The proportioning valve for drum brakes allows the pressure to equalize before pressure is applied to all 4 wheels. When you have a caliper in the rear instead of a wheel cylinder then the pressure is not alleviated by a return spring on the drum brake pads. This means that no gap is lost from the pads and friction surface therefore there will not be a need for pressure equalization. Your stock prop. valve is an automatic unit and will be able to differentiate the difference and will have no adverse effect on braking. There will be no lag or acceleration in rear brake application like the rumors and misinformed indivuals will tell you.

There are tons of people in Honda Challenge racing with stock drum prop valves racing with 4 wheel disc. If the prop valve adversely effected the vehicle, none of them would even touch the stock unit, except to remove it.

the proportioning valve has nothing to do with pressure distribution.......in a hydraulic system all pressures equalize over time. The proportioning valve is designed to allow a quicker pedal response for drum brake vehicles by allowing the rear brakes to get the brunt of the fluid first to allow for the pads to make contact. As soon as there is resistance then the pressure through out the system equalizes immediately. Therefore, if you have very little to no gap (like every disc brake on a Honda) then you will have no deviation in pressures between the front and rear brake fluid distribution.

The prop. valve acts as an automatic orifice tube that senses pressure equalization. Once pressure throught the system is qualized then the porp. valve is nothing but a brake fluid passage.......that is it.

Do not confuse a Proportioning valve with a brake control metering valve. The metering valve (kinda like Wilwood's adjustable unit) is nothing but a controlled orifice that is not allowed to alleviate after pressure is equalized.

I will post up Honda's explanaiton of its function as soon as I find it on ISIS.

 

I'm sure you have probably seen this, but what is your take on this guys opinon?

http://stoptech.com/tech_info/...shtml

 

did you happen to notice that he was talking about a Mechanical proportiong valve that is found on dual master cylinder setups......it was not very clear but it is apparant that was what he is referring to. I have done brake adjustment using the systems he referred to in his article and it has nothing to do with what I am referring to.

 

I thought I had a visual of what he is referring to but I was mistaken.....maybe I will take a picture the next time I am at the race car shop doing some welding.

 

So basically what you are saying is that the oem proportioning valve sends fluid to the rear drums to "take up the slack" between the shoe and the drum and once the "slack" is taken up the pressure is 1 to 1 on the front and rear brakes. I'm not sure I believe that. Have you ever done a rear disc conversion and left the prop. valve then switch to a disc prop. valve later?

 

Also on the honda challange cars do they use oem brakes front and rear or do they swap calipers/rotor sizes. All of that will affect the brake bias and they can compensate for that by selecting different sizes of pistons in their calipers.

 

HC guys usually have disc brake conversions and use larger brake setups in teh front. I have experienced that almost all of them have not changed proportioning valves and there were not and continue not to be any rear brake bias issues.

 

Thanks for the informative post! I only hope it's correct!!!

I'm still leaning on swapping out my Prop Valve for the EM1s, but it's now mostly because my butthole is this big:

.

when it comes to EMu1ating my setup. The money's already spent... I've heard of mounting problems, and if I encounter any, I'll guinnea pig my stock PV with the disc setup and post my experiences... posthumously if need be...

That's why they call me
JasonGhostz

Thanks again for the clarification

 

So why does Honda/Acura use several different valves on it's various vehicles?

 

due to hose lengths, master cylinder, caliper size, drum size etc.

 

then why: does a 2000 civic ex with factory rear drum brakes have a different prop. valve than a 2000 civic si with rear disk.

they both have the same size MC, the same front calpiers and rotors and brake hoses, and same hard lines ran through the car.

the only difference is the rear brake system. so there must be something to the different prop valves????

 

dirty sol...good post. check your pm please

 

Side Question.

