Sorry for keeping the post alive (2015) LOL.
Oh well, just wanted to add my experience in case it might help others having similar problems with severe steering wheel shake at highway speeds (50+ mph)
I was frustrated doing a recent search online because it brought up a gamut of potential solutions from checking the braking system to possible transmission problems or installing new motor mounts!
As most everyone else has mentioned so far it could probably be something as simple as a failing brake component but my case is slightly different.
I had recently bought new tires for my 2001 Honda Civic LX and got them balanced.
In my case it simply turned out to be that I needed new struts (front shocks). Apparently my shocks were pretty bad but I never noticed a problem. I'm a calm driver; not one for aggressive driving so I guess the old tires were worn down in a way so that the wheel oscillations didn't get too bad to where the entire steering would shake. This being the case, I did not know I needed new shocks when I bought my new tires.
So I'm posting just in case it might help someone. Check your shocks if you have severe shake in the steering wheel while driving at high speeds and you have brand new tires and they were balanced. Same as others, it took me a while to figure this out because the car would drive just fine slower than 40 mph but getting on the freeway was like off-roading on boulders; the shake was so terrible.
After searching online and trying to narrow down what could be the issue as well as asking a few questionable "mechanics" at supposedly "reputable" shops and noticing not any good simple solutions to this problem posted anywhere, I decided to post this to hopefully help someone who might have a similar issue.
I went to 2 different shops and the guys were trying to tell me that I needed a new driveshaft, cv joints, and motor or transmission mounts, or new rims and tires!!!!
Moral of the story - do your research and try to get a second opinion if possible.
After looking on different boards I kept on reading stuff where it sounded like people were telling the person to replace the entire suspension. After searching a bit I just decided to grab a flashlight and try to "see" what was going with my front wheels. The cv joints were fine. No leaks or clicking sounds when I turned the steering wheel left or right...but then I noticed the torn strut dampers inside the springs...yep shocks were pretty much dead. The shocks were leaking hydraulic fluid all over the place. The odd thing was that they weren't soft either. In other words the car didn't just wobble up and down if you pushed down on the front bumper as you might think if the shocks were bad. With my old tires the car's performance didn't indicate that my shocks were that bad.
Took my car to my neighbor's mechanic with some new shocks and asked him to install them. Car was riding smooth again!!
No suspension overhaul or new transmission or some other more costly repair.
Like others have mentioned:
If your steering is normal at low speed but really bumpy at higher speeds with brand new and balanced tires it could be most likely some suspension component.
Check out for:
- leaky front shocks
- warped brake rotors
- warped rims or bulge in defective tires
- tires not properly balanced when installed
- or some failing suspension component - tie rods, stabilizer bars, missing bushings
My guess is that since shocks are supposed to dampen the wheel oscillations as the tires roll down the road; your car might not shake too bad when you are driving slowly, but once your tires are spinning really fast and you have bad shocks it can feel like your car is going to drive off the road.
I am not a mechanic, but just use common sense and try to figure things out for myself. This might not be the same problem you might be having with your shaking car...but I encourage you to take a look under the car and have a friend turn the steering wheel left and right to see if you can find if something is loose or missing from one side of the suspension or the other. Sometimes that's all you need to do to solve the problem.
Obviously, be safe at all times...make sure the car is in park and reinforce the tires to keep the car from rolling over or away from you whenever your are working on your car.
Good luck - hope this helps.