DIY GM prop valve Disc/Drum conversion to a 50/50 non-adjustable setup,
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- เผยแพร่เมื่อ 11 ต.ค. 2024
- “This is a Test, this is only a test of the emergency broadcast system”...
FAILED LMC proportioning valve had o-rings not compatible with brake fluid.
Rumor has it you can convert any prop valve to a 50-50 setup for Disc/Disc setups. *This is non-adjustable unless you add a restrictor/adjuster valve setup. Fingers crossed!!! - ยานยนต์และพาหนะ
A couple of days ago i finally found this leak (the MYSTERY hole) . After extensive interrogation of all my mech minded friends and hours of research i stumbled across this video by accident and out of curiosity mostly. I just got the new combo valve #4 for disc/disc (76 stingray) with no hole in it from amazo for like $40 bucks? lol. installing today. Anyway, what got my attention was the thumbnail pic with that fitting like mine. Good job on video breaking down this little gremlin. Btw, my little hole wasn't visible even with mirrors due to the clocking orientation putting it facing the mounting bolt flange out of sight. I had to remove combo valve to get to it so after i tore i down i torched the hell out of it and added solder to the hole enuf to seal it and no i don't recommend it because i don't know how long it will last. it got me home and worked fantastically, that's all i got to say about that. These valves are common and cheap, i recommend replacement the whole valve on your classic weather or not it needs it. there's rubber o rings in there and they are old. Happy motoring.
btw i think the hole is a vent to atmosphere on the backside of the tiny valve inside for panic stopping feature. the fitting goes to rear brakes but, my vette came with disc all way round so, who knows if its the original prop valve.
I had no brakes on the rear of my truck, 92,Silverado. For years, I only noticed it after smoking a 2000 cobra mustand, and run out of road!! It stopped! Barely, I thought something was going to catch fire on the front end! Things got HOT!!! The rear was warm, you could touch the drum! Crazy!! That was when I was younger & dumber!! I was playing with that mustang with a full size extended cab truck!! Especially through the curves! That truck would hang, lime it was on rails!! I hope all goes well! Ya need brakes!!
I believe that extra weep hole is actually for panic stop situations where it will release more pressure to the rear drum brakes so they don't lock up as easily. If you stab the brake pedal it will tend to lock up the rear drums, with that little pressure release it bleeds off just a little more pressure o help in those situations. Over time of course what ever that little "reed" is made out of gets brittle and/or the star washer retainer gets weak.
You answered your own question about why there is a weep hole. It's there to give warning and let you know the seals within are failing. That's literally the weep holes purpose and guess what? It gave you an early warning and let you know.
Remember that the master cylinder had two sections that hold fluid. Front (larger bowl) section is for the rear brakes. Back (smaller bowl) section is for your front brakes. If you lose a lot of fluid in either bowl, the proportion valve will shift over internally to prevent total loss of brakes. The break down of the proportion valve having rubber pieces is due to containments (dirt and water) and/or fluid that needed to be changed out much earlier. There is a tester that can be utilized to tell you the condition of the brake fluid. Brake fluid should be changed every two years or @ 20,000 miles. Check your vehicles maintenance manual.
I know, it’s dangerous like the older model vehicles! If I blow a line anywhere in the system all brake functions stop. Even though I really like the way the brakes are working and how they hold strong stronger than they ever have for safety sake I need to set it up with the real proportioning valve.
Great thread my friend, just like you I found nobody could tell me why that hole was there but it just hit me watching your video why and you exposed it, seeing all that rubber from the O rings and seals that had broke down and ended up in the system that hole was put there to let you know that the system has failed internally allowing fluid to pass the seals therefore putting to much pressure on that hole with the rubber lid and star retainer, I'm calling it a lid and a star retainer because it's not designed to seal and lock into place but more of a design to slow the flow of fluid in-case of internal valve faileir. just like a weep hole on a water pump, I don't know if I'm right just my theory. But in my opinion I wouldn't seal that hole it's there for a reason and the reason you exposed the O-rings and seals failed badly I would just rebuild the valve and make sure to use better O rings and seals hopefully they won't fail like the original ones did. thanks for your posting. Dennis White
So far so good, I gutted the valving to create a full time 50/50 distribution block. I haven’t had any panic stops yet but it works great for average driving and moderate stopping without any rear brake lock up. I’m sure if I was going fast enough and hammered the brakes the back tires would surely lock up from the weight transfer unloading. JD
its when your pressure regulator goes out and doesnt build up to much pressure and blow a brake line. that pressure relief goes out before it gets too much pressure and the proportioning valve kicks in and shuts thats side down that blew out
Jordon Woody Thank you, you should post a video about it because I couldn’t find any information on it at all. Thanks again! JD
I asked on another video about getting the injector wiring harness from Richard for his typhoon. I would really like to buy it from him.
