Brake pedal is pulsating at slow speeds?

Tiny
KELLYJOJIMBOB
  • MEMBER
  • 2001 CHEVROLET SILVERADO
  • 190,000 MILES
When I am stopped at a light and have my foot on the break peddle the ABS kicks in and then peddle goes to the floor and I have no breaks. Only at low speeds does this happen. Breaks work fine at high speeds. I would like to know what some of the causes for this might be. The ABS light does Not come on.

Thanks Kelly h
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Friday, September 30th, 2011 AT 5:42 PM

12 Replies

Tiny
DAN_K
  • EXPERT
I just dealt with this identical problem with a friend's Silverado. I fixed it by removing the front wheel speed sensors and cleaning the mounting surface where the sensor meets the hub. Corrosion builds up on the surface and changes the air gap of the hall-effect sensor. Unfortunately, if you live in a "rust belt" state, this may become periodic maintenance. On extreme cases, I've read that the corrosion contaminates the grease in the hub and collects between the teeth of the tone ring. Cleaning is difficult because you don't want to wash the grease out. The alternative is to replace the hubs - this is only necessary in extreme cases; it's also costly in terms of both parts and labor. Here's an informative video that will help you fix it.

https://youtu.be/ZgiPRG6jffc

Please run down this guide and report back.
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Friday, February 17th, 2017 AT 4:31 PM
Tiny
DAN_K
  • EXPERT
1) Safely raise and support the vehicle.
2) Disconnect the front wheel speed sensors from their harness and frame.
3) With a digital volt-meter attached to the terminals of each wheel speed sensor connector, rotate the wheel in a clockwise direction approximately one revolution per second. The minimum reading on the meter should be at least 350 ACmV s. If the reading is less than that, remove the sensor.
4) Plug the sensor bore to prevent debris from falling into the hub.
5) With a wire brush, sandpaper, or another suitable cleaning device, thoroughly clean the speed sensor mounting surface.
6) Examine the sensor head for warpage or distortion due to corrosion build-up. Check the mounting surface of the sensor head for flatness at three or more positions.
7) GM recommends applying two thin coats of rust penetrating lubricant (GM P/N 89022217) to the sensor mounting surface on the bearing hub and allow to dry for 3-5 minutes. Once it has dried, apply a thin layer of bearing grease (GM P/N 01051344) to the hub surface and sensor o-ring, prior to sensor installation.
8) Install the original sensor or replacement sensor in the hub and make certain it is seated flush against the hub.
9) Re-check the sensor voltage while rotating the wheel as previously described. The voltage should read a minimum of 350 ACmV s.
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Friday, February 17th, 2017 AT 4:31 PM
Tiny
RICKMOHR
  • MEMBER
  • 2000 CHEVROLET SILVERADO
Brake rotors warp causing shuddering stops. Mechanic says there's not enough meat there to turn them. Replaced with new OEM rotors. New ones warped too. I'm not hard on brakes! I don't ride them. I have always gotten (and still do get) excellent mileage out of brakes and tires on all my other vehicles (I currently have 5). Is there a better quality non-OEM replacement rotor available?
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Tuesday, February 23rd, 2021 AT 9:47 AM (Merged)
Tiny
BMRFIXIT
  • EXPERT
Here's how to do the job get the parts from Amazon or Rockauto.

https://youtu.be/cFwjBwhpZ4o

Please run down this guide and report back.
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Tuesday, February 23rd, 2021 AT 9:47 AM (Merged)
Tiny
RICKMOHR
  • MEMBER
Thanks you worked perfect this site is so nice.
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Tuesday, February 23rd, 2021 AT 9:47 AM (Merged)
Tiny
CUP1981
  • MEMBER
First we need to clear up that "warping" of a rotor typically does not happen on regular passenger cars. You will see it only in extreme cases (i.E. Airplanes and auto racing). Driving your truck normally will not cause rotor warping.

What you are feeling is hot-spotting. This is where a hot section of the rotor causes a small amount of friction material to bond to the rotor. I would suggest changing to a higher grade of brake pad that dissipates heat better (i.E. Premium semi-metallics or ceramics). Then have the rotor resurfaced.

You should be able to get at least one cut from the rotor, unless the run-out is extremely bad.
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Tuesday, February 23rd, 2021 AT 9:47 AM (Merged)
Tiny
LOWE2453
  • MEMBER
  • 1999 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 174,000 MILES
When the brakes are applied the whole truck shakes and it feels like the brakes are pulsing or you have flat spots on the tires every time they go around the more speed the worse it shakes I have replaced the ball joints pitman arm idler arm calipers rotors and pads
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Tuesday, February 23rd, 2021 AT 9:47 AM (Merged)
Tiny
MASTERTECHTIM
  • MEMBER
Sounds like bad rotors again. Also check to make sure your calipers are not sticking.
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Tuesday, February 23rd, 2021 AT 9:48 AM (Merged)
Tiny
2CIXPT
  • MEMBER
Moderator reinforcement:

I totally agree with Tim-to prove it: Mike it or use a dial gauge and check for out of roundness and the parallelism of the rotor-Caliper piston might not be retracting due to its seal or its binding inside the bore.
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Tuesday, February 23rd, 2021 AT 9:48 AM (Merged)
Tiny
MERLIN2021
  • MEMBER
Where do you feel the shake? In the seat or the wheel? If fronts are warped you will feel the pedal bounce and maybe the steering wheel shake, if you feel the truck shaking and it seems to come from the seat area, check the rears, get the truck up to speed and use the parking brake, feel anything? Before you do this get under it and pull on the cables to make sure they work, then as you do the test keep the release lever pulled, or if it's a locking pedal apply the pressure so it releases as you do it! Start with light pressure and continue the force unless you can feel it right away.
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Tuesday, February 23rd, 2021 AT 9:48 AM (Merged)
Tiny
LOWE2453
  • MEMBER
As soon as the brakes are applied the shaking starts and gets worse the harder you brake. The shaking is the whole front end but it doesnt pull to either direction it is like it is loping. This all started after replacing ball joints.
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Tuesday, February 23rd, 2021 AT 9:48 AM (Merged)
Tiny
MASTERTECHTIM
  • MEMBER
You need new rotors is my opinion.
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Tuesday, February 23rd, 2021 AT 9:48 AM (Merged)

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