Buying Advice

First time buyer of a dozer and wanted to ask about what seems to be a concern. Would repair to only one half of an undercarriage be a red flag? So far I have inquired on a Komatsu D31 where the seller is including one sprocket and chain to replace what I could see in the picture was some pretty sharp edges to the teeth. He didn't mention nor could I see anything on the other side. Another seller replaced one final drive on a Case 450C along with both tensioners. No elaboration as to what led to one side going out. Both of these were not viewed in person.

I was under the impression that if something on these undercarriages is worn to the point of needing replacement, then both sides should be addressed or else if only one side is, that the other would soon be needing the same done to it as well in a sooner than later time frame. Am I correct with this analogy or are there instances where the untouched half lasts?

Also, is there a general standard thickness for idlers to help determine if what I am being told is the wear percentage as a guide to judge the sellers claim? Kind of like tire tread depth having its rule of thumb for what is too minimal, or does each dozer manufacture have its own specifics that I wou8ld have to look up beforehand when going to inspect in person?

Sorry for the long post, I just didn't want to gamble away the amount of money involved, only to have it cost me even more in the end. Thank you all for your time and help.

The undercarriage specs will be specific to a given model or models of a manufacturer's machines using that size undercarriage. While a few cases occur that some parts can be used between some brands that is the exception, not the rule.

One side worn out would normally indicate the other side is due as well. Someone saying a percentage of wear, or life left, is just a guess unless they used a guide, measured everything and did the math to relate it to the new dimensions.

There is a good article on undercarriage you should read. I don't think it will let me make a live link on this site as it is on a competitor's site. You can try copying and pasting this address in your browser and searching.

https://www.tractorparts.com/PDFs/undrcarguide.pdf

Find an old dozer operator and take him with you to look at it. He'll spot potential problems and give you good advice. Buy him and his wife a nice steak dinner for his time and trouble. It will be the cheapest money that you will ever spend on a dozer education.

Thanks Jim, I was kind of afraid it wouldn't be that easy to go in with just one set of specs. And I guess maybe is why the 450C has been listed for so long with a reduction in price over a lengthy time span, others with more experience and knowledge are passing it up. I had previously read the article that you suggested, and you are right, it is a good source of information.

That is the best thing to do, I agree PJH. I once knew an older gentleman who was an operator all of his life and still on the job into his 70's on everything up to D9's. He was someone I would have bought more than just a dinner for. This was back when I was being paid to run a D4 Hystat. Unfortunately he has since passed away and I am out of that line of work for hire.

also a quick crude way to get an idea of the undercarriage wear is to see if the pin and bushing boss has been cut into by the roller flanges and how close the idlers are to the front of the track frame

The idlers are the second thing I glance at after seeing how square or sharp the sprocket teeth are. Seems the easiest to see right off before having to get down and look closer. The reason I asked about if there was a standard idler thickness was that I've seen some with replaced sprockets but the idlers looked thinner on edge than what would think they would have. I'll need to do some research on a particular model before inspecting to try and find what that would be so I can take my caliper with me.

Undercarriage for many older crawlers has become 'no longer available'. Checking with an after market u/c supplier would be worth your time when you know what make/model you are interested in. I read all the time that, I bought this 'crawler'. Where do I get u/c? Then they learn that there isn't any.
Just be aware.
Dennis

I was sticking with either a Case, JD, or Komatsu. I was already thinking about long term needs before coming on here and those are ones that I see parts are still readily available for. The reason I was asking what I did was after seeing my uncle fall victim to buying one and having to have it repaired before he could even use it. Luckily it wasn't anything damaged or needing replacing but turned out to be a nut that had backed off inside the transmission. Unfortunately the amount of work and diagnosis to get to it ended up costing the same as his initial purchase price, so he doubled what he had wanted to spend to have it. Thankfully it worked flawlessly after that. I am trying to be cautious and learn from his ordeal by seeking knowledge here from others before committing to one with info on what should be what, so posted here.

I was just informed that the Case I asked about earlier has had another price drop. But the replacement of the one final drive and not the other is still keeping me hesitant to gamble on it. Could last five years or five days on the untouched one. It's a lot of money to risk. Not like the seller is willing to give any short term guarantee on what he's claiming on his ad is an Excellent working machine. Needs nothing. People will say what they think others want to hear, but that doesn't necessarily mean its true.

It is quite possible for a final to go out on one side and not the other, some operators tend to be handed and can only operate the machine on one side, draining the oil from the other side and examine it closely for filings or have the oil tested will be a good pointer as to the condition of the final, we usually try to keep the tracks even, on the machines we try to sell, nothing looks worse than a worn track with a good one, the undercarriage is the most important factor on a crawler and costs the most so have an experienced crawler man look the machine over as the last thing anyone wants is a money pit.
AJ