Hydraulic leak and undercarriage questions?

On my Cat 931B I had a nagging hyd. leak where 2 steel lines with a flare fitting go together. They are the lines for lowering the loader. I tried to tighten it before but it was already super tight. Today with a good pull on the wrench, I got it to loosen so I took the connection apart and everything looked OK. It might have had a tiny bit of rust on the tapered end that goes in the flared end. I got the nut on the flare end to move and turn a little easier and after cleaning both ends as good as I could, put it back together. Not quite as tight as it was. There is another steel line right underneath it. It was a very small leak but still enough that the top of my final drive case, etc. is covered in dirt because of the oil leak. I spayed some super clean and water over the connection and dried everything off. It didn't appear to leak even when I lifted the front of the machine off the ground at let it sit there for a little while. I put some business card I didn't need right under the connection to check for a leak. No leak. At least not yet. Can some fitting leaks be fixed just by taking them apart and putting them back together without doing much else? Or by not having them super tight? My elbow slammed into the brake pedals when it finally broke loose. Ouch!
The other question is about weld on sprocket teeth. The sprocket rims I got are cast steel and the teeth aren't machined real perfect like bolt on segments. I assumed and was told by the supplier that the teeth will wear in. It's almost like the opening for sprocket teeth is slightly undersize. I left the tracks just a little looser than recommended till the bushings fit the sprocket better. Is this common on cast sprocket rims? It is getting better but I'm just curious. The bushings at first would fit in when at the top of the sprocket but at the bottom the bushing was inline with the point of the sprocket tooth. The teeth weren't perfectly square from one side to the other as well. Like I said it is getting better but I'm wondering if it's just normal for cast sprockets. Thanks for any input. Dave

Next time take a hammer and smack the sides of a tight fitting before you try loosening it. You'll be suprised how much easier it breaks loose. I have hit them just right and just the hammer blow alone would knock the nut loose. yes, on a JIC fitting it isn't uncommon to take the an old fitting apart and clean it up a bit and stop a leak without actualy changing anything. As for your track problem it sounds like you've got alot more wear in the rails than you might think you do. The teeth spacing doesn't change, the change would have to be the distance between the centerlines of the bushings due to the pins being worn out. Wear such at this is the only thing that would make the bushings fall down and fit in the sprocket one time and then be too close together or far apart at another.

Everything is brand new. Rails, rollers, sprocket teeth, idlers and even pads. The only thing I didn't change was the top carrier rollers. They are still fairly good and easy to replace if I need to down the road. Maybe just because the sprocket rims are cast and not machined, they are made slightly oversize to wear in? I had to play in the mud a little today to do some drainage work. I drove through some standing water to get where I needed to be. It was about a foot deep. Does driving through water hurt anything? I wouldn't think so unless it was really deep or you sat in it for a while. Dave

Operating in the water and or muck, hopefully not salt water, should not be a problem if the final drive case/compartments are sealed and not leaking anywhere an can allow water in. You could check the lube and see if you have taken on water, if not leaking anywhere, nothing to worry about.

Not familiar with that particular tractor, on the older ones that had those bellows type seals, if let sitting too long something about the metal backing getting stuck and the seal failing when you go to run the tractor, after it's sat awhile, manual called for these to be run back and forth 1x week, probably one of those things that not too many people did. I know mine leak and have to stay out of water, as it can get into the housing, water and silt not good for those bearings and gears etc., would have to pull both sprockets and replace the seals, easier to top off and stay out of the muck for now.

Nothing leaks that I could see. I think it uses duo-cone seals. I know on some of the high track models they went with an upgraded seal/back to duo-cone because of problems with the idlers. On one side on mine, the cap that goes over the sprocket nut leaked a little bit. The guy at Cat said it's probably just leaking on one of the splines or something and I should only worry if I get a leak coming from the inside of the sprocket. I put some silicone gasket maker on the cover so it would stop the tiny leak. I didn't end up taking the sprockets off to weld the new teeth on. Less work and less potential problems doing them in place. It was just rain water I drove through. The bottom was firm and wasn't muddy. I did work in some softer stuff but not under water. I drove back through the water to help clean the mud off. It kind of helped. Dave

Probably nothing to worry about there, did not realize there are weld on sprocket rims for that crawler loader, figured that being a later tractor, would have bolt on segments, then again probably a smaller sprocket anyway. I would think doing that in place would be less aggravation, and like you said less potential problems, you must have rotated the sprocket to place it in an easier weld position. Wasn't this one with some minor track frame alignment issues ? Lots of fun doing U/C work, but looks like you got it done without too much trouble.

New sprockets from Cat are listed over $1100.00! My machine is an 86. The C models I think had segments or were optional. The cheapest 1 piece sprockets I priced were about $450.00. The weld on teeth were $125. Cat also has a weld on segment adaptor ring or hub for segments. All are real pricey. $600 plus just for the segments. The new hub for segments is over $1000. There is seals behind the sprocket and the sprocket is on a tapered spline. The guy at Cat said you need about a 30 ton puller to get the sprockets off and then an even bigger press to put them back on. The sprockets were welded vertical up with 7018 after grinding a bit of a bevel on the ring with the new teeth. I could lift the whole machine up and turn the sprockets into position for welding. On the backside (inside) we lifted up the back end of the Cat as high as we could with the hoe and stabilizers. My buddy welded 2 passes while I tried to slowly turn the sprocket a couple inches at a time with the machine running. Very hard to turn smooth but he figured out how the sprocket kind of jumped when he yelled at me to turn it. He made sure to move the rod back to the puddle when the sprocket turned. The weld was done at the bottom and was basically a roll welded horizontal weld. Twice around each sprocket. My leg was getting sore from holding the brake so much. I had to hold it down except when I turned the sprocket every 5 seconds or so. Turned out pretty good considering my buddy was laying under the Cat to do the weld. Probably not something to try if you haven't done a lot of welding in position or roll welding. If the sprocket would have been off would have been way easier and faster for welding because we could lay it flat and put a good pass with 3/16 rods on both sides.I put a chain and boomer on the 2 stabilizers to keep the machine from falling in case a hose blew or something. I also had the hoe down to help hold the machine up. My track frames were pretty straight but I can't seem to get the idlers to line up just right. Having good help to put the new teeth on really helped. Even if I still had my own welding truck, it would be very hard to line everything up and hold it by yourself. It was kind of wierd doing the sprockets. On one side we put the ring over the hub and it was all out of wack. Turned the ring about 1/2 a turn and everything measured OK. We took a measurement from the front, back and top of the thick plate the final drives bolt to and then turned the sprocket and took measurements again. Easy to cut out the tacks if it's off but a pain to cut the whole thing off if it was wrong. We took our time to make it as straight and true as possible. It could have been a lot worse. Changing undercarriage is a big job. Dave

That is an interesting project, having seen a lot of those weld on sprocket rings on tractors, you just imagine what it takes to tack one on and keep it straight, though once done, 7018 ought to hold up just fine. The pullers used on these type of tractors, to remove sprockets, I'd have to pay someone to do that, or bring the assembly to them, which I think is possible on the old D7's. That is definitely a plus not having to pull those and or having to repair any final drive parts as well, in addition to the U/C, these things can become a money pit quickly.
They must have really been worn as when that new chain goes on, new rollers etc. would seem to correct the pitch and place the pin properly in the sprocket, even if higher up the teeth were worn from the old chain. Good thing is now yer done, ought to hold up awhile, hopefully you can get the idlers situated to line up correctly too.