could but if it was that why does it do it now with the 31s but didnt with the 235s

[Fraser_Brown]

I'd say the tires are not balanced right. Or you have a CV joint issue. Look under it and make sure the CV boots are not ripped, then take it and have the tire shop re-mount the tire and roadforce balance it.

[austtill]

is there a difference between a regular balence and a roadforce balence it doesnt shimmy hard just alittle bit and it only around 50 or so.

[cologc46]

Larger tires put a larger tire patch on the road, and that can amplify the seriousness of a suspension problem that exists. If it was me, I would do the following:

Rotate the tires, see if the nature of the shimmy changes. If so, you have a wheel balance problem or a bad tire. Bad tires happen.

If the tires are good, I would next check the front track bar for any play. Get a friend to help. Start the car on a flat spot. Have your friend steer back and forth a small amount while you watch the track bar on each end. If you see any play, your track bar bushings are worn. This caused some shimmy on my jeep around 45mph.

Next check the front upper control arm bushings. Upper control arm bushings seem to deteriorate before the lowers, and are stuffed up high and hard to inspect. Bad control arm bushings can lead to shimmy or death wobble.

You said you checked the suspension, also make sure the steering linkeage is tight, has no play. Inspect steering joints at the same time you are checking the track bar bushings.

If none of these suggestions help, then search the forum using 'death wobble' as key word and read, read, read. A shimmy at one speed is often a symptom of a problem that will escalate into death wobble.

In my case, I recently had similar symptoms and it turned out to be totally failed bushings on the pass side front upper control arm. After seeing those bushings, I am surprised I did not experience more serious death wobble. I probably would have if I was running larger tires.

YMMV, hope this helps.

[austtill]

ok so where and what does the track bar look like and can it be seen easily from underneath. also it is smooth up to that point and just shimmies just enough for u to notice in the steering wheel if track bar bushingsare bad will it do it at different speeds thanks for your help

[cologc46]

The track bar is easily viewed from under the front. It is a strong looking bar that connects the front axle to the frame. It is bolted to the D30 axle on the passenger side, and the frame on the drive side, angling upward between the bolts. If you search jeepforum, somewhere there is a photo with all the front suspension components labeled.

My jeep would running smooth, then would exhibit some wobble around 45mph, then smooth again. I took it in for a wheel alignment, and the alignment tech told me the track bar bushings needed to be replaced. Changing out my loose track bar bushings tightened things up enough that the shimmy went away. That was a year ago, and lately it happened again, this time, due to worn out upper control arm bushings. Many things can lead to shimmy or worse, death wobble. In general, larger tires amplify front end defects.