LPSV replacement tips

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namsag

namsag

10 Year
Joined
Mar 23, 2015
Threads
54
Messages
323
Location
north Mississippi
My LSPV was a collateral casualty of my rear lift installation so I guess I will replace it (yes, I have read the threads about deleting it). I think I must have let the rear end down too fast/far and the valve is leaking from the sensing spring boot on the bottom. The underside of my cruiser is not bad at all but oddly the LSPV is basically a ball of rust so out it will come. This ought to get interesting.

I am looking for some pearls/pitfalls from those who have experience in replacing this valve. Also I am wondering what exactly do I need to order. The valve alone, or do other parts (boots, bushings, load sensing spring, etc) need to be changed as well?

I have an FSM and I have familiarized myself with the section on LSPV but tomorrow I will just have to get under there with the manual pages in my hand and have a closer look to get myself oriented, and then get the parts ordered.

Any advice appreciated, thanks,
namsag
 
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I had mine go bad as well, it took for ever to diagnose it. All symptoms pointed to a MC or bad hoses, the list goes on. I deleted mine, the only difference I could see is that the brakes work again.
 
Eventually I will replace my soft lines as well. Lines have been flushed and calipers and pads gone through. I was working on other things but as often happens with old vehicles, this problem jumped the line for immediate attention.

I would prefer to keep everything stock.
 
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Well I spent most of last night reading the threads about deleting ABS and LSPV. I'm sure it seems to some like a great idea. But I would have to think the Toyota engineers put those systems in place for good reason. I saw some thought-provoking posts by Idaho Doug and several others on the subject. For legal and insurance reasons I would prefer to have all systems functioning as close to stock design as possible. I guess we each have to do what we are comfortable with. My "lift" kit is an OME stock height so hopefully I can get the LSPV replaced and get it adjusted appropriately. I will try this before I am anywhere near ready to go messing with Toyota's design on a system as critical as the brakes.
 
Adjustment is misunderstood and unnecessary. It is only for when the rear is loaded with the said weight in the FSM to compensate in a STOCK setup. With the additions of bumpers, winches, gear and stiffer lift springs all that goes out the window. Also, after enough lift is added the angle of the upper control arm interferes with the LSPV's arm. However, most importantly the LSPV operates independent of lift height as would any other type of static proportioning valve so deleting it would be dumb. This leads to unsafe rear brake pressure and rear lockup long before the fronts.

I will acknowledge that the LSPV is a bitch to bleed adequately and has caused me much grief on my previous mini-trucks and LC. I have found that it is necessary to employ multiple techniques to bleed the system once the dreaded mushy pedal manifests after replacing brake parts. I use a power bleeder at 30 psi to push new fluid thorough, the phoenix reverse bleeder and the two man method.

I would recommend removing the MC cap and filter cup, then placing a piece of cellophane wrap over the opening tied off with a rubber band. Then open the bleeder on a rear caliper and let it gravity bleed a bit. You should notice the cellophane being pulled deep into the MC reservoir if you have an air tight seal. This will prevent the hard lines form gushing fluid when you remove them from the LSPV and it reduces the possibility of air being pulled into the hard lines. Remove the old valve and replace with new one and then remove cellophane. Using the two man method, bleed the LSPV at each hard line first (cracking the fitting just as you would a bleeder valve), then the LSPV bleeder valve, then the rear calipers and then back to the LSPV bleeder valve. There should be no reason to bleed the front calipers.
 
Having done this three times in the last six months, and preparing to do one more before summer, I can share my experiences, FWIW.

Get a new valve and boot kit. And a gallon of fluid (now is the time to flush the system). And a quart of denatured alcohol to clean up the spilled fluid. Be very OCD about cleaning up after yourself or you will never find any leaks. Soft lines would be on my list too, if I could afford them (all six).

Don't bother trying to remove any rust; it's due to brake fluid residue which was never cleaned properly. If the two 8mm nuts don't comply, remove the valve with a sawzall and metal cutting carbide blade. Get the blade with the smaller end; the one with the wide blunt end runs into the frame and bends easily.

It will take longer to jack up the rear end (which you will have to do) than to remove the valve. I have it down to five minutes now. Start cutting between the valve and bracket on the inside first. Lower right bolt (looking forward), then the upper center pin, then the lower left bolt.

