Intermittent Vibration Above 45 mph

[CardFan]

Need some help troubleshooting this one. I'm getting some fairly severe front end vibration above 45 mph. It starts to happen after I hit any sort of bump in the road, such as a transition to or from an overpass, slightly rough pavement, etc. It's severe enough that I feel like I need to slow down to avoid damaging something, and it goes away when I get under 45. Using the brakes, engaging the clutch, putting it in neutral, etc doesn't seem to have an affect. Had the tires balanced and rotated (needed rotation anyway) at Sears, made no difference. I have a full size USP spare, so I switched things out tonight so that both wheels that were in the back when this started are now in the front, but still no difference. I didn't notice anything wrong (nothing loose, CV boots look fine, etc.).

I did install ST coilovers and new brakes and rotors (Adams Rotors) about 5,000 miles ago. Not currently running spacers in the front, 10mm in the rear (for around 4,000 miles). Stock USP wheels.

One suggestion I read based on searching is to get a road force balance done. Another is to swap wheels with someone (don't have anyone to do this with). I struggling with the fact there is not much change after switching the wheels around, since it's making me think there is something mechanically wrong with the car instead of the wheels. Any suggestions? Thanks.

[Lockon_B7]

Is it possible for you to go above 45mph at all without the vibration happening?

[CardFan]

Is it possible for you to go above 45mph at all without the vibration happening?

Yes, but it starts as soon as I hit any sort of imperfection in the road.

[Lockon_B7]

The last thing would be if you feel any of the vibration directly in the steering wheel or if it is only in the chassis.

You could check to see if the motor mounts are leaking and see if the snub mount is deteriorating at all.

I would also inspect the upper control arm bushings. You could also put the car on a lift and try and rock the front wheels vertically (12 and 6) and horizontally (9 and 3) to see if there is any play in the ball joints/tie rods.

I realize those are all very generic suggestions but that's a very interesting issue you've got there, where the vibration is constant after going on some rough road.

One other thing you might also want to check is if the top strut mounts on the coilovers has shifted and the coil is properly seated. If they have I'd remove the coilovers and make sure that top nut is tight.

[Fast4esT]

Check your front axles, having a torn boot. They are fine for a while, but when they dry out they shake, let off gas and they smith out, you generally feel it at high speed,50 and above, and they will randomly smooth out. Likely an inner joint is bad

[Lockon_B7]

Check your front axles, having a torn boot. They are fine for a while, but when they dry out they shake, let off gas and they smith out, you generally feel it at high speed,50 and above, and they will randomly smooth out. Likely an inner joint is bad

^
This was another thought I had, just seems unusual that you wouldn't feel it until you hit uneven pavement. However, it is entirely possible especially because you just went to coilovers.

[CardFan]

Thanks for the suggestions. I'll get back under it tonight to see what I can figure out.

[old guy]

Check your inner and outer tie rods for any slop at all.

[CardFan]

Thanks guys. Found my passenger side outer tie rod loose/failing at the joint. Somehow missed that last night. Only 15k on it, changed it when I did the steering rack.

[Lockon_B7]

Glad you found it!

[CardFan]

So the boot didn't fail, but the joint was very loose/sloppy. With only 15k on it, should I chalk it up to a bad part, or could this be a sign there's other things wrong? Inner and outer CV boots look good, and I put on new adjustable control arms when I did the coilovers. I didn't take the time to check out the motor mounts though.