The most frequent service necessary for drum brakes is replacing the brake shoes. Some drum brakes have an inspection hole on the back side, where you can see how much material is left on the shoe. The brake shoes should be replaced when the friction material has worn down to approximately 1/32 inch or 0.8 mm of the rivets. If the friction material is stuck to the backing plate or it does not require rivets, then the brake shoes should be replaced when they have only 1/16 inch or 1.6 mm of material left. Just like with the disc brakes, deep scores sometimes get worn into brake drums. If a worn out brake shoe is continuously used for too long, the rivets that hold the friction material to the backing can put grooves into the drum. A badly scored drum can sometimes be repaired by refinishing. Where disc brakes have a minimum allowable thickness, drum brakes have a maximum allowable diameter. Since the contact surface is the inside of the drum, as you remove material from the drum brake the diameter gets bigger. But if you do not want to go through all that hassle, replace the worn brake shoes with an all new, high quality Bendix brake shoes. Our online catalog features the best deals of the Bendix brake shoes. Keep your Toyota Sienna safe with the Bendix brake shoes that you can order from us.