Originally Posted by holmesnmanny

Ok, here's the deal. It's really really simple, but most people can't put 2 and 2 together.

First of all, whenever you put your tires back on, it's completely imperative that you not only do NOT overtorque the lugnuts, but you also have to tighten them evenly. When you have a place work on your car and they take the tires off, normally some jackass decides to use the air ratchet to put the lugnuts back on instead of a torque wrench and what happens if you get 150 lbs or more of torque while your car only needs 80 lbs. Also, it's completely uneven through all four lugnuts. Then you get in the car and drive it and when the rotors get hot from braking they bend slightly in the most vulnerable spot on your rotor and your rotor is done for it. You will notice that when you leave the mechanic all is well until a day later. Remember that your rotors get extremely hot so it's expanding and then when ur car sits it contracts back as it cools. This essentially bends rotors as they expand and contract with the extra torque from the air ratchet.

Furthermore, when you have your rotor turned, all that's happening is that they are taking a slight amount off of the rotor so that it's not as bad. Turning rotors never helps warped rotors. It's not possible because the rotor is alway slightly bent. It can help make it so that the pads brake in properly but that does nothing for the fact that it's warped.

An easy way to verify is that your rotors are fine when they're cold, but when you drive them for a bit all of the sudden the vibration starts up because the rotors get hot and expand into their warped position.

So, in conclusion, always insist they use a torque wrench, or just buy your own from Autozone for 30 bucks and do it yourself when they give the car back to you.