Causes of steering wheel shudder

[buck91]

Figured I now have two vehicles with these symptoms, though they vary greatly in severity. One has just the slightest shudder of the steering wheel under heavy braking, the other has a greater amount though not to the point of great concern. Both vehicles brake smoothly and straight otherwise with no pedal pulsation. Both vehicles drive straight and tight. Both vehicles have the wheels torqued to first 40 ft-lbs then full torque specs with my own Matco torque wrench which goes off for calibration every few years. Tire pressures are maintained. And both vehicles have had brake work within the past few years including lubing pins, sliders and even thoroughly preparing the hub flanges prior to installing rotors.

I would like to open a discussion about possible causes for these steering wheel shudders, as well as generally what can cause these types of symptoms.

 

[Colt45ws]

Uneven pad deposition. I reburnish the brake with 6 hard (non-ABS) stops 60-10mph in a row, then drive a few miles and repeat.
My Mom's car was so bad I had to replace the front rotors. But, the other vehicles Ive come across with it, that has fixed it, so 2/3 it works.

 

[DemoFly]

Rotors can warp within hundreds of miles, though rare. Pads can also wear unevenly, simply due to bad luck or hanging slide pins/caliper pistons.

9.5 times out of 10, a slight braking steering wheel shudder is warped front rotors, rather than uneven pad wear. Though, you should change both at the time of replacement.

 

[SonofJoe]

Back in the 70's, I drove a [censored] old Austin 1100. As I was always skint, and couldn't afford new tyres, I used to put £5 remoulds on it. Usually, after a few thousand miles, I'd start to feel a judder coming through the steering wheel and this usually meant a blister had formed on the side-wall of the tyre. Of course, I'd keep driving it until the judder got too extreme in order to get my full money's worth!

One time I had a real bad judder but couldn't find the blister. I remember driving the 150 miles from my parents house to home with the steering wheel shaking in my hands! It was only when I got home and properly inspected the tyre that I found I could press on one spot of the tread and push the tyre in all the way to the hub!! Oh happy days..

 

[tig1]

Warped front rotors.

 

[09_GXP]

Originally Posted By: Colt45ws
Uneven pad deposition. I reburnish the brake with 6 hard (non-ABS) stops 60-10mph in a row, then drive a few miles and repeat.
My Mom's car was so bad I had to replace the front rotors. But, the other vehicles Ive come across with it, that has fixed it, so 2/3 it works.


+1 Depending on the time the brakes have been in service uneven pad deposition is much more likely that warped rotors. The options are to get them good and hot as suggested above or take the rotors off and clean up the surface.

 

[ARCOgraphite]

I braked hard coming off exit due to stopped car in exit. That was it for my front rotors. Shakes violently now. Tried re-torqueing lugs and repositioning wheels to no avail. Going back to dealer under warranty with 19K miles.

It seems to me that cars with cast or forged Al wheels seem to warp brakes less often.

Any one else feel that?

 

[Lyman]

Cheap rotors you buy nowadays are junk. Inferior metals that warp easily. Buy quality rotors. That is if you can find them.

 

[mehullica]

Rotors don't warp. They never get hot enough to warp from braking. They either develop thickness variation from uneven pad deposits, lateral run out from rust, bad machining, uneven torquing, etc.

 

[BigD1]

Originally Posted By: mehullica
Rotors don't warp. They never get hot enough to warp from braking. They either develop thickness variation from uneven pad deposits, lateral run out from rust, bad machining, uneven torquing, etc.


I had a 1998 Malibu that I bought brand new, and it warped the rotors twice in less than 30,000 miles. The service manager said that there was a bad batch of rotors, and they just had to keep changing them to weed them all out of the supply line. The last time they changed them those rotors were good, and they were fine until it was totaled at close to 100,000 miles. Been a long time ago, but I think I did at least one pad slap on those rotors, and it could have been twice.

 

[BrocLuno]

Originally Posted By: mehullica
Rotors don't warp. They never ...


Uh Huh

 

[Colt45ws]

I surprised my friend by fixing the shudder on his car by doing the reburnish procedure. He swore up and down they were warped and needed replaced. Might be worth a shot if you have 'warped' rotors.

 

[DeafBrad]

I read somewhere (I believe it was a post here) that if you slam on the brakes and then stop at a light with your foot on the brake you can warp them. So the trick is if you use the brake really hard do not hold the brakes while at a light.

 

[stephen9666]

Originally Posted By: mehullica
Rotors don't warp. They never get hot enough to warp from braking. They either develop thickness variation from uneven pad deposits, lateral run out from rust, bad machining, uneven torquing, etc.


Just one note on this.

Runout is a common cause of brake pulsation, as this member noted. But it's not necessarily caused by rust. It can be caused by rust or other debris on the hub, but it can also be because of excessive runout in the rotors themselves or stacked tolerances.

Checking the runout on new brake jobs is a good idea, but it's often skipped. It's an especially good idea to check it if the brakes are being replaced because of a pulsation.

Excessive run out, whatever the case, causes the rotors to wear unevenly and that thickness variation leads to a vibration.

 

[ARCOgraphite]

They warp. They get hot enough to warp. Near Red hot.

Ive Measured run out. No Thickness or surface variation.
Think of the disk when expanding it has to buckle.

Jeeze my cookie sheet warps when it goes into the oven.

 

[DeafBrad]

I saw a video of a race car where the video was mounted to view the rotors. When the driver would use the brake the rotors would glow orange. He wouldn't slam on the brakes and hold them. He pulse the brakes (slam on them and then release, slam on the and release, etc; his cycle would be less than a half second long). They would glow and immediately cool when the driver let up on the brakes.

 

[threeputtpar]

As usual, so much misinformation on BITOG. It's a myth that just won't die that rotors warp. There is no way that a passenger car on any US road can generate enough heat during braking to warp cast iron rotors.

It's either uneven pad material deposition or lateral runout of the rotating assembly that eventually causes uneven pad deposition.

Also, don't ever think that Arco's anecdotal evidence is anything near reality for the rest of the motoring public. His history of killing cars is long an illustrious and well documented on this forum.

If you don't see any bluing on a brake rotor, that is proof that it hasn't even come close to the temperature it would take to actually warp the rotor.

 

[ARCOgraphite]

Three put, are you qualified to even comment? What is your professional experience?
Your Childish aspersion casting is a sign of very insecure boy.

If the rotor shows significant lateral runout but also same thickness mic'd in multiple locations ; this is what we are calling "warp".

 

[ARCOgraphite]

I will say its hard to put a gauge on a red hot rotor. Plus the wheel may have to be off which requires a torque plate be installed in the tire/wheels stead.

If I still worked at the lab in Wilmington could scan the surface and look at metals. I don't disagree that some softer metal shards in the pad amalgam may deposit on the surface of the rotor with high heat and hard application. If this is often troublesome, there exist a pad/rotor materials design issue.