Tom T's Tips September 5

BUFFALO, N.Y. (WIVB) - Causes of Brake Squeal

Dear Tom,
I own a 2004 GMC Yukon. It has the original brakes that came on the vehicle when I purchased it new. Sometimes they have a high-pitched squeal that is annoying and embarrassing. . I have had the brakes checked several times by the dealer as well as independent brake shops and they all insist that the brakes are fine. I am concerned that something is wrong. Please share with me your thoughts on the cause and what I can do to stop the noise. Thanks.
Wanda from Simi Valley, CA

Wanda,
Brake squeal is the result of pad vibration and can be attributed to a number of things. Have the shop check the following:
• Pad anti rattle clips. These are designed to secure the pads to the caliper. When they wear out or break, the pad vibrated causing a squeal.
• Pad insulation shims. The pads are typically insulated with shims that stop pad vibration. If these are missing or worn out, the brakes will squeal.
• Silicone insulation on the back of the pads. Sometimes the pads come with a silicone compound applied to the back of the pads to insulate the pads from the caliper. If this silicone is missing, the brakes will squeal.
• Loose pad finger clamps on the caliper. The calipers are held tightly to the spindle with a set of “fingers.” When these wear out, the caliper is allowed to jump in its seat, causing brake squeal.
• Hardened friction material on the pads. If the pads are crystallized or hardened due to extreme overheating, they will squeal.
• Hot spots on the rotors. Sometimes, during the manufacturing process, faulty casting can produce rotors with “hot spots.” This will cause brake squeal.
• Pad and/or rotor glazing. Glazing of the pad or rotor surface can make them mirror smooth, which causes squealing. There must be friction between the brake rotors and pads in order to stop the vehicle.
Good luck.
Tom

Dear Tom,
I own a 2005 Honda Pilot. They recommend a differential oil change at 7,500 miles. I did not follow this recommendation, and at 13,000 miles a heavy groaning sound started. It is coming from the rear of the vehicle when I move out of a parking spot at an angle, either a right or left turn. I took it to the dealer and they changed the differential oil. They told me that I caused the problem because I did not change the oil earlier. It’s hard to believe, but the problem is gone. What do you think?
Sydney from Ocala, FL

Sydney,
I believe it. Gear oil is critical to the proper operation of lock up and limited slip differentials. When it wears out, gets contaminated with wear material, or gets overheated, differential operation is hampered. Quite often carmakers will go to petroleum companies to engineer a fix in their fluid for a drivability problem with transmissions, gearboxes, transfer cases or differentials. The most recent example that comes to mind is Ford. They had a problem with their torque converters (chattering). Ford had a petroleum company engineer a “fluid fix” that solved the problem. Follow the manufacturer’s recommended maintenance schedule to avoid problems of this nature. Best to you.
Tom

Dear Tom,
I always change the oil and filter in my car every 3 or 4 thousand miles and follow maintenance schedules to avoid costly problems. How do you feel about the change in Florida regarding gasoline? Do you think that engines will perform less efficiently? The price of gasoline is going up, and we are not getting all gasoline. If this is good for the environment, great! I am all for a cleaner environment. However, I would like to know ahead of time what effect this stuff will have on my car. I don’t want to have to wait and find out if it has negative and costly consequences. Thank you.
Mildred from Tampa, FL

Mildred,
I assume you are referring to gas mixed with ethanol. Ethanol is mixed with gasoline to act as an oxygenate to lower tailpipe emissions. You won’t notice any loss of performance or gas mileage, so don’t worry about it. As I see it, this move to part ethanol is a temporary “fix” to lower tailpipe emissions. I believe we need to spend our time and resources to develop a real alternative fuel options like hydrogen-based fuel cells, batteries for electric cars, diesel/hybrids, plug-in electric hybrids, diesel, and bio fuel. But that's just my humble opinion.
Tom

Dear Tom,
I own a ‘96 Chevy Lumina. The dash/radio lights, taillights, and front corner markers quit working. However, the brake lights and headlights still work. I checked all the fuses and they are okay. Please help?
Justin from MI

Justin,
Check for a common ground problem. I would access a service manual and check power and ground distribution. It sounds like you have a major electrical power or ground connection issue. This is quite common with today’s vehicles because they are governed by computers. Also, have the computer system scanned to see if any codes come up. This should put you on the right track to identify and solve the problem. Good luck.
Tom

‘Til next time…Keep Rollin’
For more articles by Tom Torbjornsen, visit AMERICA’S CAR SHOW web site: www.americascarshow.com