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Brake line reduction instead of a proportioning vlave

Discussion in 'The Garage' started by BlitzK5, Oct 21, 2005.

  1. BlitzK5

    BlitzK5 1/2 ton status

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    Could you use a smaller brake line like 3/16" to supply a 14bolt converted to disc brakes using 1/2 ton brake calipers instead of installing a proportioning valve to prevent the rear brakes from locking up.
     
  2. monster man

    monster man 1/2 ton status

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    I could be off, but I think a larger line would have that effect since the line pressures would be lower than with a smaller line. Is that wrong?
     
  3. divorced

    divorced 3/4 ton status

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    I doubt the size of the brake line would have any noticable effect on the braking power. Are you having problems with the rear locking up?
     
  4. BlitzK5

    BlitzK5 1/2 ton status

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    Well by decreasing the line there will be more friction (line loss) which will decrease the output pressure however there will be a greater increase in the pressure before this line(back pressure). By going to a bigger line you will need less pressure to flow a given amount of fluid. By going to a smaller line you will need more pressure to flow that same out of fluid. So in this case by reducing the line size, less pressure and fluid will be provide to the rear brake for any given amount of braking. As to the ratio between the front and back I don't now unless you installed gages of course. I think im correct about all this theory. Atleast thats how it works for water.
     
  5. BozoWise

    BozoWise 1/2 ton status

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  6. BlitzK5

    BlitzK5 1/2 ton status

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    Not yet beacuse I haven't driven it yet since I converted my just recently installed 14 bolt FF into my blazer. It just seems like everyone else that has have been installing proportiong valves to reduce the pressure applied to the rear to prevent to rear from locking up. Im assuming that it will happen to me.
     
  7. divorced

    divorced 3/4 ton status

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    Wow, that sure is technical. I always though that brake lines were just a conduit used to transfer brake fluid from the master cylinder to the calipers. :confused:

    It seems to me thought that the master cylinder wouldn't care what size the line is. Fluid in = fluid out. I don't see how the amount of fluid transfered or the pressure would be any different.
     
  8. divorced

    divorced 3/4 ton status

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    On my K20 and my bud's K5 we just put on the disc brake and ran it - no extra prop valve was needed.
     
  9. BlitzK5

    BlitzK5 1/2 ton status

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    N0t really, I picked up a 100" line of 3/16" brake line for about $7. I was just going to run it from the coupling thats about halfway down the truck and use a reducer. I just wanted to see if anybody else has tryed it on here.
     
  10. BlitzK5

    BlitzK5 1/2 ton status

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    ok well I need to replace my rear brake cable anyways since I cant get the old rubber rear brake line off to put on a new stainless steel one on so I have to brake it off. I just figured I would try to kill to birds with one stone. Maybe I will just replace the line with normal stuff and see if there is any problems first. Thanks
     
  11. theperfectgarage

    theperfectgarage 1/2 ton status

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    I put discs on my 14 bolt ff with the factory prop. valve from a 84 k10 and it works great. Did I get lucky somehow?.
     

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