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Axel upgrade brake parts

Discussion in 'The Garage' started by mkinnunen, Sep 3, 2003.

  1. mkinnunen

    mkinnunen Registered Member

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    A while back I swapped axles (C14FF and 8lug 44) from a 76 truck to my 73 blazer. My braking power went way down but his went way up. What part didn't I switch that I needed.

    Also I'm having trouble deciding if I should put in a D60 or not. I broke the R&P in the 44 (from stupidity) but the rest of it has not broken. If I do the swap again to D60 what else will I need to watch out for.

    I have 44" boogers on 16.5X14 (3.5 BS I think) wheels

    Oh, and I just installed a BB454.

    Thanks,

    Michael
     
  2. cegusman

    cegusman 3/4 ton status

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    You will need a 60 with those boggers
     
  3. mkinnunen

    mkinnunen Registered Member

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    So are you saying that a D44 and 39" boggers is ok but 44's are bad?
     
  4. Shaggy

    Shaggy 3/4 ton status

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    <font color="green"> D44 and pretty much anything 38 or bigger is bad news. 44" Boggers and a big block are waaaay out. </font>
     
  5. mkinnunen

    mkinnunen Registered Member

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    Yes I know what must be done but:

    Is the dia of the housing much bigger?
    Will my rims fit without grinding?

    I don't want any more lift as I only clear my garage by about 1/4 inch.
    Grinding on the caliper just does not seem right so it is not an option.

    And what about the three other brake parts; booster, master clyinder, an pvalve. which one did I neglect to change with the swap?
     
  6. 4x4Freak

    4x4Freak 1/2 ton status

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    Have you pulled the drums on the rear axle to see what kind of shape the shoes, etc. are in? I'm betting that's probably where your problem is. My brakes on my 79 with 3/4 tons work great with the stock 1/2 ton brake system. It might also be possible that you still have some air in the lines.

    The 16.5" rims should work fine with the D60. However, the D60 will also give you about 1" of lift from what I understand.
     
  7. mkinnunen

    mkinnunen Registered Member

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    Just before I did the swap the guy had just done $1000 /forums/images/graemlins/eek.gif worth of brake work, including the new drums rotors and pads. He was a buddy of mine and decided to sell the truck so we swapped axles. the braking was noticed imeditally after the swap, I mead during the around the block test drive. His were very "twitchy" and mine sucked. Both trucks brake lines were suction bled well.

    I saw a post for # 1257225 P valve its for a 79-94 would fix it. its $79.

    My axles are from a 76 3/4T and the dealer said that's P valve # is 1257203 it costs $100.

    I don't know witch one I should try.

    1" of lift that sucks I won't be able to just "drive" into my garage. Maybe adding a wintch (hydroulic) will drop the front an inch. I really want to be able to "drive in"
     
  8. mkinnunen

    mkinnunen Registered Member

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    Bump.

    Come on guys someone must know what part to use.
     
  9. Blazer79

    Blazer79 1/2 ton status

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    I swapped a 14bolt and a Dana 60 into my Blazer. First I was disappointed because of the soft pedal and bad braking. Last week I powerbled the system again and my brakes are as good as with the original axles. I'm still using the same master cylinder and prop. valve.

    I think you just might have some air in the system. It is a pain to bleed it. I used 3 liters to bleed it and I think I still might have some air left.
     
  10. 4x4Freak

    4x4Freak 1/2 ton status

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    Maybe the rear brake shoes arent adjusted right. It might be worth checking into before throwing a bunch of money at it.

    If his brakes worked better after putting the 1/2 tons in, then most likely something isnt right with the brakes on the 3/4 tons. The 3/4 tons should be a lot better. I noticed a big difference with just swapping the front axle into my truck.
     
  11. DBLAZER

    DBLAZER 1/2 ton status

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    That 44 is no where near enough axel for what you are doin. A 60 is more along the line. BUT you can still break stuff with that bigblock and the 44's.
     
  12. ntsqd

    ntsqd 1/2 ton status

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    Either stock prop valve will be out to lunch because of the change in vehicle weight and difference in wheelbase. Dump the stock parts and go to an aftermarket adjustable prop vale. You might also consider an LBS instead of, or in addition to the prop valve.

    You also should check that the shuttle valve in the stock combo valve hasn't shifted thereby partly or totally shutting off pressure to either the front or rear brakes. Did you also swap master cylinders ? There could be a difference on the bore diameter.
     
  13. mkinnunen

    mkinnunen Registered Member

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    Re: Axel upgrade brake parts. Update.

    So, I just put on a 1ton m/c bled everything and adjusted back the brakes, and that changed everything. Now I can lock up the rear with very heavy pressure but the front is "touchy" meaning that very light pressure will activate the front allot. I can control the front with foot pressure but there is absolutely no feedback and minimal travel.

    I think I'm looking at a new p valve. it's $100 from the dealer. Will an after market one have the feature of the "fronts don't engage until rear pressure is detected". I kinda think thats what is wrong with mine, it is set for less (1/2 ton) rear pressure and I'm engageing the front brakes too soon too heavy.

    Any other suggestions?

    Thanks.
     
  14. ntsqd

    ntsqd 1/2 ton status

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    Re: Axel upgrade brake parts. Update.

    With a slow speed stop which brake works the hardest isn't an issue (up to the point of the available traction). It's the high speed stops that are important to brake balance. When you mash the brake pedal @ 60 mph a lot of the truck's weight shifts onto the front axle. Therefore the front brakes are doing most of the work. If you mash the pedal and the rears lock up first then you have too much rear brake pressure. If you lock up the fronts first then you have too LITTLE rear pressure. Ideally the rears should lock up just barely b4 the fronts do.

    Which does what will depend on how you're loaded. With a heavy load in the back you can stand more rear brake pressure because less weight shifts under braking. If your loading varies a lot then set the prop valve for the lightest loading. You'll give away some braking when heavily loaded, but that's better than the rear end passing you on the outside when lightly loaded.

    Late second gen Subs (&amp; maybe others too) have an LSPV (Load Sensing Proportioning Valve) on them. Not sure how well they work, or if you could adapt one but it might be worth looking into if your loadings do vary a lot.
     
  15. mkinnunen

    mkinnunen Registered Member

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    Re: Axel upgrade brake parts. Update.

    Yesterday I had problems with the front brakes dragging and heating up almost to full lock, so off comes the M/C. I put the orginal one back on and I now have no brakes. I have pedal with the truck off but when I start it, the pedal goes to the floor. I have another 1/2 ton booster So I may put it in to see what happends.

    I'm really starting to not like brakes.
     
  16. mkinnunen

    mkinnunen Registered Member

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    Re: Axel upgrade brake parts. Update.

    I put on the other booster and now I have brakes, spongy and in need of a good bleed but much diffrent the they were. I didn't break open any lines to change the booster so I can only assume the other one was bad. At this point I have no clue and will just wait until I get the M/C, booster, and p valve for a 76 1 ton install them all at the same time and see what happends. /forums/images/graemlins/confused.gif
     

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