Load Sensing Proportioning Valve - LSPV Gauge

[Filmpros]

Does anyone know where I can purchase, rent, or find the gauge used to measure the Load Sensing Proportioning Valve pressures? I tried a few Toyota Dealers and they no longer seem to keep them around.

Also, does anyone know the spec for the stock settings / pressures?

 

[gotmud]

Rich,

Not sure if the SST (09709-29017) will even work for you unless you return the rear axle weight to stock. All of the specs for adjusting the LSPV are based on a rear axle weight of 2,932lbs. Judging by your sig, it looks as though you are well beyond that. I would say trial and error might be your best bet. I ran into this with my '94 when I replaced the valve. To "dial it in", I adjusted everything to the middle setting and increased the pressure until it started to lock up (disconnected the ABS). Then I backed it off slightly and reconnected the ABS.
I now wear out one set of rear pads for every two sets of front pads. HTH

 

[Filmpros]

Yes, I thought of this. However, I am trying to find out what you are assuming as being a fact. I am looking to dial in my brakes. The Back brake pads are wearing at twice the rate of the fronts. This has been an issue since day one of the build being competed.

Then I changed the pads ... put more aggressive pads in the front and new pads in the rear ... and had the calipers rebuilt. Now it is horrible. I mean like put your foot to the floor and close your eyes and say holy crap is this thing gonna stop or what horrible. Not sure what is wrong, but are changing the master cylinder next. It seems to get better as it warms up.

I have basically the same Hawk Performance brakes pads and DBA Rotors that I had before. The truck stopped MUCH better prior to changing the front pads to the most aggressive Hawk Pad, rebuilding the calipers, and power bleeding the system.

The truck is not stopping like it used to.

It does weigh 8,000lbs but it stopped well before the brake work that was done. Mysterious.

Rich,

Not sure if the SST (09709-29017) will even work for you unless you return the rear axle weight to stock. All of the specs for adjusting the LSPV are based on a rear axle weight of 2,932lbs. Judging by your sig, it looks as though you are well beyond that. I would say trial and error might be your best bet. I ran into this with my '94 when I replaced the valve. To "dial it in", I adjusted everything to the middle setting and increased the pressure until it started to lock up (disconnected the ABS). Then I backed it off slightly and reconnected the ABS.
I now wear out one set of rear pads for every two sets of front pads. HTH

 

[gotmud]

The SST is nothing more than a brake pressure gauge. You can find them at NAPA or here: Sure Stop; Brake Pressure Gauge Kit-RH1

 

[rhyary]

Rich,
Not sure if this idea helps, but performance brakes require heat. On a DD car, it may not generate enough heat to be effective. To test this theory, try stopping multiple times, best during a long down hill. If the truck is stopping better as you heat up the brakes, then may be this theory has merit. If it gets worth with heat, the theory does not hold.

Rami

 

[tirewater]

Assuming all the work done was done correctly...

Are the front pads glazed over? Did you go easy on the brakes the first few miles to bed them in properly?

Pull the pads and take a file to them, see if it helps.

 

[Ebag333]

If you have the old pads try swapping them in and seeing what happens.

 

[CharlieS]

Rich,

I don't think it is in the least bit mysterious. That is what real high performance pads are like and one reason that they aren't especially good for street use. Until they are warmed up they don't stop as well.

My advice for whatever little it is worth, replace the high performance pads with a set of front factory pads from a 100 series, and put a set of factory pads on the back. Even with a load of armor, this setup stops well.

Charlie

Then I changed the pads ... put more aggressive pads in the front and new pads in the rear ...

The truck is not stopping like it used to.

 

[gotmud]

My advice for whatever little it is worth, replace the high performance pads with a set of front factory pads from a 100 series, and put a set of factory pads on the back. Even with a load of armor, this setup stops well

Agreed!

FWIW, I'm running 100 series pads on the front and OEM on the rear. Now that everything has been "dialed in" (using the method I mentioned previously), my brakes work quite well. Even fully loaded with gear and passengers and 35's, stabbing the brakes on my '94 is like throwing an anchor out the back.

 

[Filmpros]

Interesting...Gets better as they heat up...so maybe I should go back to the less aggressive compound.

Rich,
Not sure if this idea helps, but performance brakes require heat. On a DD car, it may not generate enough heat to be effective. To test this theory, try stopping multiple times, best during a long down hill. If the truck is stopping better as you heat up the brakes, then may be this theory has merit. If it gets worth with heat, the theory does not hold.

Rami

 

[Filmpros]

Thanks...now all i need to find out is if the stock specs will apply to a lifted truck. Worst case scenario, this will at least tell me how much pressure I am sending front / rear...which is really what I want to know anyway. Thanks..

The SST is nothing more than a brake pressure gauge. You can find them at NAPA or here: Sure Stop; Brake Pressure Gauge Kit-RH1

 

[Filmpros]

Work was done correctly, I m thinking it has to be the upgraded pads. The truck stopped better with the mid-level SUV Hawks pads. The pads I have now are for stopping a 5,000lb truck towing a 10,000lb load.

Assuming all the work done was done correctly...

Are the front pads glazed over? Did you go easy on the brakes the first few miles to bed them in properly?

Pull the pads and take a file to them, see if it helps.

 

[Filmpros]

I am not sure I do...they were practically new...but gave them away. I can easily buy another set to try....which may be a good idea after reading some of these posts.

If you have the old pads try swapping them in and seeing what happens.

