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Write-up: Toss the LSPV and install a manual proportioning valve (9 Viewers)
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lumbee1
Native American
I marked the "W" on the top of the Wilwood proportioning valve. At full open, the rear would lock sooner than the front. I set it to 3 turns from full open. I recently replaced the brakes and found the rear brake pads almost gone with a decent amount of meat still left on the front brakes. I installed new OEM pads (100 series in the front) and set the proportioning valve to 6 turns from full open. I think I measured 15 turns from open to closed.
Takes some experimenting to find the best setting.
A P-Valve doesn't operate like many folks think (like a gate valve). The adjusting knob/shank simply applies more or less pressure to the spring inside the valve which establishes pre-load on the piston. In essence... it is a pressure regulator that we can set to operate at a certain pressure threshold. The ratio is predetermined by the piston.
The valve actually does nothing during normal driving/braking situations.
With respect to nomenclature... the easiest way to describe the setting is to still refer to it being more Open or Closed...even though that isn't what is taking place inside the valve. Knob position In or Out is actually what we do and what controls the pressure threshold for activation. I only mention that so folks understand the two terms mean the same thing.
How Does a Proportioning Valve Work? And How Do You Adjust It?
When setting up a street car for performance driving or converting a classic to disc brakes, it is essential to include an adjustable proportioning valve in your brake system. This valve is typically plumbed into the rear brake line or built into the combination valve below the master cylinder...
shop.wilwood.com
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lumbee1
Native American
Thank you for the link!Takes some experimenting to find the best setting.
A P-Valve doesn't operate like many folks think (like a gate valve). The adjusting knob/shank simply applies more or less pressure to the spring inside the valve which establishes pre-load on the piston. In essence... it is a pressure regulator that we can set to operate at a certain pressure threshold. The ratio is predetermined by the piston.
The valve actually does nothing during normal driving/braking situations.
With respect to nomenclature... the easiest way to describe the setting is to refer to it as being more Open or Closed...even though that isn't what is taking place inside the valve.
How Does a Proportioning Valve Work? And How Do You Adjust It?
When setting up a street car for performance driving or converting a classic to disc brakes, it is essential to include an adjustable proportioning valve in your brake system. This valve is typically plumbed into the rear brake line or built into the combination valve below the master cylinder...
alia176
SILVER Star
Excellent information, thank you for that. I needed this education as well.Takes some experimenting to find the best setting.
A P-Valve doesn't operate like many folks think (like a gate valve). The adjusting knob/shank simply applies more or less pressure to the spring inside the valve which establishes pre-load on the piston. In essence... it is a pressure regulator that we can set to operate at a certain pressure threshold. The ratio is predetermined by the piston.
The valve actually does nothing during normal driving/braking situations.
With respect to nomenclature... the easiest way to describe the setting is to still to refer to it being more Open or Closed...even though that isn't what is taking place inside the valve. Knob position In or Out is actually what we do and what controls the pressure threshold for activation. I only mention that so folks understand the two terms mean the same thing.
How Does a Proportioning Valve Work? And How Do You Adjust It?
When setting up a street car for performance driving or converting a classic to disc brakes, it is essential to include an adjustable proportioning valve in your brake system. This valve is typically plumbed into the rear brake line or built into the combination valve below the master cylinder...
Doing this later today. @flintknapper Can you share any pictures?I saw multiple ways of getting this done in different threads.
You deleting both ABS and LSPV?
Will you be using a manual Proportioning Valve....or no?
Deleting both. Using a flying miata kit, willwood valve and thread adapters. Ordered few extra 3/8th 8’ universal brake lines. Plan was something along the line of
MC (rear line) -> thread adapter -> universal brake line -> prop valve -> universal line into toyota line.
Now that I wrote it out, I think I’m missing an extra elbow or male to male joint fitting. Maybe I can bend OEM brake line. I’m not sure how long the rear brake line is, if it can reach to the prop valve.
First order of business is to mark your brake lines (or take good pics). Then remove the ABS unit so you'll have more room to work.
Then decide where you want your Proportioning Valve to be. The spot you pick will dictate whether or not you can reuse a factory line or make one. You don't have to mount it to anything....but I chose to make a mount to attach mine to the inner fender well. I had a piece of 1" x 1/16" flat stock handy, so it was easy to bend.
Your routing for the brake lines can take any form you like, but do try to leave enough room to replace either the Master Cylinder or Brake Booster in the future. It would be easy to 'paint yourself into a corner' with short brake lines that look nice but would all have to be removed later in order to replace anything.
