Raised rear = adjust load valve

[david allan]

rich

how much did you extend the rod by

[Rich]

David,
I did exactly the same thing as the pictures on the previous page, extended it by 50mm with a cheap bolt from Bunnings!

The rod is sitting about in the middle of that at the moment, I still havn't taken it for a drive yet to test it out.

It's cloudy today so if we get some rain that will be perfect for testing it. I want the rear ABS to activate on wet roads (along with the front when it activates).

So, in short, althoughi have extended the rod the same as the pictures, I havn't fine tuned it to see how far above the old set-up mine will be set at...

What are you going to do about yours?

Rich.

[rodw]

Guys, I have not done this mod yet but I have noticed on the door beside my Tyre placard, there is a sticker that has a little diagram. If I have interpreted it right, on an unladen ute, there should be 76mm of travel at the end of the arm. It even lists the theoretical brake pressures front and rear at these measurements.

So you should be able to unhook the arm when you extend it, measure the height off the floor with the arm in the topmost position, deduct 76mm and set the arm to this height of the floor after you extend the shaft. Sounds pretty simple really, but never seen anyone talk about doing it this way...

Rod

[Macca]

Rod, mine also has that sticker.

The problem as I see it, 76mm is from stock, no tools drawers canopies e.t.c.

This will no doubt cause more confusion, I believe the best idea is to adjust to where you think it should be and road test.

Mine is set to maximum braking at my ride hieght, noting there is a bit of wieght over the back axle.

I disconnected the adjustable rod and tied the activating rod up out of the way without a problem.

If I had an accident it might of caused some grief so now it is set as above.

Macca

[Rich]

Rod,
I just went and had a look and I have this diagram also...never noticed it before.

My ute is usually unladen so in theory this should work for me.

Unfortunately, even prior to extending my rod recently, I had less than 76 mm of travel left to its top position and my brakes were still terrible.

I am going to road test today. If that does not satisfy me, the truck is almost due for its 50,000km service so I may ask Toyota to have a look at it.

Toyota up here are pretty good and I do have confidence in them, but they will probably tell me that since it has been modified they don't really know....

I don't think the brakes are good enough to cope with larger diameter tyres. Which is a shame cause they are met to be able to tow 750 kg's unbraked plus carry nearly 1 tonne in the tray and operate safely on the standard brakes....

Rich.

[rodw]

OK Rich, when you stop and think, there are a few variables in this other than ride height I had not thought of including:
1 Stiffer springs so the expected travel is less.
2 Larger tyres applying more torque around the axle

The other variable that we might be able to play with is the length of the actuating arm attached to the valve which the sticker says should be 750 mm long. So if the stiffer springs caused there to be say 20% less travel (61 mm instead of 76mm) from unladen to laden, if you reduced the arm length by 20% to 600mm wouldn't everything be in proportion? Problem will be how to relocate the vertical rod attached to accommodate the shorter actuating arm.

The same principle would apply to accommodate larger wheels. If the larger wheels increased required braking effort by another 10%, you'd need to lop more off off the rod. I think you could probably convert the additional stopping force required to a load factor to an unladen ute, after all we are talking about the same thing (momentum) in both instances (ie, the braking calculations would be based on the momentum of the vehicle at highway speeds and tyre size will affect momentum). If you could work out how much the springs would compress under this equivalent additional weight, you could calculate how much more to lop off the rod. So if for example, the tyre calculations equated to 6.1mm (10% of travel in the springs), You'd need to lop off another 10% (eg 60mm) off the rod making it 540mm long.

Now I might have made this a bit complicated, but surely there a member with some engineering knowledge who could comment on this. I might have missed a few steps in this. 30 years ago, I might have known how to do some of these calculations but not now

Rod

[Rich]

Hi Rod,
yeah it all makes sense but who could really be bothered to take the risk and modify it that much.
in Reality, the LSPV should not even be there on a truck with ABS.

I am convinced the brakes are just crap.

I drove my truck yesterday after raise it and extending the rod and noticed no difference or any improvement.

There is nothing left to do as far as this LSPV issue is concerned. Its made for trucks that are not meant to be modified.

Rich.

