Another Brake issue after replacement

[SLX5]

I replaced my brake pads and got the rotors resurfaced. I have done this many times before, but has never experienced this before.

Even at low speeds 10 to 20mph, the car shakes violently when I press the brake pedal. What worse is the brake pedal moves back and forth about quarter of an in at these speeds.Took everything apart and put it back together, the issue continues.

I have changed brakes several times including the X5's but has never experienced something like this before. When I decided to change the pads and rotors resurfaced, I didn't have any issues at all. Worked perfectly prior to to change,........Please help

[petener999]

Did you check your brake fluid level? How many time did you resurfaced your rotor?

[SLX5]

I opened the master cylinder cap and pushed the calipers in. So there was no risk of air getting in. The first time they were resurfaced.

[TEMA]

Originally Posted by SLX5

I opened the master cylinder cap and pushed the calipers in. So there was no risk of air getting in. The first time they were resurfaced.

how did you resurface them? do you have the specific tool that resurfaces them? my indy has one of those where he mounts rotors like a tire and then presses the shaving blade onto rotor and lets the rotor spit - that is the right way of doing it.

[SLX5]

I took it to Oriely's Auto Parts. I am not sure how they do it. I have had several rotors refaced without any issues.

[jdd]

It sounds like a disc run-out issue to me.
Either the discs weren’t machined correctly or they’re not sitting flat against the hub.
Take the wheel off and rotate the disc slowly whilst looking at the contact between the pad and the disc. For the problem to be as bad as you state it should be obvious which side is causing the problem, unless it’s both. There should be no visible movement (in/out) between the pad and the disc as the disc is rotated
The other thing that can cause an issue like this is a badly worn wheel bearing (or poorly adjusted on some vehicles) but it’s unlikely to be the cause in this instance.
Make sure the mating surfaces between the disc and the hub are clean and free of anything that can cause the disc not to seat correctly on the hub. It may even be worth tapping the disc in several places (not on the friction area) onto the hub with a soft faced hammer just to make sure it’s seated properly. Make sure the counter-sunk screw holding the disc to the hub is removed when doing this.

If it’s not a disc seating problem then it is likely one or both discs weren’t machined correctly in which case you will probably need to replace them.
All discs have a minimum thickness that should be adhered to and no reputable machine shop should allow them to be machined under this limit.
You probably won’t get two lots of machining, plus normal wear and still be over the minimum thickness, especially if they have to fix a run-out issue.