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Disc Brakes aren't Brakin!!!!! HELP

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Corey-88K5, Jun 17, 2000.

  1. Corey-88K5

    Corey-88K5 1/2 ton status

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    Disc Brakes aren\'t Brakin!!!!! HELP

    Well I got the new TSM Disc's in stalled and lines are blead, but now I've got a problem. The caliper pistons only move about 1/4" and then retract. They don't even contact the rotor enough to stop the rear axle when its off the ground and in drive. The main problem seems to be that the pistion doesn't act like the front. When you pump the brakes they just go in and out, not contact the rotor. Does anybody have any suggestions? These are 85 Eldorado calipers. If anybody has any knowledge of the rear system, please let me know. I tried to push the reset button on the proportion valve. I'm not sure if it has to be held in when doing this.

    Thanks ,

    Corey
    88K5

    [​IMG]<font color=red>Girls Like Guys In Bow Ties
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  2. jarheadk5

    jarheadk5 1/2 ton status

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    Re: Disc Brakes aren\'t Brakin!!!!! HELP

    I think you may need a bigger master cylinder. I think I've read somewhere (many places actually) that drum-to-disc swaps often need bigger master cyl. due to more fluid required by rear calipers vs. rear wheel cylinders. I could be wrong here, but at least its someplace to start. Hope it helps!

    [​IMG] Semper Maintenance!
     
  3. Corey-88K5

    Corey-88K5 1/2 ton status

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    Re: Disc Brakes aren\'t Brakin!!!!! HELP

    The thing is, the pistion isn't "pumping up" so to speak. The front, if you change your pads and press the pistion in to the caliper, you have to hit your brakes a couple times to get the pistion to touch the rotor. The rear's aren't doing that. They just go in and out...

    Corey
    88K5

    [​IMG]<font color=red>Girls Like Guys In Bow Ties
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  4. jarheadk5

    jarheadk5 1/2 ton status

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    Re: Disc Brakes aren\'t Brakin!!!!! HELP

    I think that might be a master cylinder issue also. I believe disc brakes have a check valve built into the master cyl. that maintains like 10 psi or something in the lines. Again, I could be wrong. I sure hope not though; I hate giving bum scoop!

    [​IMG] Semper Maintenance!
     
  5. Chris Demartini

    Chris Demartini 1/2 ton status

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    Re: Disc Brakes aren\'t Brakin!!!!! HELP

    <font color=blue>This truly sucks... i just got a dana 60 8 lug rear today and was planning on putting on TSM disks with the Edlo calipers. The guy I bought it from said he has disks on his Dynatrac 60 rear, and the eldo calipers sucked so he got Monte Carlo front calipers and he says they're way better. he said they work better, but they don't have the hook-ups for the cable p-brake, which of course, is illegal not to have in NJ. What master cylinder would be necassary?</font color=blue>
     
  6. titanic

    titanic 1/2 ton status

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    Re: (Set ER cable first)Disc Brakes aren\'t Brakin!!!!! HELP

    You have to take the play out of the ER cable. The Caddy brakes are not self adjusting-you have to adj. the parking brake so it works first then the piston will push from that point toward the rotor. Apply parking brake and test by turning tire-if tire turns with brake set tighten the cable-on mine I had to rotate the lever arm one complete turn before the piston started touching the rotors.You might even have to remove the lever arm and turn bolt with wrench because of the built in stops on the caliper castings. Oh, one other tip, if you don't have ABS-use Dot 5 fluid ,it's pricey but it keeps the pistons from rusting if you see deep water or mud.
     
  7. titanic

    titanic 1/2 ton status

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    Re: (Pic)Disc Brakes aren\'t Brakin!!!!! HELP

    picture of a caddy calipers
     
  8. titanic

    titanic 1/2 ton status

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    Re: Disc Brakes aren\'t Brakin!!!!! HELP

    pic was too big-I had to reduce-sorry
     
  9. Waxer

    Waxer 1/2 ton status Author

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    Re: (Pic)Disc Brakes aren\'t Brakin!!!!! HELP

    where's the pic?
     
  10. 6.2 man

    6.2 man 1/2 ton status Premium Member

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    Re: Disc Brakes aren\'t Brakin!!!!! HELP

    <font color=red>You should swap the master cyl. and also the proportioning valve .</font color=red> [​IMG]
     
  11. HarryH3

    HarryH3 1 ton status Author

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    Re: Disc Brakes aren\'t Brakin!!!!! HELP

    Titanic's got the answer to your problem. You have to cycle the parking brake lever a few times to get the pads seated against the rotor. Sometimes you have to remove the nut that holds the lever in place, pull the lever forward, then remove the lever and re-index it to take up the slack.

    If you don't get the pads snugged up to the rotor, you'll never get a solid pedal. Been there.... [​IMG]

    <font color=black>HarryH3 - '75 K5</font color=black>
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  12. Shawn

    Shawn 1/2 ton status Premium Member Author

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    Re: Disc Brakes aren\'t Brakin!!!!! HELP

    Both Titanic and Harry are correct. You have to turn the parking brake lever a couple times to adjust the calipers to the rotor. The p-brake lever acts like a ratchet. I'm using the stock master and pro. valve and have great stopping power.

    Shawn
    87 K5 TSM disks
     
  13. Corey-88K5

    Corey-88K5 1/2 ton status

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    Re: Disc Brakes aren\'t Brakin!!!!! HELP

    Cool!

    Thanks guys. I'll give that a try tomorrow. I did mess with the lever a few times, but it didn't make a difference. I'll do it with the intent of getting the damn things to seat.

    Corey
    88K5

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  14. Shawn

    Shawn 1/2 ton status Premium Member Author

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    Re: Disc Brakes aren\'t Brakin!!!!! HELP

    TSM told me that sometimes you just have to keep playing with it until it catches. You want to get it real tight on the rotor.

    Shawn
     

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