mechohaulic Posted February 10, 2023 Share Posted February 10, 2023 I did have a trailer 3-4 weeks ago come in with one wheel smoking opposite wheel same axle hot. cause == the clevis pins were rusted solid to point I had to cut them off with die grinder. this trailer also sat for weeks at a time. possibly your front axle is slow due to rusted hardware ?? Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525003 Share on other sites More sharing options...
1961H67 Posted February 10, 2023 Author Share Posted February 10, 2023 Thanks for the guidance, both the parts LJs has some sort of relay valve on the frame going to front brakes, and I couldn’t find a shuttle valve on them either. I’ll double check the plumbing and put a gauge on the front , the copper plumping is 100% original , ( I replaced a few pieces because they had bad rubbed spots) I think there was too many hands involved in the 70s , possibly taking a piece of copper off and plugging something. Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525005 Share on other sites More sharing options...
mechohaulic Posted February 10, 2023 Share Posted February 10, 2023 the "some sort of relay valve " could be a standard quick release valve. purpose just as title says. the valve dumps air from brake cans faster to release brakes, other wise air has to travel back to treddle valve to release. if the parts trucks were/ are tractors not straight trucks the shuttle valve may be connected directly on treddle valve if there is one. no trolley in cab no need for a shuttle valve. Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525051 Share on other sites More sharing options...
mowerman Posted February 10, 2023 Share Posted February 10, 2023 On 2/8/2023 at 5:46 AM, Mark T said: That couldn't be from sanders or something like that.... could it ? I thought of that also they were very common and ingenious idea my uncle used to run them on the brockways Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525052 Share on other sites More sharing options...
Mark T Posted February 10, 2023 Share Posted February 10, 2023 That one picture doesn't look like any valve I've ever encountered . But then again , age wise compared to the truck.... the truck has quite a few years on me. Sure has my curiosity go'n though. Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525055 Share on other sites More sharing options...
mechohaulic Posted February 11, 2023 Share Posted February 11, 2023 a unit such as sanders or other air devise wouldn't (shouldn't) be tied into brake system. the valve first pictured i would go with it being an early TTP valve. air from left side line (brake application) would unseat a diaphram / o-ring equipt plunger to allow air from top constant air to right side plug ( brake cans). another test would be take the 1/4 = 3/8 plug out of right side ; put brakes on check for air out open port. do test twice one with treddle valve other with trolley valve. inside under the removable bottom cover might be a spring : possibly hd tension. new style TTP valves have a hefty spring held in with snap ring. Coffee and doughnut bet the mystery valve in rear not associated to slow front brakes. these are one of many moments I "kick my ass" for not keeping sooo many books (parts included) and tools. Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525084 Share on other sites More sharing options...
Joey Mack Posted February 11, 2023 Share Posted February 11, 2023 Oh My F'n Word!!! Mech.. You are AMAZING !! Yeah I wish I had that book too... Why??? because I can not quote one tenth of what you just posted.. But on the serious side... You have a gift of knowledge that will help many people.. BMT struck GOLD, with you sir.. Jojo 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525085 Share on other sites More sharing options...
mowerman Posted February 11, 2023 Share Posted February 11, 2023 What he said bud…. Was thinking the same thing.. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525105 Share on other sites More sharing options...
mowerman Posted February 11, 2023 Share Posted February 11, 2023 He’s becoming the new Rob4?????????? Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525106 Share on other sites More sharing options...
1961H67 Posted February 11, 2023 Author Share Posted February 11, 2023 Ok , I took about a hour yesterday double checking the brake plumbing, Mechohaulic is totally correct! There is a quick release valve inside the left frame rail of this truck and both parts trucks, air goes from treadle to dash limit valve to top of this valve, each bottom port to right & left steering brakes ( so next I will have to hook a gauge up for them being slow) . So the first valve pictured is in the system has something to do with trailer brakes. I’m not sure if the “tee “ in the second picture is factory. Air comes from one delivery port on treadle to shuttle ( or double check valve) on the front side, the delivery from the trolley loops around to back port of shuttle valve. So when brakes are applied or treadle is pulled air comes out center port where the tee is , one line goes to service side of tractor protection, the other goes to left bottom port of the relay/ quick release valve with constant air to top port and right bottom port plugged . ( first valve pictured) . Since the first pictured valve has constant air, maybe it is a relay valve, air coming from delivery port at shuttle ( remove tee) to left bottom port, remove plug and run line to service of TPV ??? Maybe it had this relay valve in the system to give a extra boost of air to trailer service??? Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525109 Share on other sites More sharing options...
1961H67 Posted February 11, 2023 Author Share Posted February 11, 2023 I put both pictures on in order , hopefully my explanation will make sense, That line that loops around to rear of shuttle is from trolley , line going straight in is from treadle in second picture Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525110 Share on other sites More sharing options...
