*** Update ***

What I'm probably going to end up doing in the next few weeks is replace the front brake calipers and replace the new rotors with slotted ones.

If that doesn't fix the shaking, then the issue has to be with the ball joints, etc.

 

You have hot spots on rotors you just replaced?
How long ago is just replaced mean to you? You replaced them and didn't machine them correct?

 

You're probably as confused over the situation as I am. I replaced them myself yesterday. They were from O'Reilly's, the Select Best brand. They were an OEM match.

But this is what's frustrating. Every person that has had this problem replaced their pads and rotors and still had the vibration or the vibration returned within a month. And each time, service techs say it's hot spots (warping) on the rotor. I don't get it. Also, the vibration doesn't slow down as the speed slows down. It actually increasing in my car.

There's a noticeable pulsing in the brake pedal above 40 MPH. When the car starts to reduce speed under 40, the vibration increases and continues to increase until the speed hits 20MPH. Then the vibration completely stops.

I don't get it. I...simply...don't...get...it. And I'm tired of hearing it's warped rotors.

What the guys at the shop were telling me, is what they've been doing is machining the new rotors for the Malibus to reduce the vibration.

 

Get the new rotors machined on the car. A on car lathe with cut the rotor and account for the stacked llateral runnout I was describing. The problem is runnout in the hub and bearing assembly.

Once then are machined on the car; they are now indexed to the hub and must be put back on the same lugs they came off or the runnout will return.

 

Thanks tech2,

That is the best explanation and resolution I've heard. Seriously.

 

tech2 & sledge.impy,

Wanted to thank you for all your help. I ended up fixing the shaking myself.

I disassembled the driver side brakes and went over everything again. The lower guide pin has a rubber gasket that was preventing the pin from collapsing. It was slightly frayed and it looks like the frayed rubber got wedged between the pin and the gasket preventing it from moving.

I replaced the gasket and greased it up and voila, the shaking stopped.

It's all good.

Thanks again,
Ed

 

gm uses a/c delco silicone brake lubricant. the wrong type of grease can swell the rubber.

 

Great find and thanks for posting the fix!