Am at a loss with the torque converter I'm attempting to install on my 79 580c backhoe. The book says runout on the hub of the installed converter should be a max of 0.004, however my attempts to measure have all given back wild measurements from ~0.040 to ~0.080. The pilot pin(?) on the rear of the converter, that goes into the flywheel, seems to be a snug slip fit with zero noticeable play so I am confused as to what the book means by adjusting to try and reach this .004 of runout. A unique thing with this machine is the flex plate was slightly bent near one of the bolt holes where it attaches to the flywheel by a prior owner. I mostly corrected the bend but I suppose that could be contributing to this issue? The bend was super mild, no creases, just as if someone had pried in one spot. My dial indicator and stand are attached to the back of the block and reaching around to land on the smooth outer side of the converters hub. I currently am rotating the flywheel by hand, which may also be contributing to some runout(?) - should I start figuring out how to bar the engine over from the front? It looks like a tight space up there. Any help would be appreciated. The wife has me signed up for spring projects so i need this thing running soon!
What does the manual say about correcting it? Put shims between the converter and the flexplate?
Sadly it doesn't seem to elaborate there, just mentions "adjustment as needed". After sleeping on it, I'm starting to think the flex plate, despite my best efforts, still has just enough warp to it that it's pushing harder to one side, just enough to throw things off. It doesn't help that the alignment tool for the flexplate to converter is unobtanium but am also thinking about measuring and 3d printing my own to see if that helps. EDIT: Might grab some shims off McMaster too, not a bad idea, because at this point I'll try anything!
Thinking about it further, I might also try counter-bending the flexplate to compensate - it's possible that's what they mean by "adjustment as needed"
Your flex-plate is junk. They cannot be bent back once they are damaged. It also weakens them. Get a new one and you will see how easy it is to install and and get the proper clearance. Adding shims will create a whole new nightmare. It is extremely important that the flex-plate is perfectly centered on the torque convertor.
Yes, I can imagine the bad things the uncentered torque converter would do to the shuttle shift transmission.
Ya after lots of fiddling this morning I have come to the same conclusion, it's not recoverable, and have ordered a replacement. I really appreciate yalls input on this. I'm prepping an alignment tool and will see what precision I can get when used with the replacement - if it works out I'll upload the 3d print file here for folks to use.
Your measuring on the seal surface correct?
You'll probably never get that thing to that spec, and I have some doubt it was that good even when it was brand new. Even if you do seem to get it, when you snug it down it'll go right back out again. I had a fight with that when I redid mine, even made the 'alignment tool' the service manual shows and still couldn't get that .004" spec. HeavyEquipmentForums I can't recall what mine ended up being now, and also apparently didn't jot that info down anywhere, but IIRC it was maybe around .008" (double the spec or so at most) but it for sure wasn't 10 times or more out though. That was almost a decade ago now, and it hasn't come flying out of the bell housing yet.
Update! Ordered a "new to me" flex plate, a little rust, one ding on it even but after cleaning it up and going through about 10 iterations of a 3d printed alignment tool (I never did find any official measurements) I just went for it. I'm never this lucky but on the first try I landed right at .004, once installed, measuring on the seal surface of the TC hub. After thinking of all the geometry and forces involved it does totally make sense that there's no substitute for a nice flat flex plate. Anyway, for those that run into this situation with a busted up flexplate and no alignment tool I've attached a Fusion360 file and STL file for 3d printing one. Here are the specs for 3d printing that I used: Prusa MK3S+ - PLA - 0.4mm nozzle - 0.3mm layer heights - sliced in PrusaSlicer, Generic PLA, 20% infill (just needs to be rigid enough) - enclosure around the printer The model includes stepped pins, partly to align with the holes of the flexplate and reinforcement ring, then another to drop into the bolt holes. The bolt hole pins though are possibly unnecessary. The print wasn't 100% perfect but to get an even better fit one could use a wrap or two of tape on the various surfaces to add .001 or two as needed depending on your printing setup. Note that I used the print as-is without tape or other gap fill strategies. Anyway, I appreciate all the inputs here, hope the 3d print option can save the next guy some trouble.
Nice write up on how to make the tool clr ! Unfortunately I, and I suppose many others have no machinist skills. Alrman and Coy both have their own a way to do the alignment wit out the tool. I used Coy's method on my 680C and it worked quite well. It is described in detail in this thread. ↓↓ HeavyEquipmentForums