2stacksuperdog Posted February 23, 2013 Share Posted February 23, 2013 Does anyone have the schematic for the air lines on a twelve speed? Quote Matt Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/ Share on other sites More sharing options...
leversole Posted February 23, 2013 Share Posted February 23, 2013 Here you go... 1 Quote Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/#findComment-166980 Share on other sites More sharing options...
rsb502 Posted February 23, 2013 Share Posted February 23, 2013 How many times has this come up in the last few months, we may need to send out a group email of the schematic. Quote "Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin"If your gonna be STUPID, you gotta be TOUGH" "You cant always get what you want, but if you try sometimes you get what you need" Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/#findComment-166989 Share on other sites More sharing options...
2stacksuperdog Posted February 23, 2013 Author Share Posted February 23, 2013 What up with the air line that comes from the tranny to the aneroid valve, we heard it was to reduce power when to muchtorque? Quote Matt Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/#findComment-166998 Share on other sites More sharing options...
rsb502 Posted February 23, 2013 Share Posted February 23, 2013 Um that's a new one on me, I can't say I remember seeing that line on my 84. Quote "Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin"If your gonna be STUPID, you gotta be TOUGH" "You cant always get what you want, but if you try sometimes you get what you need" Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/#findComment-167003 Share on other sites More sharing options...
2stacksuperdog Posted February 23, 2013 Author Share Posted February 23, 2013 Um that's a new one on me, I can't say I remember seeing that line on my 84.Thats the problem, my dad has been working on Macks for 35 years and hes never seen one besides our 93 RB had it but that was a 8LL. He was at mack one day and asked the service manger what it was and he didn't know either. We didn't notice it until today on our superliner when we the aneroid valve was leaking because of it. We just put another rebuilt 12 speed in it and we were trying to figure it out so my dad asked his friend who has a 12 speed in his R-model what it was and he said there was some torque valve on the tranny that went to the puff eliminator/aneroid. he never noticed it on his till his air ride cab broke and broke it off the transmission. he said he never put it back on so it cant be too important? Quote Matt Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/#findComment-167009 Share on other sites More sharing options...
2stacksuperdog Posted February 23, 2013 Author Share Posted February 23, 2013 Also the line is pressurized Quote Matt Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/#findComment-167035 Share on other sites More sharing options...
rsb502 Posted February 23, 2013 Share Posted February 23, 2013 Ha puff eliminator, well since I remove those pesky air leakers I guess I wouldn't know about that air line. Good tip, find an 1/8" pipe plug and put it where the off limiter was. Quote "Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin"If your gonna be STUPID, you gotta be TOUGH" "You cant always get what you want, but if you try sometimes you get what you need" Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/#findComment-167080 Share on other sites More sharing options...
anco361 Posted February 23, 2013 Share Posted February 23, 2013 I thought it was to limit Torque when backing up...at least that what I was told back in the 80's when I worked on them often... 1 Quote Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/#findComment-167085 Share on other sites More sharing options...
Lmackattack Posted February 23, 2013 Share Posted February 23, 2013 It limits full engine power. I would suspect it limits when in low low and reverse. Only? 1 Quote Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/#findComment-167152 Share on other sites More sharing options...
rsb502 Posted February 23, 2013 Share Posted February 23, 2013 My trucks have not had the valve you speak of I say remove it and thats one les air leak in the future, if you flat foot it in low or reverse under a load you dont need to be driving anyway. Quote "Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin"If your gonna be STUPID, you gotta be TOUGH" "You cant always get what you want, but if you try sometimes you get what you need" Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/#findComment-167154 Share on other sites More sharing options...
2stacksuperdog Posted February 23, 2013 Author Share Posted February 23, 2013 Its not pressurized in reverse only in neutral, direct, and high it goes into the manifold where it connects to aneroid valve. Quote Matt Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/#findComment-167183 Share on other sites More sharing options...
farmer52 Posted February 23, 2013 Share Posted February 23, 2013 How many times has this come up in the last few months, we may need to send out a group email of the schematic.Post it in the Wiki section Quote Ken PRR Country and Charter member of the "Mack Pack" Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/#findComment-167195 Share on other sites More sharing options...
Lmackattack Posted February 23, 2013 Share Posted February 23, 2013 can someone please Idendify these valves so I hook them up to the shifter correctly.I guess starting at 12 and going clockwise...Thanks Quote Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/#findComment-167236 Share on other sites More sharing options...
rsb502 Posted February 24, 2013 Share Posted February 24, 2013 Its not pressurized in reverse only in neutral, direct, and high it goes into the manifold where it connects to aneroid valve.well yeah that would make it a limiting valve if its got air in everything but low and reverse, I dont know how that works, seems it would be the other way around in my mind, oh well I always give em all the fuel they can get all the time anyway. I got no puff limiter, and the governor is turned up about 4 turns, of course they say turn it a half a turn and try it to keep the egt's low but I go about 1-2 turns then try it myself, makes it fun if you have someone driving in a diesel pickup trying to blow smoke and you can bump it thru a couple gears leaving a light then skip a couple and get the rpm down to about idle and just lay on the throttle, most of the time it will make automatic headlights come on behind me! Quote "Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin"If your gonna be STUPID, you gotta be TOUGH" "You cant always get what you want, but if you try sometimes you get what you need" Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/#findComment-167298 Share on other sites More sharing options...
