Brake Proportioning Valve Adjustment

[Robo]

Just pulled bias spring bracket off diff to make and install bracket extension for 2" lift.
Noticed the bracket has adjustable slotted hole to pivot bracket, adjust the angle of bracket and spring tension.
Gave it a tweak, "less than 1/4 the adjustment available", to increase spring tension.
Now Mav sits flat when braking, where she used to nose dive abit.
Sound good so far ??.

My worry is now to much extra rear brake pressure?.

Mav has approx 2" lift but NO ext bracket fitted yet.
Tried straight line hard braking with no rear lock on a dry Rd.
But what about Round-abouts and off camber ?.
advice/comments please.
I first posted this on another thread,comments here now, so not to hijack the other thread please.
cheers

[Robo]

Ok made a extension for bias bracket to suit 2".
To be honest I cant tell the diff between it or the adjusted setting .
Think for 2" it would be easyer to simply tweak the arm a little simply by loosening bolts a tilt bracket away from bias valve till your happy.
And leave the ext bracket for 2"> +.
Bracket was a waste of time for < 2".
M2CW

[04OFF]

On my GU wagon, (also 2'' lift) i found no real difference in road braking and stopping in the adjusted positions as you describe, the brake pedal felt a touch firmer with more rear bias, but thats all.

What i did notice, was when i did a beach trip, if i braked hard at some speed, such as on Fraser Island (80k speed limit), slowing down rapidly on "hard" sand for a washout etc, it felt like the rear of the car wanted to slide and overtake the front, this felt quite un-comfortable.



I ended up setting the bias valve so the valve plunger/piston pin, was at half travel (ignore the arm and spring, look at the actual valve pin), i did this when the car sat level and flat , full tanks of fuel, and all the stuff inside that i normally carry on a average day to day basis,( so not loaded with camping gear etc)

Since adjusting the valve like this, i did many beach trips with different loads (fully packed, and empty) not once did the car feel un-easy braking on the sand again.



Road manners still remaind unchanged, but i guess i thought, the way i had it before, in emergency braking on a wet road, the car may have also NOT stopped 100% straight ?

[Robo]

I agree with the above ideas of Rd and sand, brake sensitivity.
Wear and tear would also come into play.
Really think 2" isn't enough for the std setting to be out by all that much.
The bias bracket arm is factory made to be adjustable.
2" seems to be within it's range of adjustment.
I to noticed, once I adjusted bracket away from valve that the peddle was firmer.
Luckily for me when I did it the first time Rd was wet so I gave it a good test hard braking in a straight line going up & down a slight hill and it seemed settled.
Seeing as no-one responded to my first post on subject I thought I'd give the bracket ext a whirl.
Conclude for 2" lift bracket ext waste of time.
I had no problem since first post 28/7/12 to date.

2" lift constant load may have different manners , as it would not settle like a more tame lift and the bracket in this instance may be worth trying.
I had 2" constant load before & it was clearly sitting higher than 2" LPG springs that are on car at the moment.
LPG 40mm lower front and 20mm lower rear from memory.
2" constant load is more like a 3" lift.

The ext in theory sounds like good practice, actually may not be needed depending on setup.
I conclude this as Nissan developed the bias valve settings to be gentle on braking as it works it a constantly changing world with axle movement and this alone affect braking ,you don't want your vehicle spinning out of control while braking simply because you hit a bump/wet Rd or came across some loose sand.
Cheers.

HAPPY FATHERS DAY GENTS.

[Silver]

thanks for the info. I have just installed a second hand 2" lift from a GU into the Mav. The rears are extra heavy duty TJMs. For some reason I didn't take before measurements so I don't have an accurate measure of the lift.

Driving it the pedal feels firmer. I will try the the piston adjustment before altering the bracket.

Thanks again!

[Robo]

On my GU wagon, (also 2'' lift) i found no real difference in road braking and stopping in the adjusted positions as you describe, the brake pedal felt a touch firmer with more rear bias, but thats all.

What i did notice, was when i did a beach trip, if i braked hard at some speed, such as on Fraser Island (80k speed limit), slowing down rapidly on "hard" sand for a washout etc, it felt like the rear of the car wanted to slide and overtake the front, this felt quite un-comfortable.



I ended up setting the bias valve so the valve plunger/piston pin, was at half travel (ignore the arm and spring, look at the actual valve pin), i did this when the car sat level and flat , full tanks of fuel, and all the stuff inside that i normally carry on a average day to day basis,( so not loaded with camping gear etc)

Since adjusting the valve like this, i did many beach trips with different loads (fully packed, and empty) not once did the car feel un-easy braking on the sand again.



Road manners still remaind unchanged, but i guess i thought, the way i had it before, in emergency braking on a wet road, the car may have also NOT stopped 100% straight ?

Do you recon the actual amount of rear bias was increased more so by adjusting the bias pin bolt, rather than adjusting the arm it self ?.
eg-- arm oem adjustment wasn't enough.