How to identify brake combo valve 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 |
Re: How to identify brake combo valve 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. |
Re: How to identify brake combo valve 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? |
Re: How to identify brake combo valve 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. |
Re: How to identify brake combo valve 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 |
Re: How to identify brake combo valve 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. :lol: Maybe that means we should both just get different brakes! |
Re: How to identify brake combo valve 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 |
Re: How to identify brake combo valve That link is a pot of gold, man! :thumbsup: |
Re: How to identify brake combo valve
Originally Posted by QwkTrip
(Post 6282651)
That link is a pot of gold, man! :thumbsup: |
Re: How to identify brake combo valve 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. https://farm8.staticflickr.com/7880/...e0478f83_c.jpg https://farm8.staticflickr.com/7879/...fe4a8876_c.jpg https://farm8.staticflickr.com/7927/...c30632c1_c.jpg https://farm8.staticflickr.com/7809/...ec7c0899_c.jpg |
Re: How to identify brake combo valve
Originally Posted by QwkTrip
(Post 6282520)
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. :lol: Maybe that means we should both just get different brakes! I agree, quite funny! |
Re: How to identify brake combo valve
Originally Posted by IROCZman15
(Post 6282695)
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. https://farm8.staticflickr.com/7880/...e0478f83_c.jpg https://farm8.staticflickr.com/7879/...fe4a8876_c.jpg https://farm8.staticflickr.com/7927/...c30632c1_c.jpg https://farm8.staticflickr.com/7809/...ec7c0899_c.jpg 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? |
Re: How to identify brake combo valve 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. |
Re: How to identify brake combo valve
Originally Posted by IROCZman15
(Post 6282695)
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. https://farm8.staticflickr.com/7880/...e0478f83_c.jpg https://farm8.staticflickr.com/7879/...fe4a8876_c.jpg https://farm8.staticflickr.com/7927/...c30632c1_c.jpg https://farm8.staticflickr.com/7809/...ec7c0899_c.jpg 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. https://i.imgur.com/rcswDxQ.jpg |
Re: How to identify brake combo valve 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 |
Re: How to identify brake combo valve 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... :D Drew - I'm pretty sure my valve is stock (it's dirty enough inside to be) and the plunger is just plain aluminum. |
Re: How to identify brake combo valve The valve bodies also have little lines on them. one is straight other diagonal. forget which is drum, which is disk. NC = 86-88 J50 setup. w 1.0 mm tube nut NB = 86-88 J65 setup w/ 1.0 mm NC = 89 J50, w/ 1.0 mm - 1st design (note, same part number as 88, not sure why book differentiates them) MB = 89 J50, w/ 1.5 mm - 2nd design And here is where it gets confusing: MC = 89 J65 w/ 1.5 mm - 2nd design MD = 89 J65 w/ 1.5 mm 2nd design - this one throws on (EXC (Y82) ,1LE, but not sure how to interpret what it is trying to indicate because of the EXC but it appears this would be the bigger front brakes. Y82 is TTA and they also got the big front brakes. What marks are received in 1990-1992 it does not say. I think the master cylinder was a difference design in those years and same for all setups, but havent heard/read on the combo valve. Also, from 82-85, there is no broadcast code mentioned, maybe a different year book will provide that answer. https://cimg2.ibsrv.net/gimg/www.thi...a084ee328d.jpg |
Re: How to identify brake combo valve The early cars have a completely different style combo valve, not the extruded aluminum style with broadcast codes. The 1st design 89 valve is differentiated from the 88 because the book is trying to point out that there are two designs in 89 without confusing the definitions for earlier years. Just an educated guess, the EXC (Y82) ,1LE is probably because the brake balance of the 1LE brakes was altered. Early 1LEs supposedly had issues with the rear brakes locking too soon, so the balance was shifted to prevent that from occurring. The TTA may well have used the standard J65 combo valve because GM was trying to avoid the braking issue. The master cylinders on 89-92 cars are the same drum vs 4whl disc. Before 89 the disc cars had a specific master cylinder. The pistons on the PBR calipers are smaller than the Delco-Moron calipers, so the fluid needs were different. 90-92 drum cars used an MB combo valve. 90-92 Disc cars used a MC, MD, or LF. Here is a later P&I illustration. https://i.imgur.com/mmrKyuo.jpg |
