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The brakes on my wife’s 2017 Acura ILX were pulsating. The car has less than 50,000 kilometres on the odometer. My mechanic said the rear rotors were warped so I had them replaced. I asked why the rotors were warped after so few miles, the mechanic replied by asking if the car sits for long periods of time? Yes, it sits for four months each winter - we are snowbirds. Apparently, the mechanisms get rusty when not used. Since it’s not practical to drive the car regularly in the winter, is there anything I can do to prevent warped rotors? - David M.

Warping, whether it’s the front or the rear brake rotors is typically caused by overheating. Your brakes are not overheating when they are not in use. Additionally, heat-based warpage usually affects the front brakes, not the rears. It does happen, but it is not nearly as common because the front brakes run much hotter than the rears.

Quite often when you walk up to your vehicle during the winter months you can see a build-up of corrosion on the brake parts. When you first drive away during this time of year the brakes will be noisy and feel sort of crunchy. After a few minutes they return to normal. And this is just from sitting overnight, imagine after a few months of inactivity.

Because your technician asked if the vehicle was sitting for an extended period this suggests to me that the brake pads corroded to the brake rotors and became stuck to the rotor. After returning home from down south your first drive resulted in a significant noise and pulsation. This is because a small amount of unwanted brake pad material was stuck to the rotor. Every time that corroded spot on the rotor passes the brake pad you feel a thud or pulsation whenever the brakes are applied.

Can you do anything to prevent this? Sometimes the brakes will return to normal after driving for an extended period. The longer the car sits the less likely this will work. There are anticorrosion sprays that can be applied before you go away. The idea of these products is to dry out any moisture and apply a thin protective coating. However, I’ve never really seen any notable positive results from these products. Storing the vehicle in a climate-controlled facility will definitely help though. Unfortunately, the best answer is to find someone to drive the car several times while you are away.

Here is a video I made on the subject around the beginning of the pandemic when most people were staying home and driving a lot less:

Lou Trottier is owner-operator of All About Imports in Mississauga. Have a question about maintenance and repair? E-mail globedrive@globeandmail.com, placing “Lou’s Garage” in the subject line.

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