CV Joint cause steering wobble?

I have a 2000 Ford Taurus Wagon that has a wobble in the steering wheel at around 70 mph. It also shakes violently when braking. I just replaced the brake pads and rotors (seemed to help, but shaking is back worse than ever). I also swapped wheels with my other taurus with no luck. I noticed that the inner CV joints have a lot of vertical motion if I grab the shaft and wiggle it. Could worn CV shafts cause the steering wobble?

Yes. They are part of the rotating mass of the axle. Do you hear any noise from the CV joint when turning, ie clicking and popping? Or like marbles rolling in a jar? The axle shaft should only be able to push and pull into the joints a little bit. If you can shake the axle up and down and all around, you have CV joints in terrible need of replacing. Good joints will not allow this to happen.

No audible noises when turning, but there is a buzzing when driving straight that gets louder as the car bounces over bumps in the road. I initially thought it was the wheel bearings, but replacing those did not make any improvement with this noise. I’ve also tried driving in reverse as suggested in some of the other postings to check if the inner joints are worn but I don’t hear any clicking or popping then either.

Let me make sure I understand on the movement. If I grab the shaft in the middle and can move it up and down that’s bad. I mean, without holding the inner joint at all. It seems like much of the movement is coming from where the cv joint goes into the transaxle. If I hold the inner joint and try to move the shaft, there is little movement if any.

I’m confused. The inner joint connects to the transaxle. The outer joint is at the steering knuckle. The inner joint should be tight with the transaxle, just as the outer joint is tight with the steering knuckle. It is loose? And the movement in the axle is at the transaxle? If you have this much movement at the transaxle, do you have any leaks from the transaxle? I can’t believe the axle seal can hold up if the inner joint can move like that. I think your having serious problems with the transaxle if the above is accurate.

Yes, the inner joint is nearest the transaxle. I can’t really see where the movement is, but when I grab the shaft in the middle and raise it up I can watch the inner joint flex upwards (approx. 0.100"). It looks like the joint housing (the side toward the transaxle) angles a little when this happens, so I assumed that the play is in the inner-jont / transaxle interface. The manual says to replace the cv joint if there is “excessive” movement, but I have yet to figure out what that means.

Also, no transaxle leaks or shifting issues at this point (maybe I’m catching it early?)

FYI, I checked my other taurus (1998) and found a similar, although not quite as large, movement. This one does not have any of the vibration issues.

If you can see the inner joint flex, imagine when it is spinning very fast a 70 mph, and begins to flex. This will cause a vibration. I think this could qualify as ‘excessive’.

Just to update everyone, I ended up going with my gut (and my wallet) and trying the easiest (read - cheapest) solution first. I went back and got a new set of rotors and replaced them since they were under warranty. When I took the rotors off the car, I set one on the concrete and performed the highly technical “wobble” test. Yep, when I set the rotor flat on the floor it rocked back and forth on the concrete. I know the concrete is not perfectly flat, but it did give me a little confidence. Anyway, new rotors on and the steering wheel shake is gone, hopefully this time for good.