[FIXED] Pedal Pulsation Caused by Tapered Brake Pad Wear?

[Stephen Carney]

Hi,

I am helping my mom with her 2003 Hyundai Elantra GLS, without ABS. There is a pretty strong pedal pulsation whenever the brakes are applied with any moderate pressure. I did a little research, and expected to find a rotor with significant lateral runout. I purchased a dial indicator with a magnetic base and measure the runout. However, I was surprised to the find that the runout was only 1 to 2 thousands of an inch. I checked all the other brake hardware and observed the following. The inside brake pad on both sides showed a tapered wear pattern. On the right side, the pad was thinner at the top and thicker at the bottom, by about three hundreds of an inch according to my micrometer, it was visible to the naked eye. On the left hand side, the pad was thicker at the top and thinner at the bottom. Both outside pads weren’t tapered and were of the same uniform thickness.

I have only changed brake pads on my 1996 Honda Accord, however I noticed the following. The brake pads had so much room inside the caliper mounting bracket. For my Honda I remember they were very snug and I kinda had to snap them into place. The pads on the Elantra were very loose. I took out the brake pads and reattached the caliper so I could test the caliper slide pins. They moved very easily side to side. However I noticed another discrepancy, the caliper itself seemed to have much more play than in the Honda. In the Honda, the caliper slid side to side along the guide pins, on the Elantra, the caliper had room to twist a little back and forth as well as side to side. Finally, I noticed that the inside pad was damaged a little on the top and bottom of the pad. Also, the rotor surface facing the inside of the car was rusty, while the surface facing the backside was not. Also, the line down the middle of the brake pad seems to have been filled up with material on the pad on the right hand side. I have attached several images. Any idea what could be causing the tapered wear, and whether or not the tapered wear is causing the pedal pulsation. Thanks.

Steve

Attachments:

• Rotor1.jpg
• Rotor2.jpg
• BrakePad.jpg

Topic

[James]

I would suggest in line for new rotors and pads. If when you take calipers off. The guide pins look bad or stick or the caliper its self is difficult to push in or leaking, replace caliper assemblies as well. They are fairly cheap. Best of luck.

[simon a rawle]

im with jjohnson1 new pads and discs . also clean your slide pins and the holes there go in to in the caliper

[Stephen Carney]

I bought rebuilt Hyundai calipers because I didn’t like the slop in caliper move when I slid it from side to side. I also bought new pads and rotors, all from RockAuto. When I replaced the rotors, I cleaned the hub up really well, it was very rusty. I have read the hub, as well as the rotor hat should be cleaned up as excessive rust can cause lateral runout. After the replacement, so far the pedal pulsation is gone. Thanks to everyone for their help.

[Author]

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