Wayne Reid I’ll text him now 👍
@@HeadFlowInc thanks
@@HeadFlowInc did you hear back from him about the wiring harness? Also I asked on another video if you know if the Brodix heads will fit the typhoon intake.
After disassembling the prop valve a fun "check" would be to put the old shuttle valve back in with no or minimum rubbers.
Why would you do this Steve?
To check the emergency stop function of 50/50 vs. Unknown vs unknown.
If you have time and patience its good to. Improve my education.
Line locks on my rear brakes?
Manual control VERY interesting.
No load-nearly off heavvy load-open up a half a turn.
Ruptured rear cylinder-close em down till we get to the shop.
Good ideas and information. Right now it’s unsafe because it’s an equal 50/50 equal pressure full time. So if any brake lines fail All brakes will fail. JD
I agree with Dennis. I think it's a weep-hole indicator
Yeah it’s a warning ⚠️ you have a problem hole!
Been fighting with brake system.. replaced every part including metal lines..got 1 bad PV .sent bac .got 1 from Another company Online Tube..for couple weeks been trying figure out .. Come find out after taking that PV apart after talking to Technical Rep .. found bad rubber seal @ tip of spring had came apart 🤦🏾♂️. After many hours & multiple parts being returned..Moral those things maybe defective
One thing that is dangerous about using a gutted prop valve is that there’s no safety features left, if you bust a brake line, you’re gonna lose all brakes, front and rear. I’m still running the gutted prop valve, but I really need to and intend to upgrade it For safety reasons.
It's like a weep hole on a water pump it shows you that internal seal is leaking
How did you go about plugging the front of the valve? Or what size plug did you end up using?
Reused the factory plugs.
I’m keeping drums in the front and rear. Should I convert mine to 50 50? Or can I use the disk drum valve?
Wow, I don’t know for sure I learned the idea from a Saturday morning car show. I’m wonder how much difference the distribution would make between disc and drum? I know you have to be careful running a 50/50 distribution on the brakes because on a panic stop it can lockup the rear brakes from the weight transfer forward. I haven’t had any issues so but I haven’t had any panic stops either. Very good question! JD
You need a gm drum/drum combination valve. They're $40 or so new
that hole probable has no other purpose other than to tell you the internal valves are compromised and leaking past the seals. Kinda like the weep hole on a water pump.....but I don't know but since it is for the braking system If it was me I would replace the valve and adaptor either with new or salvage yard part......
johnsont963 Your idea makes sense, once there’s a leaking internal o-ring seal it would hydraulic the Star retainer out of its groove. You’d sure think that’s what it’s for.
I wanted to show how it works as a 50-50 setup, but one of my front bleeder screws is seized! Once I can finish flushing/bleeding the brakes I’ll make an update video.
Thanks for the feedback I appreciate it! JD
That's what I was thinking, could the brakes drag?
JAMES! Since the 70's My friend Richard noticed it and I noticed, once I went to disc brakes in the rear, the Disc/Drum prop valve had a delayed release of the brakes. Apparently it was holding pressure or not bleeding pressure effectively. 🤔
I have a 1982 Chevy G30 box.truck dully I tow a race car with, I have 0 rear brakes. Disk front drum rear. I've been wondering if I could do this... even with load equalizer hitch truck still slides front tires very easy , relying on trailer brakes to stop,
I can’t accept responsibility for modifying your prop valve. I do know with a full time 50/50 distribution on a panic stop the rear tires lock up way sooner. I’ve been using mine without issues but I also haven’t tested slowing down from 130 mph at the track yet.
