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Load sensing valve replacement with ....

Chris

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Ok just flying an idea here and all replies welcome. I know that the LSV on my 80 does work but frankly I find it a pain. Sometimes I'm fully loaded for a trip out, sometimes as light as I can for off road. I don't speed about and doing emergency stops from MACH 10 is not something I'd like to have to experience anyway. This weekend both Rob and I experienced almost complete brake loss off road, but oddly mine seemed great in reverse. When I came to clean it, the LSV was jammed solid in clay. Once released my brakes seemed OK again.

So, as this is an external physical interference issue rather then a malfunction of the valve, (due to it being big and in the way), I wondered if I could replace it with a brake bias valve something like this:

http://www.ebay.co.uk/itm/Adjustable-Br ... 2c624ab5d8

Would Mr MOT get cross? Would it work? It's adjustable far more easily than the current set up (even from inside the car with some systems). It would allow pretty fine tuning of the brakes but what it wouldn't do would perform the automatic adjustment under heavy braking. But, as I explained, my truck is barely loaded the same twice, so the LSV setting is never right most of the time either. Surely it's a better option that a piece of coat hanger stuck to the underside of the floor pan. Isn't it? BTW if my brakes were half decent, I wouldn't be bothering. But they're not.

Chris
 
Hi Chris,

That looks a nifty, and simple piece of kit.

I don't know the 80 series brakes layout, but I guess you just have the single brake line feed to the rear brakes?
(Are all Land Cruisers just single brake feed to the rears?)

It looks like it would be quite easy for you to have that mounted, in the dash, with the piping to the rears, diverted through it.

As you say, you could be sitting in your drivers seat, and quite easy to adjust it to your weight carried in the rear.

So what would you do? would you load your truck up, and weigh the weight on the two rear wheels? then empty the truck and weigh what weight is on the rear wheels then<

Then you could have yourself a min and max setting, and any thing in between?

Interesting, very,

Gra.
 
Chris said:
my truck is barely loaded the same twice, so the LSV setting is never right most of the time either.
Chris, this doesn't make much sense/logic - the entire point of the LSPV (if working) is to give you the right brake bias front vs rear under different loads. The LSPV isn't "set" for one load.
Your LSPV setting might be wrong following your lift but set correctly, the brake bias would be right for all loads within reason. Of course if your LSPV isn't working properly, then all bets are off.

If MOT man tests for brake bias and your LSPV isn't functioning correctly, then presumably you'd be looking at an MOT fail anyway? I can't believe he would recognise whether an 80 series had its OEM LSPV or not. However, in the event of an accident I imagine your insurance company would be very interested in the mod if they were aware of it.

What got jammed in clay on yours - the lever presumably? Maybe the answer is protect the LSPV system to make fouling less likely. Or maybe to limit the range of travel on the lever? It sounds like yours got shifted to an extreme bias, which directed all the braking force to the rear.

Cheers,
 
Andrew says it all.

As long as you have reasonable front/rear bias at the time of the MOT it won't matter if you have an LSPV or not.

The most common problem with the LSPV is that it doesn't get correctly adjusted when suspension lifts are added and you end up with too much front end bias.

As a guide, when adding a 2" lift loosen the LSPV and drop it down about 1/4" - the hardest part being loosening it off because usually the mounting bolts are rusted up.

Once you have the truck setup how you like it, run it around on some gravel tracks and do a few bits of hard braking - if the front locks before the back you need to shift the bias towards the rear and vice versa - the fine tuning can be done using the adjuster on the rear axle, but it pays to give that a good soak with WD40 well before hand because it also has a habit of rusting up.

With the LSPV correctly set it should then automatically adjust the bias for you as your load alters.
 
That's the point though chaps, I know how to set it, it does operate, but it never actually seems right all of the time. Not logical I know - that's the whole function of it; to automatically adjust. But I guess with off roading, it keeps getting bashed and bent and balled up solid in clay leading to different settings all of the time. Replacing it with something not exposed so that I can just set it for 90% of the time would be satisfactory.

