Adjust your LSPV today!!

[Rich]

Regarding the ABS, keep in mind you get no ABS when the center diff is locked.

With the way the ABS is setup I believe if either rear wheel locks up then the braking to both rear wheels will be pulsed by the ABS, based on the same observation made by Dan that there is only one hydraulic line from the ABS unit runing to the rear.

To adjust according to factory procedures it cost me $10 bucks to get my truck weighed. A pair of pressure gauges with adaptors to fit the calipers cost $80. I considered the cost minor in comparison the the money spend on the lift, bumper, and sliders.

 

[LandCruiserPhil]

Rich,
How about some more info on your brake presure gauge set up and your adjusting process.

Thank Phil

 

[Rich]

Below is a picture of the gauges. Following is the procedure I used.

1. Weigh truck on truck scale, getting a separate weight for each axle.

2. Go home and remove or add enough weight from over the rear axle to get rear axle weight to factory spec of 2932 lbs (note that this spec is for a '97; I have seen other numbers posted for earlier models). I used a home scale to measure the weight of the misc cargo items I removed.

3. Install a gauge on one front and one rear caliper. They replace the bleeder screws.

4. Now you need 3 people to complete. Somebody sits in the the driver seat and presses the brake pedal. One person observes the front pressure gauge and directs the driver to adjust the pedal effort until the front gauge reads the factory spec of 1138 psi and then you adjust the lspv valve mounting position until the rear gauge reads the factory spec of 870 psi. Note that when the truck is static the valve mechanism is sticky. Have somebody bounce the rear bumper a few times in between gauge readings to ensure that the valve has reacted to the adjusted position.

It is less trouble to do than it sounds. Here is a previous topic where I had posted some of this info: https://forum.ih8mud.com/index.php?board=2;action=display;threadid=6969;start=msg58719#msg58719

 

[LandCruiserPhil]

Thanks Rich for the info and link

……..The logic for bringing the rear vehicle weight to a factory 2932 lbs in setting the LSPV is that when you load the vehicle the drop in the rear suspension and movement of the LSPV rod will adjust the brake bias to compensate for the additional weight. The problem is that not reality, some 80’s have 2000lbs of stuff front to rear. With all the additional running weight (bumpers,winches,sliders,ect.) should it not be look at from a percentage of weight (front to rear) and try to match the factory percentage F-R rather than a 2932lbs. Otherwise when you put all stuff back on and in you are going to drop 2". How much is the range of travel of the LSPV?

I probably should quit thinking and just do something. It will be better than what I have now - zero

Phil

 

[landtank]

Phil, that's basically the problem. When you repring you're not only changing the height of the vehicle but how it reacts to additional weight. And as you stated the factory proceedure would only be valid with an otherwise stock vehicle and at that weight in the vehicle.

So from my experience there is some trial and error involved. I recently added a ARB bull bar and it's counterweight raised the rear slightly. Soon after I was getting some brake squeel when stopping slowly. If I braked a little harder it wouldn't happen. So I raised the rear proportioning spring arm and it has gone away.

You'll know that you are light in the back if the front rims powder up rather quickly.

Just some of my observations.