Roscoetaggart Posted August 9, 2019 Share Posted August 9, 2019 Hi guys, My r model has the 10 speed box in it, and it tends to grind somewhat excessively (more than I think it should) when switching between direct and overdrive. I have never played with a truck gearbox but there is a handy YouTube video demonstrating auxiliary box removal that shows the process. Our local dealer mentioned a while back that some mack boxes are synchorised and if not assembled correctly can cause somewhat catastrophic problems. Is this something I should be attempting myself? Is it likely my 10 speed box on my 1983 688 needs to be synchro? What is likely to be the problem? Gearbox is already removed during truck restoration so easy to work on. I would call myself mechanically minded to the point where I have reconditioned quite a few motors in my time, just never a truck gearbox. Thanks in advance Quote Link to comment Share on other sites More sharing options...
mrsmackpaul Posted August 9, 2019 Share Posted August 9, 2019 Could be lots of things If you have the box out at the moment then I would lift it apart and have a look as its a much bigger job to pull it out later You need to stand the transmission on its bellhousing and lift it apart with a chain block The air split section is the rear section and once this is off it comes abart pretty simply The sliding dogs in there collect all the rubbish as in silicon dirt and what ever else you can think of that may be getting pumped around in the oil Make sure the dogs dont have bad bevels worn on them or very rounded corners as this can cause the dog not to slide in The 10 and 12 speed maxi torques I know of have no synchros at all, however I do know later model Mack boxes do have synchros Im not enough of a expert to advise on later model boxes as I have never touched one , just old rubbish for me Paul Quote Link to comment Share on other sites More sharing options...
Roscoetaggart Posted August 10, 2019 Author Share Posted August 10, 2019 13 hours ago, mrsmackpaul said: Could be lots of things If you have the box out at the moment then I would lift it apart and have a look as its a much bigger job to pull it out later You need to stand the transmission on its bellhousing and lift it apart with a chain block The air split section is the rear section and once this is off it comes abart pretty simply The sliding dogs in there collect all the rubbish as in silicon dirt and what ever else you can think of that may be getting pumped around in the oil Make sure the dogs dont have bad bevels worn on them or very rounded corners as this can cause the dog not to slide in The 10 and 12 speed maxi torques I know of have no synchros at all, however I do know later model Mack boxes do have synchros Im not enough of a expert to advise on later model boxes as I have never touched one , just old rubbish for me Paul Thanks very much for your help, you certainly know more than me! I agree with sorting everything I can find while the box is out. I was just wondering as someone said the gears need to be all timed together on reassembly so I thought I had better check! Quote Link to comment Share on other sites More sharing options...
JoeH Posted August 10, 2019 Share Posted August 10, 2019 Gears will have dots stamped into their faces where they need to be timed. Take pictures on your way in, print them out and circle timing marks for reassembly reference. Quote Link to comment Share on other sites More sharing options...
mrsmackpaul Posted August 11, 2019 Share Posted August 11, 2019 The smaller gears have dits cast into them Larger gears have holes cast into them They are very simple to work on, or at least I have found so Yes there is lots of parts and timing etc But if you have to force any gears in they arent lined up, they just drop in when all lined up The hardest put is splitting them and linig them back up when putting the sections back together A friend to steady the box sections and a tape measure to ensure its lined up square will help a lot I have done them on my own several times A car engine hoist is pretty helpful and once it's on its end is all you need Paul Quote Link to comment Share on other sites More sharing options...
Roscoetaggart Posted August 11, 2019 Author Share Posted August 11, 2019 5 hours ago, mrsmackpaul said: The smaller gears have dits cast into them Larger gears have holes cast into them They are very simple to work on, or at least I have found so Yes there is lots of parts and timing etc But if you have to force any gears in they arent lined up, they just drop in when all lined up The hardest put is splitting them and linig them back up when putting the sections back together A friend to steady the box sections and a tape measure to ensure its lined up square will help a lot I have done them on my own several times A car engine hoist is pretty helpful and once it's on its end is all you need Paul Thanks, so your saying that the 3 shafts within the auxiliary box at the back of the main box do have to be in the correct timing on reassembly? On a side note, does my gearbox have a clutch brake? It certainly feels like it needs one... I am assuming it would normally be on the input shaft but there is nothing I can see that resembles one. Quote Link to comment Share on other sites More sharing options...
