I have a 1995 77 Series with a 4 inch body lift and ARB suspension. I went to put it through a vehicle inspection here (Mongolia) and they said the rear brakes weren't working. Toyota here told me it was because of the lift, there is a valve connected to the rear brakes which modulates the brakes by how loaded the vehicle is. The lift gives the valve the appearance of being very light. Any solutions to this? What have other people done that have lifted their vehicles?
77 Series rear brakes
- Thread starter Geobaerg
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Basically they bend the curved bit so the Load sensing Proportioning Valve works.
But once you have increased the suspension travel and added a body lift ,it can never be perfect again .
Ron R
Drive a Landruiser, enjoy life
The sensor of the LSV (Load Sensing Valve) is nothing more than a flexible rod, connected to the valve and axle.
What I did to compensate the lift was the following:
Took the sensor off.
Then I clamped the valve-side of the rod in my workbench so it was pointing horizontally with the curve pointing towards me.
Then I measured the distance from the point towards a certain point on the wall, perpedicular as possible.
Next thing was to bend the rod that way that the distance to the wall increase the same amount as the lift, easily measured against that point on the wall.
This works real well.
What I did to compensate the lift was the following:
Took the sensor off.
Then I clamped the valve-side of the rod in my workbench so it was pointing horizontally with the curve pointing towards me.
Then I measured the distance from the point towards a certain point on the wall, perpedicular as possible.
Next thing was to bend the rod that way that the distance to the wall increase the same amount as the lift, easily measured against that point on the wall.
This works real well.
Don't bend the rod, you'll never get it right doing that. You can just unbolt the body of the valve mechanism (2 bolts), then buy and cut 2 pieces of steel tubing about 2 inches long - buy longer bolts and bolt it in. I got a lifted truck from japan that had it done and that's what I do with all my trucks now.
If you bend the rod on a 4 inch lift it might work but won't actuate the same way - if anything you would have to lengthen the rod.
Add spacers is my recommendation.
Regards,
louis
If you bend the rod on a 4 inch lift it might work but won't actuate the same way - if anything you would have to lengthen the rod.
Add spacers is my recommendation.
Regards,
louis
They got vehicle inspections in Mongolia? We don't, but I do know alot of lower 48 states do. What Louis said. Instead of tubing I would use flat stock to raise the mounting point the same amount as the lift.
Ron R
Drive a Landruiser, enjoy life
Louis,
always willing to learn, but I don't understand what you're saying. When I would add two tubes the way I think you say, that would not help at all.
The LSV is sitting against the right frame rail with bolts. Four that is, but that doesn't matter.
If I would place the LSV on two (or four in my case I think) studs, all it would do is move the LSV away from the rail but parallel to the axle. So to mmy opinion that wouldn't alter anything in regard to the way it is 'steered' by the axle moving up and down.
On the picture you can see the LSV sitting against the RH rail. Photo is taken from a point near the attachpoint to the axle (Arrow).
Extending this point upward - instead of bending the rod is no option either. The extension would pierce or at least hit the body floor with the axle in most upward position.
That's why I've bend the rod and I can assure it's working as it supposed to. Had the annual inspection about a month ago and no complaints but that was no surprise as I've done this bending several years ago and the pads are wearing evenly and towing a heavy load is no issue as well.
So I assume the 77 has a fully different setup or I'm misunderstanding what you wrote.
always willing to learn, but I don't understand what you're saying. When I would add two tubes the way I think you say, that would not help at all.
The LSV is sitting against the right frame rail with bolts. Four that is, but that doesn't matter.
If I would place the LSV on two (or four in my case I think) studs, all it would do is move the LSV away from the rail but parallel to the axle. So to mmy opinion that wouldn't alter anything in regard to the way it is 'steered' by the axle moving up and down.
On the picture you can see the LSV sitting against the RH rail. Photo is taken from a point near the attachpoint to the axle (Arrow).
Extending this point upward - instead of bending the rod is no option either. The extension would pierce or at least hit the body floor with the axle in most upward position.
That's why I've bend the rod and I can assure it's working as it supposed to. Had the annual inspection about a month ago and no complaints but that was no surprise as I've done this bending several years ago and the pads are wearing evenly and towing a heavy load is no issue as well.
So I assume the 77 has a fully different setup or I'm misunderstanding what you wrote.
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Ron R
Drive a Landruiser, enjoy life
Thanks Louis, now I understand.
Instead of bending the rod, you extended the part (adjustable connecting point)that sits on the axle.
Have you any explantion as why this should work better than bending the rod?
As said in my previous posting I did this several years ago and I found no bad behaviour what so ever.
And this way you don't have to fabricate extra parts, as long as you bend the rod carefully for the amount you lifted the rig.
To my opinion the character of the new springs (stiffer?) has much more influence on the compensation character of the LSV. Theoretically the rod should be attached to the axle on a point closer to the LSV when stiffer springs are used.
The rod should never be bent - check the manual, and go to the 80's section and see what they are doing as the 80's have the same thing and it needs to be adjusted when it is raised. As you bend the rod and raise the truck you actually straighten the rod and extend it - so you are actually limiting the movement of the device (decreasing the movement) which will make it work not as well.
Imagine lifting the truck 18 inches (an over example), the rod is completely straight trying to reach the actuator and it is completely straight - now imagine the axle going up and down - the action doesn't seem right eh?
Louis
Imagine lifting the truck 18 inches (an over example), the rod is completely straight trying to reach the actuator and it is completely straight - now imagine the axle going up and down - the action doesn't seem right eh?
Louis
Ron R
Drive a Landruiser, enjoy life
Yeah, can understand the reasoning. The more extreme the lift, the bigger the problem. Because my 'lift' is about 2" I won't worry about it, but it's good to keep your solution in mind for the future.
Thanks Louis for clarifying.
Hi
Don't know if this will help
I have a HJ79 and the diagram of the LSV is somethong like this picture
The weights for unladen on the rear axle is 939kg and for fully laden on the rear axle is 2100kg. The diagram shows that you have to have a fixed amnount of travel for the different axle weights for the correct pressure distribution. So you would have to move the attachment point of either the LSV or the contact point on the axle the same amount as the lift so tha the lenght of the bar and the travel for the different axle weights stay the same. That you will stay legal as well as safe
Don't know if this will help
I have a HJ79 and the diagram of the LSV is somethong like this picture
The weights for unladen on the rear axle is 939kg and for fully laden on the rear axle is 2100kg. The diagram shows that you have to have a fixed amnount of travel for the different axle weights for the correct pressure distribution. So you would have to move the attachment point of either the LSV or the contact point on the axle the same amount as the lift so tha the lenght of the bar and the travel for the different axle weights stay the same. That you will stay legal as well as safe
Ron R
Drive a Landruiser, enjoy life
Yes, quite right. That's what we have been discussing. Difference was that I suggested to bend the rod and Louis extended the attachpoint.
Louis though has a point in that it's better to extend the attachpoint - certainly in extreme situations.
But what you're on here is what I touched as well when I said that the characteristic of the new spring is important as well.
In case the new spring is stiffer then the original spring, the body won't sag as much with a certain load.
The LSV will only set the right pressure if the rod has moved the right distance - or better - the right angle. So if the new springs are stiffer than the old ones the attachpoint on the axle should be moved towards the LSV. That way the angle can be kept the same with smaller movements.
One would need some investigation to get it all right tho.
