Comments for
Car shakes between 55-75 mph

Click here to add your own comments

It's probably NOT the tires
by: Lee Brown

Normally when the tires are balanced, and properly inflated and aligned and there is still a vibration at normal speeds (30-75>)

Then there is one or more of several problems:

-Bad shocks allowing the tire(s) to bounce as you are moving down the road (the springs hold the car up while the shocks hold the tires down and in contact with the road). Usually a bad shock just causes the car to become ill-handling and "boing-eee" over dips and swaying in curves, but not really vibrations (at least not until the tires cup-out due to excess bouncing caused by a bad shock).

-A broken motor mount (especially on a front wheel drive car) which allows the engine and transfer case to be oscillated by the tires (through drive-line torquing) moving over an undulating surface as you are traveling down the road (especially on uneven tarmac), or you have an internally worn C.V. Joint (usually the inner joint) causing the half-shaft to bind-and-release bind-and-release in one or more spots at each revolution of the shaft. The inner joint(s) can be bad while the "boot" may look fine.

If you have determined through a visual inspection and a "bounce test" and verified that the shocks are all good and that none of the motor mounts are broken (you can easily check these by placing the car alternatively in reverse and then drive, holding the brake and GENTLY accelerating in each gear while someone watches the reaction of the engine relative to the engine compartment;

If it jumps too high or too far back in either drive or reverse, you've got a broken mount).

To test the C.V. Joints you must first remove the primary drive axle (usually the right hand axle as you are sitting in the car) as it normally wears the quickest of the two and manually rotate it while holding it in a bent or joint-binding position (about a 30-45 degree angle).

If it is worn, you or your mechanic will easily be able to feel the binds at the same point(s) at each revolution of the shaft. The inside (inner) joint usually causes vibration while the outer usually becomes noisy and "clicks" when turning.

One other thing to check is to make sure there is no water in your tires. Sounds a little crazy, I know, but more than one tire has been partially filled with water due to a poorly maintained and undrained air compressor and/or air hoses (especially in the rainy season!).

Check the shocks first, then the motor mounts and tires (for water), then the C.V.Joints.

Remember, slight misalignment does not cause vibration... things that bounce, oscillate or bind DO.

Oh yeah, have your inner and outer tie-rod ends checked to. They don't usually cause vibrations but they will cause the steering wheel and car to shake back-and-forth left-to-right.

Stay safe, Lee

Click here to add your own comments

Join in and write your own page! It's easy to do. How?
Simply click here to return to Tire Concerns

Return to Car shakes between 55-75 mph

tireguy

Other useful links

Did you know we have a special
place to show-off your favorite wheels?
See the Hot Wheels Show Room

tell a friend image

Add To Favorites

Return to Tire Information World HOME page

Complimentary Treadwear Calculator
Click Here to Download your portable Treadwear Calculator Now!

Visit Tire Information World'sExclusive TireCare and Accessories Store.

More Offers