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Vibration @ 70 MPH...

D

docboy209

NAXJA Forum User
Location
Selkirk, NY
Been having a vibration at highway speeds for a while now, it's getting worse though. The steering wheel starts to vibrate at 65, then the front end starts to shake at 70, and at 75 it's back to a steering wheel vibration.

It's a stock '98 Sport, 4.0L, 5-Speed, 3.07 gears, 231 T-case, 235/75R15 Goodyear Wrangler Radials.

I've replaced the axle u-joints, front shocks, steering stabilizer & sway bar links. Tried different wheels/tires from a good Jeep. I've removed the front prop shaft. Still there, maybe a little worse with the shaft removed.

Also, the original 225/75R15s made the speedo read wrong (65 speedo was actually 62 by radar and GPS). The 235s are dead on. Anybody else experience this?
 
How about the drive shaft u-joints ? The speedo is always a bit optimistic on later XJ's.
 
Check the TRE's on the steering rods/drag links, check your ball joints as well, wheel bearings, everything!

That happened to me, ended up replacing/upgrading my front end components and it was all original stuff that were deteriorating little by little.
 
One thing I noticed not mentioned was ALIGNMENT. Definitely confirm tires are balanced as well. Toe is easy to check/adjust.
 
I've road force balanced the tires, all good. Like I said, I tried tires and wheels from my dad's '99 non-vibrating Jeep. I even tested my tires and wheels on his. Wheel bearings are tight and noise free. Alignment is perfect. Ball joints are tight and well greased.

I found a TSB that applies to 99-up XJs to replace all 4 front control arms and the axle bushings for "a self-sustaining front end shimmy or vibration after the vehicle front suspension has struck a bump or pothole." But I'm not getting that.

@Johnnie Walker - Say car ramrod!
 
Track bar is in play here. ANY tiny bit of play on either end, you should replace.

That TSB that you refer to is for "death wobble", which isn't your problem BUT many of the same components that can cause or contribute to death wobble can also create a vibe.

I had a vibe between 57-62 for a long time that I couldn't resolve; eventually turned into death wobble. Found a very small amount of play on the track bar; replacing it resolved both the vibe and the death wobble.
 
Kinda dumb question... Could being centered by the lug nuts, and not the hub cause this issue? The '98 came with the composite rotors, I have the full cast which have thicker hats. Since I put the cast rotors on a long time ago I found that the hub center doesn't reach the center hole of the wheel anymore. The Mopar brake kit that I got from the dealer only comes with the cast rotors, that way they are compatible with all years ('99-1/2 - '01 switched to the cast, and composite will not fit). Should I try to get the composite? Or will the newer hubs have longer centers?
 
Last edited:
The rotor difference is centered around the hub bearing. 99.5-01 had a different hub bearing to accommodate for the rotor. If you put an earlier rotor on that hub it would bind the brakes. That is if the caliper would even fit over it. The hub and rotor need to be from the same year.

As far as the wobble I had a slight wobble at 55+ that got worse in turns, but never developed into death wobble. Everything was tight and mostly new. Tires balanced numerous times, several alignments at different shops. I replaced the lower control arms with RE adjustables and the vibe was minimal. I replaced the uppers with Iron Rock adjustables and the vibe is 100% gone and has stayed gone. However, this is on a 3.5" lift w/ 31" tires.
 
I've yet to have my wife help with checking the trackbar. Hopefully she'll help me tonight.

I can only get the full cast rotors now. Mopar and aftermarket don't offer the composite style anymore :(

I'm not getting the dreaded "death wobble", just a bad vibration. It's been there for a while and it got worse when I up-sized the tires from 225 to 235. I tried my rusted winter OE steel wheels and it's still there. I'm beginning to wonder if the people driving beside me can see it, lol.
 
Having exactly the same problem with my 97 XJ. Had wheel alignment, had wheels balance twice, added a CROK steering brace and welded the frame and it still vibrates between 60-70.
Did you check to see if the frame is cracked around the steering box?
Not that it helped me.
 
A vibration that appears at certain speed and disappears at a higher or lower speed (commonly 50/55 - 65/70) is almost always tire related.

Have a real tire shop Road Force Balance your tires. It requires a specialized tire machine and not all shops have one. Rotate the tire on the rim to offset high spots if needed.

Most brand name retail tires stores are helpless and clueless unless the balance machine or alignment machine tells them what to do. You need a real tire technician that has some experience with problem solving.
 
I am a technician at a Honda dealership with a Hunter road force balancer. The tires are fine. And as I already stated I used tires from a '99 that doesn't shake. I even drove that '99 with my tires and it still didn't shake.
 
Thanks, you just saved me some bucks. Will put it up on my mechanics lift and see if there is anything obvious. If your a mechanic and can't figure it out, I have little to no chance. :(
 
@buytick: That's what's driving me nuts!

I can't really be without a car, but my next option is to send out my rear prop shaft for balancing. I'd love to be able to remove it and test drive it first, but 70+ in front wheel drive doesn't sound too safe or good for the t-case.
 
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