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ABOUT Proportioning valves

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miliman13

10+ Year Contributor
1,957
276
Jan 1, 2011
tampa, Florida
This at first was meant to be a how to fix your valve article...
But i failed. So i wanted to show my results and data.

I did a NON-ABS P-VALVE swap, unfortunately it was a bad valve.
Non of the rear brakes bleed, so i checked the valve and the ports for the rear were dry.
I soaked it in PB Blaster for 24hrs and nothing...

I destroyed it and found what i believe to be the cause... HARD braking may have damaged this valve before.

I also drilled into a ABS Valve for comparison and found that the aluminum piston inside was in better condition the other piston from the NON- abs one.


In my search i only saw illustrations, so i wanted to show the inner workings for members and visitors.



This is my illustration :
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The force of fluid is what pushes the piston forward and causes it to seal a small chamber where the rear brakes get their fluid from.
As you can see the fronts are unaffected by this motion. Which is essentially what this valves is supposed to do.

But the piston is made of a weak metal and may bend itself causing it to not return to position with the help of the spring.

Below is a view of the chamber i mentioned that leads to the rear.
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Here is a view of the front brakes
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And this is the view from the Master see how they in essence share the same galley
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Below is the inner working of the valve.
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And the one on the left is from a ABS which was working just fine. The one on the right is from the non ABS which was not working. See the difference, so even though i cannot with certainty say what the cause was it's possible to believe that extreme hard braking may have lead to this.
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Which brings up another point.....
If you are considering the NoN ABS swap, its a lot cheaper to just buy this valve and make your own hard line.



https://www.amazon.com/Wilwood-260-11179-Proportioning-Valve/dp/B003LT619Q/ref=sr_1_3?ie=UTF8&qid=1469310316&sr=8-3&keywords=proportioning valve

I mentioned it because getting screwed over is never fun...
And i believe its 250 usd for the swap from our favorite vendors.
and a used P-valve may leave you disappointed as it did for me.


I just wanted to give back, since this site and its members have always been there for me.
 
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Impressive detective skills.

I've never disassembled one, but those are by far the worst looking valves I've seen (in-bore) from any of the prop valves I've had in hand.

Good info and pics.
 
We've often wondered if an adjustable portioning valve would be the ultimate solution. It would be easy to adjust for mods like brake setups, tire changes, or fine tune track day performance.

Thanks for the warning. Brakes are just too important to not work perfectly.
 
We've often wondered if an adjustable portioning valve would be the ultimate solution. It would be easy to adjust for mods like brake setups, tire changes, or fine tune track day performance.

Thanks for the warning. Brakes are just too important to not work perfectly.
An adjustable valve is not the ultimate way to go but its a start, the ultimate way ideally is dual masters, with a bias valve your only limiting the rear brakes to a point and the front still gets full pressures reguardless or how the bias valve is on the rear, while some do report if its restricted to the rears the excess pressure goes towards the fronts i think that could be down to how each system works and this may aplly to our systems due to this valve inside.

Dual masters are the ulitmate way forward as your can pick and choose sizes and most of the time depending if its designed for it, they have whats called a bias bar! This is a great way to control F/R bias as you can infact move pressures from front to rear and not just control rears like on a bias valve. Overall its a much better system and infact the best system to use when thinking about this or racing.

Another thing to note is line, when doing this you dont really need to keep 2 lines going to the rear, thats only there for the ABS as its more controlable for the ABS system to each wheel then 1 lined ABS systems, so once you ditch ABS you can also ditch the 2 lines.

Me and another member (green goblin) are currently doing a dual Master and bias bar setup, we have not got anything in place yet and are both going in slightly different directions but the end result will be the same and as controlable as the other
 
<snip>
Another thing to note is line, when doing this you dont really need to keep 2 lines going to the rear, thats only there for the ABS as its more controlable for the ABS system to each wheel then 1 lined ABS systems, so once you ditch ABS you can also ditch the 2 lines.
<snip>

This is not quite correct, the dual rear lines are because the car has a diagonally split brake system, like most series production cars. The dual master cylinder ties the LF & RR to one circuit and the RF & LR to the other circuit. 2Gs have 2 separate rear lines whether they have ABS or not. I can't speak for 1Gs, but I would guess the same.

Regarding adjustable proportioning valves, the last time I checked (several years back) Wilwood (or anyone else that I could find) did not offer an adjustable prop valve that would retain the rear isolation - the rears had to be plumbed together, losing the diagonal split of the OEM setup. One could theoretically use two prop valves, but AP Racing and Wilwood advised against that because no two "click-adjust" APVs will have the same setting, it would require "stepless" APVs with inline pressure gauges on each to adjust correctly. Can be done, but that was outside SP rules back then.
 
