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k-30 rear proportioning valve?

Discussion in 'The Garage' started by leadfoot067, Feb 3, 2005.

  1. leadfoot067

    leadfoot067 1/2 ton status

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    gonna lift my k-30...can i remove this thing? or leave it alone and just extend the bar that connects the rear end to the valve? thoughs...suggestions...what have you done?
     
  2. AkMudr

    AkMudr 1/2 ton status

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    I cut mine off and ran a SS brake line to it. Brakes work much better, a lil more touchy but you'll adjust.

    I have a 14bFF waitin to go in and will be doin the disc swap so I will have a prop valve to put on which will tone down the sensitivity of the rear brakes
     
  3. 4x4k20

    4x4k20 1/2 ton status

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    leave it off its just made for handing a heavy load . the more rear load you have the more brake pressure you add to the rear brakes
     
  4. leadfoot067

    leadfoot067 1/2 ton status

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    well keep in mind this is my tow rig...what i was really looking for was did you remove it and did it make a big difference? this truck will haul a camper and tow my blazer on the trailer...its only getting lifted 2.5 inches...just enough for a 32x11.50x16 tire..
     
  5. u2slow

    u2slow 1/2 ton status

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    I removed the valve linkage on my Burb when I did the brakes, (cuz I changed the axle:whistle: and the bracket didn't work). Brakes work good now - that's all I care about :D

    Of course, the Burb has some weight over the back end. I would imagine in an empty pickup it could be a little touchy.

    You may not even need a lift for those tires. I ran 255/85R16's (~33") on my crewcab (w/bagged springs) and no rubbing.
     
  6. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    I took the valve off of my crew cab after I lifted it. I was going to extend the linkage but later just decided it was easier to remove it. I haven't noticed any big difference in braking, it does seem a little sharper but, as stated, you get used to it. I have not towed with mine yet but I will not hesitate to do so.
     
  7. mountainexplorer

    mountainexplorer 1/2 ton status

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    When I put 3" blocks under the rear of my '87 1-ton, I didn't do anything to the rear valve. It just extended down more, but I didn't notice much braking difference.

    I had an '85 K20 a couple years ago. It had a 4" lift and if I remember right, no one changed its factory mounting either, and it braked normally.
     
  8. leadfoot067

    leadfoot067 1/2 ton status

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    thanks doods:thumb: :thumb:
     
  9. DieselSub

    DieselSub Registered Member

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    I just finished taking mine out yesterday. I know a lot of people say just to bypass the proportioning valve and plumb the brake lines straight through.

    The risk you run is that the stock front proportioning valve (the one that splits line pressure front to back) is designed to give the back more pressure than it usually needs. The inline height sensing proportioning valve, uses the rear height as a load "guestimator" and usually reduces the rear braking pressure. If you take out this rear valve, then you might run into premature lock-up of the rear tires under heavy breaking when you're not carrying a full load (which is most of the time). This can be very dangerous, and would happen during that "once in a blue-moon" event, the exact time you really need your brakes working right :eek:

    It's a little more work, but you should either replace the front proportioning valve with one that is valved for a straight through rear brake line, or replace the rear valve with a manually adjustable one (such as a Wilwood).

    I did the latter, and put a Wilwood valve in. I used the existing break in the brake line along the frame rail, and scavenged a straight through brake line from a C20 I have for parts. Total cost was $46 ($38 for the valve, $8 for hydraulic adapters).
     
  10. sled_dog

    sled_dog 1 ton status

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    I run my 89 3/4 ton burb without the valve. The Previous owner broke a fitting off in the valve so he bypassed it with a piece of brake tube. Once in a while when I am braking really hard and down a hill my back brakes will lock up. My K5 with sticky drum syndrome was far worse than this is. So yes it makes a difference cause it gives you full brake power to the rear when there is no load, do I think its bad? nope. I bet if anything it helps woah my Suburban down, cause I will tell you what, my Suburban stops better than my 1997 2wd 3/4 ton Chevy with new brakes all around did and I haven't touched the brakes on the Burb. Sooner or later I may put a Wilwood proportioning valve back by the brake line for some adjustment. Maybe adjust it just enough that it doesn't lock up but still has good brake power. If I had disc brake upgrade in the rear I'm sure it would be an issue.
     
  11. AkMudr

    AkMudr 1/2 ton status

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    touchyness will also depend on how "tight" the rear breaks are adjusted into the drum via the break adjuster.
     
  12. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    I agree with keeping it. Those massive brakes on the 1 ton axle have way more braking ability than the unloaded rear tires can handle, but if you have a heavy load, you want that capacity back. That's why the factory put it there.


    If you are going to use it to haul, then the best approach (IMO) would be to extend the arm and keep it. Whether you can "get used to it" or not, I think it's obvious that your better off with it in a working truck.


    On my truggy I couldn't keep it hooked up since the articulation would make it nuts. So I started off by modifying the lever to make it clamp and slide for adjustment. But that was too touchy and too much trouble to adjust. So I now have a Wilwood adjustable prop from Summit for less than $40.
     
  13. AkMudr

    AkMudr 1/2 ton status

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    I will be running one once the 14boltis in place. I will say that since I bypassed the valve I am having to adjust the rear brakes more often... obviously becuase the pads are wearing faster.
     

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