Your proportioning valve simply gets the front line from the M/C (which is for the rear brakes) connected to the 'In' side of the Pvalve and the 'Out' side goes to your rear brakes.
The rear port of the M/C is for your front brakes. So just take that port (line) and run it to your 'Tee' (factory Tee reused or a new aftermarket). From there your two front brake lines (left and right) also attach to the 'Tee'.
Plumbing wise, you are finished under the hood. How you choose to run the lines is up to you, but basically we are just omitting the ABS and connecting the front brake lines to the M/C and the rear brake line to the M/C but with a Pvalve inline.
Continued next post for LSPV info.
When you get to the LSPV you will see that it has 3 lines. One of the lines ( the lower left) is the 'sense line' that goes from the LSPV to the 'Tee' under the Master Cylinder (in OEM configuration). This line will NOT be used again and can be removed or left in place but it has no function for us any longer.
The two upper lines on the LSPV are what we need to join together. Some folks use the 'L' removed from the line up under the drivers side wheel well. I chose to simply use a 'Tee' that I already had and blocked off one port. Others have bent the factory lines and use a simple coupler. Whatever you decide is fine. Just join the lines together.
IF you need pics of anything else or have questions, just let me know. I have other pics, just trying to keep this brief.
Note: Brass plug in Tee will be replaced with a steel High Pressure Suitable one. It's just what I had on hand for testing.
The two upper lines on the LSPV are what we need to join together. Some folks use the 'L' removed from the line up under the drivers side wheel well. I chose to simply use a 'Tee' that I already had and blocked off one port. Others have bent the factory lines and use a simple coupler. Whatever you decide is fine. Just join the lines together.
IF you need pics of anything else or have questions, just let me know. I have other pics, just trying to keep this brief.
Note: Brass plug in Tee will be replaced with a steel High Pressure Suitable one. It's just what I had on hand for testing.
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alia176
SILVER Star
Awesome sauce Flint, thank you for taking the time to write this up, amigo
Just to clarify if just deleting LSVP for now, I join the two lines at the rear as described above. That i'm clear on.
Then under the hood you just need to connect ports #2 and #3 in this pic from the original post?
Are you wanting to delete the LSVP and NOT add a proportioning valve or delete and install a Pvalve?
this might be helpful
I’m your picture,
The coiled up line get removed. It feeds fluid to the ABS for the rear brakes. Rear brake line, lower left most ABS line, gets connected into outer MC port.
Remove the jumper from rear of MC and the tee is attaches.
Line in the bottom right corner(this line runs on top of the brake booster), underneath line 2, gets connected to the new tee.
Line in the lower middle of ABS is another front line and it attaches to the new tee.
Then you need a line from the rear of MC to the new tee.
This is what I got so far
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Couple of pics of the ABS unit and OEM routing....for those visual learners (like me).
The ABS unit has top and bottom 'tiers'.
The TOP tier pictured below accepts the brake lines as follows:
The line labeled 'front' (for the front brakes) comes off the bottom of the 'Tee'. The line labeled 'rear' comes directly off the M/C port for the rear brakes (which is the port nearest the front of vehicle).
The Bottom tier distributes the fluid as seen below. There is a single Rear line that runs to the rear of the vehicle (and the LSPV). The two Front lines are separate Left & Right.
OEM routing '95-'97
The ABS unit has top and bottom 'tiers'.
The TOP tier pictured below accepts the brake lines as follows:
The line labeled 'front' (for the front brakes) comes off the bottom of the 'Tee'. The line labeled 'rear' comes directly off the M/C port for the rear brakes (which is the port nearest the front of vehicle).
The Bottom tier distributes the fluid as seen below. There is a single Rear line that runs to the rear of the vehicle (and the LSPV). The two Front lines are separate Left & Right.
OEM routing '95-'97
I learned that the “long” style OEM fitting will not work with the adapters (not enough thread engagement), so you have to use the “short” side. This caused me a headache as I had to rebend one of the lines, and it looks like crap.
LSPV deleted. Rebuilding the rear and then we’ll see how it feels.
Good Job! Take your time on the rear caliper, get it good and clean. Your pistons look good.
Did mine a few years ago, still working great.
Am I crazy for thinking that deleting the LSPV and maintaining ABS will prevent the rear from locking up?
The system is already inherently front brake biased based on piston # and size.
The system is already inherently front brake biased based on piston # and size.
