'08 T4R V8 AWD Brake Vibes
 

So I installed Powerstop slotted/drilled rotors on the front and rear back in 2018. Noticed some shimmying of the steering wheel and pulsing of the brake pedal about 6 months ago. This past weekend I had the rotors turned at O'Reilly's - the guy doing the work said one of the front rotors was ever so slightly warped and the other was running true; also one of the rear rotors was warped on the inside the other rotor was perfect. So I told him to take a skim cut on all four.

I installed the rotors and followed the break-in procedure and all was good. I drove the vehicle a couple of times to work with no issues. However this morning when I applied the brakes at 60 mph I felt the shimmy in the steering wheel again! No pulsing in the brake pedal though. I tried it a few times and anytime I applied the brakes when travelling over 40-ish mph I'd get a slight, but noticeable steering wheel shimmy.

So what's going on?

Thanks.

How did your pads look? Any chance you have seized calipers? I have PS rotors too since 2018 and no problems.

Pads looked okay, though I didn't examine closely. How do I check for a seized caliper?

Any possibility that the tie rods could cause such behavior?

Seized caliper normally one pad from caliper will be significantly more worn down than the other because it is being held against rotor when it should be fully retracted, which causes heat/warping. Could be in the early stages.
Can't see relationship between tie rods and brakes.

I'm wondering why I only experience the shimmy at high speeds. My boss suggested some slop in the tie rods - it's possible as they have 114k+ miles on them.

I'm going to check for any rotor runout tonight with a dial indicator setup and will look more closely at the brake pads. I'll also try to check for any looseness in the tie rods.

Thanks.

Ball joint would be an item to inspect but with the issue disappearing then reappearing after a short period of time leads to an issue with the calipers.

Yep! The front calipers were partially frozen; I didn't bother to check the rear as I ordered rebuild kits for both sets. I also ordered a whole new set of front and rear rotors and brake pads...might as well do a full brake restoration. Now the waiting begins as items start to ship!

I'll likely rebuild the calipers and use the vehicle as-is until I receive the new rotors and pads...any reason not to?

Thanks.

Its fine, if there was an issue with your ability to control the vehicle ala the ford shimmy of death then it would be a different matter.