I did say it was just an idea. Sounds like the presence of the LSPV is not an mot requirement then. Just good bias. OK that's one down. Protecting the LSPV sounds like more work than just replacing it. It may be that having the spare tyre underneath has served as some protection in the past, but now it's gone, there is a lot more scope for clag to get up there.

Can't resist trying stuff. You should know that.

Chris
 
With higher rate springs fitted the LSPV will never get it right, chuck a few hundred kg's in the back and the suspension won't drop as much as on standard springs so the LSPV won't bias to the rear as much as it should / would on standard springs either. ISTR having the bar there but not connected at the axle end was an MOT fail for Ray but cutting the bar so it only filled the hole in the boot on mine and adjusting it manually was not noticed at MOT time and so passed ...
 
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That's a good point Jon. Honestly hadn't thought of it like that. It's not just a height difference, it's a spring rate difference and I guess it makes all the difference whether you set the preferred bias with the truck empty or when it's full. Anyway, continually bashing the load bar can't be helping.


Chris
 
I guess the LSPV not only needs moving, but also needs to be re-callibrated for the size of springs, something that you can't do.

Chris - do you have any standard loadings - loaded for shooting, loaded for laning, loaded for family trip - the key would be do what Jon did and cut the rod off so you can manually adjust it and then remember the settings for each type of load - a bit of a pain, but better than nothing.
 
No Julian, not really. But there are graduated bias valves similar to the one that I posted. I saw one with 7 click settings. Not cheap mind. That would work and as I said, the more expensive ones are cab controlled by a cable so you can alter on the move. I like toys. You could use that off road on say a really steep descent to put all the braking to one set of wheels. :dance:


Chris
 
Guys, I've just bought another 90 model HJ-75 with stuff all front braking and the load sensing valve arm and diff housing bracket has by the previous owner been seriously crunched and pushed up a good inch or so and had the arm was jammed and twisted on the bent bracket, now it's freed up and workable to a point, what is the rough setting in say % of the arm travel from the arms bottom most position and raised ?? to where it should be on level ground unloaded and where it should be set to on the bottom bracket, 10% up or what ? given that it moves about a foot up and down in total travel from either limit.
Surely there is a sitting std measurement in the arm movement where it will work enough to be at least driveable with some front brakes.
Much appreciated.
 
I compensated mine when I had the lift fitted, but take the point that with stiffer springs, normal load variants will rarely depress the springs enough to move the LSPV to compensate for anything.

I once had a tonne (or maybe more :whistle:) in the back of my truck and during the 450km journey as loaded, the brakes appeared to function very well indeed. Unloaded, I've never had any rear wheel lock up (which is the most dangerous effect of brake imbalance) so I've never considered it malfunctioning.

I also thoroughly jetwash the underside of my truck every week, so clag cannot build up too much... (A well trained lad at the local car wash does it!).
 
had to remove the one from my 60 during the rebuild as it was fooked. In the month or so I have had it back the rears have locked up under heavy breaking, either in the wet or going downhill, which is interesting!

I don't think the HD OME springs help much.
The garage suggested fitting a manual adjuster like race cars have, and that is probably the line I will go down.
 
Guys, I've just bought another 90 model HJ-75 with stuff all front braking and the load sensing valve arm and diff housing bracket has by the previous owner been seriously crunched and pushed up a good inch or so and had the arm was jammed and twisted on the bent bracket, now it's freed up and workable to a point, what is the rough setting in say % of the arm travel from the arms bottom most position and raised ?? to where it should be on level ground unloaded and where it should be set to on the bottom bracket, 10% up or what ? given that it moves about a foot up and down in total travel from either limit.
Surely there is a sitting std measurement in the arm movement where it will work enough to be at least driveable with some front brakes.
Much appreciated.

Not many guys on here with 75's unfortunately. :thumbdown:

Might be worth having a look and a measure under one if you see one parked up some where. Either that or buy a replacement one from a wreckers yard maybe. :think:

Oh and welcome to the club. :thumbup:
 
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