By Tony K
Anybody who has driven a 60 knows the brakes are not very good. But part of the problem is actually self induced. It has to do with one of the components in the brake system on our wagons. At some point in your messing around with wagons you will come across the following, LSP&BV. This is short for Load sensing, proportioning and bypass valve. What this thing does is tell the brakes what to do when you slam on them and lets them know how loaded your rig is. In the most basic sense it is a mechanical anti-lock braking system. Pretty smart on Toyota’s part if you think about it.
-Just how does it do this?-
You have to look under your rig on the rear axle. Just to the side of the differential is a mechanism bolted to the housing. And going from this mount is a rod hooked to a valve. And bear with me as this valve is tied into the brake lines.
What happens when you slam on your brakes is that the weight is transferred to the front axle and the rear axle is “unloaded”. The valve in this situation allows more of the brake force to be applied to the front axle, preventing the rear axle from locking up.
Having a load on the rear axle keeps the rig from tranfering weight to the front, this tells the valve to let the brakes in the rear do more of the work.
And the valve does all this by referencing the difference in height between the axle and the frame where the valve is located. Remember that rod attached to the rear axle, it controls the valve by the shifting weight of your rig during braking. The farther the axle moves away from the valve the more it tells the valve what to do.
Just what does a lift kit have to do with this? When you add lift to your suspension you are altering the relationship of the axle to the valve. The axle is getting farther away from the valve exactly what happens when you slam on the brakes. If you have not adjusted the valve or compensated for the lift you will probably find that your rear brake shoes are not showing any signs of wear. And this is not from misadjusted shoes, the valve is telling the brake system not to send fluid to the rear brakes because it thinks you are stepping on the brakes and an unloaded rear end will lock up. And like me you may notice some pretty rapid wear of the front pads and rotors. This is not the valves fault, it is working as designed.
-How to fix it-
Yes the rod on the system is adjustable . But the factory fix involves some special service tools that next to no one short of the dealer has. And I don’t think there is enough adjustment for the additional height we put on our rigs when we install a lift kit. There is a simpler way to make things work again. Or at least it has worked for me.
All I did was add a spacer, equal to the lift I put on my rig, under the rod mount on the axle housing. This once again tells the brake system that the height difference between the axle and the valve is the same as if you did not install a lift kit in the first place. If you put a 2 in lift on the rig, add a 2 inch spacer like I did. The photo shows how I did mine with a cut out section of square tube and an additional chunk of aluminum (it’s what I had on hand at the time)
You should find that your brakes are more effecient than they were, the front brakes will wear at a slower rate because they are not doing all the work and you should once again see wear on the rear drums and shoes. While this works just fine for mild lifts, if you have something more drastic, such as a springover, you may have to do some more engineering.