This is not quite correct, the dual rear lines are because the car has a diagonally split brake system, like most series production cars. The dual master cylinder ties the LF & RR to one circuit and the RF & LR to the other circuit. 2Gs have 2 separate rear lines whether they have ABS or not. I can't speak for 1Gs, but I would guess the same.

Regarding adjustable proportioning valves, the last time I checked (several years back) Wilwood (or anyone else that I could find) did not offer an adjustable prop valve that would retain the rear isolation - the rears had to be plumbed together, losing the diagonal split of the OEM setup. One could theoretically use two prop valves, but AP Racing and Wilwood advised against that because no two "click-adjust" APVs will have the same setting, it would require "stepless" APVs with inline pressure gauges on each to adjust correctly. Can be done, but that was outside SP rules back then.
Ap racing does offer a dual in/out valve to keep the oem prop valve but its like $400+ so its pointless,

Reguarding the rear lines though, yes it may be produced like this by many but this is from goodridge and HEL brakes im quoting " they do this to better aid the ABS system" they keep it on the non abs cars aswell because its cheaper to produce 1 set of lines but they give the same pressures across both so going to 1 line does not make or have any difference in effect, also no effect change on the adjustable prop valve or even the oem valve if it was to be kept depending on what route is being taken, because its offering the same pressures,

So if i was to tie in from the oem prop valve straight away and have 1 line going back it was not make any difference and thats coming from 2 brake companys telling me this, i an see where your trying to come from as ive asked every question on why not keep the 2 lines a d they all said the same thing i their own wording. Going dual masters is of course the best way and having 1 line to a T back by the pump would be perfect,
 
That's very interesting that AP has that - they did not mention that when I talked to them; the date on the engineering drawing is 2009, the latest I would have talked to them about this would have been 2006, so perhaps that's why. The great thing for me is that now I'm not running SCCA any longer, I can use that APV; at $400 that's actually less than the cost of one brake rotor on my car, so it's peanuts in terms of budget...I'll probably spend more $$$ creating the brake lines for it and it will make everything _SO_ much easier...Thank you - that will be in my car in the next few months :)

I'm quite disappointed that the people you talked to at AP and HEL (particularly the AP representative, since they co-invented this innovation back when they were called Lockheed) did not understand what they were talking about. Tandem master cylinder with the diagonally split brake system was a 1960's safety innovation, long before ABS was even contemplated. My 1967 G15 had a single master cylinder pressuring all 4 wheels, my 1971 G15 had a dual master cylinder with a diagonally-split brake system. My '68 HB GT had a dual master cylinder with diagonally split system. Yes, I'm old - archaic even, I was born during the Suez Canal Crisis...

IIRC, the very first ABS that appeared was from Bosch on a Merc coupe in 1973/4 or so. My failing memory says they ran that car in the European rally championship that year to showcase the system, and that car was featured in an exclusive article in a late season edition of Cars and Car Conversions magazine that same year - I still have that edition. Somewhere...

Either way, the dual master cylinder/diagonally split brake circuits predate ABS by close on a decade, so the people telling you this have no concept of their history. The diagonal split affords a failed brake system a far better chance of stopping - 2 rear brakes barely equal even 50% of one front brake at speed. The idea is that the opposite corner rear brake limits the tendency to pivot around the sole remaining front brake. If the system was split front-to-rear- the car would be fine if the rear circuit failed, but completely F****d if the front circuit failed.

If your car is a competition car then by all means go to a bias pedal box - I drove that for 1 or 2 decades back in the UK every day - but understand that one master cylinder controls the front brakes, the other the rear brakes - if the front circuit fails you WILL crash in a HUGE way. Which is why WRC/ERC competition regs require a full roll cage when a bias pedal box is in the car. And many other requirements too, but do not lose sight of that coupling. Bias pedal boxes are not legal in cars that do not meet class regulations that also require 22-point roll cages. Used to be 8-point back in my day, then it became 12-pt, now apparently it's 22-pt...

Also, bias pedal boxes give you a million different settings - but only half a dozen of those are actually useful, the other almost-a-million will put you into a wall. Kind of like Penske 8760 dampers...Lots of bad days before you hopefully get a good day. Be careful what you ask for. The more adjustability you add to a vehicle the more opportunity you have to get it wrong.

And the less to get it right.

