Anybody know a trick how to identify which brake combo valve I have?

There is a code stamped in the side of it. Kind of hard to read what it says because it's been stamped twice. My guess is NB 35 KH2378

An 86-89 4-wheel disc brake line kit screws into all the fittings so I'm guessing that rules out the possibility of a gen 2 design.

Still hoping to become more enlightened about this before I do anything with this combination valve.

Here's the back story. Years ago I bought a used four-wheel disc combination valve. Problem is that I don't know how to confirm what it really is. I'm fairly confident I have a pre-'89 combo valve. But I'm still not sure how to tell the difference between drum vs. disc.

But maybe that doesn't really matter. The end game here is to convert this sucker to 1LE specs. I'm not sure what are the differences and hardware I need to do that. If it is just a matter of changing spring rate for rear line then I know how to do that. But I suspect the 1LE might be more than just a spring rate change.

Anybody have knowledge of this?

Been having an offline conversation with Drew who is always helpful and full of knowledge. Seems the first 2 letters in the code signify what kind of valve it is. NB might be from an '87 IROC with four-wheel discs using the Delco-Moraine iron calipers.

Now the question is whether there is any difference between the Gen 1 design and the later 1LE Gen 2 design, other than tube nut sizes, and perhaps the rear valve spring.

I wrote back to you on my prop-valve thread, but just in case you didn't see it..

.. I can take detailed photos of the prop valve assembly in the aftermarket Ed Miller 1LE prop valve setup I have had in my car..
...AND I can take photos of the disc/drum prop valve (and its internals) that was on my car when it left the factory in 1987.

gimmie a day or so and i'll get it done

This is kind of humorous because we've got two threads with ideas going in opposite directions and we're helping each other through the questions. I'm giving some thought to going where you've been and you're giving thought of going where I've been.

Maybe that means we should both just get different brakes!

Broadcast code will tell you the info you are looking for. click link, then click on photo to see page. scroll down. http://www.gmpartswiki.com/getpage?pageid=129796

That link is a pot of gold, man!

yeah it is! always seen it, but never really paid much attention to it until recently.

ok, so here is what I found. let me know if you need more photos or info.

excuse the dirt and crud on the old prop valve, it has been in opren storage on my parts shelf for about 9 years. I did notice that the external size of the nut/head is smaller on the drum one. it take a 3/4" socket, where as the 1LE one took a 13/16" socket. the thread size and pitch is exactly the same though so either one can be installed into a GM prop valve housing (good for my dilemma). Obviously the spring and plunger are different and i think that is what you wanted to see. I also wrote down the stampings on both housings, as best as I could read them. The plungers only fit into each respective end nut, one is larger than the other in diameter. and maybe its just the discoloration, but are both nuts made of aluminum? I would assume they both are, but would it make sense that the 1le is brass? color looks a bit off.

I agree, quite funny!

Ha ha. love the Craftsman -vs- Taiwanese stuff in order to help your comparison.

Seems like the spring is well known. What is not, is the valve body itself. What are the diameters of the inner channels/tubing if you will that make up each of these. Is it really just a spring that differentiates them?

Huh.... so Ed calls the 'NB' valve a 1LE, huh? Maybe he converted it. Can you measure out those springs, especially the 1LE? That would help me tremendously! My stock 'NB' spring has,

1.5 inch overall length
0.504 overall diameter
0.055 inch wire diameter
9.625 total coils

It's starting to make sense why people get such variance in brake performance when they swap to the same spring. Looks like the drum and disc piston have different length to spring seat, so the compressed spring force will be different when installing the same spring in both. The disc piston will produce more initial spring force at the seat.

Looks to me like the Flynbye valve internals are aftermarket. The stock parts are red anodized aluminum same as the drum style. The end cap would be bare steel on an original too. The Flynbye parts look like machined brass instead of steel and aluminum. I'd say ask Ed, but he hasn't been around in a loooooong time.

yea. I can measure for you, but unfortunately I do not have a digital mic or anything past a simple tape measure and a $5 hand caliper. I'll do my best.

yes, I definitely got the prop-valve from Ed off his website about 9 years ago. http://flynbye.com/catalog/i160.html
I do think that he converted another one he had to work for the front/rear setup on my car (which the brakes at all 4 corners were bought from him). I didn't send him mine (obviously because I have had it in storage all this time), but I did buy it from his website. if something is odd about it, I am not well versed enough (yet) to know what that would be, but perhaps you guys are. hope this helps you. I guess for my setup (in my thread in the brake forum) my goal is to eliminate all the mystery of springs and valves by just using the MC, the hardline, and an in-line wilwood adjustable valve for the rears

IROCZman - is that "1LE" valve the same one that delivers weak braking on your car? I don't have a micrometer either. I just used a cheap caliper. Maybe not $5 cheap though...

Drew - I'm pretty sure my valve is stock (it's dirty enough inside to be) and the plunger is just plain aluminum.