The Car started vibrates when I use the brakes. Before this started I had the back brakes replaced last November. The vibrations started later and I had the front brakes and calipers replaced in March. The car is still vibrating when I brake. I have a good mechanic but I am curious The car is a 1998 with 90,000 miles.
Usually this is due to warped rotors. When you had the brake work, were the rotors replaced, resurfaced, or not touched?
This is a classic symptom of warped brake rotors, usually in the front.
I’m guessing the pads and calipers were replaced in March, but not the rotors, which may have been turned, which makes them even more prone to warping.
The rotors can be measured to determine whether or not they are warped. If they are, replace them with new rotors.
Did you tell the mechanic about this problem when the front brakes were replaced in March?
After March it was better for a while and is starting up again. Rotors were replaced in March
You might have gotten cheap rotors, or the shop might have torqued each lugnut to a different spec, which would put unequal stresses on the rotor and cause warping.
You might also have a sticking caliper (just because they replaced it doesn’t mean that it is impossible for the new part to fail).
One bit of information that could be helpful is to know what kind of car we are dealing with. There were many different cars made in 1998. Fortunately, brake problems are fairly generic, although different makes and models have weak spots and known issues. Some things that can cause a brake pulsation include warped rotors, scale on the hub where the rotor seats, sticking/dragging caliper, frozen or missing hardware, brake hose restriction/constriction, improper installation, overtorqued lug nuts, inferior parts quality, and aggressive or poor driving habits. Any decent mechanic should be able to pinpoint the cause of the problem in reasonably short order.