Hey guy's this is my frist post here , so i hope this is the right place . I am rebuilding allison mt40 out of a 1969 school bus, i finally located all my internal parts it required, this was a task in it's self . but i have been looking for a manual or at least a exploded view of this ( bohemuth ) transmission with no luck . not even from the parts suppliers, the parts i found had to identified from dusty archived box's of part's stored long ago ...... so as you see i am stuck between a rock and that proverbialy hard spot. any input on this issue would be deeply appreciated .
1969 allison mt40
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At one time where I worked we had about 30+ mid duty trucks with (I think) that same model and maybe one bigger, 5 & 6 speeds. The failure rate was high and I and others overhauled dozens of them before that fleet was phased out. With that said, I consider a shop manual absolutely mandatory for an overhaul. There's an unbelievable amount of steps, amount of components, parts that can be installed a right or wrong way, tricks to installing the teflon drum piston seals, using Vasoline to assemble the sprag unit, and on and on. At the time Allison was owned by Detroit Diesel and IIRC our manuals came through Detroit Diesel. The manuals were fantastic, step by step photos (not crude drawings) on the countless pages for an overhaul. I'm a heavy truck gear guy and was predjudiced against the Allisons and didn't give a crap how some of their internals worked. However I never had one comeback because I ALWAYS went step by step, page by page according to the manual. Over the years I had lots of complicated components apart and repaired with no help from a manual but a medium or HD Allison would not be one I'd attempt. Hopefully you can find one to be able to get the job done and preserve your sanity. I think a first step might be to check with a Detroit Diesel dealership.
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