Brake proportioning valve adjustment

Finally got my longer brake bias bracket in but have no idea what the correct adjustments are?

Is the spring supposed to be tight, closing the valve or should it be a little looser so the valve is open?

Hope that makes sence lol ??

Im thinking the spring should should be tight so when weight is added to the tray, the spring will loosen and open the valve. If its open, its only going to stay open when the tray is loaded isnt it?

Pretty much no point in even having it if thats the case or am I missing the point?

Cheers for any advice!

I think the biasing point is set up as a distance "measurement" when the vehicle is stationary and level no load (spose it would be hard to do if it was moving eh) ROFL

I used to have the distance written down in my old manual but I gave it to the dude who bought the truck. I'll try and find it again but here's hoping someoone else knows off th etop of their head

If you're fitting the bracket that raises the bias valve attachment point at the diff end then you shouldn't need to adjust the bias valve. Just raise the attachment point the same amount as the suspension lift and it should be very close to right - assuming the bias valve was adjusted correctly before the lift.

Tony

Yes thats the one I am talking about. I didnt check how it sat before doing the lift but there was not much tension on the spring so the valve was open (after the lift). Im pretty sure this allows full power to the rear brakes, never had them lock up so I will probably just leave it like it was but would still hope to get confirmation

Cheers

You can find a very well explained purpose and the adjustments required for a proportioning valve after a lift kit and it also comes with pictures.

http://www.nissanpatrol.com.au/forum...ence-Document.

Sub quote from the document Message me and I can provide more on the document if you want.

"DO NOT touch the allen head screw on the valve these are pre-set from the factory. The spring needs to measure between 175mm and 178mm end to end of the spring not just the coils. Some will tell you that the spring is self adjusting, meaning that when you lift the vehicle the spring will stay at the correct length, this in fact it actually does with a 2” lift. What changes is the ability of the spring to provide the correct tension at the correct angle. As for higher lifts check out the picture in this section of a GU4 that has a 5” lift, the spring is almost vertical to the BPV lever.

Thanks robbo!

Hi GUte
I fitted a GVM upgrade and then air bags, the lift was adjusted for but after fitting the air bage there was no rear brakes (as the air bage stop any rear end droop due to load) so when I fit the camper I slip the spring off
(the camper and fuel/water is around 950 kg loaded so need full rear brakes)
So just be aware when and if you fit load assist air bags they have the effect of deducing the rear brake bias
Hope all this makes sense
Joe

Hi again
when the spring is streached the proportioning valve is open and minimum rear brake pressure
when it is loose maximum rear break pressure!
thats why it is normaly set mid way to give higher pressure on loading up and lower pressure when loose (unloaded or heavy braking and the back lifts)
Joe

A test I did yesterday
Chock front wheels, sit back axel on jack stands with wheels off ground. Make sure your in 2WD.
Start engine put in gear, in my case 2nd as its a manual. Release clutch now the rear wheels are spinning.
Stand on brakes to stall engine.
Mine didnt stall so the valve was stopping the rear brakes from being effective.
I want full pressure to the rear so fitted a small bungee to the lever on the valve and redid the test, stalled even at 2000rpm.
Adjusted how I wanted and now have better braking performance. The bungee has some give in it not to damage the valve.
I took the spring completely off.
Hope that makes sense.
JoeG taking the spring off and doing nothing else gives no rear brakes from my experience.
Macca

Done a few K's on all sorts of terrain and alot happier wth the braking now.
I'm thinking I will leave it like this as it stops better on the black where a front would lock up.
The spot this happens is off camber down hill in the wet approaching a roundabout.
Scared the cactus out of me the first time it happened. Doesnt do it now.
Macca

I havent read all the other posts but my understanding was the brake proportioning bracket was to be matched with the appropriate lift. Mine was sold to me as part of my 4" lift and have had no issues at all and it does seem to sit 100mm higher than standard (4")

Hi Growlers
Yes the lever arm needs to be lenghtened when you fit longer springs
The issue I was refering to is when you fit air bags and raise the loaded height
If you raise the rear (back to unloaded height to remove the sag) when loaded with the air bags the proportioning valve then bleeds off brake pressure as the
Valve thinks the vehicle is unloaded.
Of course if you have ABS no problem as no load sensing valve, however one more thing to go wrong
Joe

is it the same deal with leaf springs?---i have a couple of extra helper springs in my ute,and the rear brakes seem very toucy when unloaded !