JoeH Posted August 11, 2019 Share Posted August 11, 2019 I just went to see why my clutch brake wasn't working on my 8LL a couple weeks ago, I had adjusted it a few months before. Stuck my head in and it wasn't there! Somehow the clutch brake broke off and fell out! It gets sandwhiched between the transmission and the throw out bearing on the input shaft. 2 Quote Link to comment Share on other sites More sharing options...
mrsmackpaul Posted August 11, 2019 Share Posted August 11, 2019 All three shafts need to be timed thru all sections of the boxes It really is pretty self explanatory when your working on it, or at least thats how I have found it to be When you pull the box apart put all the parts in the order they come apart in I dont wash anything until Im re reassembling what Im working and then I wash each part or group of parts as it goes back together This I feel adds a lot to reduce confusion for me and ensures everything is spotlessly clean I dont worry about putting marks on things as they will only go together one way Paul Quote Link to comment Share on other sites More sharing options...
david wild Posted August 11, 2019 Share Posted August 11, 2019 If it is a Mack transmission you need to find the nearest dumpster and rid your self of a problem and replace it with a smooth shifting quiet Fuller. 1 Quote Link to comment Share on other sites More sharing options...
david wild Posted August 11, 2019 Share Posted August 11, 2019 only the truth hurts Quote Link to comment Share on other sites More sharing options...
JoeH Posted August 11, 2019 Share Posted August 11, 2019 My Eaton shifts like junk. Someone beat on it before we bought the truck. No thanks, I'd rather a Mack. Though the 2 sticks are the only Mack transmissions I've driven. Quote Link to comment Share on other sites More sharing options...
david wild Posted August 11, 2019 Share Posted August 11, 2019 There you go, "it was beat on" still works though, and yes I will agree about a 2 stick Mack but then how people are still running a 2 stick Mack in a commercial operation today, a toy is a toy, not a commercial truck used to earn money, you guys amaze me comparing your toy or part time used truck around the farm to a truck used every day running in commercial operation, look at all the people who write into BMT about noise or grinding sounds, people who trying to earn a living, if my toy grinds who cares, if my work truck grinds then it is on it's way to failure, and that costs money, not just repair but lost confidence from my customer and so on. check into reality and not Macktopia. 1 1 1 Quote Link to comment Share on other sites More sharing options...
JoeH Posted August 12, 2019 Share Posted August 12, 2019 Lol my 2 stick is a `79 and works just about every day. Had 350k miles on it as a tractor when we bought it, we have about 250k miles on it since we got it in '86. We run a 15 mile radius delivering concrete. Lots of short runs in traffic, lights, stops, hills... very few highway miles. Lots of shift cycles. This one isn't a hobby truck, we drive it like a work truck. Shift, floor it. Shift, floor it. Shift, floor it. It has never complained. I'm assuming the Eaton was beat on but I have no idea if it was or not. But the 2 stick survived my brothers and I learning to drive on it right out of high school. Still shifts as good as ever. Up time in the 11 years since I started driving is close to 99%. And you have to factor that 1% downtime can be the mixer`s fault, not the truck. Compare that to anything new. Quote Link to comment Share on other sites More sharing options...
david wild Posted August 12, 2019 Share Posted August 12, 2019 You are one of a few, most companies need new trucks to attract drivers and many insurance companies do not want to insure older trucks, I too run older trucks, but there are fewer and fewer old trucks out working, If I was in the market looking for a driving job I would be driving a new what ever I want, that is the way it is, and you are right new trucks do not have the up time that the older trucks had, I too drive older trucks and look everyday for older clean trucks, hope is that I can get enough to last till I retire which after this last purchase I think I have done, but our experience with the 2180 and 3180 has been very disappointing, I am beginning to think that the problem is with the case being aluminum and it expands faster than the steel parts which then creates binding or alignment problems which leads to their demise, maybe a steel case would be better, and yes they all have coolers. Quote Link to comment Share on other sites More sharing options...
JoeH Posted August 12, 2019 Share Posted August 12, 2019 My company is just my dad and I. No one but family has driven our trucks in over 20 years. Don't need some idiot breaking my old trucks because he wants a newer one. He would find himself out of a job real fast with a pretty salty employer reference. You can't beat multi speed reverse transmission for concrete truck work. A 2 stick in 3rd reverse will get me in places the 8LL will die in. 1 Quote Link to comment Share on other sites More sharing options...
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