Decoding prop. valves?
bam-bam
Council Member
From my reading and searching, I see that I need the brake proportioning valve from a DA Integra to match my new EX front/DA rear disc conversion, makes sense to me, but...
Does anyone know what the numbers on the valves signify? The one on a still-complete DA I have is a 4040. I have a loose one here that I would almost swear came from another DA, it says 3540.(This one may have come from an EX sedan, but I didn't think so) Stock wagon says 3030. Are these 4-digit numbers just code, or are they percentages or something?
Also, I read that the prop.valve is sequential, sending fluid to the rear first because of larger volume/distance, then once it opens just acting like a big hub or manifold. Really?
Does anyone know what the numbers on the valves signify? The one on a still-complete DA I have is a 4040. I have a loose one here that I would almost swear came from another DA, it says 3540.(This one may have come from an EX sedan, but I didn't think so) Stock wagon says 3030. Are these 4-digit numbers just code, or are they percentages or something?
Also, I read that the prop.valve is sequential, sending fluid to the rear first because of larger volume/distance, then once it opens just acting like a big hub or manifold. Really?
Comments
Changing the proportioning valve;
"When you swap around brakes, you should also change the proportioning valve so it balances out how the brakes work. The weight distribution is also a factor.
This gets into a real "dark" subject that nobody has valid answers for!
The early Hondas and Integras use proportioning valves that are all the same on the outside. There are numbers stamped in them and the idea is that it has something to do with the proportioning "ratio". However, I couldn't find anybody that could tell me what the numbers really mean. Believe me when I say that I looked real hard. The information is not available outside of the factory in Japan, as far as I can tell.
The most common recommended valve is marked "4040". I couldn't find one and got a "3540" from a car that had similar brakes and weight distribution. It's worked just fine!
There are just two things that have to be addressed.
The first is that you have to use a flare nut wrench to prevent rounding off the nuts.
The other is that the steel bracket needs to be swapped. All you have to do is use some vise grips to remove the two screws and then replace them with normal bolts."
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Goto down to the end & read Brake Bias - Proportioning Valve.
In my research,I've found as little as you.My theory is the numb3rs will tell u the rate the fluid flows,% of fluids going forward or rearward & if it goes forward or rearward first.If the num63r5 I read do mean something,then I disagree with Brakeexpert 'cuz I've seen a drum prop.valve on a OEM 4 whl.disc Accord.So if you're using the 4040 .How would the 3030 work :?:
By the way how did you adapt the rear disk? did you fab a bracket? I'm dying to have that rear disk conversion too for my 88RT.
Thanks again.
wagon.......................................4ever
The 99-00 Civic Si comes with the same shaped proportioning valve as any 96-00 Civic, so swapping the proportioning valve is a bolt on job, which can be done with a few offset brake line wrenches. The stock drum proportioning valve, when the brake pedal is applied, sends fluid to the rear drums only. This is because the drum shoes are a few millimeters from the drum, so the fluid initially moves the pads to touch the drum, whereas with a pad and rotor, the pad is so close that it brushes along the rotor while driving. After the shoe touches the drum, the proportioning valve sends fluid to the front calipers as well, and then acts as a hub for the fluid. So a rear drum intended prop. valve in a car with four wheel discs is not the end of the world.
The 99-00 SI proportioning valve acts as a hub more of the time, since the back brakes are calipers, there is no need to send so much fluid initially to the back brakes because they are calipers, and use pads that also brush against the rotor constantly. Therefore, a rear disc intended prop. valve in a car with front discs and rear drums would be very bad.
When you swap from drum to disc rear brakes, obviously its best that you use a prop. valve that was meant for it. Though I recommend that you install the 99-00 Si prop valve on your 96-00 Civic when you put rear discs on it, because of how it works, I do not have it on my rear disc equipped 1996 Civic. I do not track race, and have good tires, and on the streets, have not locked up the rear tires before the fronts because I can brake very hard and not lockup the tires. I do not have ABS.
(end quote)
(Disregard the '96-'00 part, the theory applies) From this I glean that you DON'T want to put a disc/disc prop. valve on a disc/drum car, presumably because of the danger of locking/sliding the rear wheels. My suggestion in your case would be to get one from a '90-'91 EX sedan- that's the most similar setup I can think of.
I adapted the rear discs by modifying the wagon trailing arms to fit the Integra disc spindles. There are pics in my thread, but mine is 2wd. I don't know how different the Rt arms would be, I've never actually looked at any.
http://www.stoptech.com/tech_info/tech_ ... pers.shtml
not Honda-specific, but lots of tech.
edit: more specifically on topicvv
http://www.stoptech.com/tech_info/wp_pr ... lves.shtml
i just got the EX prop valve from the JY and its 3540. I will try to put this on and see if this is better than the stock RT prop valve.
wagon..........................4ever..........................
From reading the stoptech pages above, I gather that valve functions backwards from the first info I posted, i.e. flows evenly to front and rear up to a point, andthen does its thing. It's all very confusing.
To recap: I think I'll just trust Honda's engineers, they seem to have been good at their job!
Since my setup is practically identical to the DA, I'll use that PV.
ricefighter, since an EX is the closest thing to yours, I think the 3540 is wise.
wagon...............................4ever..............
I actually bought a cheap set at Advance (3 wrenches for $16!
so heres the update!!!
to review my brake set-up is 11.1" legend/prelude for the fronts and stock drums for the rears on my 88Rt4WD. my brake master cylinder is 15/16". i did got a 3540 and 4040 prop valve but i opted to install the 4040. the nose diving characteristic is minimized or even elimanated. i also observed that i can lock up the fronts during hard braking. however there was no rear wheels locking experienced. i am bit satisfied for now but i am still dreaming of that rear disc conversion.
im sorry but i don't mean to jacked this thread, just sharing of what i observed from the upgrade. thanks
wagon......................................4ever..........................
Okay here is what I know, I'm much more of an EK expert, though the theories of hydraulics applies still.
For cars with rear drums -
While calipers work with pads in constant contact with the disc (even when you do not push the pedal), drums do not touch. There is a gap, that has to do with its design. A rear drum brake like ours is going to have three springs. These springs in essence hold the drum's shoe where it is suppose to be. When the pedal is depressed, you are pushing fluid from the MC to the drum slave cylinder. For the first part of the pedal stroke, fluid is sent ONLY to the rear two brakes. If this did not occur, the front brakes would engage first, resulting in more than needed nose dive. Then as the pedal pushed more, the rears would engage, causing a slight snap as the rear brakes start to slow the car.
Because of this, drum prop. valves (I will not comment on other makes of cars) send fluid just to the back first, and then the rest of the pedal stroke acts more like a hub.
The only really undesirable setup then is if your car came stock with discs - a stock disc prop valve, and you changed the rears to drums. I have not heard of this to feel how the car drives because most everyone wants to convert the rear to disc. Only a very few track racers have I seen convert the back to drums for weight reasons with custom applications.
Regarding the numbers...I don't know. I have run over 30 different front/rear brake setups on my EK and all of which have had 16" wheels and performance tires. The braking is so good that I don't have bias problems. The car stops so well that getting the front or rear to lockup before the other is just not something that happens, the only time I prematurely locked the brakes before the tires got the most of their stopping power was when I had NSX Type-R rear brakes (the car was about 70% rear biased at the time, where stock our civics are about 30-20% rear biased which is more appropriate.)