Help me figure out why my X shakes on the highway

[srvblues00]

Around 63 to 75mph, my X shakes pretty badly. Enough to cause a full drink in the console cup holder to splash over. I got my X last November, and it was not shaking then. I have since had the center link replaced, I replaced the radius arm bushings, installed Monroe Reflex shocks, and had an alignment. I have no idea how long centerlink and radius arm bushings had been bad before I got the X, but it had caused uneven tire wear on the front. After all the above had been done, I rotated the tires, but the shake was still present. Do you think uneven tire wear could cause shaking this badly? Or do you think another suspension component is going south? If the front end is supported by jackstands, I can grab a front wheel and it will rock side to side slightly. if I grab the top and bottom of the wheel and try to rock it back and forth, it's rock solid, so the wheel bearing should be fine. Also, the steering seems kinda sloppy, but I am used to driving Mustangs, so it might just be me, but even Dad seems to think it's a little non-responsive. Any ideas?

 

[jimbo74]

what pressure do you run your tires at?

 

[srvblues00]

Originally posted by jimabena74
what pressure do you run your tires at?

Around 31 to 32.

 

[Got Lift?]

try going down the road at that speend and putting it in neutral, or hold in the clutch. if it stops then your u-joint is going out and it needs to be fixed immediately. if not then maybe your tires and wheels need to be balanced and rotated. if that still doens help try aligning your front end

 

[tbomb]

ill bet your tires just need to be re-balanced.

 

[srvblues00]

It keeps on shaking the same in neutral.

I had all 4 tires balanced a few months ago, and it actually made the problem a lot worse!!

 

[Got Lift?]

maybe it could be one of your driveshatfs is bent and is causing a nasty vibration, also if u have a greasable u-jiont then grease them and see if that helps

 

[Texan01]

I bent the driveshaft in my old Chevelle once and it would cause the whole car to seem to jump up and down around 65-80. I found it by jacking up the rear wheels and let the engine spin the shaft, took the shaft to a driveline shop and had them straighten, rebalance and install new U-joints for 60 bucks. drove like new after that.

If your tires are cupped then it's most likely tire related, try rotating them to different positions on the car and see if it follows.

 

[Kodiak]

You may have already checked them but I had a simular problem (high speed vibration with uneven tire wear) It was my tie rod ends. Just a thought.

 

[srvblues00]

Good points, I'll try to check the drvieshaft. I have rotated the tires many times, front to rear and left to right in a few different combinations, but it still shakes about the same any way I put it. Funny thing is, only two tires are slightly cupped (what used to be the fronts). The rears have worn evenly across. Oh yeah, it shakes a lot worse going around a curve on the interstate than when going straight.

 

[srvblues00]

Last night I went out and lowered the tire pressure from 31.0 to 26.5 in all 4 tires. The sticker on the door says to run all 4 at 26psi. I took it for a spin, and it greatly reduced the shake. I'm not too sure I like that "solution," however. Seems that it's just kinda hiding the problem. What pressures do you run at? The recommended 26psi seems a bit low, IMHO.

 

[Hank]

Not trying to sell bushings here but I had the same problem on my 91 till I replaced ALL the bushings...

All the bushings were mushroomed but the axle pivot bushings were in really bad shape, one radius arm bushing was missing a chunk causing the arm to tap on the mount.

I can pull 80 on the hwy with no shake.

Good luck,

hg

 

[srvblues00]

I'm just brainstorming here... could it be a motor mount on it's way south? Or would that only be evident at idle? Truck idles pretty smooth.. no shaking other than what appears normal.

 

[dgibson]

I recently had the same problem with my x. My tires were just wore down. When I put new tires on, it now drives better than it did when I first got it 2 years ago.