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Mild Thump Under Right Foot

Old 08-21-2017, 08:13 PM
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Default Mild Thump Under Right Foot

Often, while gently pulling away from a stop, and typically right after Iíve started driving, I feel and hear a double ďthump.Ē The feel is pretty mild, but you wouldnít miss it. Kind of like a light tap with a mallet. It usually feels like it is right under the accelerator, but always somewhere under the area covered by the floor mat, letís say.

With that lousy description, any guesses what Iím hearing and feeling? Iím thinking it is something engaging, or disengaging, but thatís a guess. Any insights are welcome.
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Old 08-21-2017, 08:26 PM
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It's normal. It has to do with the ABS. It occurs at 25 MPH each time you start the car.
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Old 08-22-2017, 11:47 AM
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Originally Posted by SYMAWD View Post
It's normal. It has to do with the ABS. It occurs at 25 MPH each time you start the car.
Thanks. I glanced at the speedometer this morning when I felt it and it was right at 25 MPH.
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Old 08-22-2017, 12:07 PM
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Originally Posted by dadrocker View Post
With that lousy description, any guesses what Iím hearing and feeling? Iím thinking it is something engaging, or disengaging, but thatís a guess. Any insights are welcome.
Noticeable by almost every owner of the new generation A4 on the first pull away from the dealer's lot. We bought ours when they first hit the dealer showrooms. Many staff didn't know what it was but was "probably" normal. Some said they heard it was nothing to worry about but that a tech services bulletin would be forthcoming. Most recently I've been told it's a proper pre-positioning of the brake calipers.

It doesn't happen in my two day old RS3, FWIW.
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Old 01-09-2019, 04:54 AM
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Originally Posted by SYMAWD View Post
It's normal. It has to do with the ABS. It occurs at 25 MPH each time you start the car.
I've been wondering about this too - I'll have to check the speedometer the next time I drive.
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Old 01-09-2019, 11:34 AM
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It's the ABS check. Completely normal.
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Old 01-09-2019, 12:02 PM
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My B8 A4 does exactly the same thing.
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Old 01-09-2019, 02:38 PM
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What exactly is it checking though and why don't other cars check it?
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Old 01-09-2019, 03:55 PM
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My Honda did it at 10 mph.
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