steering wheel shimmy when I get on the brakes - Toyota 4Runner Forum

johnpinetree · 06-30-2024, 12:35 AM

Wits end over here. I've replaced damn near all of the front suspension components with OEM stuff:

Lower control arms
Inner and outer tie rods
Shocks
strut mounts
sway bar bushings
One of the upper control arms maybe 5 years ago
Rotated tires

Shimmy is still there! Only happens when you're at highway speeds. If you get on the brakes and then enter a turn the shimmy does go away.

Thoughts? I'm about to replace my front calipers and get the rotors turned but figured I'd ask the community before blindly dumping more cash into this.

stevelikesrhino · 06-30-2024, 01:54 AM

It's almost ALWAYS warped rotor.

SurferUK · 06-30-2024, 05:31 AM

Quote:

Originally Posted by stevelikesrhino

It's almost ALWAYS warped rotor.

Yeah, I had this when I picked up my new (To me) 4Runner. Around town it was fine but juddered badly under braking on the motorway. The discs were corroded a little and had some contamination possibly from prolonged pad contact. I don't know for sure if they were even warped. It felt like something major at 70mph but that's all it was.

thennen · 06-30-2024, 08:32 AM

I've read several articles that explain rotor warp vs brake pad material buildup on rotors. According to those, rotors rarely warp because they're typically not subjected to enough heat to distort them. I think they actually need to glow red for that to happen. More often it's uneven buildup of pad material on rotors due to improper bedding.

Berty_K · 07-01-2024, 03:36 PM

I'd look at your upper control arms. Is the OEM original worn? Was your replacement OEM?

My JBA UCAs were worn and causing the exact symptoms you described. Went away with new bushings + ball joints.

MikeinNH67 · 07-01-2024, 04:22 PM

Quote:

Originally Posted by thennen

I've read several articles that explain rotor warp vs brake pad material buildup on rotors. According to those, rotors rarely warp because they're typically not subjected to enough heat to distort them. I think they actually need to glow red for that to happen. More often it's uneven buildup of pad material on rotors due to improper bedding.

This. You can often make it go away temporarily by sanding the rotors by hand on both sides. The fix to limit from happening is to bed new brakes in properly and in a hard stop try to limit the pads from sitting in one spot. It's now a habit for me to creep slightly after a hard stop.

Flooder305 · 07-01-2024, 11:24 PM

Had this, replaced my calipers, and rotors and the shimmy went away. There are many threads on how one puck of the rotors freezes up and creates this condition... It's so prevalent in the Midwest that guys buy the Napa Calipers with the lifetime guarantee and change them out almost once a year to prevent the warped rotor...

fkheath · 07-03-2024, 11:06 AM

Quote:

Originally Posted by thennen

I've read several articles that explain rotor warp vs brake pad material buildup on rotors. According to those, rotors rarely warp because they're typically not subjected to enough heat to distort them. I think they actually need to glow red for that to happen. More often it's uneven buildup of pad material on rotors due to improper bedding.

Rotors can warp without getting that hot if they are splashed with water -- going though a puddle. I've had that happen numerous times.

Another thing, though rare: I had a car once with the vibration from braking. Turned out to be a casting flaw in the rotor. For some reason there was a spot in the casting that was harder than the rest of the rotor, thus when the rotors wore, the hard spot did not wear as much, thus was higher than the surrounding surfaces. IT WAS NOT a pad material build up.

OopsIBrokeIt · 07-08-2024, 08:53 AM

As others have said, the brakes are a common issue on these and will lead to vibration.

The thing almost everyone missed though, is that wheel bearings can also cause vibration under braking. I have fairly fresh 5th gen brakes all around and still had a minor vibration/shimmy when braking hard. Finally did the front wheel bearings a little while back and while they weren't totally trashed I could clearly see some signs of wear. That totally fixed the vibration issue and it's been nice and smooth since.

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