Power brakes peddle travel on my '96 Z71

Discussion in 'General GM Discussions' started by semper fi, Jul 14, 2017.

  1. semper fi

    semper fi New Member

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    The pedal travel on my '96 Chevy Z71 seems to be too long, IMO. I'll guess that when I first apply pressure to the pedal, it must travel about an inch or more BEFORE any pressure is applied to stopping. It al;most feels like the braking is less when I first step on the brake pedal. Is this normal? My truck only had just under 70k miles & I've had it from new. I did have to replace the power booster unit back in Feb '07 at 47k miles due to a leak. I bought the replacement from AutoZone. That being 10 years ago, I can't remember if this long travel started then or not BUT for sdome reason I think that it did. Is it possible that I put a wrong unit on or a "universal" one?
    Is this pedal travel normal? is there a way to fix or reduce it?
    I have several BMW's & their brakes afre applied as soon as you push on the pedal.

    In an emergency stop in my truck, I feel like I travel a "bunch" BEFORE stopping starts.
    Any feedback or suggestions appreciated.

    RV in WNC
     
  2. thendrix

    thendrix New Member

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    I used to have a 97 that had a lot of pedal travel. I don't know if it's normal or not but I never had a stopping issue with mine
     
  3. 00fxd

    00fxd New Member

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    Does your truck have anti lock? Locally trucks like mine have a reputation for soft brakes - 2004 Sierra 1/2 ton 4x4. I had a very good repair center bleed my brakes with an $11,000 Snap On scanner attached. The shop owner said there was a chance but he wasn't too optimistic, that this could help, as the scanner "Talks" to the brake system. After 3 hours of dicking around no change. I too would like to have a harder pedal. Brake linings etc are like new.
     
  4. tinfoil_hat

    tinfoil_hat New Member

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    These vehicles are known for mushy brake pedal. Even working 100% perfect the pedal will feel a little numb and the braking distance ain't that great.
    That being said, there are definately issues that you can address. In my experience older pickups are usually working off the front brakes alone with the rears doing little or nothing. The rear should be 40% of your braking but the adjuster screws will get frozen ir the wheel cylinders crap out, etc.
    If you worked on the system it is also possible you got air in the ABS unit which won't come out during a normal bleed. Like the post above says you need a scan tool capable of talking to the ABS unit to activate the bleed cycle.
     
  5. 00fxd

    00fxd New Member

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    Thanks for the reply tin .... Rears discs on mine .... The [Expensive Snap On] scan tool the mechanic used did talk to the abs but it didn't get the air out as was his fear. Sure doesn't seem right.
     
  6. tinfoil_hat

    tinfoil_hat New Member

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    Did you upgrade your master cylinder as well? The stock master does not provide sufficient pressure to operate rear discs.
     
  7. 00fxd

    00fxd New Member

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    Original master, will look into that.
    Thanks.
     
  8. daved931

    daved931 I have t-rex arms

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    My 99 OBS had shitty pedal feel, too. From what I've read, really the only way to get good pedal feel and half way decent braking is to swap in a hydroboost system from a 3/4 ton.

    I would also mirror what others have said about needing to cycle the ABS when you bleed the brakes.
     
  9. 00fxd

    00fxd New Member

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    Tin, What upgrade master would you suggest?
     
  10. tinfoil_hat

    tinfoil_hat New Member

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    I am certainly no expert on this topic. Lots of good info on GMT400.
    You might be looking at a MC from an NBS truck, a proportioning valve, and a hydroboost swap for your vacuum brake booster. The hydroboost swap does not sound too hard and you can source most of the parts from the junk yard
    http://www.gmt400.com/threads/gmt-400-hydroboost-swap.13105/
     
  11. 00fxd

    00fxd New Member

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    Thanks tin, I will search that site.
     
  12. firestorm

    firestorm GMFS Member

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    Of the past 13 years, my '01 (4 wheel disc) generally has had good pedal feel when everything is working properly. I've had 3 front calipers develop leaks over the years, and that's the most common problem for me. About 3-4 years, I was chasing down a lack of braking power, plus what felt like dragging brakes. I started to suspect the line going to the rear was rotten internally and was getting clogged with debris. I had seen a few particles in the fluid when I flushed the system back in 2009, so I was expecting it to only get worse. Later, it became apparent that line was weeping somewhere, so all hard lines were replaced. Most recently, it was the 3rd leaking caliper that caused the problem. A couple months ago, I finally replaced the original rear calipers, since the pistons took considerable effort to compress. Now it feels about as good as when I bought it in 2004, except the pads and rotors require more pedal effort when they're cold. Once they get some heat in them, they're great.

    Regarding the OP with the '96... It sounds like the hydraulic system has never been opened, so I doubt there is air in there. I'd flush out that old brake fluid though, unless you're one of the few that does that regularly already. Unless you've modified the truck, it would have drums in the rear, and ALL of the initial pedal travel is dictated by the drums. I'd inspect those, and make sure the adjusters are working. The combination valve will *not* engage the fronts until the rear shoes make contact with the drum. If the shoes are too far from the surface of the drum, the result is additional pedal travel to push the shoes out, and you will feel virtually no resistance until the shoes hit and all 4 wheels engage.
     
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