Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

My brakes lock up!!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BANKO, Jan 5, 2002.

  1. BANKO

    BANKO Registered Member

    Joined:
    Nov 21, 2001
    Posts:
    18
    Likes Received:
    0
    Location:
    Sunnyvale, CA
    I just finished installing a 6" lift and 35x14.50 SSRs on my '85 K20. I also turned the front rotors and added need brake shoes. I noticed my truck has a tendency to lock up and slide especially the rear drums. I first noticed this after driving around in the rain on slick roads but it happens on dry roads as well. My truck can't stop for anything. Do I need an adjustable proportioning valve to adjust the line pressure to the rear drums to a very small amount? I need suggestions from the guys on this board who drive rigs with large tires.

    Thanks, BANKO
     
  2. 95 Silverado

    95 Silverado 1/2 ton status

    Joined:
    Nov 9, 2001
    Posts:
    467
    Likes Received:
    0
    Location:
    Central PA
    do the front brakes seem like they are working at all? check your lines and hoses, be sure you didn't pinch or kink a front brake line or hose when doing the lift. you didn't change the weight distribution or brake system on the truck, you shouldn't need a new proportioning valve. were the brakes ok before you did the lift?

    '95 Chevy Silverado 1500
    5.7 V8-NV4500- 3.73 rears
    See My Toys: <a target="_blank" href=http://community.webshots.com/user/wdb172454>http://community.webshots.com/user/wdb172454</a>
     
  3. Storm Trooper

    Storm Trooper 1/2 ton status GMOTM Winner

    Joined:
    Nov 24, 2000
    Posts:
    4,640
    Likes Received:
    1
    Location:
    Dillon Colorado, Hang'in in the mountains. Renting
    Double check everything you did.
    Are you sure they didn't turn the front rotors beyond spec's?
    Bleed the front brakes and make sure the caliper are working properly and you didn't get any grease on them.
    Just a few ideas....

    [​IMG]<font color=red>[/b]"Rid'in HigH in my K5"[​IMG]
    ....[​IMG]<font color=blue>[/b]"8" Lift -<font color=purple>38.5's"[​IMG]....
     
  4. HarryH3

    HarryH3 1 ton status Author

    Joined:
    May 31, 2000
    Posts:
    10,384
    Likes Received:
    2
    Location:
    Georgetown, TX
    Are you sure that your brakes are properly bled, so there is NO air in the lines? Once you have a firm pedal, then check out how well the braking works. Drum brakes will grab when they get oil on them, so make sure that you don't have a leaking seal in the back.

    Keep in mind that your front brakes do 80% of the braking, so if they aren't working well then the truck won't stop wortha darn and the rear brakes will tend to lock up.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
    It's a great day to be alive...
     
  5. k5'er

    k5'er Registered Member

    Joined:
    Nov 29, 2001
    Posts:
    92
    Likes Received:
    0
    Location:
    PA
    hey man make sure your rear brakes are adjusted properly. if they're not then they will lock up like that. take the rear wheels off and turn the drum. if it sticks real bad then they need to be adjusted. a couple clicks. enough to spin about 1 or 2 turns. hope that helps!

    When i die,bury me upside down so the world can kiss my a@# goodbye! lol thought that was a hoot!
     
  6. shawnboy

    shawnboy 1/2 ton status

    Joined:
    Jun 22, 2001
    Posts:
    468
    Likes Received:
    0
    Location:
    Toronto, Canada, eh.
    you might want to check for oil contamination from a leaky axle seal or a leaky wheel cylinder.
    Shawnboy.

    <font color=red>If you are having too much fun it's probably illegal.</font color=red>
     
  7. BANKO

    BANKO Registered Member

    Joined:
    Nov 21, 2001
    Posts:
    18
    Likes Received:
    0
    Location:
    Sunnyvale, CA
    Thanks for all the advice, here is some more info for you guys.

    The brake lines were changed to stainless steel extended lines and the brakes were bled properly resulting a firm pedal. The rotors were not turned beyond specs because there was another .010 per rotor that could be taken off. I made sure the rotors were wiped clean with solvent prior to installing the pads on the front to prevent any grease contamination. I pulled the rear drums off after I did the lift and both sides are dry so I don't think there are leaks coming from my axles.

    I know the front disks do a majority of the stopping but I din't expect the rear to lock up under panic/quick stopping. I realize the larger tires have more rotational interia compared to the small radials I previously had on the truck. I just thought the brake fluid pressure might need to be adjusted for the big tires. Naturally the truck is lighter in the rear if I'm not towing or hauling heavy loads. Maybe I should try to put some weight over the rear axle and see if this prevents my truck from skidding the rear tires when I need to stop quickly.

    Thanks for your help.
     
  8. 84_Chevy_K10

    84_Chevy_K10 Banned

    Joined:
    May 30, 2001
    Posts:
    17,669
    Likes Received:
    0
    Location:
    IL, USA
    It's very common for 3/4 ton trucks to lock the back tires without a load--but it should still stop good if everything is in good condition. You just don't hit the pedal as hard and it stops. :smile:

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  9. talison79

    talison79 1/2 ton status

    Joined:
    Feb 25, 2000
    Posts:
    110
    Likes Received:
    0
    Location:
    Tucker, Georgia
    Mine did the same thing after putting in a new brake system. It ended up being the proportioning valve . I took everything apart and cleaned out 22 years of crud that had accumulated inside, put it all back together, and viola, front brakes that actually work. Or you can drop $75 for a new one, but there really isn't much to it, just check all the seals, and make sure their in good shape.
    Hope this helps.
    Talison79
     
  10. prjt_blzr

    prjt_blzr 1/2 ton status

    Joined:
    Mar 4, 2001
    Posts:
    352
    Likes Received:
    0
    Location:
    COS, CO
    Did your truck have the rear proprortioning valve?? If you disconnected or did not relocate the brackets properly, you could have over bias the rear brakes.

    If this is the case get a new bushing from GM and measure the height change on the truck. Reposition the lever to the same height that it would be in if it was not lifted.
     
  11. sinchphoto

    sinchphoto 1/2 ton status

    Joined:
    Mar 7, 2000
    Posts:
    366
    Likes Received:
    0
    Location:
    Southern California
    whats a proportioning valve. ive heard that term before but i have no idea what it is. Maybe thats part of MY brake problem. thanks
     

Share This Page