Ap racing does offer a dual in/out valve to keep the oem prop valve but its like $400+ so its pointless,

Reguarding the rear lines though, yes it may be produced like this by many but this is from goodridge and HEL brakes im quoting " they do this to better aid the ABS system" they keep it on the non abs cars aswell because its cheaper to produce 1 set of lines but they give the same pressures across both so going to 1 line does not make or have any difference in effect, also no effect change on the adjustable prop valve or even the oem valve if it was to be kept depending on what route is being taken, because its offering the same pressures,

So if i was to tie in from the oem prop valve straight away and have 1 line going back it was not make any difference and thats coming from 2 brake companys telling me this, i an see where your trying to come from as ive asked every question on why not keep the 2 lines a d they all said the same thing i their own wording. Going dual masters is of course the best way and having 1 line to a T back by the pump would be perfect,
 
That's very interesting that AP has that - they did not mention that when I talked to them; the date on the engineering drawing is 2009, the latest I would have talked to them about this would have been 2006, so perhaps that's why. The great thing for me is that now I'm not running SCCA any longer, I can use that APV; at $400 that's actually less than the cost of one brake rotor on my car, so it's peanuts in terms of budget...I'll probably spend more $$$ creating the brake lines for it and it will make everything _SO_ much easier...Thank you - that will be in my car in the next few months :)

I'm quite disappointed that the people you talked to at AP and HEL (particularly the AP representative, since they co-invented this innovation back when they were called Lockheed) did not understand what they were talking about. Tandem master cylinder with the diagonally split brake system was a 1960's safety innovation, long before ABS was even contemplated. My 1967 G15 had a single master cylinder pressuring all 4 wheels, my 1971 G15 had a dual master cylinder with a diagonally-split brake system. My '68 HB GT had a dual master cylinder with diagonally split system. Yes, I'm old - archaic even, I was born during the Suez Canal Crisis...

IIRC, the very first ABS that appeared was from Bosch on a Merc coupe in 1973/4 or so. My failing memory says they ran that car in the European rally championship that year to showcase the system, and that car was featured in an exclusive article in a late season edition of Cars and Car Conversions magazine that same year - I still have that edition. Somewhere...

Either way, the dual master cylinder/diagonally split brake circuits predate ABS by close on a decade, so the people telling you this have no concept of their history. The diagonal split affords a failed brake system a far better chance of stopping - 2 rear brakes barely equal even 50% of one front brake at speed. The idea is that the opposite corner rear brake limits the tendency to pivot around the sole remaining front brake. If the system was split front-to-rear- the car would be fine if the rear circuit failed, but completely F****d if the front circuit failed.

If your car is a competition car then by all means go to a bias pedal box - I drove that for 1 or 2 decades back in the UK every day - but understand that one master cylinder controls the front brakes, the other the rear brakes - if the front circuit fails you WILL crash in a HUGE way. Which is why WRC/ERC competition regs require a full roll cage when a bias pedal box is in the car. And many other requirements too, but do not lose sight of that coupling. Bias pedal boxes are not legal in cars that do not meet class regulations that also require 22-point roll cages. Used to be 8-point back in my day, then it became 12-pt, now apparently it's 22-pt...

Also, bias pedal boxes give you a million different settings - but only half a dozen of those are actually useful, the other almost-a-million will put you into a wall. Kind of like Penske 8760 dampers...Lots of bad days before you hopefully get a good day. Be careful what you ask for. The more adjustability you add to a vehicle the more opportunity you have to get it wrong.

And the less to get it right.

This is the dual in/out valve https://www.apracing.com/product_de...ever_type_prop_valves/twin_bore-cp4550-1.aspx im not sure when it was released but its out.

Im sure when they told me all this they must have over looked it on the stock dual line system but i did specify im going dual masters so maybe thats why they over looked it more and maybe it would have been a different convo if i was sticking to the stoxk lines and prop valve, but i dont know so i wont talk for them both LOL. So can i assume insode the stoxk prop valve both sides are seperated inside to keep this FR/RL - FL/RR split for safe braking if the system fails? As if its all in 1 how does that system manage to split it inside,

Duals can be dangerous and so can any system really, at least we have a seperate E brake to
help assist a bit and as long as the rear MC size is not overly too big then you will still be ok on pressures to at least be able to set the car down safely.

A couple other things i wanna say is i feel the bias valves are good if you want to reduce rear pressures but with brembos i really feel the need for more rear bias as the fronts just grab alot, it may be the pads im using (XP10 F - XP8 R) so i canot comment for everyone but with a bias valve i cannot increase pressures to the rear as the system wont allow that from stock form. So this only left me to switch to the dual masters and as im doing this im going to do the 1line rear to a T by the pump as i will be removing the non abs prop valve. Another safe way would be to install a hydro hand brake in the cabin for the front brakes, line line lock but less abrupt, so if Nything does fail you can activate it for hopefully a safe stop at least. Something to consider but doing this would be a job and a half to get it done right
 
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