Braking sound likely surface rust build-up on rotors
Posted Nov 20, 2009 By Brian Turner
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Tweet ThisEMC Lifestyle - "Dear Mr. Turner,
I find your articles in the EMC paper very interesting and informative and read your column faithfully. My question is: I drive a 2005 Toyota Camry purchased new mileage to date 23,500 km. During the winter months when snow gets into the rear wheels and I brake the car makes a terrible noise, (like a snorting horse). Once the moisture has evaporated it stops. I was told by the dealer's service dept. that that is normal and there is nothing they can do about it. Could you please give me your opinion."
Thank you kindly in advance.
H.
The noise you are hearing can be quite common for lower mileage vehicles and even some that see longer distances traveled on a daily basis. The likely cause is rust coating the surface of the front and rear brake rotors when the vehicle is parked overnight or for any prolonged period of time when the outside moisture level is high (such as during milder winter days with snow and sleet precipitation).
When the vehicle is driven after these rust naps, it sometimes takes several kilometers of driving and a dozen or so applications of the brakes in order for this surface rust to get rubbed or worn off by the brake pads. Brake rotors and drums are made of steel that is not treated with any anti-rust applications or galvanization processes. And just like a tin can or BBQ implement left out in the rain, it only takes a few hours for rust to appear on the surface.
As your Camry is traveling only a fraction of the average car on an annual basis, the rust on the brake rotors isn't the only corrosion you should be concerned about. The moving parts of the braking system such as the calipers, brake pad sliders, and parking brake system should get an annual service to keep them in good working order. This would be a simple process of having a technician grind or buff any rust off of the moving parts and lubricating them with an appropriate heat-proof grease.
At the same time, your tech can remove any heavier corrosion build-up on the rotors' edges and maybe even scuff the surface of these rotors and the brake linings to try to reduce the noise.
"Mr. Turner,
A slight dilemma re. our 2008 Impala LTZ. In the fall of 2008, we purchased four Yokohama snow tires. In the early spring of 2009, we drove to Florida. The snows stayed on and served us well in some severe rain en route. Upon our return, we changed them back to the summers.
At that time, our tire man said we should have the rear alignment checked as he thought there was abnormal wear on rear tires. We did have it checked on our next dealer visit (33,000 km on car) last week and our mechanic there showed me wear and said it should be aligned and possible new tires installed. We do maintain proper inflated pressures. He also said the Impala was notoriously light in the rear end and driving it as we do, two bodies only, could result in the above situation. We discussed it at length but I left dealership with no rectification work attempted.
I went back to my tire man and discussed all of this with him and he more or less agreed with the tech at our dealership. His suggestion was to ignore "a slight" misalignment for now as our yearly meterage is so low (perhaps 10,000 km) and no trips planned, and then come spring, come in for a "custom" alignment and swap winter/summer which he said were OK for another season or two.
It is the "custom" alignment suggestion that is bothering me and I am not sure if the tech at the dealership even mentioned it.
I was wondering Mr. Turner, if you were aware of this apparent rear end misalignment on Impalas or perchance you had a similar inquiry."
Thanks
F.
I had a change to try to set things in a straight line by calling on Duncan Heins, the manager of a very busy service department at Jim Tubman Chevrolet in Ottawa for his advice. Duncan's shop sees a large number of Impalas as they are a very popular sedan and quite a few of his clients use them in commercial service such as taxis, delivery vehicles and the like. Duncan couldn't recall any concerns with wheel alignment difficulties on these versatile cars but does advise that if abnormal tire wear was noted (such as the tread face wearing more on one side than the other) then the alignment should be measured.
A technician, no matter how experienced, will never be able to tell if a vehicle's wheels are in proper geometry unless he or she sets the vehicle on a wheel alignment rack and actually uses the equipment to measure the various settings. After this specialized shop tool is set up, completing any required adjustments is a relatively minor affair for the most part. This is why most shops charge the same rate for measuring or adjusting wheel alignment.
I am assuming that your tire shop tech is referring to adjusting your Impala's wheel alignment to other than factory settings when he or she refers to a 'custom' adjustment. I would highly recommend against this, as the engineers and designers who built your Chevrolet had very specific handling and safety goals in mind when they set up the wheels in the first place.
It is possible that your rear snow tire wear pattern is a result of a low weight load in the rear of the vehicle. Keep in mind that the rear suspension on your Impala was designed to easily carry up to five adults and all their gear. When you drive it with a relatively light load, the rear suspension doesn't do much work in absorbing all the road imperfections we travel over, but instead the rear tires can take this beating. This usually leads to cupped wear marks on the outer edges of the rear tires without any appreciable wear difference across the face of the tread.
This can be quite normal and regular tire rotations can help to even things out. I agree with Duncan, that the only way to be sure is to have your Impala's alignment checked (meaning measured) and adjusted if needed. If the alignment is OK, then make sure your rear snow tires are mounted on the front for the upcoming winter season.
If you have any questions, opinions, or stories on anything automotive please drop me a line, (By email to emc@perfprint.ca listing 'Question for the Car Counselor' on the subject line or by post to Record News Communications, 5 Lorne St., P.O. Box 158, Smiths Falls, Ont. K7A 4T1).
Yours in service,
Brian Turner
