# Bumping brakes **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [August 9, 2007, 7:00pm UTC](https://community.cartalk.com/t/bumping-brakes/2868 "2007-08-09T19:00:10Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![rdmmos](https://avatars.discourse-cdn.com/v4/letter/r/e99b99/32.png) [@rdmmos](https://community.cartalk.com/u/rdmmos)\ **Post date:** [August 9, 2007, 7:00pm UTC](https://community.cartalk.com/t/bumping-brakes/2868/1 "2007-08-09T19:00:10Z")
I have a 1997 Cadillac DeVille. When I step on the brake they make a bumping sound and the car vibrates. We have changed the brakes and calibers. What else can be wrong? ---
**Author:** ![Joseph\_E\_Meehan](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/joseph_e_meehan/32/21_2.png) [@Joseph\_E\_Meehan](https://community.cartalk.com/u/Joseph_E_Meehan)\ **Post date:** [August 9, 2007, 10:20pm UTC](https://community.cartalk.com/t/bumping-brakes/2868/2 "2007-08-09T22:20:41Z")
Dose your car have ABS? If so does it feel like the ABS? ---
**Author:** ![Midwest\_honky](https://avatars.discourse-cdn.com/v4/letter/m/eb8c5e/32.png) [@Midwest\_honky](https://community.cartalk.com/u/Midwest_honky)\ **Post date:** [August 10, 2007, 6:09pm UTC](https://community.cartalk.com/t/bumping-brakes/2868/3 "2007-08-10T18:09:34Z")
Ok, are you braking hard? If so, you may be triggering the ABS - anti-lock brake system. But if this happens all the time when braking, then my first guess is warped brake rotors. They can warp for a variety of reasons. But when they are warped, they have a high spot on them. So each time that high spot hits the brake pads, it sends a pressure spike back through the system to the pedal so you can feel that. The high spot is also suddenly much tighter when it hits the pad so the car shudders which is the vibration you feel. Very common. What to do? Have a good mechanic measure the rotors to see if they can be machines or just replaced. The cost could be about the same depending on replacement parts or the machining could be cheaper. Only way to find out is to start asking. ---
**Author:** ![rdmmos](https://avatars.discourse-cdn.com/v4/letter/r/e99b99/32.png) [@rdmmos](https://community.cartalk.com/u/rdmmos)\ **Post date:** [September 15, 2007, 12:43pm UTC](https://community.cartalk.com/t/bumping-brakes/2868/4 "2007-09-15T12:43:20Z")
Thanks! Your advice was right on the mark!!! I knew I’d find the answer here.