Re: How to identify brake combo valve I used a basic ruler and verified it with a hand caliper to measure the springs today real quick. heres what I found. My measurements are not exact . sorry. If you need more info, let me know. I will be out in the garage all day tomorrow installing my brand new Moser 12 bolt that arrived today. OEM disc/drum spring: 1and9/16" long, 7/16" diameter, 10.5 coils 1LE spring from Ed: 1and1/2" long 1/2" diameter 8.5 coils https://farm8.staticflickr.com/7831/...97697d18_k.jpg https://farm8.staticflickr.com/7882/...a2b4da33_k.jpg https://farm8.staticflickr.com/7907/...4659a98f_k.jpg https://farm8.staticflickr.com/7802/...cc57e48d_k.jpg https://farm8.staticflickr.com/7856/...d7204aaf_k.jpg |
Re: How to identify brake combo valve
Originally Posted by Drew
(Post 6282866)
90-92 drum cars used an MB combo valve. 90-92 Disc cars used a MC, MD, or LF. |
Re: How to identify brake combo valve Do you have the wire diameters too? I'm going to use all this to calculate the spring rates. |
Re: How to identify brake combo valve
Originally Posted by LiquidBlue
(Post 6282919)
Thanks for the LF - I have one on my hands and been scratching my head as to what it is. Where do you see that listed? (I may be half blind) |
Re: How to identify brake combo valve
Originally Posted by Drew
(Post 6282947)
Well see, LF isn't listed in the book, but if you look at a 90-92 PBR valve, the originals are marked LF. You can also see the LF tag on low mileage cars in pics. It's hard to say why the book doesn't list the LF. https://cimg8.ibsrv.net/gimg/www.thi...b8726db04.jpeg |
Re: How to identify brake combo valve
Originally Posted by IROCZman15
(Post 6282916)
OEM disc/drum spring: 1and9/16" long, 7/16" diameter, 10.5 coils 1LE spring from Ed: 1and1/2" long 1/2" diameter 8.5 coils I really suspect your 1LE is the same exact spring I have with 9.625 coils. If you hold the coil in front of you looking on end, and put the far end at 12:00 position (high noon), is the end closest to you really at the 6:00 position or more like 8:00 position? Assuming both coils use 0.055 inch wire, the "NC" drum brake spring has 24.6 lb/inch spring rate, versus the "NB" disc spring at 19.56 lb/inch. But if you installed the drum brake spring in a disc unit then it would act like an even heavier spring because it would be compressed much more when assembled than it is in the drum unit. |
Re: How to identify brake combo valve Drew / IROCZman, How much difference is there in length to the spring seat between the drum and disc pistons that you have? (Reference from where the piston seats to the valve, not from the end of the spring guide rod.) Based on the scale of parts in the side-by-side photo that Drew posted, I'm guessing the spring seat of the drum piston is 0.150 inch deeper into the valve body than the spring seat of the disc piston. That means you can install the same spring onto both pistons and get different spring force when assembled, and that will change the valve knee point on the pressure curve. In other words, there could be a lot of combinations available using just stock parts. |
Re: How to identify brake combo valve So I set up a spreadsheet that calculates the spring force on the plunger when assembled. I just need to refine it based on the measurements of the pistons that I asked for. Once I get that info then I think we're in business, boys! People focus only on spring rates in all the threads I've seen about the "spring mod". But I don't think that is the key characteristic that determines how the prop valve works. The key characteristic is the spring force on the plunger, as assembled. Bottom line is you've got to know how far the spring is compressed. The differences in spring free-length, and the spring seat position on the piston (disc vs. drum pistons) needs to be taken into account. For example, using a disc plunger vs. a drum plunger might change the force by 40%. That's HUGE! Installing a longer drum spring in a disc valve might increase the force by 40% too. I think this explains why there are so many different reports from people about how their brakes work when they swap springs; and why one guy gets away with a 20 pound spring and another guy needs a 30 pound spring. I think things are going to come in to focus if you guys can help with with the measurements I requested. |
