Intense Brake Judder…that Disappears Under Threshold Braking

ResIpsa

I just wanted to post this thread to help anyone else trying to diagnose the particular brake judder issue I was having. Here were my symptoms:

1) No braking issue (judder) at the track with track pads at about 75% pad remaining.
2) As the weekend progressed I started to notice a slight judder under braking.
3) The judder got progressively worse after each subsequent track session. The judder was more pronounced under trail braking.
4) By the end of the weekend, when my pads were <25% remaining the judder got so bad the car felt dangerous and trail braking was all but impossible.

Now the key symptom.

5) If I just kept the car in a straight line and applied 100% braking force (aka threshold braking) the judder would disappear and my braking would be smooth. However, when I backed off to anything less than threshold braking the intense judder would reappear.

Rather than go into the multitude of possible fixes I will let you know what worked for me. I suspected that the issue had something to do with the pistons when they were overly extended. Maybe sticking, maybe the years of track use has slightly rounded out the caliper seats, who knows.

My fix was to take an old set of street pads and use a hammer and chisel to remove all the remaining pad material creating a backing plate. I then cleaned the caliper and pistons best I could and lubricated the pistons with plenty of brake fluid. After compressing the pistons I inserted the backing plates behind my badly worn pads and voila! The judder is completely gone!

So the problem did have something to do with the over extension of my caliper pistons. If you ever run into this problem I hope this helps.

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The Reed Law Firm; Michael Fasano VA Attorney and Counselor at Law: A Virginia Traffic, Criminal, and Family Lawyer.https://reedlawva.com/