More on the Test Drive!

The issue of a steering wheel wobbling while applying the brakes is attributed to the front brake rotors being warped. The best fix is to replace the rotors with new premium rotors of a reputable manufacture. I offer the customer this as the best repair.  I suggest this because experience has taught me that the normal repair of turning the rotor only makes it thinner and it will warp as soon as it is under extreme stress. In time I have learned it is easier to sell this repair now then try to justify doing the job again in a short period of time.
    The other problem I hear often is "I hear a squeaking noise at slow speed or when I first start out in morning.  The noise usually goes away when I apply the brakes for the first couple of stops."  I can usually solve this problem by having the rotors turned only to remove a crusty buildup around the edge of the friction area and to make the rotor flat.  Many times the problem solves itself by making a estimate.  This is not a safety hazard and is sometimes not worth the expense.  I mentioned that the car is usually warm when I road test and most times will not make the noise. Inspection will show if this is the problem.
    When I accelerate I am listening for a clunk or a click.  A clunk can be a motor mount or exhaust pipe mount.  On hard accelerating, a broken or worn motor mount will allow the motor and transmission to shift and move to the extreme, hitting the body or frame.  Exhaust pipes usually rattle more then clunk.  I am also listening for clicking in the front area of the car.  I turn sharply to the left and right while accelerating to put pressure on the CV (constant velocity) joints.  Theses joints are found on all front wheel- drive cars.  A clicking noise means the joint is warn and needs replacing.  There are two CV joints on the drive shaft that drives the front wheel on each side of the car.  If the left and right drive shafts are the same or interchangeable - I switch them, left to right.  Why? CV joints wear in one direction and by changing the left to right, I am changing their direction and they are now pulling in a new direction and will last almost as long as a new joint.
    As I write I realize that I should talk about the different ways that power is applied to the drive wheels and the reason that some drives shafts have to be able to bend or flex. The automotive world changed when front wheel drive cars became the norm.  Some all wheel drive cars have CV joints in the rear but they last a long time because they only have to transmit power and do not have to bend to flex due to the turning of the wheel for steering purpose.  Also on all wheel-drive cars more power is transmitted to the front wheels due to the weight for traction purposes. This is called a power split and it is as little as 10 percent to the rear.  They do flex or bend a little because of the movement of the suspension up and down.  Before the CV joint came into use, the front drive shaft on four-wheel vehicles used universal joints and some still do. They have very little problems but when the do it is more expensive to repair.
    Well, now you know why I accelerated fast and applied the brakes, then went in circles left to right. The mystery is solved. Next time I will do some testing, open the hood and make a visual inspection, raise the car and inspect the undercarriage.