Re: How to identify brake combo valve Hmmm.... it seems I don't have things figured out yet. Apparently the diameter of the piston effects the proportioning ratio and there are multiple size pistons made. That's why Drew has a red piston and I have a different color piston. The color signifies the diameter. Going to have to study this more. |
Re: How to identify brake combo valve
Originally Posted by QwkTrip
(Post 6282981)
I think this explains why there are so many different reports from people about how their brakes work when they swap springs; and why one guy gets away with a 20 pound spring and another guy needs a 30 pound spring. I think things are going to come in to focus if you guys can help with with the measurements I requested. |
Re: How to identify brake combo valve I'd have to find the prop valve, and tear it down to check. Pics I posted are from awhile back as I was refurbing bits for the green car. I've been boxing parts up as I go and tucking them away on the shelf until I need them, so I'm not entirely sure where my spare PBR prop valve is at the moment. |
Re: How to identify brake combo valve Alright, I've got a better understanding of this now. The actual proportioning ratio (the percent reduction of rear line pressure) is based on the dimensions of the piston, specifically the diameter of the spring rod. The spring delays proportioning until the line pressure is high enough to overcome the spring. There are multiple sizes of spring rods and changing those out is how you change the proportioning ratio. Changing the spring out will only change the "cracking" point of the valve where it begins to proportion the rear brakes. The valve doesn't work at all like I had imagined. Whoever came up with the idea was a genius. .
|
Re: How to identify brake combo valve I've got a spreadsheet that spits out prop curves for our OE valves, using any spring and piston. I'd really really really really like to know these dimensions for the "red" piston. PRETTY PLEASE WITH SUGAR ON TOP! :thanks: I just made up these terms for lack of better knowledge. https://lh3.googleusercontent.com/Ba...cl-WYYvA=w1200 |
Re: How to identify brake combo valve Water? Like out of the toilet? |
Re: How to identify brake combo valve Fine. I'll pull out the LF and fight the dying battery in the caliper... Red LF Piston (91 J65 PBR Rear) ========== Spring Tube Diameter = .261 Shelf Diameter = .420 Spigot Diameter = .334 Red MB Piston (Drum Rear) ========== Spring Tube Diameter = .250 Shelf Diameter = .420 Spigot Diameter = .334 The operative diameters are the same. |
Re: How to identify brake combo valve LF Spring ========== 1.48 Free Length 0.505 overall diameter 0.055 wire diameter 9.5 - 9.625 total coils MB Spring ========== 1.625 Free Length 0.461 overall diameter 0.050 wire diameter 12 total coils |
Re: How to identify brake combo valve Great stuff. Simplest explanation is usually the correct one. Will read again in morning when head is clear. |
Re: How to identify brake combo valve Thanks, Drew. Yep, the '90-92 LF red piston produces more rear pressure than the '86-89 NB piston, even though the springs are the same. Now we're starting to get a better idea what makes the later 1LE work better. Now you want to sell that to me so you don't have to lose it all over again? |
Re: How to identify brake combo valve
Originally Posted by QwkTrip
(Post 6283169)
Thanks, Drew. Yep, the '90-92 LF red piston produces more rear pressure than the '86-89 NB piston, even though the springs are the same. Now we're starting to get a better idea what makes the later 1LE work better. Now you want to sell that to me so you don't have to lose it all over again? |
Re: How to identify brake combo valve I went back and looked at my Wilwood graph and figured out the pressure ratio is only 43%. But the spring has a huuuuuge range of adjustment. Not wholly confident my calcs are totally correct, but I'm getting 54% ratio for a stock NB valve, and 65% ratio for a stock LF valve. The stock valves appear to have a more aggressive slope than the Wilwood, but the hysteresis point where the valve cracks is waaaaaaay lower than a Wilwood. |
Re: How to identify brake combo valve
Originally Posted by QwkTrip
(Post 6283136)
If you only remember one thing from this then remember this: Swapping pistons is the best way to increase effectiveness of rear brakes. It would also give you a sanity check on your calculations to see if they are correlate. |
Re: How to identify brake combo valve
Originally Posted by QwkTrip
(Post 6283169)
Now you want to sell that to me so you don't have to lose it all over again?