My old VeeDub had somehting they called a "proportioning valve". it was towards the rear of the car and was actually liken mechanically to the rear suspension. the more weight you had in the rear the more the "porportioning valve" would actuate. Is this actually the correct use of the term "proportioning valve" or am i thinking of somehting else?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by built562 &raquo;</TD></TR><TR><TD CLASS="quote">then why: does a 2000 civic ex with factory rear drum brakes have a different prop. valve than a 2000 civic si with rear disk.

they both have the same size MC, the same front calpiers and rotors and brake hoses, and same hard lines ran through the car.

the only difference is the rear brake system. so there must be something to the different prop valves????</TD></TR></TABLE>

The prop valves for 96-00 Honda Civics are all the same part numbers, regardless of whether they are DX, CX, LX, EX or Si. Check on http://www.slhondaparts.com/br...=true:

46210-S04-902 VALVE ASSY., PROPORTIONING - 2000 Dx Hatch

46210-S04-902 VALVE ASSY., PROPORTIONING - 2000 Si Coupe

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dynamo &raquo;</TD></TR><TR><TD CLASS="quote">

The prop valves for 96-00 Honda Civics are all the same part numbers, regardless of whether they are DX, CX, LX, EX or Si. Check on http://www.slhondaparts.com/br...=true:

46210-S04-902 VALVE ASSY., PROPORTIONING - 2000 Dx Hatch

46210-S04-902 VALVE ASSY., PROPORTIONING - 2000 Si Coupe

</TD></TR></TABLE>

hate to break your bubble, but the dx and si share the same prop valve.

the ex prop valve is part number 46210-S04-962, not the same as the si.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DirtySol &raquo;</TD></TR><TR><TD CLASS="quote">due to hose lengths, master cylinder, caliper size, drum size etc.

</TD></TR></TABLE>
So if Honda felt it necessary to change proportioning valves when changing some of these items, then why shouldn't we? Something is just not clicking here.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Targa250R &raquo;</TD></TR><TR><TD CLASS="quote">
So if Honda felt it necessary to change proportioning valves when changing some of these items, then why shouldn't we? Something is just not clicking here.</TD></TR></TABLE>

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Targa250R &raquo;</TD></TR><TR><TD CLASS="quote">
So if Honda felt it necessary to change proportioning valves when changing some of these items, then why shouldn't we? Something is just not clicking here.</TD></TR></TABLE>

thats what Im saying about the civic ex and si prop valve, why would they change them, there has to be somthing behind it

 

Thank you!

This is what I've been posting for over 2 years, the porp valves don't do what most people think. Change it if you want to but for most people in most driving scenarios it's a waste of time.

BTW: I race Honda Challenge, H1 and have been running a 99-00 civic SI rear disk swap and an ITR front caliper w/11" 2pc front rotor for over the past year on my 97 CX hatch. Original porp valve, w/ ITR M/C and booster.




Modified by 6ghatch at 2:49 PM 11/28/2005

 

Nobody is saying it doesn't work...we're just wondering why Honda used different valves in the first place?

 

i think the reason of the this post has gotten lost...

he was stating that

1. its not bad to run on the stock (rear drum) propotioning valve if you swap to rear disk's
2. the propotioning valve isnt much different from rear disk to rear drum
3. its not that it doesnt work, but the information being spread around is not true for why you should change it

my take on it... you will be fine using the same ro swapping prop. valve...

i swapped mine... it wasnt expensive... and it wasnt hard.

but i do beleive that the parts are a bit different.... honda wouldnt make 2 different parts if they didnt have too.

good post... but some actual proof would make it go down easier to some.... like flow comparison per side of the valve.

 

i swapped out my rear drums for discs and havent been able to change my prop valve because one of the nuts stripped, and my pedal feel is the same as it was with the drums.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pornstarSR &raquo;</TD></TR><TR><TD CLASS="quote">i think the reason of the this post has gotten lost...

he was stating that

1. its not bad to run on the stock (rear drum) propotioning valve if you swap to rear disk's
2. the propotioning valve isnt much different from rear disk to rear drum
3. its not that it doesnt work, but the information being spread around is not true for why you should change it

my take on it... you will be fine using the same ro swapping prop. valve...

i swapped mine... it wasnt expensive... and it wasnt hard.

but i do beleive that the parts are a bit different.... honda wouldnt make 2 different parts if they didnt have too.

good post... but some actual proof would make it go down easier to some.... like flow comparison per side of the valve.</TD></TR></TABLE>

I will do my best to show proof when I figure out a way to convert Adobe Acrobat to a .jpg file

 

if that becomes too much of a pain i got a teeny program off the net called Capture that takes a photo of the whole screen, so if your lookin at a movie or pdf, itll save that screenshot to a jpg or bmp.

 

Great post. BTW, open the file in photoshop, select the page you want to open and then save as JPG.