i meant touchey as in easily grabbed

this is from the service manual

Thanks Joe will have a look at that, have you jacked the rear axel and tested the brake effectivness?
Be interested in your thoughts.
Was told to do this on my last 4B and all of a sudden I had brakes again. Airbags had just been fitted and it thought the tray was empty as it sat higher.
Good luck mate
Macca

Hi Macca
Yes jacked up the chassis then slight load on diff to simulate heavy braking
then tried 2000rpm and spring on and off.
it stalled every time
tried at 3000rpm same story always stalls
what i did discover is that the suspension lift did not include lengthening the arms for the rear sway bar and it bottoms out before the shocks- so will pull the arms off and lengthen 50 mm to match the lift- this should then make the sway bar work better if the bar is normally parallel to the road. the rain has finally stopped so can start on out side jobs
Joe

I'm trying to adjust my brake bias valve... have clicked that link which takes me to another post which has a link to a PDF file which I can't seem to access. What's the go?

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Originally Posted by damaverick

I'm trying to adjust my brake bias valve... have clicked that link which takes me to another post which has a link to a PDF file which I can't seem to access. What's the go?

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Not sure why it's not working mate ... were you using the PC or tapatalk on a phone/iPad?

I just opened it from my phone an it worked ...

Bumped this up so i can tinker tomorrow.

When I had the GVM upgrade part of that involved the brake bias being changed. Surprisingly (to me) this involved putting more bias to the rear brakes than standard, with taller front springs (as opposed to heavier duty front springs) ensuring that the vehicle remains level under heavy braking.

I just went out and measured my spring and have also disconnect it so i can test something tomorrow and see if there is any difference. ..

Failing this round of tinkering it will go to jpc for some work as i am sick of the brakes not working properly.

what troubles are you having with your brakes mate?

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Originally Posted by billyj

what troubles are you having with your brakes mate?

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Just feel like things are not working as they should and the wear in the back brakes has been very very minimal.

I disconnect the spring off the bias valve and did some very hard braking and i am pretty sure there is a big improvement.

One way i will know for sure is in the morning when it is still dark i head off to work and at the end of my street i have to brake a bit harder if traffic is coming past and twice last week i thought i was not going to stop in time.

I have heavy duty bendix brake pads and good quality brake discs and extended braided brake lines..

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Originally Posted by Bloodyaussie

Just feel like things are not working as they should and the wear in the back brakes has been very very minimal.

I disconnect the spring off the bias valve and did some very hard braking and i am pretty sure there is a big improvement.

One way i will know for sure is in the morning when it is still dark i head off to work and at the end of my street i have to brake a bit harder if traffic is coming past and twice last week i thought i was not going to stop in time.

I have heavy duty bendix brake pads and good quality brake discs and extended braided brake lines..

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What's it like when you brake in the gravel or something slipery? If the brake preprotioning valve isn't working properly should be able to feel one end doing most of the work and locking up fairly easy.

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Originally Posted by Rossco

What's it like when you brake in the gravel or something slipery? If the brake preprotioning valve isn't working properly should be able to feel one end doing most of the work and locking up fairly easy.

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On gravel the fronts would lock up but that was after i did a lot of work to get it to that point... before all the work i did i nearly plowed into a car in front a few times.. part of my problem was vacuum but that has recently been sorted.

Really struggling with this at the moment. Brakes have been virtually non existant for months now and I'm losing the plot.
Front end locks up easy, brakes spongy as anything (eventually goes to the floor), and complete bugger all stopping power.

Really desperate for advice at the moment.

Is there supposed to be a gap between stopper bolt and the lever ? Mine has almost an inch.

Sent from my HUAWEI RIO-L02 using Tapatalk

Have you bled the LPV? There is a bleed nipple on it and it is a bit difficult to get to. I had much the same problem as yours some time ago. I bled the LPV and a fair bit of dark coloured muck came out of it. Obviously it had not been bled in a long time - if ever. That improved my braking by a fair amount but it was still not perfect. I replaced the LPV, re bled the system and the brakes came up perfect. I think the muck in the valve seized it up.

Might help if you tell us what you have already done...

Am I right in assuming that when you go higher in lift without the bracket, you will lose brakes at the rear? Or will braking at the rear increase?

I currently have a 3" lift in mine. Was told by the reputable 4x4 shop when it was put in that it's not need for a lift of this height, and as such have no bracket. Braking isn't bad, but as with anything, if it can be improved, why not.

Lift is as the same as when I've got it and brakes only stopped working when I fitted new pads and rotors (x4).

Thanks billsgu and yes I've have bled all corners Including the lsv more than once. Fluid is solid all round.