Originally Posted by LiquidBlue
(Post 6283170)
are you referring to J65 or 1LE? It’s my understanding that 1LE includes bigger 2 piston brakes up front and that is yet another, different combo valve? |
Re: How to identify brake combo valve you are correct about your count of the number of coils. my mistake! Qwk, what valve/piston/plunger are you looking to buy? If I compiled my brake system correctly (my other thread with the wilwood valve) and it works properly, I will have no need for most of my prop valve parts. Unfortunately, I wont know for about 3 weeks until I get a driveshaft built and can road test the car(brakes) etc |
Re: How to identify brake combo valve
Originally Posted by IROCZman15
(Post 6283339)
you are correct about your count of the number of coils. my mistake! Qwk, what valve/piston/plunger are you looking to buy? If I compiled my brake system correctly (my other thread with the wilwood valve) and it works properly, I will have no need for most of my prop valve parts. Unfortunately, I wont know for about 3 weeks until I get a driveshaft built and can road test the car(brakes) etc |
Re: How to identify brake combo valve
Originally Posted by Drew
(Post 6283266)
They're the same thing. The only part of the valve that's different is drum/disc. The front half of the circuit is the same regardless of 1LE or J65. |
Re: How to identify brake combo valve
Originally Posted by QwkTrip
(Post 6283374)
Maybe. What is the outer diameter of the hollow tube of your pistons? (both the EB Miller unit, and the drum unit) the ed Miller piston is 19/64” the drum one is 1/4” https://cimg1.ibsrv.net/gimg/www.thi...401d099a8.jpeg |
Re: How to identify brake combo valve Thanks, I sent you a PM. |
Re: How to identify brake combo valve Well folks, I've concluded I have to stay with the Wilwood valve that's on my car. My rear brakes are just too wimpy and need more line pressure than any modified 3rd gen prop valve can deliver. Posts #1135 and #1137 explain why, https://www.thirdgen.org/forums/ltx-...ml#post6283966 Absolutely could not have figured this out without your help! Thank you for all the measurements and data points! :thumbsup: |
Re: How to identify brake combo valve My Formula was a regular (not daily) driver back in the day.... Back in Houston, back in her hey day when the freeways had not yet reached 24 lanes. Hang with me now.... Back then, it was a regular occurrence to go from 90mph to 0 in short order. Other option was accident and tow. i can tell you, back then, the Formula was fully capable of braking from 90 to 0 in VERY SHORT order. No ABS, JUST good old fashioned slamming the brake pedal to to floor and correcting the steering for tail spin. What I am trying to say, is the brakes preformed magnificently. Now if you want to compare them to your modern day Toyota XXXXX well, its not a proper comparison. These are old school race car brakes, plain and simple. cheap but they work. The reason I say this is because I'm somewhat mystified by people saying the braking systems in these cars are no good. for 1990, they were pretty damn good. We're not talking expensive European cars here. Anyway, my 3 cents, thought I'd toss that out. food for thought. |
Re: How to identify brake combo valve Ya, the brake bias is actually pretty good in these cars. But the brakes heat up real fast! The big brake craze is kind of goofy too though. People are spending gobs and gobs of money to put really large & heavy brakes on their cars and making their cars slower when they don't have to. A good 12" brake will stop faster than a 14" brake as long as both are managing the heat. There's no need to be hauling the extra inertia of the 14" brake if you don't have to. And there's only so much braking torque you can use.... you can have too much brake! I found this interesting, https://www.pro-touring.com/threads/...Tobin-of-KORE3 |
Re: How to identify brake combo valve Ya, that is interesting, so much goes into thinking about brakes. out of curosity, I was looking for braking performance and found this: 82 Z28 - 60-0 in 149 feet https://www.motortrend.com/news/12q3...vrolet-camaro/ 90 Porsche 911 Carrera - Braking, 70-0 mph: 161 ft. https://www.caranddriver.com/reviews...d-test-review/ Of course fast forward to 2019 and if you are driving your thirdgen down the freeway in an emergency braking situation, 149 feet may no longer do the trick like it once did. |
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