2stacksuperdog Posted February 24, 2013 Author Share Posted February 24, 2013 well yeah that would make it a limiting valve if its got air in everything but low and reverse, I dont know how that works, seems it would be the other way around in my mind, oh well I always give em all the fuel they can get all the time anyway. I got no puff limiter, and the governor is turned up about 4 turns, of course they say turn it a half a turn and try it to keep the egt's low but I go about 1-2 turns then try it myself, makes it fun if you have someone driving in a diesel pickup trying to blow smoke and you can bump it thru a couple gears leaving a light then skip a couple and get the rpm down to about idle and just lay on the throttle, most of the time it will make automatic headlights come on behind me!We have a switch hidden in the cab that turns it on and off that way if they want to check emissions its all good. My dad disconnected the line for tranny since hes the only one that drives it. Quote Matt Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/#findComment-167301 Share on other sites More sharing options...
rsb502 Posted February 24, 2013 Share Posted February 24, 2013 Emissions! thats one of them thar dirty words in Truckin mister! 1 Quote "Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin"If your gonna be STUPID, you gotta be TOUGH" "You cant always get what you want, but if you try sometimes you get what you need" Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/#findComment-167303 Share on other sites More sharing options...
leversole Posted February 24, 2013 Share Posted February 24, 2013 Valve on the far right is the reverse high low valve.Valve on the bottom is for the front compoundReference my post above to see how the valve on the far right is plumbedThe front compund is plumbed similarly to the reverse from the dash switchThe valves are inversion valves, they close the delivery port when the control port has air. The other port is supply. Quote Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/#findComment-167323 Share on other sites More sharing options...
2stacksuperdog Posted February 24, 2013 Author Share Posted February 24, 2013 Emissions! thats one of them thar dirty words in Truckin mister!CT has two guys that go around checking Quote Matt Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/#findComment-167328 Share on other sites More sharing options...
rsb502 Posted February 24, 2013 Share Posted February 24, 2013 CT has two guys that go around checking Time to move! Quote "Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin"If your gonna be STUPID, you gotta be TOUGH" "You cant always get what you want, but if you try sometimes you get what you need" Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/#findComment-167419 Share on other sites More sharing options...
EWB555 Posted August 11, 2013 Share Posted August 11, 2013 I have a 95 rd with a 12 spd. The outside inversion valve is constantly leaking air from the botom of the valve, not from an air line or fitting(two bolted together on side of tranny, one closest to frame leaks)I replaced it and still acts the same. The only way to make it stop is if I flip the switch on the dash for low low, then i flip the switch back and the air leak is gone but will come back after driving.The transmission works fine, anyone have any ideas what's causing the air leak? Quote Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/#findComment-199163 Share on other sites More sharing options...
frantzevan Posted March 17, 2019 Share Posted March 17, 2019 I’m having the same issue with the inversion valve mounted closest to the transmission. I just replaced it with a new valve and it is still blowing air out the bottom. Did you ever figure out what your issue was or can anyone else point me in the right direction? I’m at a loss right now. The only thing I can figure is the pressure reducing valve is failing and there’s to much pressure? The supply line for the inversion valve that is leaking is the yellow line that comes down from the transmission shifter. Quote Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/#findComment-418358 Share on other sites More sharing options...
frantzevan Posted March 18, 2019 Share Posted March 18, 2019 Anyone with insight? Quote Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/#findComment-418436 Share on other sites More sharing options...
JoeH Posted March 18, 2019 Share Posted March 18, 2019 (edited) I had a Combination Cylinder crack on my 8LL trans a couple years ago. It's the disc that air pushes against to change from high to low and low to high. Easy part to change. Air would leak through the crack to the vented side. Switch range and it'd still leak, because you're just inverting which side of the disc is pressurized and which is vented. I'll bet thats where you'll find your problem. Edited March 18, 2019 by JoeH Quote Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/#findComment-418442 Share on other sites More sharing options...
JoeH Posted March 18, 2019 Share Posted March 18, 2019 Will likely be called Splitter Cylinder or Shift Cylinder on a 12 speed. Combination Cylinder is what it was called on my 8LL Quote Link to comment https://www.bigmacktrucks.com/topic/30110-12-speed/#findComment-418444 Share on other sites More sharing options...
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