Load Sensing Valve
- Peter and Sandra OKA 374
- Offline
- Posts: 1321
Rendering Error in layout Message/Item: fopen(http://open.api.ebay.com/shopping?callname=GetSingleItem&appid=JamesByl-KunenaOK-PRD-869e2c47f-0be7bf4a&siteid=0&responseencoding=JSON&ItemID=113469180724&version=889&trackingid=5337415630&trackingpartnercode=9): failed to open stream: Connection refused. Please enable debug mode for more information.
Please Log in or Create an account to join the conversation.
- Peter_n_Margaret
- Offline
- Posts: 820
Cheers,
Peter
Cheers, Peter.
OKA196 tinyurl.com/OKA196xtMotorhome
Mob.0428171214
Please Log in or Create an account to join the conversation.
- Peter and Sandra OKA 374
- Offline
- Posts: 1321
OKA 374 LT Van, converted to camper/motorhome,
400ah Lithiums, 1100w solar, diesel cooking heating and HWS,
Cummins 6BT, Allison 6 speed auto, Nissan transfer.
Please Log in or Create an account to join the conversation.
- mort
- Offline
- Posts: 848
Well that is a good question.
The balance between front and rear is usually 60% front 40% rear or there abouts depending on vehicle.
There are a few ways to do this.
1 take it to a brake place that has rollers and set up for it usually truck service centers.
2 get a set of manual ajusters which the driver can set while driving like race cars.( too much trouble )
3 do it yourself ajust drive brake ajust drive brake untill you are happy the only thing is you wont know what the % is between front and rear.
At the moment you have the rear doing most of the braking which in an emergency braking its not good.
Martyn
Please Log in or Create an account to join the conversation.
- Peter Davis
- Offline
- Posts: 271
Did you work out why your front brakes aren't working as hard as the rear?
Mine does the same. The rear brakes get very hot and the front warm.
In the process of changing front calipers. Hopefully that will help. Except I broke the retaining bolt which holds the slider spring arrangement holding the caliper in place.
Please Log in or Create an account to join the conversation.
- Peter and Sandra OKA 374
- Offline
- Posts: 1321
A crude and simple fix is to bend the bracket on the diff up to increase braking on the rear or down to decrease braking on the rear. To put it simply the arm needs to go up to increase braking force on the rear and down to decrease braking force.
Up here in NSW heavy vehicles need an annual inspection for rego and last year after resetting the springs I discovered on the brake testing rollers that the rears were doing virtually nothing. A quick removal of the cable between the diff and the proportioning valve arm saw the rears back to full braking for rego purposes and then when I got home I spent a bit of time on a dirt road adjusting the length of the cable/bending the bracket and adjusting the adjustment bolt to get it right.
The dirt/loose surface allows you to easily lock the rears when you jump on the brakes so as to easily adjust the rears to get them braking correctly.
OKA 374 LT Van, converted to camper/motorhome,
400ah Lithiums, 1100w solar, diesel cooking heating and HWS,
Cummins 6BT, Allison 6 speed auto, Nissan transfer.
Please Log in or Create an account to join the conversation.
- Peter Davis
- Offline
- Posts: 271
Please Log in or Create an account to join the conversation.
- Rick Whitworth
- Offline
- Posts: 399
I replaced the rear pads but then got caught up with major house reno so have not gone further with setting up sensor valve yet.
My truck stops well. Just trying to even up wear rates front and back.
Have had a couple panic stops where I had to throw out all anchors. One with the boat on the back crossing the Swan St Bridge when a bike did a u turn from left without looking. I locked up all 4 oka wheels plus trailer brakes in huge cloud of smoke and left rubber on the bitumen from all tyres.
It was nice to find it stops that well but not something you would do on purpose, even in a test.
On each occasion the wheels were straight, otherwise I am sure I would have turned it over.
I did a brief search for a City service center with front and rear rollers who might be able to test it but no joy. If there is one I bet they charge, bit like the suspension shaker places
Local center that sold me the pads said I should just monitor the difference in the front rear pad thicknesses but there may not be direct relationship between equal wear and good braking performance anyway. Maybe when sensor is well balanced for bitumen on a motorhome setup, rears do wear quicker.
So when I get time I plan to do some adjusting and drive testing as suggested above.
re your question I figure the sensor must affect both the front and rear, it is a proportioning valve, so for a given peddle pressure modifying the sensor lever to decrease pressure to one end, increases pressure to the other end.
This is supported by owners who say if it is set too tight (ie low lever) all pressue goes to the front causing dangerous lockup effecting steering.
It will be a while before I get back to my adjustments/tests but will report back if I have any success
Rick Whitworth:  OKA XT 149.    Digital Twin.   Loaded 4x4.
Please Log in or Create an account to join the conversation.
- Peter and Sandra OKA 374
- Offline
- Posts: 1321
There is probably some very small effect on pedal pressure due to fluid being forced through a smaller aperture but it would be negligible.
Peter you want less braking on the rears the less weight is on the back, in mine and Ricks case and probably yours where we have a lot of weight in the back with a motorhome fitout the weight is pretty well balanced, even with a 6bt and Allison mine is within 100kgs front and rear normally but goes rear heavier when fully loaded with fuel and water for a long trip.
But the problem is that the weight doesn't stay in that exact relationship during braking as the weight "shifts" forward under braking as the front of the truck drops and rear lifts, the harder you brake the more it occurs.
