The last stubborn vibration left on my Lumina...

[ptcfast2]

I've normally been able to find solutions to various problems involving my Lumina by lurking around, but I'm having a hard time figuring this one out!

Here's the scoop: I'm the proud owner of a 1998 Lumina 3.1 with about 234,000 miles on the odometer. I've spent the past 2 years replacing part after part trying to get her (almost) as good as new. As long as I've owned this car I've had vibration problems. I started to tackle them about a year ago by replacing anything and everything related to my suspension/wheels with new parts:

-CV Joints
-Front Wheel Bearings
-All 4 Struts
-Inner/Outer Tie Rods
-Balljoints
-Subframe Mounts
-Swaybar Bushings
-Trailing Arms
-Lower Engine Mount & Transmission Mount
-Front Dogbone Mounts(or w/e they are called )
-New Calipers, Rotors, Drums, Pads
-4 New Tires (Aligned & Balanced Twice!)
-Transmission was rebuilt about 3,000 miles ago

The ONLY vibration left is one that occurs between 65-80MPH. It will come and go when I hit bumps between 65-80MPH (it almost seems like something gets knocked loose and gets bumped back into place later). The vibration is most noticeable in the driver's side footwell/floor and it can be felt slightly in the steering column. I've verified that it is not the tire as it occurs with any other tire I try. I've also noticed a loud "clunk" when breaking hard from a high speed (it's occasional - not able to reproduce every time). The clunk seems to originate from the same location as the footwell/floor vibration.

I've verified the sway bar bushing bolts, checked for play, verified torque on the drive axle nut and wheel, caliper is not loose. I just replaced the CV axle on the driver's side due to shudder/vibration upon acceleration (it's gone now! ) as well as the balljoint...the one I put on a year ago already failed!

Any ideas guys? This is driving me crazy!

[maxwedge]

Look for worn or loose steering rack mounts, also loose caliper mount bracket. without driving the car for an onsite test this is impossible to accurately diagnose on the net.

[jeffcoslacker]

Originally Posted by maxwedge

Look for worn or loose steering rack mounts, also loose caliper mount bracket. without driving the car for an onsite test this is impossible to accurately diagnose on the net.

The rack mounts were my first thought as well, seems he covered everything else pretty well.

If you can't find it, see if you can lay hands on a factory NVH (noise, vibration, harshness) manual. I have an old Ford one. They are great. They "flowchart" specific ways to narrow it down to the source that most of us wouldn't think of easily, and then give a lot of tricks for actually hearing the source or things you can do to test to see if that is your problem (like putting hose clamps on CV shafts to see if the balance can be perturbed or made better, etc)...neat stuff. Don't know if they still produce them...