Mark T Posted February 11, 2023 Share Posted February 11, 2023 If that one's a relay, it should have three lines hooked to it. One constant supply, one to delivery (should be to quick release before air chamber(s) and one to signal air to it (from shuttle valve or foot brake) 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525111 Share on other sites More sharing options...
mechohaulic Posted February 11, 2023 Share Posted February 11, 2023 it's all coming together now. some where in the past the shuttle valve has been discussed. valve has that name based on it's operation. Inside the shuttle ; a5/8 dia +- X 3/4 +- long metal unit having rubber caps slides back and forth capping one port as needed . trolley application the shuttle blocks port going to treddle valve. and vise versa with treddle pedal application. without the shuttle valve air would exhaust out treddle valve when trolley handle applied. the rear frame mounted TTP valve possibly was leaking air because the inside plunger corroded. plugged right side port fed trailer brakes. hopefully slow acting front brake issue is simple as rusted clevis pins or lack of air coming from limiting valve. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525114 Share on other sites More sharing options...
mowerman Posted February 11, 2023 Share Posted February 11, 2023 Thankfully, most of that stuff is still available. Good luck bud. Glad you got it figured out…. Bob Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525115 Share on other sites More sharing options...
mechohaulic Posted February 11, 2023 Share Posted February 11, 2023 I do know the location of a guy who attended my auction that bought boxes of my truck stuff. will make a trip and look through what ever he still has. can't get my hopes up ; for an old style TTP valve there, won't know if I don't venture there. mentally it is a challenge : same as driving by my parents home. seeing my old stuff brings in the memories. it sucks when you were/are "married" to your profession. Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525118 Share on other sites More sharing options...
mowerman Posted February 11, 2023 Share Posted February 11, 2023 lol we all are ….. oil, bolts , auto, truck , mower parts … never gots old… Bob Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525125 Share on other sites More sharing options...
mowerman Posted February 11, 2023 Share Posted February 11, 2023 Forget garage work benches tools yeah baby Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525126 Share on other sites More sharing options...
1961H67 Posted February 12, 2023 Author Share Posted February 12, 2023 Many thanks for all the replies, I’ll hook it up the way We All think it should be and find out what is leaking, and make repairs. OH how I wish that’s all I have to do before finishing it ! I’ve been putting the floor panels in today. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525174 Share on other sites More sharing options...
mowerman Posted February 12, 2023 Share Posted February 12, 2023 Hell man you about got this bud. Bob Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525191 Share on other sites More sharing options...
mechohaulic Posted February 12, 2023 Share Posted February 12, 2023 On 2/11/2023 at 6:07 AM, 1961H67 said: I put both pictures on in order , hopefully my explanation will make sense, That line that loops around to rear of shuttle is from trolley , line going straight in is from treadle in second picture line left rear (loop) from trolley; line RIGHT REAR from treddle (brake) valve. the Tee fitting front middle line to right covered with autoloom goes to rear axle brake quick release valve ?? line straight out (uncovered) is line going to TTP valve left side ??? if so that's a match and makes sense now . as earlier stated plugged line would go to trailer . Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525206 Share on other sites More sharing options...
1961H67 Posted February 12, 2023 Author Share Posted February 12, 2023 That’s the way I’m going to hook it up and try it, I might still have to replace/ repair the relay valve that’s plugged now. I’ll eventually get it back to normal. Thanks again! Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525213 Share on other sites More sharing options...
Mark T Posted February 12, 2023 Share Posted February 12, 2023 No reason you couldn't just use an R12 for a relay valve. 2 Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525216 Share on other sites More sharing options...
1961H67 Posted February 12, 2023 Author Share Posted February 12, 2023 Your correct, I’m sure it would work just fine, I was trying to use as many original parts as possible, but I’m not going to spend a lot of time and money when parts like your talking about are more dependable and available. Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525221 Share on other sites More sharing options...
mechohaulic Posted February 12, 2023 Share Posted February 12, 2023 as earlier stated, if this unit is more for show not hauling a trailer or tag along having brakes ; another option (cheap) would be plug feed line to old style TTP (top line) AT THE AIR TANK for appearance it would look good. technically with the right side plugged valve has not been doing anything now except giving unit an air leak. Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525223 Share on other sites More sharing options...
1961H67 Posted February 12, 2023 Author Share Posted February 12, 2023 Agreed, I’m going to focus on steer axle brakes for now, I have shop air hooked to it so I’m going to check some pressures . Quote Link to comment https://www.bigmacktrucks.com/topic/69289-coca-cola-lj-mack-colors/page/14/#findComment-525224 Share on other sites More sharing options...
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