[rodw]

Maybe a new Proportioning valve without the load sensing. Spidertack make one see here for a Suzuki one.
http://www.lowrangeoffroad.com/sambrakes.htm

Looks like this is adjustable.

Email Sean there and ask if there is one that would work on a Tacoma. He is very good and reliable. I have bought from him.

Rod

[rodw]

Rich,

Here s an idea:
http://www.ttora.com/forum/showthread.p ... ning+valve

[david allan]

rich

im susprised that after extending the rod it made no difference

Have you done the To-much brake test that was explained a while ago
Jacking up the rear of the vehicle & seeing if the rears work

[Rich]

Hi Rod,
No I havn't done the too much brake test as I don't have the trolley jack and car stands.

I am trying to avoid going out and buying these for this test as I will probably only use them once and I already have enough unused stuff in the garage.

I don't anyone from whom I can borrow the tools.

Rich.

[rodw]

Rich, You don't need a trolley jack, Worst case buy some jack stands from Super Cheap, but you might be able to rest the axle on timber blocks or firewood or something like that. Just use the factory jack , and if you need to, put some timber blocks under it to get the height. A pine 70x35mm stud is prety cheap and will make a lot of jack blocks, but hardwood is better as pine can crush if you put it on top of the jack, but you only need one or two hardwood blocks to use where something crushes and pine in between.

Rod

[Dluxv6]

Guys
spoke about this subject ages ago, am seeing my mate (owns a brake place)again tmrw about removing LSPV and putting in an adjustable one in its place , the only weight i carry is camping gear and tow the trusty old tinny, last time i spoke to him he could get for about 150 bucks. brakes are atrocious with just camping gear and towing the boat, disgusting for a 50,000 thou vehicle
will keep you informed.

Cheers Drew

[rodw]

Keep us informed Drew, It will be handy to know the brand and model.

[Quinny34]

Rich,

Sorry to hear your outcome mate... not sure what the go is... When I did mine it was very noticable.. Have since done a few trips 4x4 wise and today I brought bake a medium load of wood.... still all good (Well, better than what they where like after the lift). No doubt they could have better brakes but mine are okay... better than some cars I've driven.

Will be interested in how the other suggestions turn out...

[mblux]

hi guys

find a local brake or mechanic that has brake pressure test equipment and get your pressures tested front and rear this is the only true way to set prop valve without guessing and same as quinny i could notice it a massive difference straight away 9000kpa front 5000 kpa rear drum s or 8000kpa rear disc cheers mark

[Rich]

Thanks for the suggestions fellas.

I have to take my truck into Toyota for the 50,000 KM service soon, so I may ask them what they can do to check it without costing me a lot of money. Probably not much if I don't want to give them lots of $.

The Toomuch brake test does not really tell you how well that they are working, all it really does is tell you that there is some braking to the rear wheels, and it wouldn't have to be much to stop the wheels turning with no load on them...

Agreed???

Rich.

[TOMUCH]

Rich, you would be surprised how much pressure isnt there.. on most trucks I have done this test, the rear wheels just keep on turning with the engine idleing over... Yes your right, it doesnt take much pressure, but again, no pressure = no stopping.. I then adjust the valve until i have reasonably good stopping power at the rear. This is certainly a back yard fix, but will definately give you better brakes than you had. I would then advise giving Toyota a call.. book it in specially for the brake adjustment and pressure test.. make sure you tell them you want this.. and make sure they have the gauges on hand the day you bring it in.. most dealers dont have their own set available.. they borrow from each other( this can take a couple of days to orgainse). This really is the only way to correctly have your brakes adjusted. My test is only there to quantify that you do indeed require a professional adjustment. But will certainly produce better brakes in the interim.

[Rich]

Thanks mate.

Rich.

[david allan]

I asked toyota a while ago to look at it for me.
They said they used there pressure things & they actually adjusted the nut down abit.
Didnt understand why so i put it back up.
The prob is that whith the original suspension the LSPV works on the amount the rear drops as it thinks there is more load.
But once we put heavy duty suspension it it will hold the weight better & not drop the rear as much causing the LSPV to still think it dosent have alot of weight in.