1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Rear brake issue after hydroboost

Discussion in 'Brakes' started by usar17, May 21, 2019.

  1. usar17

    usar17 Full Access Member

    Posts:
    596
    Likes Received:
    17
    Joined:
    May 3, 2012
    Location:
    PA
    First Name:
    Shawn
    Truck Year:
    1985/87
    Truck Model:
    K20 Silverado
    Engine Size:
    TBI350/700r4/NP208
    4-5 years ago I swapped in the hydroboost unit from a newer Chevy commercial van. I also swapped the brake proportioner out to an aftermarket disc/disc model. I have a 14bolt rear with disc brake conversation that has the 1/2 ton front discs.

    Since doing all this I have had constant issues with my rear brakes; Fast wearing pads, easy rear lock up on rainy days, warped rotors, hot hubs, rear hop, and squeaking. Seems like I'm getting way too much pressure to the rear.

    Did I miss something? Wrong proportioned valve? I plan to swap the rear out again for a newer 2000+ 14bolt axle this summer. IDK if the newer double calibers will do better.

    Sent from my SM-G975U using Tapatalk
     
  2. climb-101

    climb-101 Full Access Member

    Posts:
    258
    Likes Received:
    271
    Joined:
    Mar 12, 2018
    Location:
    montana
    First Name:
    seth
    Truck Year:
    974
    Truck Model:
    c2 crew cab
    Engine Size:
    6.0 LS
    i just set my crew cab up with hydro brakes and i just ran new lines to the front 2 and one to the rear. In the back before the drop to the rear alxe i just added an after marker portioning valve so i can set the rears
     
    77 K20 likes this.
  3. usar17

    usar17 Full Access Member

    Posts:
    596
    Likes Received:
    17
    Joined:
    May 3, 2012
    Location:
    PA
    First Name:
    Shawn
    Truck Year:
    1985/87
    Truck Model:
    K20 Silverado
    Engine Size:
    TBI350/700r4/NP208
    I may need to add that. Thx

    Sent from my SM-G975U using Tapatalk
     
  4. dvdswan

    dvdswan Full Access Member

    Posts:
    1,626
    Likes Received:
    1,093
    Joined:
    Mar 11, 2014
    Location:
    Port Orchard, WA
    First Name:
    Dave
    Truck Year:
    1978
    Truck Model:
    K10
    Engine Size:
    350
    I could be wrong but a van may have a different proportioning valve than a truck
     
    Snoots likes this.
  5. usar17

    usar17 Full Access Member

    Posts:
    596
    Likes Received:
    17
    Joined:
    May 3, 2012
    Location:
    PA
    First Name:
    Shawn
    Truck Year:
    1985/87
    Truck Model:
    K20 Silverado
    Engine Size:
    TBI350/700r4/NP208
    I only put in the hydroboost/master cylinder. The proportioner was an aftermarket for GM trucks

    Sent from my SM-G975U using Tapatalk
     
  6. 77 K20

    77 K20 Full Access Member

    Posts:
    2,526
    Likes Received:
    1,737
    Joined:
    Nov 9, 2012
    Location:
    Montana
    First Name:
    Mike
    Truck Year:
    1977
    Truck Model:
    K20 5" lift
    Engine Size:
    HT383 fuel injected
    I did the rear brake conversion, used a disc/disc master cylinder, used a disc/disc aftemarket combo(proportional) valve and had the same problems as you. Mine would even lock up on dry pavement. I too added an adjustable valve inline with the rear brakes. It isn't perfect, but a lot better than it was before.

    [​IMG]
     
    Snoots and usar17 like this.
  7. usar17

    usar17 Full Access Member

    Posts:
    596
    Likes Received:
    17
    Joined:
    May 3, 2012
    Location:
    PA
    First Name:
    Shawn
    Truck Year:
    1985/87
    Truck Model:
    K20 Silverado
    Engine Size:
    TBI350/700r4/NP208
    Thanks! I figured I was just getting way too much pressure to the rear

    Sent from my SM-G975U using Tapatalk
     
  8. Frankenchevy

    Frankenchevy Lying Dog-Faced Pony Soldier

    Posts:
    4,896
    Likes Received:
    5,142
    Joined:
    Jan 3, 2018
    Location:
    USA
    First Name:
    Jeremy
    Truck Year:
    Square
    Truck Model:
    CUCV
    Engine Size:
    Small
    Weird, mine never locks up, but I do feel like one of my rear rotors has a slight warp. It’s been there since before swapping to a disc-disc prop valve.

    I’m going to get new rotors and rebuild my 14bff hubs with new bearings, races, etc. and hope it cures it.
     
  9. usar17

    usar17 Full Access Member

    Posts:
    596
    Likes Received:
    17
    Joined:
    May 3, 2012
    Location:
    PA
    First Name:
    Shawn
    Truck Year:
    1985/87
    Truck Model:
    K20 Silverado
    Engine Size:
    TBI350/700r4/NP208
    Adding the manual proportion valve was gold! Fixed a lot of issues as I dialed it in. Thank you!!!


    Swapping the front brake calipers to the 3/4 tons, is it as simple as just the caliper and the hose? Since I believe the banjo is different

    Sent from my SM-G975U using Tapatalk
     
  10. TPISly-C10

    TPISly-C10 Full Access Member

    Posts:
    303
    Likes Received:
    390
    Joined:
    Apr 1, 2019
    Location:
    Boucherville QC Canada
    First Name:
    Sly
    Truck Year:
    1986
    Truck Model:
    C-10 shortbox
    Engine Size:
    LQ4 6.0L
    usar17 i want to upgrade my oem 86 HB to a newer (2005) too can you tell me how you do it? since my old HB got a input master hole smaller i can't just swap the 2005 master and reservoir ( master too big wont fit small input hole from the old one) i see that newer HB got diffente mounting plate....can i swap my old mounting plate to the newer HB unit? thx for the help! :)

    HB1986.jpg

    HB2004.jpg
     
  11. climb-101

    climb-101 Full Access Member

    Posts:
    258
    Likes Received:
    271
    Joined:
    Mar 12, 2018
    Location:
    montana
    First Name:
    seth
    Truck Year:
    974
    Truck Model:
    c2 crew cab
    Engine Size:
    6.0 LS
    i pulled the plate off the newer master and made a new plate that mounts to the factory studs. I also cut the loop off the rod and threaded it since it needed to be longer to reach the stock pedal. I measured the distance from the pivot point to the mounting point for the rod on the truck i got the hydrobost from and made it the same also.
     

Share This Page