Rear Brake Proportioning Valve

[bushpig]

If I've installed OME heavy duty springs all round (about 2" lift), why can't I just slide the brake proportioning valve down & retighten when it is in permanent contact with the load spring. Surely this would give the same pressure as if there was a really heavy load.
Would the ABS system not come into play in case the rear wheels wanted to jam?

Old bushpig

'94 HDJ80 1HD-T

The job is not done until blood has flowed freely.

 

[topend yobbo]

4mm down seems to be the go .A bit written on this subject recently.

 

[e9999]

yes, there was a thread a couple of weeks ago or so on this, with pics.
I just don't get why some guys will futz around with brackets etc on the axle when you can just move the valve body down a tad, takes all of 5 mins....

 

[Rich]

ABS is not a substitute for brake pressure porportioning. ABS only kicks in after a wheel begins to lock. In contrast, the proporitioning valve is always "in action", regardless of whether wheel lockup is happening or not.

 

[XXXR]

yes, there was a thread a couple of weeks ago or so on this, with pics.
I just don't get why some guys will futz around with brackets etc on the axle when you can just move the valve body down a tad, takes all of 5 mins....

You're right, but taking a few minutes and building the bracket that mimicked the original location to the mm, took the guessing part out for me. (short of doing pressure testing) Didn't feel like "gravel testing" my weekend away, as just moving the body down isn't as accurate in my view. Either one works and really takes about the same amount of time. My 2 cents.

 

[Bearcat80]

I thought i had it right by moving the valve body down by 4mm or so, but when it snowed I couldn't stop well, too much ABS. PLayed with it a bit (I'm good at that...) till it stopped best in the rare snow we have here. It seems mine likes about 3mm down from stock. We'll wait & see how the brake wear goes. If you move it down all the way, you won't stop right and you will burn through the pads really quick.

 

[SUMOTOY]

I thought i had it right by moving the valve body down by 4mm or so, but when it snowed I couldn't stop well, too much ABS. PLayed with it a bit (I'm good at that...) till it stopped best in the rare snow we have here. It seems mine likes about 3mm down from stock. We'll wait & see how the brake wear goes. If you move it down all the way, you won't stop right and you will burn through the pads really quick.

This placement and testing is pretty key, btdt. If you have too much braking force in the back, you can lose control very easily, especially in the icy conditions where ABS algorithyms aren't fast enough. Proportioning on all vehicles is done so that the fronts lock before the rears. Just about all ABS systems before 1998-1999 use what's referred to as "select low" principle applied to the rear circuit (3, 4 channel). This means that both rear wheels get the same braking force as the one with the most slip (least grip). This is also to prevent loss of control at the rear.

Make sure you test any setting modification in slippery conditions to make sure you don't have premature rear lockup. Amazingly enough, that rear Prop valve looks kinda cheezy, but it's very sensitive to ride height vs effective rear braking and control.

Scott Justusson
'94 FZJ80 supercharged airbag inserts x 4

 

[bushpig]

Thanks for all the input--------I feel a lot more educated now.

Bushpig
'94 HDJ80 1HD-T