R20 burb pulling left under brakes

Discussion in 'Brakes' started by shanegtr, Oct 25, 2018.

  1. shanegtr

    shanegtr Full Access Member

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    Hi all, still learning thomgs about my burb - got an issue with it pulling left under brakes. Just wondering if there's any common issue to these trucks that cause this? At this stage I suspect the right front calliper may not be doing its job and also has a bit of a squeal from that side when brakes are applies, has plent of brake material left
     
  2. idahovette

    idahovette Full Access Member

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    When it pulls does your steering wheel noticeably turn or does it just drift. defines front or rear brake problems
     
  3. dvdswan

    dvdswan Full Access Member

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    Several things can cause a brake pull; sticking caliper, corroded slides, bad cut on rotor, dirty pads or shoes, brake cylinder leaking, worn out brake hose, just to name a couple of things.

    What I'm getting at is inspect both front and rear brakes.
     
  4. Obwonkonobe

    Obwonkonobe Full Access Member

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    Which problem means front or rear? I’m having the same issue but mine pulls the wheel to the left like I’m steering the truck
     
  5. shanegtr

    shanegtr Full Access Member

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    It's a noticeable turn left, the harder you jump on the brakes the more it will pull left. I think it will be something not right with the right hand front
     
  6. idahovette

    idahovette Full Access Member

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    If the steering wheel physically moves against your grip it usually means something in the front brakes, pulling in the direction of the least applied. If it just "drifts "one way with brake application it is usually the rear. A fairly good rule is grease (of some sort) pulls and brake fluid slips, meaning if you have grease on the lining it should pull or bind up on the side with the grease and the opposite for brake fluid contamination.. YMMV
     
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  7. shanegtr

    shanegtr Full Access Member

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    Gave the brakes some attention today. Flushed the brake fluid and checked out the front brakes, all seems ok there. Left rear brake is locking before the rest so that could be a possible cause (either left rear is coming on to hard or the right rear too soft). But the rear seems willing to lockup long before the fronts do. I noticed what looked like a load proportion valve under the back - as this truck is lowered is it possible that the valve needs a tweak?
     
  8. skysurfer

    skysurfer Full Access Member

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    The LSPV affects pressure to the rear brakes but equally side to side, so a pulling issue can't be pinned on that. Adjusting it to prevent rear lockup before the fronts is pretty easy. Clean off the end of the stem that sticks out of the round part of the proportioning valve and make a dot at 12:00 with a Sharpie so you have a point of reference. Remove the nut and short arm that are attached to the stem. Rotate the stem a few degrees clockwise to reduce braking pressure. It doesn't take much to notice a difference. Reattach arm and nut then test drive. Repeat as necessary.

    GM issued a tsb instructing mechanics to bypass the LSPV on vehicles with braking problems. See post #5 here. https://www.gmsquarebody.com/threads/the-brakes-breaks.5984/
     
  9. shanegtr

    shanegtr Full Access Member

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    Wasnt trying to pin the LH rear early lockup on the LSVP. It looks like the RH rear is not doing its job fully. Had a weird issue a couple of times today where the brake pedal dropped to the floor. Cant see any leaks at any of the lines or at the wheels so I may also have a leaking master cylinder.....
     
  10. shanegtr

    shanegtr Full Access Member

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    I've had a search around the forum, are there any tech write ups on adjustment of the 13" drum?
     
  11. Stewy

    Stewy Junior Member

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    When it comes to the front, don't forget, the rubber flex hose that connects to the caliper, over time, will collapse internally over time. I know 1st hand because I have had both sides on mine do it on my 79 GMC.
     
  12. WHEELMAN

    WHEELMAN Full Access Member

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    Bad calipher..bad brake hoses.change the two front hoses first.then if it's pulling.change out the caliper.the problem is some of the older vehicles.we can't get new parts.dont buy.autozone.
     
  13. idahovette

    idahovette Full Access Member

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    Looks like you got your PERIOD ?
     
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