on my taurus there is a loud hum when driving down the road it stops when i slightly depress the parking brake any help to fix the problem would be appreciated. I have already replaced the hubs,pads,rotors,calipers I dont know what else to do. sound also quits when I press the brake

Could be rear wheel alignment or a wheel bearing.

[QUOTE=Willyum]Could be rear wheel alignment or a wheel bearing

the bearings have been replaced also. how would you tell if it was the alignment of rear wheels?

If you have a good eye can see major misalignment but the only way for certain is to have it realigned. For alignment to be the cause it likely would have to be way out of spec's.

on my taurus there is a loud hum when driving down the road it stops when i slightly depress the parking brake any help to fix the problem would be appreciated. I have already replaced the hubs,pads,rotors,calipers I dont know what else to do. sound also quits when I press the brake

Did you replace hubs, pads, rotors, and calipers in the front or rear? The parking brake only activates the rear brakes. Do you have 4 wheel disc or disc front/drum rear brakes?

Concentrate on the rear braking system. If drum brakes, then remove the drum and inspect for a buildup of brake dust or leaky wheel cylider. If a wheel cylinder is leaking, I would expect that you'd hear odd noises when nearly stopped due to brake fluid contaminating the brake shoes.

If you have rear disc brakes, I would guess that you have rust formation on the surface of the brake rotors near one of the edges. The rust is just brushing the brake pads as you're running down the road causing your noise. As you apply either brake, the pads make contact with the rust and the noise changes/goes away. You should be able to see this as a slightly polished look at the rusty, rough edge of the braking surface. Check the inside and outside of the rotors, inner and outer diameter (4 places on each rotor). Again, since the parking brake has an effect on the noise, start on the rear of the car.

-Rod