1BlinkGone

Generally speaking, today's rotors are designed to be a throwaway "consumeable". That's just the way the business has gone. These parts are de-engineered after initial design to fall within a certain parameter for replacement, and thus, offer far less leeway to turn the rotor before they are below minimum spec. It's pretty much that way across the board with all the auto mfgr's. Why? It's all about selling parts. Auto mfgr's make their true profits selling parts, not whole cars.

What was said about pad material being left on the rotor surface is true. If you want to retain your rotors because they are in good shape but change the pad type, ALWAYS rough up the surface as was described and get the bedded pad layer off the rotor surface.

BTW- yes, always use a torque wrench. Too many svc jocks are prone to use their air impact gun and warp the rotors as noted. I'm not sure about Lexus' svc policy on this matter. Torque wrench is the way to go.

1Putt

Even if the air impact guns have torque limiters to prevent over-torquing, there's still things that can go wrong if the user is not careful- cross threading, lug not fully seated, etc.

robert1408

The main cause of rotor cracking and warping is repeated thermal cycling. Severity and frequency have all to do with it. Brake pads have little to do with it. They are only about 20% of the total braking heat sink available. Braking heat travels much faster through an iron rotor than a brake pad. Heat is absorbed and later radiated away by the rotor surfaces. This inward and outward flow of heat causes a differential in the rate of thermal expansion and contraction within the rotor. No big surprise they often warp and crack.

Improper lug nut torque can affect rotor warpage but it has to be pretty extreme, at least with oe wheels. Aftermarket wheels that use a hub ring are a real problem if improperly torqued. Since the center bore hole in such wheels is larger than stock, the clamping force exerted by the lug nuts is effectively moved towards the outer edge of the car's mounting hub face. This exerts relatively more force to the outer edge of the rotor hat, which is not supported by the car's hub flange.

Properly used, air guns with torque sticks are just fine, assuming the wheel is pushed flat to the hub by hand first.

1BlinkGone

True. Correction noted!

1BlinkGone

Properly used, I would concur to a degree, as I have done so myself in the past and adjusted my air gun settings down to do so. You get a "feel" for it.

Having said that, it's not as exacting and dependable as a Torque wrench... and I have seen many rotors warped from improper use of an air gun as the nug nuts were way too tight. All it takes is one time. Lol.