I’m not sure if it would work or not, but it sounds like something is definitely wrong with your rear brakes. JD
No the valve that you are talking about removing only serves one purpose examples if you loose a front brake line the valve moves to close the front circuit and vice versa you have same pressure on front and back and the part with restrictions is for your panic stop to help with rear wheel lock up
I gutted the block, there’s nothing left to alter distribution. Depending on the brake combo the distribution can be 60/40, 70/30 etc. You might want to do some more reading.
Different blocks: drum/drum, disc/drum and didc/disc. JD
Not very good news to hear As I'm changing a valve So you have me wondering if this isn't about the same type of problem as What I call a dry start up on a engine with no oil in the oil filter A matter of putting oil in it before you bleed it Or like the oil filter Just fill the filter with oil when you put it on Given not many options I'll give it a go ..
Thank you
Good luck on your project Thank you for watching! JD
Did it work if it did how did it perform? Thanks
So far so good if I have any issues I’ll let everyone know. To me the brakes seem to work better but who knows? JD
*rubs temples* That's a combination valve. The first piece you called an adapter is the proportioning valve. That hole is an emergency high pressure blow out.
The "shuttle" you took out is a safety feature... one port of that valve runs to the front tires, the other out port controls the back tires. When/if you have a brake pressure fail, in the front or rear, that little shuttle cuts off the depressurized side so the other still works.
Don't gut these that far. That safety valve is the difference between having only half of your brake system in a brake failure and having a run away rig. Don't risk you ass or your truck to save $50... jesus.
Good points, thanks for watching and the feedback I appreciate it! I need to install an adjustable proportioning valve to install. I’ve been using the gutted prop valve; my brakes haven’t work this good ever! But as expected if I have to panic stop the rear tires can lock up. The safety issue you mentioned is the one area making me want to change the prop valve. Drag racing at speeds well over 100 mph and have ZERO brakes doesn’t sound like a good idea. JD
@@HeadFlowInc So there's the PV2, which is Disc front and Disc back. The PV4 is disc/disc. I've got a rig with a very expensive, very hard to find parts for Teves II abs system I'm converting to power brakes (vacuum system like a normal car) and I had to do a deep dive on these combo valves.
I think I saw Wildwood had an adjustable setup that might be worth looking into. I opted for a more boring set up - mine's just a cruiser :)
What am not understand why chevy and GM installed it in very difficult place to reach..🤔
Some of the locations are ridiculous!
Did it work???
Here’s my warning:
Yes the gutted prop-valve works great and delivers 50/50 distribution.
1. With 50/50 distribution on panick stops the rear tires have a tendency to lock up.
2. If you ever pop a brake line or have a leak you will lose “All” brakes because all the safety mechanisms are removed.
3. I’m still running the gutted valve but really need to swap it out.
@@HeadFlowInc thanks hoping a oring in this one will take care of the problem plus it’s a older ranger that we can not find a replacement for tried all the parts stores. Figured if it worked on a blazer it would on this. Lucky it’s a slow stick shift truck so don’t need but so much break. Thanks for the video
It will apply too much pressure to the front brakes .you need a disc /drum prop valve and a disc/ drum master to work correctly .if you want to know if what you did works correctly just hook up that wire to the valve and see when you apply brake .good luck
I now have Disc/Disc so it works amazingly well but is dangerous because If I break a line I’ll lose everything I think.
@@HeadFlowInc yes you will .please install a new prop valve and make us all safe .👍👍👍👍😳😳
Chinese rubber the same happens to tires made over there . Anything safety by American parts at Napa
I would have just spent the $40 and fixed the car correctly.
Life’s full of choices, but I was able to learn the 50/50 valve stops really well. But it’s not safe without a check valve system in case a brake line breaks etc.
Watch this video and it will explain how a proportioning valve works and what not to remove. th-cam.com/video/qPLaPv8DITE/w-d-xo.html
You didnt even show the disassembly and assembly of the prop valve. Terrible video.