 

[Filmpros]

I was happy with the Hawks mid-level pads. They stop my other 7,000lbs Cruiser pretty well. This cruiser is 8,000lbs....but it worked MUCH better with the mid grade Hawks Pads and the DBA Rotors.

Rich,

I don't think it is in the least bit mysterious. That is what real high performance pads are like and one reason that they aren't especially good for street use. Until they are warmed up they don't stop as well.

My advice for whatever little it is worth, replace the high performance pads with a set of front factory pads from a 100 series, and put a set of factory pads on the back. Even with a load of armor, this setup stops well.

Charlie

 

[Filmpros]

Do these pads go in without a mod?

Agreed!

FWIW, I'm running 100 series pads on the front and OEM on the rear. Now that everything has been "dialed in" (using the method I mentioned previously), my brakes work quite well. Even fully loaded with gear and passengers and 35's, stabbing the brakes on my '94 is like throwing an anchor out the back.

 

[Ebag333]

Do these pads go in without a mod?

In the newer trucks, yes.


Honestly I don't think you can actually improve on the braking in the 80's.....IF everything is working the way it should.

Tools (I think it was Tools....) posted up a list comparing the 80 series stopping distance to other vehicles. While it's not a strictly fair comparison (braking distances change from day to day and track to track), the 80 series stopped every bit as well as any other SUV or truck, and as good as some sedans!

If you think about it, there's a point when the brakes working any better won't actually help you. Either because the ABS will kick in and prevent the brakes from working "better," or the tires locking up and doing the same.

Most people when they switch to the aftermarket pads/rotors/whatever rant and rave about how awesome they are. Well....yeah. You replaced old worn out stuff with new stuff.

I've replaced the rear rotors/pads/calipers (along with front pads) in the rig, and the front calipers/pads (along with rear pads) in mine. The difference was night and day. The rig will throw you through the windshield, and in my rig I was able to panic stop going down a crazy steep grade while towing a 3k lb boat.

Honestly I don't see how you could get any better than that. Nothing against the aftermarket stuff (though I'm not a fan of drilled and slotted rotors), but a lot of the aftermarket stuff I've seen isn't as large and overbuilt as the OEM stuff.

 

[UCBerzerkeley]

Another thing is that our rigs will never have the precision braking of say, a BMW. Every time I drive my girlfriend's 3-series, that first stop sign, I nearly throw us both out the front window.

 

[Filmpros]

I have seen a lot of guys who say that on here but obviously, they either have lighter trucks than I do or they have never tried aftermarket pads and Rotors.

Trust me, the Hawks Pads are a BIG Improvement over stock on BOTH my trucks. One weighs 7,000lbs and the other weighs 8,000lbs. The stock brakes were not cutting it at all.

Upgrading to Hawks Light Truck Series (LTS) Pads and DBA Rotors made a big difference. This is what worked best.

HB312Y.591 Disc Brake Pad; LTS w/0.591 Thickness; Front; HB477Y.610 Disc Brake Pad; LTS w/0.610 Thickness; Rear;
I then went to a heavier Hawks Super Duty Brake Pad up front and had all the calipers rebuilt because my Drivers Front was sticking.

Now it does not stop well at all when cold...but it does get better when hot.

We are changing out the Master Cylinder and going back to the Light Truck Series pads up front to see if that makes a difference.

Bottom line - You can greatly improve on the braking over stock as long as you don;t try to OVER improve it like I did...

In the newer trucks, yes.


Honestly I don't think you can actually improve on the braking in the 80's.....IF everything is working the way it should.

Tools (I think it was Tools....) posted up a list comparing the 80 series stopping distance to other vehicles. While it's not a strictly fair comparison (braking distances change from day to day and track to track), the 80 series stopped every bit as well as any other SUV or truck, and as good as some sedans!

If you think about it, there's a point when the brakes working any better won't actually help you. Either because the ABS will kick in and prevent the brakes from working "better," or the tires locking up and doing the same.

Most people when they switch to the aftermarket pads/rotors/whatever rant and rave about how awesome they are. Well....yeah. You replaced old worn out stuff with new stuff.

I've replaced the rear rotors/pads/calipers (along with front pads) in the rig, and the front calipers/pads (along with rear pads) in mine. The difference was night and day. The rig will throw you through the windshield, and in my rig I was able to panic stop going down a crazy steep grade while towing a 3k lb boat.

Honestly I don't see how you could get any better than that. Nothing against the aftermarket stuff (though I'm not a fan of drilled and slotted rotors), but a lot of the aftermarket stuff I've seen isn't as large and overbuilt as the OEM stuff.

 

[Filmpros]

That is like my Mom's Honda CRV ... When I drive it, which is like 3 or 4 times a year, I do the same thing...

Another thing is that our rigs will never have the precision braking of say, a BMW. Every time I drive my girlfriend's 3-series, that first stop sign, I nearly throw us both out the front window.

 

[landtank]

Using pad wear as an indicator of proper brake biasing is just not correct.

When my truck was stock I got about double the life out of the rear pads than I did with the fronts. Now if I loaded that truck up with junk it would obviously apply more braking to the rear which would accelerate the wear as well.

The fact that you altered the spring rate and possibly even went to a progressive spring would mean that the factory recommendation will no longer apply. The LSPV no longer sees the same rate of change per LB of added weight so it will no longer compensate for that weight according to the original design.

Take the truck out to a dirt lot where you can do some panic stops, disable the ABS and adjust the valve to give you the proper bias based on wheel lock up. IMO that will give you the best running setup. What that means as far as pad wear goes would depend on how the weight is distributed in the truck.