Write-up: Toss the LSPV and install a manual proportioning valve (1 Viewer)

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I did the LSPV/ABS delete on my 93 with a bunch of new brake parts also.
I'm running 100 series Hawk pads in the front and regular "good" rear pads, truck locks the front wheels slightly before locking rears.
I got tired of trying to bleed an over complicated brake system with a dead ABS and just deleted everything but the basics. It does feel a lot better now, but I almost sold my truck due to the "mushy" pedal feel.
 
People need to hire better technical writers because I interpreted that differently than you did, but that doesn't make me right and you wrong.

What I read was that the lowest you could go is 43% less line pressure with the knob all the way out counterclockwise and by turning the knob incrementally clockwise the line pressure will increase all the way up to 100%.

So, I would assume (probably horribly) that no valve present is a balanced 50/50 braking pressure. If the knob is all the way out, does that take 57% of the pressure off the rear calipers and then all the way in restores the set back to 50/50?

This is why I don't mess with my brakes...I'm not even smart enough for a portioning valve conversation....

yup, I'm confused too. Hopefully someone will chime in who has better knowledge.
 
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so the way the I read that is with the valve out (counter clockwise) position the balance will be aprox 75/25 front to rear. the valve will be reducing the pressure to the rear by 53% on a 50/50 split. at full (clockwise) in it will go to 50/50 front to rear similar to as if the valve wasn't in place.
 
I feel like the phrase "Twist it 'till it feels good" fits this discussion.
 
The proportioning valve has no reference to the front brake pressure, so all it is doing is reducing the rear brake circuit pressure. It can be adjusted for no pressure reduction, down to a 57% pressure reduction. IOW, if the rear brake circuit is making 1000 psi (to keep the math easy), that proportioning valve can vary the pressure from 430 psi to 1000 psi.
 
yup, I'm confused too. Hopefully someone will chime in who has better knowledge.

After installing mine, I’m still confused. I guess a call into Wilwood tech on Monday is in order !
 
The proportioning valve has no reference to the front brake pressure, so all it is doing is reducing the rear brake circuit pressure. It can be adjusted for no pressure reduction, down to a 57% pressure reduction. IOW, if the rear brake circuit is making 1000 psi (to keep the math easy), that proportioning valve can vary the pressure from 430 psi to 1000 psi.
I *think* that this is correct, but when we're talking about braking systems, you don't really want to operate on what you think
 
It's not rocket surgery, a valve can't increase pressure, all it can do is let it flow 100%, creating a 50/50 bias, or you can let it restrict the rear by turning the valve down (CW), which limits the pressure going to the rear.
 
It's not rocket surgery, a valve can't increase pressure, all it can do is let it flow 100%, creating a 50/50 bias, or you can let it restrict the rear by turning the valve down (CW), which limits the pressure going to the rear.

Nope, but it might be rocket science.....
 
At the end of the day, clearly there are people out there pulling off and putting on bits and pieces of their braking system WITHOUT A CLUE!

Pretty scary huh?

regards

Dave
The in spec sheeple will cry foul. Mr T was forced to add on all the lawyer parts. Also, the first thing done to a million dollar Ferrari before a track day is pull all this lawyer sh*t off.
 
Whilst ABS is mandatory now I don't think it was back in the original spec back in 1986?

I still have my ABS and limiter. I have changed the spec of the discs though, dimpled and slotted all round and use Mintex pads, the whole kit came as a matched set and work great, I can still get them hot with some 'spirited' driving but they have a good progressive braking action and can bite and trigger the ABS if the pedal is pressed hard enough.

As a note I no longer use drilled discs, not because the various comments about cracks, if they are a good enough quality in the first place then they would not crack. The reason for me dropping them is the holes fill up with mud and little bits of the volcanic dust, apart from the noise the dust makes as it along with the little pieces of granite dries and falls out of the holes, the other problem is the particles fall into the path of the pads and get trapped, this then leaves loads of tramlines in the discs and the squealing can drive you nuts!

