Willie dog Posted March 27, 2018 Share Posted March 27, 2018 Anyone have a spare nut that holds the pitman arm to the steering box they would like to sell? I can't find one anywhere, it's a super fine thread pitch. Even Fastenal can't get one. It would suck to take the Mack out for it's maiden voyage and not be able to steer clear of oncoming traffic. Quote Link to comment https://www.bigmacktrucks.com/topic/52941-nut/ Share on other sites More sharing options...
Rob Posted March 28, 2018 Share Posted March 28, 2018 I have a parts chassis out back. What size are the threads? Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/52941-nut/#findComment-395350 Share on other sites More sharing options...
Willie dog Posted March 28, 2018 Author Share Posted March 28, 2018 32 minutes ago, Rob said: I have a parts chassis out back. What size are the threads? I believe the nut is inch and a quarter, the thread pitch is fine thread. Not sure of the exact pitch though. Thanks a lot for your help! Quote Link to comment https://www.bigmacktrucks.com/topic/52941-nut/#findComment-395353 Share on other sites More sharing options...
Rob Posted March 28, 2018 Share Posted March 28, 2018 I'm going to be breaking that chassis apart soon. I'll measure it this weekend when I'm back home. Hopefully it is the same as that chassis has an 11k axle under it. 1 Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/52941-nut/#findComment-395356 Share on other sites More sharing options...
Freightrain Posted March 28, 2018 Share Posted March 28, 2018 I have an extra steering box. I'll look and see if it has a nut. If not, I will confirm thread size/pitch. After what it took to get the arm off my box a few years ago.........for the life of me I can't figure out how it would fall off?? LOL!!! 1 Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/52941-nut/#findComment-395358 Share on other sites More sharing options...
Willie dog Posted March 28, 2018 Author Share Posted March 28, 2018 3 minutes ago, Freightrain said: I have an extra steering box. I'll look and see if it has a nut. If not, I will confirm thread size/pitch. After what it took to get the arm off my box a few years ago.........for the life of me I can't figure out how it would fall off?? LOL!!! Ain't that the truth!! I broke a puller trying to pull the arm off. Quote Link to comment https://www.bigmacktrucks.com/topic/52941-nut/#findComment-395360 Share on other sites More sharing options...
Rob Posted March 28, 2018 Share Posted March 28, 2018 The spines on steering gears are usually tapered meaning as the Pitman arm retaining nut is tightened, the arm itself is physically forced further up the splines. Get really tight interference fit that way. A little heat applied around the threads direct into the arm itself will usually substantially reduce the needed force required to pull it off without cooking the seal out. . 1 Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/52941-nut/#findComment-395361 Share on other sites More sharing options...
Freightrain Posted March 28, 2018 Share Posted March 28, 2018 4 hours ago, Willie dog said: Ain't that the truth!! I broke a puller trying to pull the arm off. I have three variations. The last, a slack adjuster puller did the trick. It is really stout, fit well and with a touch of heat, a smack and the arm fell off like it didn't even fit to begin with. Ugh. I had to pull it when I converted to air steering since things were just different enough I couldn't mix/match parts. 1 Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/52941-nut/#findComment-395384 Share on other sites More sharing options...
Willie dog Posted March 28, 2018 Author Share Posted March 28, 2018 1 hour ago, Freightrain said: I have three variations. The last, a slack adjuster puller did the trick. It is really stout, fit well and with a touch of heat, a smack and the arm fell off like it didn't even fit to begin with. Ugh. I had to pull it when I converted to air steering since things were just different enough I couldn't mix/match parts. This is off topic but, speaking of slack adjusters. What is the proper way to adjust all the brakes? At the slack adjusters or the clevis rod? Or both? Having never been a truck mechanic, things are a little different than what I'm used to. 🤔 Quote Link to comment https://www.bigmacktrucks.com/topic/52941-nut/#findComment-395389 Share on other sites More sharing options...
terry Posted March 28, 2018 Share Posted March 28, 2018 If your slack adjusters and S cam bushings are in good shape, release park brake and adjust slack adj. till tight and back off a quarter turn, some guys get picky and want to jack up wheel, tighten adj. and back off till wheel will turn, generally works out about the same. terry Quote Link to comment https://www.bigmacktrucks.com/topic/52941-nut/#findComment-395390 Share on other sites More sharing options...
Willie dog Posted March 28, 2018 Author Share Posted March 28, 2018 1 hour ago, terry said: If your slack adjusters and S cam bushings are in good shape, release park brake and adjust slack adj. till tight and back off a quarter turn, some guys get picky and want to jack up wheel, tighten adj. and back off till wheel will turn, generally works out about the same. terry Simple enough. Same process as a car, just different adjuster location. Thanks a million! 🖒 Quote Link to comment https://www.bigmacktrucks.com/topic/52941-nut/#findComment-395391 Share on other sites More sharing options...
h67st Posted March 29, 2018 Share Posted March 29, 2018 14 hours ago, Willie dog said: This is off topic but, speaking of slack adjusters. What is the proper way to adjust all the brakes? At the slack adjusters or the clevis rod? Or both? Having never been a truck mechanic, things are a little different than what I'm used to. 🤔 The clevis adjustment is to get the correct rod length...I forgot the exact procedure but I think you apply the parking brakes and the slack adjuster should be 90° to the rod (somebody correct me if I'm wrong). When you install a new rod or chamber you usually have to cut the rod to get the correct length. Then you adjust as Terry says. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/52941-nut/#findComment-395411 Share on other sites More sharing options...
