Advice on Light Pulsation While Braking

[discgolf01]

Hey guys, looking for some advice on some pulsation I am feeling while light braking at highway speeds.

 

Normally, I would just assume it's the front brake rotors out of whack and replace them and the pads, but in this case, the pulsation/shaking I am feeling is not coming through the steering wheel like I've always felt before with rotor issues on other vehicles I've owned. This pulsation is felt through the seat/vehicle, nothing through the steering wheel.

 

As mentioned, this occurs with light braking at speeds over 50mph and then dissipates the harder I brake.  Pulsation is light, most would probably not notice it, but I do since I've owned the truck since new.

 

Any thoughts on this? Might it just be the rear rotors having an issue since it's not being felt through the steering wheel?

 

Thanks!

 

2015 Sierra crew cab

5.3L

60k miles

[CamGTP]

If you feel it through the seat it's almost always the rear brakes.

 

The pedal or steering wheel would be fronts.

[discgolf01]

Great, thanks for info.  Had a feeling it might be just the rears, but have never had a vehicle where just the rear rotors go out of whack and not the fronts.  Anyway to 100% verify it's the rears without replacing them first?

[CamGTP]

A dial indicator would show you the run-out in the rotor, pretty much the only way to do that.

[MikeBMW]

On 11/14/2024 at 5:38 PM, discgolf01 said:

Great, thanks for info.  Had a feeling it might be just the rears, but have never had a vehicle where just the rear rotors go out of whack and not the fronts.  Anyway to 100% verify it's the rears without replacing them first?

I brought my car to the dealer and I wanted the front brakes done because of some wobbling.
They called me back and said fronts are fine but the rears needed attention.
Sometimes it's not what you think it is.

[discgolf01]

Update:  Finally got around to replacing the rear rotors and pads.

 

Problem still exists:  a pulsating vibration through the body/seat at light braking at highway speeds.  Still nothing being felt directly through the steering wheel.  Also, tires were rotated during the brake work.

 

Anyone have any ideas?  Could it really be the front rotors even though nothing is being felt through the steering wheel?

 

 

[mikeyk101]

On mine, I started having minor vibrations in brake pedal when slowing down from higher speeds using the brakes. And that was while light braking. It wasn't violent but was definitely not right. I honestly don't recall if I felt anything in the steering wheel. I finally went and changed out the front rotors and pads. I ended up having to do the pads 3 times though. 

 

Reason for that and just a PSA, was I did use OEM rotors but for some reason has a set of pads from O'Reilly's in the garage already, brand new. I put those on and they were a tight fit. I wasn't happy but drove with them for about 100 miles. The smell of hot pads was very strong and I could see the side edges binding in caliper. I exchanged those for another set and had same problems. I then bought a set of OEM pads and they fit perfectly, no problems since then. And no more pulsing.

[discgolf01]

23 hours ago, mikeyk101 said:

On mine, I started having minor vibrations in brake pedal when slowing down from higher speeds using the brakes. And that was while light braking. It wasn't violent but was definitely not right. I honestly don't recall if I felt anything in the steering wheel. I finally went and changed out the front rotors and pads. I ended up having to do the pads 3 times though. 

 

Reason for that and just a PSA, was I did use OEM rotors but for some reason has a set of pads from O'Reilly's in the garage already, brand new. I put those on and they were a tight fit. I wasn't happy but drove with them for about 100 miles. The smell of hot pads was very strong and I could see the side edges binding in caliper. I exchanged those for another set and had same problems. I then bought a set of OEM pads and they fit perfectly, no problems since then. And no more pulsing.

 

 

Thanks for this info.

Guess I'll do the fronts next.  Its just that not feeling any pulsing in the steering wheel is nagging me. 

 

 

[TheRiver]

Isn't the ABS module below/under the drivers seat??

[discgolf01]

Update:  replaced the front rotors and pads and vibration is gone. 

 

Lesson learned:  the fronts can cause vibrations not felt in the steering wheel.  I'm wondering if the steering design has some sort of damping/isolator in it since the pulsation I was feeling was fairly light and the only vibration I felt was through the frame/seat.

 

New issue:  there is a slight metallic ping from the front left when braking from 5mph to 0.  It lasts for only a fraction of a second at 5mph then disappears.  Only thing I can thing of is the abutment clips on the pad, but I double checked each one was installed exactly as it should be before installing the pads.  I did the 40mph to 10 mph stops four times to seat the pads.  I'll give it some time to see if it changes/disappears.  Any thoughts from anyone?