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Problems with brakes after axle swap?

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by jk3078, Feb 13, 2006.

  1. jk3078

    jk3078 1/2 ton status

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    So we just got done swapping axles in my buddys 70' chevy, 76' disc brake 3/4 ton front, 84 1 ton 14bff rear. The stock axles were drum brake 44 front, drum brake 12 bolt rear. What problems will we have if we run these axles/brakes on the stock manual brake master cylinder? Will they work all right untill we find the right parts to swap over for power brakes? Also what years, models will work for bolt in donor parts? EDIT: We did do a search before posting this tread and unless I missed somthing this should be okay but I dont like to take chances on brakes! Thanks for any info.

    Oh and hears the specs on this truck.
    70' chevy custom, fleet side, long box
    costom bumpers front and rear
    350, rebuilt q-jet, headers, 3' of 2.5'' straight pipes
    465 new clutch, 205
    3/4 ton 44 front, shaved, drive flanges
    1 ton 14bff rear, welded, shaved .75''
    4'' roughcountry, 1'' zero rates front and rear
    37x13 Boggers on 16'' white spokes
     
    Last edited: Feb 14, 2006
  2. gn4u2c

    gn4u2c 1/2 ton status

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    you need a disc brake proportion valve and you wll be fine. otherwise there going to be scary
     
  3. Scrubby

    Scrubby 1/2 ton status

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    Yeah, I think the porportioning valve will do it too.

    Moyie Springs? I grew up in Sandpoint. I love that area up there!
     
  4. jk3078

    jk3078 1/2 ton status

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    What do you mean by scary? Is there a good after market source for the prop. valve? The one off of the 76' will not work, differant line size, port numbers......

    Ya, I love it up hear to. I live 15 min. from national forest so wheeling places are real easy to get to. I can even drive my Sub-buggy around on the back roads up hear! Have you heard about the Moyie Mud Bog? :bow:
     
  5. 69TowRig

    69TowRig 1/2 ton status

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    You really want to swap in a disc/drum MC. The front resevoir is much bigger to handle the extra volume of fluid used with calipers (as opposed to the small wheel cylinders). You can get a rebuilt dirt cheap at the auto parts store.

    Wilwood makes a nice proportioning valve that is not too expensive. Summit Racing is one place that sells it.
     
  6. 70jimmy

    70jimmy 3/4 ton status Premium Member GMOTM Winner

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    Just did a similar swap. Beneficial to get a new disc master cylinder. I didn't notice your post saying anything about the rear being disc???

    New master and new booster, Wilwood adjustable proportioning valve no matter if drum or disc in rear. If rear is drum also order a residual pressure valve. Mine I think is 2 lb and blue in color. Mine has 4 wheel disc and the proportioning valve is adjusted to not allow hardly anything to go to the rear. Did a bunch of testing and adjusting to get it not to skid the rear way before the front locks up. Now I can do a 50 mph skid straight as an arrow.

    Good luck!! The difference is amazing.

    One other ?? I assumed that the 70 had power drum like mine. Don't know what kind of issues you would run into going from non power to power.

    Make sure you read up on adjusting the shaft in the booster otherwise you will cuss a lot, go thru a hell of a lot of brake fluid trying to bleed, think you have a bad master, until somebody who know what the heck they are doing helps you out. I speak from experience.
     

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