d7 3t UC evaluation

If by 80-90% you mean amount worn (so only 10% of wear left to go), then that's a good starting point. I'm not that familiar with 3T sprockets but that one looks 100% or more. Clear lip seen on rollers and idler so at least 50% on them. Other folks eyeballs are more attuned than mine but I would characterize that undercarriage as generally worn out (grousers look good though)

The tracks have been run to the point of failure. I agree with Don, bushings are worn through to pins. Once you get that far there is nothing to save other than you could unbolt the grouser pads and swap to new rails if you have a big impact wrench and a torch.

I doubt the rollers are in good shape since they were most likely put in prior to or at best at the same time as those rails and I see a bit of squaring on the bottom of the pin bosses even though the rail height looks pretty good. That indicates to me the rollers are getting worn so the flanges are sticking up and getting close to the pin bosses. If it had been run much recently you could probably see the wear better.

Once I see broken bushings I don't need to measure pin to pin stretch or rail height so you didn't miss much other than to say the undercarriage is 90%. On the face of it, I take that to mean its worn 10%. I am used to hearing the remaining % quoted with no qualification. I expect the seller knew this and was hoping a novice would not question the "good" 90% figure or look very close at the undercarriage.

With that undercarriage, and the clutch problem, the tractor is scrap or parts machine. I doubt the clutch is a simple adjustment required situation. Whoever put the hours on that set of tracks knew how to adjust the clutch and the fact that they didn't adjust it so the tractor could be moved probably means there is nothing left. Thermoid links could be gone but you would usually see smoke and fuzz flying from that.

Okay mp3953, I don't see the bushing wear the other guys saw. I saved the image of the bushings to my computer and blew them up to 200% and there are marks on the most centered bushing but I saw very little sign of wear on the other bushing visible. The grousers look good and the rail height is great. I haven't seen 3T tracks in this good condition in a long time. That's the good news - the "other" news is the sprockets are worn quite a bit but they still have life left. The old D7s had an even number of sprocket teeth that means that the tractor only uses half of the teeth at a time. You can run until the sprocket is too worn then "jump" the sprocket a tooth and continue to wear the other half. The idlers and carrier roller shown are also worn as well, but you would still get a lot of hours before you ran them to destruction. I would like to see more photos and some of the bottom rollers.
The clutch problem is another matter. Please see the other post about that.
If you decide to buy this tractor please find a Operation and Maintenance Instruction Book for it along with a Parts Book and a Serviceman's Reference Book. They are available on ebay or PM me and I have some I would sell.
The 3T was a great tractor in it's day but you can do a lot of damage to it if you don't know the proper way to operate/work on it.
Good luck,
Craig

Well I am glad to hear someone who was in more agreement with me. It must be image quality because the bushings to me had almost no wear. Does anyone ha e some good pics or a manual with pics of good and bad ones so I can learn better what I am looking for? On the sprockets when I look at the rim of metal around sides it is pretty even and does not look egged out. How do I know it is worn? Thanks for all the replies

I agree with Sesicat. I do not see the wear on the bushings and the rail height looks good. I agree that the sprockets and idlers are worn, but still have some life left.

D6 Bo

Don't have a picture but your usual extremes of service life are brand new in which case the bushings are perfectly round, and 100% worn in which, even without measuring, you'll see a noticeable wear mark / scallop out of the side that contacts the sprocket. When it's really toast, the bushing will be worn through and you can see the pin on the inside. Noticeable ridges on the idlers and rollers is also another tell-tale, and then "pointy" sprocket teeth is another.

It looks to me as if someone has fitted a new pair of tracks on with well worn sprocket segments, there is also some misalignment wear on he idlers and top rollers. I would be more concerned about idler alignment wear and that bit of oil on one of the sprockets than wear on the rest of the undercarriage.

Track link pitch should be measured to know for sure true condition. Measure across 5 pins of stretched track. New would be 32" I believe. Judging by condition of sprockets I suspect internal bushing wear.