Home & Leisure

Under the Hood: What's causing shudder while braking?

Brad Bergholdt, Tribune News Service on

Published in Automotive News

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.

In a nutshell, you need to have a brake inspection performed, and likely 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 farther 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 seem to be oblivious to what's more than perhaps 100' ahead, quite reactive, too late/too much correction, 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, pavement irregularities/repairs occur? Done poorly, lane keeping can be an annoyance, a constant tug of war, and I turn it off.

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


Brad Bergholdt is an automotive technology instructor at Evergreen Valley College in San Jose, Calif. Readers may send him email at; he cannot make personal replies.

(c)2019 Tribune Content Agency, LLC

Distributed by Tribune Content Agency, LLC.



blog comments powered by Disqus