I have what I believe to be a 1989 TD8G long track with the Cummins and short transmission. When I purchased this dozer it had been sitting for over a decade and wouldn't hardly pull itself up on the trailer (had really bad hydraulic chatter) or steer. It has around 3k hours on it which I believe to be true because of the condition of the under cartridge, gauges, controls etc.. which are all in great shape. I found the drive and steering pads were delaminating from the shoes so I replaced all 8 of them as well as replace the strainer filter which was full of debris that appeared to be the epoxy that once held the pads on the shoes. I also changed the pressure filter twice between flushes as well as repack all cylinders and replace all hoses, fluid and filters on the hydraulic side. After doing all of this I never got 3rd gear back but 1st and 2nd worked great and I pushed a lot of dirt with it for almost a year until 2nd gear started to fade. I've read on here about possible broken hook ring seal on transmission clutch pack but all I see in the parts and repair manual are a teflon seal and o-ring for the input and output shaft manifold. Am I missing something or does anyone have any ideas on where to troubleshoot other than the clutch packs themselves? Any help would be greatly appreciated as I'm running out of ideas fast. Thanks, John
I’m thinking the hook rings provide pressure to the whole transmission. If they fail all gears would slip forward and reverse. Been awhile since I worked on mine but I’m positive it doesn’t have hook rings for each range.
The transmission is a countershaft type with individual clutch packs for each direction and range. Oil for each pack is routed through the shafts and into each pack. The cast iron hook rings seal each pack where they fit over the drive shafts. When the rings wear out the hooks snap off and it won't let the pack pressure fully build up and the clutches end up slipping. There are places where you can plug in a gauge for each individual pack so you can check the pressure when you put the transmission in that range. A low pressure usually means a valve problem or a leaking pack. That almost always entails removing the transmission and tearing it down for repairs.
Thank you both very much for the replies. Looks like my next step will be checking the pressure of each pack. Would either of you happen to have a part number for the hook ring seals? I have a parts book but for the life of me I can't find them listed and my schematic may not be detailed enough. Thanks for the help!
I’m sure they are in the parts book. They look like plain old o ring seals in the drawings and are listed as seals
So it's been awhile but I finally got the time to make up a test gauge and check the pressures at all the ports on the transmission per the procedure in the service manual. The good/bad news is they were all in spec in all ranges, forward and reverse. Even third gear which doesn't work at all had good pressure. So this leads me to believe that I have bad clutch packs in 2nd and 3rd and not a pump or seal issue. Does anyone have any suggestions or leads on where to get the rebuild kits for these clutch packs and is there anything else I should look to change out while the tranny is out? I rebuilt all cylinders including the steering cylinders and replace all 8 friction pads last year. The machine is really dry with no leaks at the moment. I sure hope it's the same when I get done with the tranny rebuild!