Freightrain Posted March 29, 2018 Share Posted March 29, 2018 (edited) ^^DItto, the rod length should already be set by the person that installed everything. Get online and there are layouts of what is proper. As for adjusting. I air the truck up, block the wheels, release the brakes. Then I snug the adjustment with wrench. Then back off 1/4 turn and release the lock. Make sure you pay attention to what direction is TIGHTEN. You can accidentally back them fully off instead of on. I've tried just using shop air to release the brakes but have found that you don't always get the full 120# of air and that will not release then as fully. I've had to readjust them slightly after starting truck and building air pressure. I just threw a note in my pocket so I remember tonight to check the steering box. I wasn't home last night to do. Edited March 29, 2018 by Freightrain 1 Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/52941-nut/#findComment-395414 Share on other sites More sharing options...
Rob Posted March 29, 2018 Share Posted March 29, 2018 Your brakes should release fully with as little as 60 psi applied to them. Used to be the release valve, (usually a PP1) popped and applied the brakes at 40 psi. I would think there are problems in the system if it takes more than 100 psi to fully release the brakes. 1 Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/52941-nut/#findComment-395415 Share on other sites More sharing options...
Willie dog Posted March 29, 2018 Author Share Posted March 29, 2018 1 hour ago, Rob said: Your brakes should release fully with as little as 60 psi applied to them. Used to be the release valve, (usually a PP1) popped and applied the brakes at 40 psi. I would think there are problems in the system if it takes more than 100 psi to fully release the brakes. On this one the buzzer stops at 60 psi. Then I can release the parking brake. They're a little slow in releasing unless the psi is up a bit more, then they will release just fine. I'm sure it has to do with the fact lower psi makes things a little slow in releasing. Quote Link to comment https://www.bigmacktrucks.com/topic/52941-nut/#findComment-395419 Share on other sites More sharing options...
Willie dog Posted March 29, 2018 Author Share Posted March 29, 2018 2 hours ago, h67st said: The clevis adjustment is to get the correct rod length...I forgot the exact procedure but I think you apply the parking brakes and the slack adjuster should be 90° to the rod (somebody correct me if I'm wrong). When you install a new rod or chamber you usually have to cut the rod to get the correct length. Then you adjust as Terry says. I installed all new chambers and cut the rods a little longer than the original ones to give me some "wiggle room" in adjustments. Quote Link to comment https://www.bigmacktrucks.com/topic/52941-nut/#findComment-395420 Share on other sites More sharing options...
Rob Posted March 29, 2018 Share Posted March 29, 2018 8 minutes ago, Willie dog said: On this one the buzzer stops at 60 psi. Then I can release the parking brake. They're a little slow in releasing unless the psi is up a bit more, then they will release just fine. I'm sure it has to do with the fact lower psi makes things a little slow in releasing. That is correct. The brakes should release at 60 psi and the release valve should pop and set the brakes at 40 psi. Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/52941-nut/#findComment-395421 Share on other sites More sharing options...
Willie dog Posted March 29, 2018 Author Share Posted March 29, 2018 10 minutes ago, Rob said: That is correct. The brakes should release at 60 psi and the release valve should pop and set the brakes at 40 psi. Thanks again for everyone's help! Quote Link to comment https://www.bigmacktrucks.com/topic/52941-nut/#findComment-395423 Share on other sites More sharing options...
Freightrain Posted March 29, 2018 Share Posted March 29, 2018 (edited) Never been an issue with brakes. I know the release valve works at only 60 psi, but at that point you don't have full pressure releasing the brakes and likely not pulling them hard enough to bottom them out. I can move my truck with only 60 psi, but you can feel the drag til it gets up full pressure. It's not an issue with the compressor cycle pressures, but at only 60 psi it is not fully released. My compressor in the garage might fill the tanks but won't be over 100 psi due to my 60 gal tank on compressor and getting it to cycle enough to fully fill the truck to 120 psi. Edited March 29, 2018 by Freightrain Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/52941-nut/#findComment-395427 Share on other sites More sharing options...
Vladislav Posted March 29, 2018 Share Posted March 29, 2018 5 hours ago, Willie dog said: I installed all new chambers and cut the rods a little longer than the original ones to give me some "wiggle room" in adjustments. Slack adjusters are actually the levers when the chambers act on them to lock the brakes. The largest forse applied to the S-cam is when the lever's length is the greatest. For the slacks it means when they are perpendicular to the chamber rods. The most forse is required to press the shoes finally, at the end of their travel. So with the correct settings the slacks should be at the right angle to the rods with the brakes fully applied. And if you see they don't the way of correction is turning the clevse to obtain better position on the rod and than readjust the slack adjuster. Here a trouble might be found if the rod has excessive length not allowing the clevse to back up enough (if you need it off the slack and to the chamber). And the rod should be cutted. 1 Quote Никогда не бывает слишком много грузовиков! leversole 11.2012 Link to comment https://www.bigmacktrucks.com/topic/52941-nut/#findComment-395433 Share on other sites More sharing options...
Rob Posted March 29, 2018 Share Posted March 29, 2018 And greater than 90 degree travel in the slack adjuster to rod angle is what the DOT cops are looking for in inspections. Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/52941-nut/#findComment-395439 Share on other sites More sharing options...
Freightrain Posted March 29, 2018 Share Posted March 29, 2018 Ok I have a nut and lock washer from my spare box. It is 1 1/8"-16. I forgot my pitch gages at work but using calipers it appears to be .062/ turn. Nut uses 1 13/16" wrench. If you can't come up with a nut locally I will throw this in the mail next week. 1 Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/52941-nut/#findComment-395446 Share on other sites More sharing options...
Freightrain Posted March 31, 2018 Share Posted March 31, 2018 No more loose nut behind the wheel! The Pony Express has it coming your way. 1 1 Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/52941-nut/#findComment-395529 Share on other sites More sharing options...
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