98civdx

Well I learned something today!

Kozy.

Went back to check out the threads, but they end up just as vague. Some people claim there are stamps, others not. Some claim that on a brake tester rear discs with a drum prop provided virtually no brake force, others claim that it makes no difference but without any kind of testing. The only part number comparisons are the same ones here for the US models but some people are adament that the EJ9 and EK4 use different valves.

Basically, no-body truely knows. The people that sound like they know what they are on about say they are different, but there's no solid evidence.

94eg!

iTrader: (2)

Yeah, there is really no way to test the function. On the older style valves, you could take them apart (Honda says this ruins the valve) and compare color coded springs. But the EK style block valve is just a mystery. It's even more odd they use the same valve on some drum and disc cars. The best you can do is simply emulate a factory brake system on a factory stock car. This is why I recommend the Si/CX/etc valve.

Brake pad selection also has a major factor in brake bias. If your not running the same compound at all 4 corners, you're already in mystery territory. I have a 94 CX hatch that I added rear discs too once upon a time. I put the DA Integra 4040 valve in, but also put Axxis Ultimate pads in back (Raybestos crap in the stock front). These pads gripped so much compared the front that it was VERY easy to lock-up one or both rear tires, which causes the car to get sketchy. This is what you want to avoid when modifying your brake system. I should have at least put grippy Ultimate pads up front when I did this.

Recently I added larger EX front brakes with Stoptech pads. The bias was shifted back forward and the heavy braking stability returned.

Kozy.

Hell yes, changing the mu of the pads has a massive difference to brake force, often far in excess of the caliper and rotor assembly itself.

Back to the black art of prop valves, I guess I'm going to have to return to trusting my own thoughts on the subject. My thinking was that if BrakeExpert can run NSX rear brakes on a drum prop and not get rear lockup then the drum prop is seriously under-working normal rear disc setups. The NSX rears are well over double the power of the Si 9.4" rear rotors, assuming the Si proportions the the pressure for a safe 10% front bias at threshold braking then you simply could not run NSX brakes on the same valve.

Kozy.

Found a Japanese Honda EPC and looked up some part numbers. E-EK3 (drums) is different to the GF-EK4. Interestingly the GF-EK4 and GF-EK9 use different props and that's on two different four disk models of the same chassis. Figures otherwise the bias would be different even between those two.

46210-S04-801 on the EK3 (Drums)
46210-S04-812 on the EK4 (9.4" Discs)
46210-S10-862 on the EK9 (10.2" discs)

That is all the proof I need frankly. The props ARE different and you should use the correct one for your setup.

94eg!

iTrader: (2)

Cool stuff thanks.

I can definitely say the rear-drum prop valve underworks the rear brakes. When I pulled my rear drums off, the shoes barely had any wear on them whatsoever and it was only at one corner of each shoe. The car had something like 130k miles on it. But this was a 94 CX which could have totally different valving.

Libertariat

Maybe I can convince the BrakeExpert to give me an EM1 prop valve on Sunday, He owes me.

98civdx

I am ~220k, the drums have never been touched, all orginal.

So if it turns out they are different, i am going to be upset. I had a EM1 prop valve, and sold it. lol