Auto Q&A: Shudder likely indicates need for new brake pads and rotors

"I'm feeling a shudder in the front of the car when I'm braking."

Brake rotors are like very thick dinner plates, typically constructed of cast iron. Brake calipers clamp the disc pads, which are faced with friction material, against the rotor, converting kinetic energy into heat.
Brake rotors are like very thick dinner plates, typically constructed of cast iron. Brake calipers clamp the disc pads, which are faced with friction material, against the rotor, converting kinetic energy into heat. –Dreamstime/TNS

Q: I’m feeling a shudder in the front of the car when I’m braking, more so near the bottom of a long hill. It seems to be getting worse. How serious a problem could this be?

— Kelly

A: It sounds like your brakes, likely the fronts, are suffering from distorted brake rotors. Brake rotors are like very thick dinner plates, typically constructed of cast iron. Brake calipers clamp the disc pads, which are faced with friction material, against the rotor, converting kinetic energy into heat.

Brake rotors need to have a uniform and smooth surface in order to function smoothly and without noise. Over time, especially with hard use, thickness variations and surface flaws can develop, causing symptoms like you mentioned. Assuming adequate rotor thickness remains, they can be machined to a fresh/true surface. If surface cleanup will reduce thickness below the minimum standard, they’ll need to be replaced (as a pair). Perhaps at some or various times your brakes were worked hard, causing excessive heat and rotor damage.

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In a nutshell, you need to have a brake inspection, and you will likely need new brake pads along with machined or replaced rotors. This is a fairly standard process. Should new rotors be needed, ask for options, as cheap ones are not the way to go!

 

I’ve been exploring ADAS (advanced driver assistance systems) features on various vehicles with varying degrees of satisfaction, particularly regarding smoothness in function, the vehicle seeing/understanding further ahead, how much driver input/correction is needed, and how much variation there can be between vehicle brands. Your input and comments will be much appreciated!

I’ve found in most cases the adaptive cruise control works pretty well, and as one slows and resumes in congested situations it can do a nice job pacing the car ahead, a great safety feature! I wonder if some systems are smart enough to look a little further ahead, perhaps at a sea of brake lights, and anticipate a slowdown rather than simply fixating on the car ahead. How about when another vehicle suddenly cuts in between you and the one ahead? Yikes!

How about satisfaction with lane keeping? The vehicles I’ve explored so far seemed to be oblivious to what is more than perhaps 100 feet ahead. They have been quite reactive, with too late/too much correction, and not very proactive. On a straight, well striped freeway, no problem, but getting into some gentle curves? Yikes! How well can a vehicle read the road when stripes are faded, shady spots are encountered, and pavement irregularities/repairs occur? Done poorly, lane keeping can be an annoyance, a constant tug of war, and I turn it off!

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I am blessed to have a wonderful resource for real and unbiased information: you! Please share your experiences with this emerging technology!

Make sure your tires are properly inflated in the winter

Bob Weber, Chicago Tribune

Q: I have had several Hondas, and the same situation has existed with each. When the weather changes from warm to cold, the yellow tire warning light goes on. When the weather goes from cold to warm, the light turns off. This has happened with each vehicle for as long as we have owned them! Is this something I should worry about?

— D.B., Chicago

A: A simple rule of thumb is that tires lose one PSI of pressure for every 10-degree drop in ambient temperature. Make sure your tires are properly inflated in the winter. The warning light comes on when tire pressure gets unsafely low.

Q: I own a 2011 Honda Accord with 92,000 miles. I had an oil change done and the dealership said that my right axle seal would be in need of attention soon. I decided to hold off for now. What would happen if the seal would fail and (assuming there is a left seal) should both be replaced at the same time?

— D.K., Deerfield, Ill.

A: Axle seal leaks, where the axle enters the trans-axle, are common on Accords. These seals will not fail catastrophically but leak more and more over time. Keep an eye on your garage floor and if the leak grows, have the seal replaced. You need not replace the seal on the other side until it leaks.

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Q: Your recent answer to the question of spare tires and flats, etc., reminded me that my Ford dealer told me not to use Fix-a-Flat tire sealant as it can destroy the sensor for the tire pressure monitoring system. I used to carry a can of it in my car, but now just rely on the spare. What is the true story?

— S.P., Elwood, Ill.

A: There are several brands of aerosol puncture sealants on the marker. Fix-a-Flat is one of them and it is perfectly safe for tire pressure monitoring sensors. Years ago, when TPMS was introduced, sealants did affect the sensors, but that is history. Read the label on the can to make sure the product you choose is safe.

Q: My big beef is at night you will see an oncoming car with one headlight that is blinding you. My theory is that that fender/light was replaced at a body shop and the mechanic never aimed that particular headlight correctly.

— D.H., West Dundee, Ill.

A: You may well be right about a collision repair, but better shops take care to aim the headlights before returning the vehicle to the owner. Headlight alignment problems may also come from daily driving. Hitting potholes is a common cause. Another issue is how much weight is in the trunk. That anvil collector may be totally unaware that his lights are blinding people.

Q: I have heard over and over how new cars don’t have to be warmed and actually shouldn’t be because it isn’t good for a car’s engine. So why are auto starts so popular? Isn’t this the same thing as letting your car run for several minutes to warm it up?

A: Back in the olden days, cars had carburetors. Allowing them to run at a fast idle could cause damage. Today’s engine management systems maintain the fuel mixture and idle speed. But idling gets you zero miles per gallon, so driving gently during warm-up is the best choice.

Q: I have a 2012 Mazda3 and don’t let it warm up and do not have an auto-start but am tempted to install one because I live in the frigid Midwest. What do you think?

— R.H., Chicago

A: See the previous answer.

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