Weird vibrations at highway speeds
 

I have a 2000 monte carlo ss pace car thats been having some issues with the front end vibrating at 65mph. But its also mainly when the car is on the incline to my work however it stops vibrating when taking the left hand corners and the vibrations increase when taking right hand corners. I'm wondering if maybe the differential in my car is giving out or maybe one of the bad cv axles I replaced made the motor/transmission mount rip free. Anyone else have any experience with this kind of issue?

I would take a look at both CV axles , Sometimes the joints can go bad even though the boots aren't torn . They are a bit harder to check but if there's enough movement you will have the symptoms you describe. Odds are it would be a outer CV joint. Good luck

Alright so who sells decent cv axles? Because this is the 3rd set of duralast gold cv axles that I've put on this car in the last 5k miles.

I'm sorry I misunderstood the part of you replacing axle. I'm sure you have done the obvious like loose tie rods, wheel balance. Have you checked the control atm bushings. ? I would suggest going to a transmission shop you can trust . Problem is a lot will condemn it even if its not issue.

I probably should have mentioned everything I've done to the car.

I've replaced:
Both front wheel bearings
installed ZZP's tubular control arms
front sway bar
poly dogbone mounts (both ends)

With the exception of the poly dogbone mounts everything has been replaced in the last 5k miles that I've had this issue. This time however the vibrations aren't constant like before. The highway on one end of town is mostly flat and the car vibrates very little but on the inclined section of the highway going to my work the vibrations are very noticeable. This is why I believe its the transmission/ engine mounts or the differential because its mostly when the car is working harder to make it uphill versus the more steady work on the flatter section of highway.

When was the last time you got ur wheels aligned? Could be as simple as that. My mustangs steering wheel use to wobble at 65-70 and that's what solved it.

I suppose I could get that done.

Also if you have ever over torqued the wheel lugs this will warp the rotors on the front and cause a wobble at times. Should be a 100 ft lbs. on all lugs.

Would it feel like a typical warped rotor? where it shakes the car when stepping on the brakes? Or would it make it smoothen out the vibrations when stepping on the brakes?

2004 3.4 Ls
 

I'm having the same issue, vibrations when putting my foot into it or turning right. I jacked the car up with tires off and started it and put it in drive and the driver side axle was shaking as it was spinning. So it isn't out of balance tire. I also changed the driver side axle today and it still does it. Replaced both outer tie rod ends as well. Got me puzzled