2024 CX-5 Steering Shimmy

[junebug57]

The steering wheel on my 2024 CX-5 has started to shimmy/shake when I brake. It has 21000 miles on it. The dealer is hinting that it may be an issue with brakes or rotors. Wouldn't that be unusual with that amount of miles? I asked him that and he said "they're seeing it sometimes" due to it leaving deposits or something like that. I've never had to deal with any brake issues on any car with that low mileage.

 

[paris1]

It's commonly referred to as "brake rotor warping" which is somewhat of a misnomer as it's actually caused by uneven deposition of brake pad material on the rotor surface. It can happen any time to any vehicle no matter what age and is caused by any number of driving variables. Long and short of it is you need either new rotors or have the existing rotors resurfaced. Whether the dealer/Mazda will cover this under warranty is questionable.

 

[RedBaron]

^ What he said.

The shade tree fix is to find an empty straight road and do a series of the following: Speed up to 50-60 mph and brake HARD (but not quite hard enough to trigger anti-lock) down to 15-20mph, rinse/repeat about 3-4 times. Be sure to drive around for 10mins or so after that and let your brakes cool properly before parking.

 

[Mazdiod2]

I've read you can remove deposits on the rotors with abrasives, like steel wool, maybe sandpaper.

I think the deposits occur because of hard stopping, especially with new pads.

 

[TheMAN]

^ What he said.

The shade tree fix is to find an empty straight road and do a series of the following: Speed up to 50-60 mph and brake HARD (but not quite hard enough to trigger anti-lock) down to 15-20mph, rinse/repeat about 3-4 times. Be sure to drive around for 10mins or so after that and let your brakes cool properly before parking.

it won't work well when the lug nuts aren't tightened evenly at the proper torque spec... if they were blasted on, they will be all over the place, and that makes them easy to warp/get uneven pad transfer

I would get the lug nuts refastened properly first before doing that

 

[N7turbo]

Building on what was said above, I recall reading this comment on a YouTube video talking about how rotors don't actually "warp" per se:

Firstly, I was a brake system Engineer for a global OEM, working with Bosch, Ate/Continental, Ferodo, Brembo, Akebono, Fagor Ederlan etc. All brake materials have to transfer onto the disc and is part of the bedding in process. It's the temporary bonding between the transfer and the pad that produces some of the braking force at lower speeds and braking forces. Under heavier braking, any abrasives in the material will actually remove some of the transfer layer and allow a fresh layer to develop.

What will produce a disc thickness variation is runout of the disc surface when fitted. Your brake pads
will move back from the disc when you stop braking, which is controlled by the brake seal. If the disc runout is close to this, then the outer pad will lightly rub the disc surface, which slowly wears this section of disc down. Eventually this will be felt as a pulsing of the brakes and pulling on the steering. The runout can be due to the disc manufacture, but also the hub. The hub must be cleaned of any surface rust, debris etc, and then check the runout with the disc clamped correctly. I used an old wheel cut down to just the centre and then tightened and torqued the wheel / lug nuts.

I have run standard road car brakes until they are glowing bright red in abuse test and not once did I warp a disc as long as you drive it gently until the brakes had cooled down to more normal temperatures. (Easy when you have thermocouples and IR temperature sensors fitted).