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Pulsing in Brake Pedal

Discussion in 'Chevy Trucks' started by GMC Sierra, Nov 10, 2009.

  1. GMC Sierra

    GMC Sierra Member
    Messages: 41

    I have a 1997 GMC Sierra 1500 4x4- 140K miles. When I hit the brake pedal, I feel pulsing through the pedal. If I really apply the force to the pedal, the pulsing diminishes (but is still there). New rotors up front and new drums in the back (with pads). No shaking or pull in the steering wheel whatsoever. When I apply the emergency brake and then use the brake pedal, stops smoothly with NO pulse. Seems clear to me it is coming from the rear brakes.

    I may have the "new" rear drums turned to see if I have an issue. Any thoughts....I like my stuff 100%. Any chance a wheel bearing issue in the rear? Air in the brake lines? Master cylinder? Any suggestions appreciated. Thanks.
     
  2. JR Snow Removal

    JR Snow Removal Senior Member
    Messages: 390

    My 97 1500 did that I pulled the ABS fuse and no more problem. Mine would pulse when i hit the brake but when i re-applied it went away.
     
  3. GMC Sierra

    GMC Sierra Member
    Messages: 41

    No- this is not the "ABS pulse" that is typical in these trucks (no ABS noise or rapid vibration). The ABS system is not engaging when this symptom occurs. Thanks for the reply.
     
  4. sechracer

    sechracer Senior Member
    Messages: 478

    Being that most of the stoping power is in the front brakes on these trucks, unless you are always really hard into the brakes, I would still look at the front. These trucks are known to have sticky calipers. I would look at the slide pins on the front and make sure they are lubed really well. If the pulsing stops when the ebrake is applied it may be the back drums but doubltful since it uses the same pads for the rear brakes.
     
  5. Jgrub75

    Jgrub75 Member
    Messages: 30

    Sounds like warped rotors
     
  6. grandview

    grandview PlowSite Fanatic
    Messages: 14,609

    How old are your new rotors and were they after market rotors
     
  7. GMC Sierra

    GMC Sierra Member
    Messages: 41

    Yeah- I thought so too. I actually took the rotors off and had them turned to make sure they were true....no change. So, I am 99% confidnet it cannot be the actual rotor (new and turned). Thanks for the inquiry.
     
  8. GMC Sierra

    GMC Sierra Member
    Messages: 41

    Rotors are "new" and have been turned to ensure they are "true". They are aftermarket. I heard something about a lateral test...maybe this is what you are driving at. Not sure how to perform a lateral test on the rotor to ensure it is perfectly vertical as it runs through the caliper?
     
  9. grandview

    grandview PlowSite Fanatic
    Messages: 14,609

    Try and rotate the tires maybe you have a cord out and it's causing the problem .
     
  10. GMC Sierra

    GMC Sierra Member
    Messages: 41

    Yeah- could be....but I have absolutely no "feedback" through the steering wheel (tupical when a front end issue). With that said, I can turn either front wheel at will when up on the jack..would seem the caliper is "free". Thanks.
     
  11. sechracer

    sechracer Senior Member
    Messages: 478

    might be free that way, but take the wheel off of both side, and see if you can slide the caliper on the slide pins. It wont move much since it squeezed already, but you should be able to tell if it is sliding freely on the pins. I hunted for the same problem with my truck when I first got it.
     
  12. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    I have a similar situation. Where did you buy your drums? I bet that's the problem. I put some cheapie Autozone's on, I think they are no good. Actually, I'm quite sure they are no good. I noticed when adjusting the rear shoes, The drum would "catch" at one point, not even make a peep a quarter turn away. I should have bought the good ones from Napa I guess. I might just get them turned and see what happens.
     
  13. Bruce'sEx

    Bruce'sEx Senior Member
    Messages: 873

    If it is doing it more at very slow speeds, i.e just before you come to a stop. then it's likely the speed sensor in the hub. the ring gets some play in it. we have replaced several over the years

    This is from a different year range, so might be wrong in your case but ours was not from corrosion, just wear.

    Condition
    General Motors has decided that a defect, which relates to motor vehicle safety, exists in certain 1999-2002 Chevrolet Silverado, 2000-2002 Chevrolet Tahoe, Suburban, 2002 Chevrolet Avalanche, 1999-2002 GMC Sierra, 2000-2002 GMC Yukon, Yukon XL vehicles located in the areas listed below. These vehicles may have a condition permitting corrosion to occur between the front hub/bearing assembly and the wheel speed sensor. If the brakes are applied while the vehicle is traveling at a speed of greater than 6 km/h (3.7 mph) but less than 16 km/h (10 mph), the corrosion may cause an unwanted anti-lock brake system (ABS) activation. If this condition occurred where stopping distance is limited, a crash could occur.
     
  14. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    He clearly stated this is not an ABS issue.
     
  15. Newdude

    Newdude Senior Member
    Messages: 878

    When you changed the rotors, did you change the pads as well?
     
  16. naturalgreen

    naturalgreen Senior Member
    Messages: 404

    Had same prob on 93 and it was from impact wrenching lugs so warped rotors. Exact same prob but you say your rotors are fine so you got me. I would def say rotate tires and see what happens.
     
  17. GMC Sierra

    GMC Sierra Member
    Messages: 41

    Funny you say the Drums from Autozone....That is where I got them. I think I bought the mid grade....but I had the same experience adjsuting the shoes. Weird. I am going to look into that.
     
  18. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    I'm pretty much all Napa at this point.
     
  19. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Very simple. You're bargain basment brake drums were out of spec when you installed them....as many are. You get what you pay for.
     
  20. grandview

    grandview PlowSite Fanatic
    Messages: 14,609

    God has spoken on this matter. Please close this thread!