I have the transmission apart. Several warped steel discs in the forward reverse clutch. Replacing the discs, o-rings, converter seal etc. Anything else I should be looking at before we put it back together? Reverse works on flat ground. Stalls when trying to back up a hill
Welcome to HEF Steve ! Oh what a joy pulling that one out ! To start with do you have the manual TM1108? If not you will need it. Make sure the collectors don't have grooves worn in them from the clutch shaft seals. Also make sure the grooves for the seal rings on the shafts are not worn out. Finally clutch pack clearance is important so you want to set that correctly. And obviously replace all seal rings, O-rings and gaskets.
Thanks mg2361. We do have the manual. it has been helpful so far. We have pulled the converter housing out to get access to the front of the powershift housing which allowed us to pull the forward and reverse clutches. We didn't notice any problems with first, second and third so we left those clutch packs and shafts in place. The collectors for first/second and third do show signs of where the shaft seals sit. We haven't seen what a new collector looks like so it's hard to say if they are grooved. If the inside to the collector is supposed to be completely smooth then yes they are slightly grooved. We will have to see if the collectors are still available, we have found some parts that we can't get from john deere. DO YOU KNOW OF ANY PLACES TO FIND OBSILITE PARST?? The main reason we torn into the machine was because we had a really bad oil leak from the bottom of the converter housing. It looked like all the oil was coming out of the small hole at the bottom the the converter housing, but upon tear down I noticed the fitting on the trans pump was not tight against the pump housing, feel like that might have been some of the leaking we saw. Our initial thought was that the converter oil seal had gone. Now that everything is apart it doesn't seem to be damaged but could very likely be worn. We also found that the converter housing had broke or worn threads for the 4 large bolts that hold through the frame rails into the sides of the housing. We have repaired the housing the best possible. Kinda wondering if the converter housing(which holds most or all of the engine weight) being unsupported is causing the converter seal to not be centric around the converter. Hoping that all these repairs will stop the oil leak. As for the issue with reverse being weak, it worked fine on flat ground but would not bake up a hill and barely backed onto our trailer when we bought it. Any info or advice yall have would be awesome and greatly appreciated. 1977 JD 550-C dozer serial #281241T
Your machine is a straight 550, not a 550C. Deere did not build a 550C. They went from a straight 550 to an "A" then to a "B" and then jumped to a "G" when they changed the whole design of the machine. The "C" in your serial means the dozer blade is inside the tracks. Supposed to be smooth. The rings that go in there, they worn? Nope. Common issue. Should have performed multiple pressure checks before disassembly to try and figure out why reverse is weak. Also was the shift linkages checked for wear and proper travel?
We didn't do any pressure tests. First off because we didn't know that was a helpful piece of info to have and secondly there was such a large oil leak that we felt we needed to address that first. Since we were that far in we thought it best to inspect the trans. We found a few things we could tell needed replacing, most of them we were able to order and will have next week. Once we have it back together we will be sure to do pressure tests to see where everything stands. We were pretty sure that the machine was just a 550 but i wrote it as its seen on the machines badge. All the rings i have got access to look almost new. None of the o-rings on the lube system look to have been replaced. From what i can tell the dozer has had some serious repairs done to it in the past. for example, the converter looks new, the friction discs in the forward and reverse clutches look new but we found that many of the steel discs were warped(1 in the forward and all in the reverse clutch), the clutch backs look to have been replaced. We found aftermarket sealant on every part that had been taken off and re-installed, marring on many non-sealing surfaces due to poor disassembly and install. My guess is that the logging company that had the dozer did a minimal repair just to get the machine running and sellable for auction. In regards to the clutch backs, do you know why the clutch drum doesn't have full sprogs where the clutch back sits? There looks to be decades of wear on that part of the drum and only minor wear on the clutch backs which make me think they have been replaced. When and if the clutch back no longer meshes with the drum, will the clutch start to slip? I have found that the clutch drums, collectors and a few other parts are very hard to find replacements for. We will make sure to check the shift linkage.
Pressure issues would be the most likely cause. Also make sure the clutch pack clearance (.05" - .14") is set correctly. If too much clearance it could slip as well. It is not adjustable like on other transmissions with variable snap ring sizes.