You can move the brake lines out of the way, just be careful, they are old.

Don't pry or beat on the bracket, it's too thin and will warp. Then you will have a problem because the two bolts on the fuel tank side are a PITA to remove.

Do not follow the FSM to install the rod and boot on the valve after you mount it. Do this on a bench. You will thank me later.

Center the valve on the bracket vertically, unless you thought ahead and marked the position BEFORE you removed it.

Do not worry about setting the rear end of the actuator rod per the FSM. It is already correct.

HTH
 
To fix the LSPV, unbolt the brakes lines and remove it from the frame. Throw it in the trash. Install either a M10x1.0 inverted T fitting or a union. If you install a union, you will need to plug the sense line at the T under the master cylinder.d
 
Option 3) toss the factory lspv and install a manual one under the hood if you think you need to have a front bias setup.

Anyone using the logic of liability or toyota made that way for a reason. I hope they only use OE parts and service there rig at the dealership. Oh lift, oversize tires and extra weight do nothing to the way your truck drives either. :confused: Better keep everything stock.
 
Here is a GREAT explanation of the proper operation of the LSPV, verified with pressure gauges: Diagnosing brake issues / adjusting LSPV with pressure gauges

For those professing to delete the LSPV please reference the chart in the above thread and note the unsafe rear brake pressure. In a panic situation the rear will lock and want to swap ends with the front, potentially leading to a nasty crash.

This is also a great explanation of the operation of the LSPV in the capacity of a static proportioning valve: Spongy low brake pedal LSPV revelation
 
Malleus said:
Having done this three times in the last six months, and preparing to do one more before summer, I can share my experiences, FWIW.

Get a new valve and boot kit. And a gallon of fluid (now is the time to flush the system). And a quart of denatured alcohol to clean up the spilled fluid. Be very OCD about cleaning up after yourself or you will never find any leaks. Soft lines would be on my list too, if I could afford them (all six).

Don't bother trying to remove any rust; it's due to brake fluid residue which was never cleaned properly. If the two 8mm nuts don't comply, remove the valve with a sawzall and metal cutting carbide blade. Get the blade with the smaller end; the one with the wide blunt end runs into the frame and bends easily.

It will take longer to jack up the rear end (which you will have to do) than to remove the valve. I have it down to five minutes now. Start cutting between the valve and bracket on the inside first. Lower right bolt (looking forward), then the upper center pin, then the lower left bolt.

You can move the brake lines out of the way, just be careful, they are old.

Don't pry or beat on the bracket, it's too thin and will warp. Then you will have a problem because the two bolts on the fuel tank side are a PITA to remove.

Do not follow the FSM to install the rod and boot on the valve after you mount it. Do this on a bench. You will thank me later.

Center the valve on the bracket vertically, unless you thought ahead and marked the position BEFORE you removed it.

Do not worry about setting the rear end of the actuator rod per the FSM. It is already correct.

HTH
Click to expand...

Hey guys i know this is 3 years old but I'll give it a go.

I'm replacing the LSPV with a genuine one. Im at the part where you wrote 'center the valve on the bracket vertically unless you thought ahead and marked it BEFORE you removed it.'

Well of course I didn't mark it first! I just ripped the stupid thing out and I have no idea where it was sitting vertically. How important is this and what changes by moving it up and down??

Thanks guys!
 
The position of the valve vertically relates to the input position of the actuator rod. Locate it on the bracket by eye and bleed it. It'll be OK.
 
I had my LSPV replaced about 4 months ago by a mechanic, didn’t have time to do it myself. It’s leaking again from the bottom, wondering if they put a faulty LSPV in or if it could be due to a bad connection…
 
Landschmoozer said:
I had my LSPV replaced about 4 months ago by a mechanic, didn’t have time to do it myself. It’s leaking again from the bottom, wondering if they put a faulty LSPV in or if it could be due to a bad connection…
Click to expand...
Could be any of that.

Properly diagnose and repair / replace.
 
Landschmoozer said:
I had my LSPV replaced about 4 months ago by a mechanic, didn’t have time to do it myself. It’s leaking again from the bottom, wondering if they put a faulty LSPV in or if it could be due to a bad connection…
Click to expand...
They did the work & charged you for it. Take it back & get them to fix it at their expense.
Anything you do now, will be tampering with what they did & then you'll be the one fixing it at your expense.
 
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