So if you have the rears braking as much as the fronts then the rears will lock especially under hard or emergency stops. Hence the need to adjust the valve to suit the particular vehicle. Once it is setup for your particular situation then it shouldn't need any more adjustment unless you remove a lot of weight.
OKA 374 LT Van, converted to camper/motorhome,
400ah Lithiums, 1100w solar, diesel cooking heating and HWS,
Cummins 6BT, Allison 6 speed auto, Nissan transfer.
Please Log in or Create an account to join the conversation.
- Rick Whitworth
- Offline
- Posts: 399
My use of words "for a given peddle presure" was wrong.
In practise what happens is the driver is looking for a certain amount of braking so that if the sensor lever has been set to give inadequate pressure on the rear the driver automaically compensates with heaver foot to get the required deceleration.
So the effect is that front pressure goes up to compensate.
Rick Whitworth:  OKA XT 149.    Digital Twin.   Loaded 4x4.
Please Log in or Create an account to join the conversation.
- Peter and Sandra OKA 374
- Offline
- Posts: 1321
OKA 374 LT Van, converted to camper/motorhome,
400ah Lithiums, 1100w solar, diesel cooking heating and HWS,
Cummins 6BT, Allison 6 speed auto, Nissan transfer.
Please Log in or Create an account to join the conversation.
- Dean and Kaye Howells
- Offline
- Posts: 533
In a vehicle that carrys a varying load this automatic adjustment of the rear braking force allows more efficient rear braking and overall vehicle braking. In modern vehicles this is done with ABS though there are some weird setups like in the Iveco Daily which uses both.
Which leads me to a couple of questions..................
For a vehicle that carrys a basically constant load (such as an Oka motor home) could the adjustment arm be removed and the adjustment pre set ? This would allow the space taken by the spring/arm assembly to be better utilised eg. for under floor storage or a water tank.
If using adjustable rear air bags (for example) to maintain rear ride height or to assist the springs under load by reducing sag does this reduce overall braking effectiveness by not allowing the proportioning valve to operate correctly ?
Deano.
Please Log in or Create an account to join the conversation.
- Ralley
- Offline
- Posts: 367
Rob
Please Log in or Create an account to join the conversation.
- Aussie Iron
- Offline
- Posts: 29
Dan.
Please Log in or Create an account to join the conversation.
- Alister McBride
- Offline
- Posts: 449
cheers, alister
Please Log in or Create an account to join the conversation.
- Peter Davis
- Offline
- Posts: 271
With the long spring joining to the diff by chain or cable how much shortening does it take to make a difference.
Or was there a preset length originally from the factory?
Please Log in or Create an account to join the conversation.
- Peter and Sandra OKA 374
- Offline
- Posts: 1321
You can undo the bolt holding the two halves of the arm and slide it to vary the length which will in turn change the braking slightly.
Unless you are changing suspension height drastically from standard it shouldn't be necessary to change the length of the cable/chain too much.
I have seen where the mounting bolts for the valve are slotted allowing the valve to be slid up and down on its mounts but mine isn't slotted.
I made a new cable as mine had frayed and I did make it about 15mm longer which did increase the braking so backed off the adjustment bolt a little bit to compensate.
OKA 374 LT Van, converted to camper/motorhome,
400ah Lithiums, 1100w solar, diesel cooking heating and HWS,
Cummins 6BT, Allison 6 speed auto, Nissan transfer.
Please Log in or Create an account to join the conversation.
- Holmz
- Offline
- Posts: 866
Peter Davis wrote: Does the brake proportioning valve just decrease the amount of braking to the rear brakes. Or does it effect the front brakes as well. So if it was allowing full flow to rears wouldn't that be the same braking force as the front.
My understanding is..., "just the rears".
Please Log in or Create an account to join the conversation.
- Peter Davis
- Offline
- Posts: 271
New front calipers, new front caliper brackets, new caliper retaining spring and slider.
Recently changed front brake rubber hoses, diff rubber hose, and front axle metal hoses. Shortened rear brake proportioning valve spring to diff length to about 3 inches. Valve seems to have popped out to rest against spring of rear proportioning valve.
Went for drive, measured rotor disc temperatures. Front about 60 deg, rear about 100 deg.
Plan to change rubber line under fire wall near pedals. Looks like fun for access.
If one empties the master cylinder so there isn't a puddle on the floor when changing the hose does the master and lines bleed easily?
Please Log in or Create an account to join the conversation.
- Peter and Sandra OKA 374
- Offline
- Posts: 1321
I've never had problems bleeding the brakes, I usually empty the reservoir and refill with new fluid before starting and have never had a problem. A little vacuum pump or a plastic sauce bottle fitted with a hose can be used to suck the fluid out. You can syphon it by sucking a small hose but it tastes putrid )
Just remember to put a chock under the brake pedal so that it doesn't go much further than the normal travel, if it does go down further to the floor you run the risk of the piston going into unworn possibly rusty bore surface and wrecking the rubbers which then requires a new or rebuilt master cylinder.
OKA 374 LT Van, converted to camper/motorhome,
400ah Lithiums, 1100w solar, diesel cooking heating and HWS,
Cummins 6BT, Allison 6 speed auto, Nissan transfer.
Please Log in or Create an account to join the conversation.