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Rear brake load sensing valve question


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The previous owner of my '87 MJ put a 2" lift on it.  He turned the lever all the way up (almost straight up vertical) and tied it there with chicken wire.  It will lock the rear brakes easily in a panic stop on dry pavement, so I drive in the wet like a grandma.  If I snip the chicken wire and let the lever go down to the normal horizontal position, will that be okay with a brake test before and after I make the change?  I've read in threads I searched that it didn't take much travel of the lever to increase pressure.  I wonder what effect being all the way up has had on it. 

 

 

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Yep. I've experimented with mine a bit, and I've found the best braking is when the lever is above horizontal. The lever should not be in the full up or below the horizontal with the ground positions.

 

I used a zip tie, cheap, easy, and won't rust LOL --> http://comancheclub.com/topic/45617-brake-load-sensing-valve-quick-fix/

 

p.s. I wish people that don't know what they're doing wouldn't touch the darn lever. Leave it alone unless it breaks. And if it does, use a zip tie. As you can tell braking performance suffers if someone messes with it and does not understand the thing.

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When the truck is empty the lever should be level with the ground. As the rear of the truck squats the lever is pushed up giving more pressure to the rear brakes. Having the lever wired pointing straight up would make it think you have a very heavy load in the truck and max out the rear brake pressure causing the tires to lock up. It should have been wired level to tge ground or reconected with the correct length rod.

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Thanks for the replies!  I'll lenghthen the wire or find some zip ties to hold it horizontal then test on dry pavement.  I never load the rearend, so I don't need the lever to function as designed.  I had a set of heavier and meatier '93 ZJ Laredo wheels and 235 tires on it until just recently, and the stock '87 10-spoke wheels and cheaper brand tires weigh less.  (acceleration was peppier with the swap!), so i know the rears will lock up even easier if I don't alter it from the current redneck setup. 

 

Does anyone think this valve needs to have the rear brakes bled after it's been in the WAY up position? 

 

Edit:

If the valve dies after I mess with it due to the extreme position it's been in, does anyone know what pressure it defaults to?  Low or high? 

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Brake bleeding won't hurt anything, but as long as your pedal feels good and you've got good braking performance, it's probably not needed. The valve shouldn't be capable of introducing air into the system without other problems going up.

 

 

p.s. I wish people that don't know what they're doing wouldn't touch the darn lever. Leave it alone unless it breaks. And if it does, use a zip tie. As you can tell braking performance suffers if someone messes with it and does not understand the thing.

 

Sure would make life easier for the rest of us if people didn't mess with things when they didn't know what they were doing. Could also be they thought they were adjusting it properly, though...

 

My Lada's got a similar setup to this valve on it, only much more complex... looks like it might balance left/right(!) a bit as well. But I just failed the Sask inspection in part due to the master cylinders being "seized". I can still lock up the rear brakes in a panic stop, though, so now I'm looking at that mess going "uh-oh".

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I made one for a $10 out of some all-thread, threaded eyes and plastic plumbing bushings. The thread lets me adjust the bias, too:

 

 

 

 

:thumbsup:  :clapping:

 

Or if he wants to go the extra yard you can buy/fab one that is close to factory,,,,,,IMHO if your box still works set it up correctly and let it work for you

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Thanks for all of the replies.  I lowered it down to horizontal, and no more rear lock up on dry pavement.  It was the right rear that would lock easily under hard braking.  It is supposed to rain here tomorrow, so I will get to test it in the wet, too. 

 

I could tell the overall braking was reduced a little, but having the rear end come loose is worse as far as I am concerned. 

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When the truck is empty the lever should be level with the ground. As the rear of the truck squats the lever is pushed up giving more pressure to the rear brakes. Having the lever wired pointing straight up would make it think you have a very heavy load in the truck and max out the rear brake pressure causing the tires to lock up. It should have been wired level to tge ground or reconected with the correct length rod.

 

Good info. I also used all-thread and joints to make a new rod. I had to adapt it to my after market cover, and work with a 6" lift. I was wondering what angle the lever should be when un-loaded. I did suspect level.

 

Thanks  

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Tested in the wet today. Front brakes lock first. I'm good to go for now. I'll experiment some more when I have more time.

 

If I can get repeatable results for given lever positions, I may rig up something where I can quickly switch between 2 or 3 positions.

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