However I can stall the engine if I push that bolt above the stopper bolt in and hit the brakes. (Lengthening the spring) though I thought it was supposed to be the other way around ?



Sent from my HUAWEI RIO-L02 using Tapatalk

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Originally Posted by Throbbinhood

Am I right in assuming that when you go higher in lift without the bracket, you will lose brakes at the rear? Or will braking at the rear increase?

I currently have a 3" lift in mine. Was told by the reputable 4x4 shop when it was put in that it's not need for a lift of this height, and as such have no bracket. Braking isn't bad, but as with anything, if it can be improved, why not.

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Bump, anyone know the answer to this?

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Originally Posted by Throbbinhood

Bump, anyone know the answer to this?

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Yep - that's the way I understand it. If you put more weight in the back - the back goes down - the LPV applies more bias to the rear brakes. If you put a lift in - there is more clearance between the chassis and the rear diff - so it would be the same as the Patrol being unloaded as far as brake bias is concerned - therefore you need an extension on the bracket to bring adjustment back to the norm.

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Originally Posted by BillsGU

Yep - that's the way I understand it. If you put more weight in the back - the back goes down - the LPV applies more bias to the rear brakes. If you put a lift in - there is more clearance between the chassis and the rear diff - so it would be the same as the Patrol being unloaded as far as brake bias is concerned - therefore you need an extension on the bracket to bring adjustment back to the norm.

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Thanks mate, guess I'd better make up a bracket then :)

Just wondering, when you put weight in the back of the car, does the spring tighten or loosen? As in, does that lever move towards the passenger side, or towards the driver side, and which way gives more rear brake bias?

Also, anyone know where to get a replacement spring for it? Mine measures 195cm. I've used a couple of zip ties to get it back to 178cm in the meantime.

Quote:

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Originally Posted by Throbbinhood

Am I right in assuming that when you go higher in lift without the bracket, you will lose brakes at the rear? Or will braking at the rear increase?

I currently have a 3" lift in mine. Was told by the reputable 4x4 shop when it was put in that it's not need for a lift of this height, and as such have no bracket. Braking isn't bad, but as with anything, if it can be improved, why not.

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Even for a 2-3 inch lift you will lose some braking from the rear. You may be able to get enough adjustment from the standard set up to get the brakes just right but with a bracket it is much easier. I had bugger all brakes at the rear after my lift but after I installed a bracket I was able to adjust the brakes correctly. Takes a few attempts though until you get it right. Too much bias to the rear and you lock up brakes as well.

I think the bracket was worth every cent ($32 delivered) as you can really set it up to brake like a stock Patrol.

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Originally Posted by Rock Trol

Even for a 2-3 inch lift you will lose some braking from the rear. You may be able to get enough adjustment from the standard set up to get the brakes just right but with a bracket it is much easier. I had bugger all brakes at the rear after my lift but after I installed a bracket I was able to adjust the brakes correctly. Takes a few attempts though until you get it right. Too much bias to the rear and you lock up brakes as well.

I think the bracket was worth every cent ($32 delivered) as you can really set it up to brake like a stock Patrol.

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I installed the bracket yesterday. See post above about the spring.

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Originally Posted by Throbbinhood

I installed the bracket yesterday. See post above about the spring.

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From memory when you open the lever it sends more pressure to the rear. Closing the leaver restricts the pressure so there is less braking. I have noticed that different model years have the brackets mounted in different ways and maybe the valves themselves are different. For instance the set up on my 2007 model is slightly different to a mates 2004 model. What you need to do is get the spring in a horizontal position and then look at what would happen if the rear is lowered. Normally the spring will open the lever (from memory). It does not take a lot of adjustment on the lever to change the bias. It's a lot of trial and error. Try adjusting the lever so that its in the middle of the range of movement that it has and then drive it to see what it does.

Can anyone confirm the measurement for a GQ? I've seen 175-178 listed here, but think it may be for a GU. Have seen 207-220mm listed elsewhere.

My car: 1993 Patrol Y60 2,8 turbo diesel SWB. Euro. 2" lift. (guess you call it GQ)


When the car raises in the rear, tension on the spring DECREASE, and so does the braking pressure. When the brake pedal is applied, the valve is pushed outwards, increasing tension on the spring. If the spring does not hold it back, pressure to the rear brakes are cut of. The more tension on the spring, the more brake.

I will alter the bracket on the differensial, making it higher and adjustable. I do a lot of heavy towing, and optimum braking balance is important.

The spring sits at an angle from the differensial, down to the valve on the right hand side. It flats out when the car is lifted, and causes less tension / less braking.