The dimples and slots are not deep enough to trap mud when I am crossing flooded rambla's, and have proven to be the perfect all round solution.

regards

Dave
 
good post... I delete de LSPV valve.. but didnt delete the return line to the front caliper.. to keep the pedal feel the same... the first time I delete the return line .. and was hard to tune the manual proportional valve... then I re instal the return line and know its much much better.. and my ABS works perfect
 
I am going to be deleting my ABS and LSPV soon but have a question. IF I need/want to make any new lines with fittings are ALL of them double flare (no bubble flares or something else) and are ALL the fittings inverted M10 x 1.0.

Anything else that would trip me up? Not interested in 'just use all the existing hardware' answers, I get that it can be done....but if I need to make any new lines....is reason for my questions. Thank You in advance.

Flint.

Edit to add: @Dave 2000 please do not respond to this.
 
I am going to be deleting my ABS and LSPV soon but have a question. IF I need/want to make any new lines with fittings are ALL of them double flare (no bubble flares or something else) and are ALL the fittings inverted M10 x 1.0.

Anything else that would trip me up? Not interested in 'just use all the existing hardware' answers, I get that it can be done....but if I need to make any new lines....is reason for my questions. Thank You in advance.

Flint.

Edit to add: @Dave 2000 please do not respond to this.

you can use a double flare for everything, i only deleted the lspv but was able to use all factory lines and fittings. if i remember correctly up in the first few paged i believe someone had a part number for a proportioning valve that was a double flare not a bubble. and unless your planning on making the lines with nico tubing the factory lines should be available and fairly cheap, i think my lines were only about 40 or so

671430%2fMC6039B_29_47311B_RL.png

Toyota Part No.: 90413-10058

i used the fitting pn above where the lspv went, i just had to make a short line and union for the sense line going back to the abs since i kept the abs
 
you can use a double flare for everything, i only deleted the lspv but was able to use all factory lines and fittings. if i remember correctly up in the first few paged i believe someone had a part number for a proportioning valve that was a double flare not a bubble. and unless your planning on making the lines with nico tubing the factory lines should be available and fairly cheap, i think my lines were only about 40 or so



i used the fitting pn above where the lspv went, i just had to make a short line and union for the sense line going back to the abs since i kept the abs

Thanks. So no quirky bubble flares to deal with? Everything will be (or I will need to make) double flares and use only M10 x 1.0 fittings.

I did find a proportioning valve that will work and I have ordered (received some of) the various M10 fittings I thought I might need as well as some bulk 3/16" line.

I'm not interested in the least in saving money....just want to do the job the best way I can and have a plan 'B'.

I'd rather just start with a new 'Tee' where needed and not have to butcher anything. Same in the rear, I can just make a union for the LSPV lines and not have to 'graft' an old one in from the front. Nothing wrong with that....but just easier (for me) to use new parts.

Still trying to get it straight in my head exactly where and what lines are omitted, rerouted or altered. But I guess I'll figure it out.

Thank You so much for your reply. Was beginning to think the question and thread was going to get lost.

M10 Fittings.jpg
 
I'm hoping to attack this project this spring 🤞
 
you can use a double flare for everything, i only deleted the lspv but was able to use all factory lines and fittings. if i remember correctly up in the first few paged i believe someone had a part number for a proportioning valve that was a double flare not a bubble. and unless your planning on making the lines with nico tubing the factory lines should be available and fairly cheap, i think my lines were only about 40 or so



i used the fitting pn above where the lspv went, i just had to make a short line and union for the sense line going back to the abs since i kept the abs
I thought that sense line was deleted when removing the LSPV even when keeping the ABS. Original post went through the ABS to the portioning valve and then to the rear. You have a diagram on how you ran yours?
 
I thought that sense line was deleted when removing the LSPV even when keeping the ABS. Original post went through the ABS to the portioning valve and then to the rear. You have a diagram on how you ran yours?
I agree, I didn't the sense line needs to return back to the ABS because it is only for their proportioning valve to detect when there's extra weight over the rear axle. However, I could very well be mistaken.
 
I agree, I didn't the sense line needs to return back to the ABS because it is only for their proportioning valve to detect when there's extra weight over the rear axle. However, I could very well be mistaken.

Doesn't the 'sense' line go back to the Tee/MC and then ABS?
 
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