LMTV Rear air brake components

[@marioprzepiora]

Thank you. I'm going to have to watch that 7 more times just to absorb 10% of what you covered. Thank you.

[@elgoogsucks9005]

Thanks for not just the video, but all the help you give.

[@klmsinc8243]

I am glad that you did this! Thank you! This is timeless!

[@NEILSWORLD]

Another great instructional video. Thank you for taking the time to do this. 👍

[@krisbarnes1223]

Outstanding video Ron. Thanks for doing it.

[@ethanturner5567]

Wow, Ron, this is very helpful. Thank you!

[@pauld6102]

Ron, your understanding of this system is amazing. I only wish you could go thru this explanation with a 1083A1, as our lower relay valve was removed during the demilitarization process, and because it's an electronic ABS 6x6, no one seems to have good photos or schematics of the seven nylon lines that attach to that previously missing valve... The TM is very vague....

[@rronmar]

Paul D sorry, havn’t ever got the chance to go over the systems on one of those... 7 lines huh... do you have the replacement valve, does it have 7 ports? 2 of those lines might be simply “T’d” off of two of the 5 connections on a relay valve like the one in this video and are used to sense individual wheel brake pressure... What year is yours? I have a friend here in town who has one with an expedition box on it who might let me look his system over...

[@rronmar]

Hey Paul, I got a chance to look over my friends M1088(06 model) and think I have my brain around how the main brake relay works. It appears to be the same type relay valve as I have in my A0, but two of the lines are T’d to feed other components. I was able to identify where the 7 lines go if you want to discuss it...

[@pauld6102]

Yes sir! Would really like to talk with you about this... We have the replacement valve from Haldex. It'd probably be best if I could send you photos of what the line set up looks like currently. It's far different from earlier models. I'm in the process of finding the fittings (Parker Hannefin) since those were removed also.... Let me know what is the preferred way to contact you. Thanks again

[@rronmar]

Paul D sure, you can Email me at [e-mail] we can probably converse that way easiest...

[@templer4295]

Thanks for going over this. My problem is the four rubber air lines that go to the wheel brakes are dry rotted. Napa and the places around me all want to make up hydraulic lines. So I guess my question is can I buy all this lines from some where? The truck is Stewart & Stevenson 2003 4x4 and only has 1100 miles, but all the lines are just dry rotted. I would like to buy new ones. Is there someone selling them or NOS surplus or do I have to go and have each line made up? Any help would much appreciated! Thanks!

[@rronmar]

Well brake system components should be DOT approved. Try lmtvparts.com. Give them a call they may be able to help you…

[@templer4295]

@@rronmar Thank you!

[@HelicoolsHelipad]

Ron, very nice explanation. My question is, regarding my truck to trailer build, do you recommend only hooking up the service brake relay, since when the trailer valve is pulled to evacuate air to the trailer, in essence, the parking brake is set with zero air being given to the trailer. Or, does it need to have that relay to release the parking brake spring pressure?

[@rronmar]

Helicool's Helipad I would keep both the brake relay and the anti-compounding valve(both the center valves on that crossmember). Compounding the pressure(coil spring + service diaphragm is still an issue and can cause problems/damage...

[@HelicoolsHelipad]

@@rronmar I had no idea that the service line on the truck would be active through the service glad hand, even though the trailer pull valve in the cab was not activated. Thanks for taking my call... I believe I have a good idea and path to follow to get this build done, and do it safely. Many blessings!

[@miatasixh5915]

Hi, Appreciate all the info in your videos. I have an M1083A0. I starting having brake release delay issues, 1st from foot valve, then from dash parking brake valve. It would be 3-4 second delay at brake shoes release after foot / dash valve release. Now, unable to supply air to release brakes from either source. Pressure up in primary & secondary tanks, just can't seem to release brakes. Thoughts? Any guidance on where to start trouble shooting (which valves to test for presence of air)? Thank you

[@rronmar]

Are your front glad-hands vented? They must be vented, if the front blue glad-hand is capped, and you step on the brake pedal, air can leak past the remote service 2way and build up pressure in that capped line. When you let off the pedal, that stored air comes back thru the 2way and keeps brake pressure applied to the service brakes, just as if you were still stepping on the pedal… The front red glad-hand can effect the parking brake circuit…

[@miatasixh5915]

@rronmar I don't think the front glad hands are capped. I connected an air line to the blue glad hand, and that released the front brakes. Then I removed the airline, and the front brakes came on. I connected an air line to the red glad hand, and it filled the tanks and the rear brakes released. When I removed the airline from the red glad hand, the rear brakes came on, and the air tanks were at 120 psi still. I tried cycling both the foot pedal and the dash switch, but still no brake release. I have been driving this truck for 2 years, and then this just occurred. Is there a common place both the foot valve and dash valve are connected to that may have failed or is stuck maybe ?

[@rronmar]

@@miatasixh5915 ok, thats the way the red GH is supposed to work, but did you by chance describe the blue GH operation backwards? When the towing vehicle steps on the brakes it sends pressure out its rear blue GH. When that pressure is APPLIED to the front blue gh on the towed vehicle, it applies ALL the brakes, just as if you stepped on the pedal in the cab. Since it takes time for air to flow the brake system uses relay valves to manipulate the brake pressure remotely. Each release should vent air. So when you step on the pedal it applies air to front and rear, when you release the pedal it vents air thru a port up behind the grill in front of the radiator. Thats the same place the dash park control vents air when you set the brakes. The park circuit operate in reverse, you apply air to release and release air to apply park brakes. When you step on the pedal air flows to the front quick release/relay valve, and on to the front brakes. When you release the pedal the quick release valve(in behind the front bumper) vents the air that was sent to the front actuators. In the back the pedal air goes thru the proportioner and on to the relay and anti-compound valves. The relay applies tank air to the rear actuators. When you let off the pedal the relay should release the actuator air to atmosphere. The relay and anti-compound valves have vent ports on the bottom. You need to make sure that the front QR and rear relay valves are venting when the pedal is released.

[@miatasixh5915]

@rronmar I just double-checked the blue GH, and that's the result I was getting. I am not getting any venting or air discharge sounds from behind the front bumper. Good place to start. See what I can find. Thanks again. Will

[@rronmar]

@@miatasixh5915yea thats pretty weird . Applying air to the blue service glad-hand should send air thru a pair of 2way check valves, one feeds that front qr valve and the other goes to the rear brakes. Applying air should apply those brakes same as the pedal does, and releasing that air should release the brakes. Having trouble getting my brain around it releasing the front brakes when you apply air at the GH… One thing the pedal and park control have in common, both their vents are tied together and vent out thru that port up in front of the radiator. If that were blocked and the pedal could not vent that would keep the brakes from releasing. That doesn’t necessarily explain why the park brakes would not release, unless air fed into the park valve exhaust effects it somehow? It is easy enough to test this theory, on the pedal valve there is a plastic elbow on the rearward face of the valve(side towards drivers seat). It has a hose connected to it(usually has a white line spiraling around it) that runs over to the vent behind the heater(and the park valve). If you loosen the hose clamp and remove that hose, the pedal valve will be able to vent out that port into the cab. The park valve can also vent out the end of the disconnected hose. See how it works with that hose off…

[@tedneb3459]

Excellent video! Thanks!

[@SeanFillner]

Hi Ron!

[@FIDAHUSSAIN-y7z]

❤

[@UtibeEdem-bk4ri]

I love this job o

[@peak2ride]

A video made by a pro with papers in hands 1,5k views. Another made by fastidious no clue butcher 15k views 1000 likes. Important is to speak foul language.