And another brake issue
 

Wife picked me up at the airport last night in the X and I drove home. Took me one application of the brake to say “what the covfife!”. The steering wheel jumped and vibrated badly in my hands the instant I applied the brakes. Long story short, repeatable at any speed, no issues when not braking. Car stops ok with no pulling to either side tho.

I’m going to pull the wheels today and recheck all the brake work I did over the past few months (new front rotors and pads, new parking brake pads and springs), and check all the fasteners on the suspension pieces/links (all changed last year). Beyond shoddy workmanship by me and missing the torque on something bake or wheel related, or a blown out bushing (which seems unlikely with only 6k on the new links) the only other thing I can think of is a very badly warped rotor, except that they are brand new from FCP and the car just took me 2000 miles and back to hunt with zero issues a few weeks ago. All the suspension bolts are witness marked so they should be easy to verify.

What else is there I should check? Could a caliper cause this if it fails? I would think the car would pull to one side though if this were the case.

Thanks for any thoughts before I get into it gents.

Check the thrust arm bolts. The inner ones!

Put it up in the air today and checked every bolt and nut on the suspension and calipers. All were torqued ok. Pic below is of the rust in 1/3 of the rotors, after I hit it with a scotch bright.

https://i.postimg.cc/432zp89F/B913-D...-B8-EEC1-E.jpg

Clearly the pad isn’t hitting that area. I Put it all back together and suddenly no wobble. Crazy, because I didn’t really do anything.

Wow, it's a big area not to be touched by the pad. Were pads flat? I would suspect the vibration was cause by such a big none touching area.

They seemed fine when I installed them. New TRD ceramic pads, sold as a kit (FCP) with Zimmerman rotors. After I put it back together this morning I took it out and hammered the brakes. Up to 60 a few times and jumped on the binders, just like the TRW break in instructions that I followed a few weeks ago. That cleaned the rust off that wouldn’t clean up with the scotch brite.

Who knows….one of the more strange x5 happenings I’ve experienced in 20+ years of owning the car. FCP tech support is supposed to get back to me with their thoughts, and hopefully a new rotor!

The pads couldn't have caused this... almost sounds like the rotor came loose and got cocked slightly sideways. Never heard of something like that happening but also never heard of this kind of problem before. Super weird!!!

Hmmm, that picture was taken after driving it or after it sat for a while? it almost looks like the shape of that rust spot mimics the shape of the caliper.

In any case, brake vibration can also be caused by uneven pad material transfer to the rotor. Maybe you cleaned off a high spot and that was it.

Also, I've had that same jack since 2006 and I recently bought the same one brand new to have as an extra. Stout little thing!

It had been driven the night before, which was when the steering wheel vibration began. Before that it had sat for a few days. The pic was taken after I hit the rusted area with a green scotch pad. Some of the rust came off, but most didn't, which lead me to believe it had been building up for longer than a few days.

After checking the torques, I drove it and essentially did the pad/rotor break in again. Up to 60, jump on the binders to 10 mph or so, rinse/repeat a several times. No shimmy or wobble at all. I don't think I took off too much of the rust, but maybe it was enough. Assuming the built up rust was causing the wheel to wobble under braking, which was then coming up the steering column.

That jack is super old and I have been thinking I need a new one. Its been a champ though. Although I've been eyeballing an aluminum higher lift one. I need to put a few blocks under it to get my X5 up enough to get the wheels off. Aluminum would be easier too for me to lug back to my shed after use. Read: I might actually lug it back to my shed instead of leaving it outside like my current one!