93 Grand Am Strong vibration when braking!

[Felix02]

I get a very strong vibration when brakeing. It does not happen all of the time so I do not think the rotors are warped. Usually when brakeing from hwy. speeds., then it feels as though it is bouncing. Any ideas?

[J-Ri]

A brake pulsation can only happen at higher speeds. The caliper slides will allow for some out-of-parallel, but at higher speeds, the side-to-side movement is greater and if the slides can't move fast enough, you get a pulsation.

I'd check brakes first, but if you don't think it's warped rotors, check to make sure the front end is tight.

[xeroinfinity]

Welcome to AF Felix02.

I would also make sure your lug nuts are torqued to 100 ft lbs.
If they are higher or not all the same, you can warp your rotor(s) and cause simular issues.

[Felix02]

I want to add that the strong bouncing vibration I felt continued even after I let up on the brakes. I then quickly moved the steering wheel from right to left and the vibration flattened out. What does tightening the front end involve.

[J-Ri]

There is nothing to tighten unless a fastener is loose. A loose steering or suspension component must be replaced, and you'll want to have the car aligned afterward.