First off this is a customers car that has really got me stumped. It has a brake pulsation at high speed, it is pretty slight, but were dealing with a picky customer, which is totally understandable. It pulsates only at high speed, usually 60mph and above. You can hear the noise and feel it in the steering wheel, and maybe a tiny bit in the pedal itself. The customer told me this has been and on going problem and he's taken it to the dealer several times and they put new pads and rotors and it either came back within a few days or so or didn't change at all. He lives where there are lots of hills and noticed it gets a bit worse as they get hotter which I myself have also noticed.

First off, I do not own, nor anyone I work with, a dial caliper to measure rotor runout and I informed my boss that this should be the first step in determining what wheel or wheels the pulsation is coming from. I was told to do my best without one. So the first thing I did was replace all 4 rotors ( pads were still in decent shape so I left them). The pulsation did not change at all. When changing the rotors I noticed the front hubs had been cleaned very agresively and a decent amount of material was ground away. So next I changed both front hubs which was a bit of a pricey job. IT STILL DID NOT CHANGE!!!!

All suspension parts are tight, all wheels are properly torqued. IM STUMPED

 

Are the brake pads sticking on the slides of the caliper adapters?

I've seen vehicles in wet areas, that guides start to rust and the pads get hung up and kind of ride the rotors

Or could be something simple like tie rods or ball joints or half shaft bent

 

Start with the simplest thing first. Are the tires balanced correctly? No bubbles on the sidewall?

 

The first thing is to determine rotor runout, the check the hubs for excessive runout. Use an on car brake lathe to resurface the rotors(even new rotors), use factory pads, don't over torque the wheels. A dial indicator is about $100, much less than what your customer spent already.

 

Put a 3rd set of rotors on it and it's fixed believe it or not. I'm gunna say its a bad batch of rotors from napa.