350B Final Drive Gearing

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Kaiverol
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Re: 350B Final Drive Gearing

Post by Kaiverol » Mon Sep 21, 2020 12:11 pm

Not sure what the rail is? Sprocket has seen better days. Should I replace? Crawler won’t be operated too many hours per year (maybe 10), so beyond the most important I don’t want to go too far right away.. I also have two broken adjuster springs.

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Lavoy
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Re: 350B Final Drive Gearing

Post by Lavoy » Tue Sep 22, 2020 8:19 am

Track rail. Put a new one on, and a new sprocket.
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Parts and restoration for antique and late model John Deere crawlers.
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LeonardL
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Re: 350B Final Drive Gearing

Post by LeonardL » Tue Sep 22, 2020 6:40 pm

Lavoy is right. If you're going to fix this thing then fix it correctly. Whether you run it ten hours or ten thousand. There is only one right fix. Unfortunately it is never cheap when it comes to these crawlers. No matter what their age or how small they are. We all want to do it as cheaply as possible. The problem with that is you are taking a chance of having to do something over. Then you're paying for it twice. So do it once and get it over with. We all would love to have a can of "Fix It" that we can just pour over something and it be good as new. Unfortunately that doesn't exist. Your "Fix It" is your billfold or pocket book.

To answer your question about what is a track rail... A track rail is the chain that the machine runs on. Some people call them "Track Chains." They are essentially a chain that your pads bolt onto and then rides underneath your lower rollers that have flanges to hold the machine on the rail or chain. The lower rollers along with the front idler or wheel is what keeps the rail or chain in place while the crawler rides on them. Make sense? I'm not real good at describing things.

These broken springs you mentioned? Are they the track adjuster springs? Just want to clarify what you're saying here. No offense but we seem to be getting more and more information as we go along here. That's partly my fault for not asking. I assumed you had a good and functioning undercarriage. So what we need to know is exactly what you have as far as your undercarriage. What exactly is good and what is broken.

If the broken springs you mentioned are the track adjusting springs, you can't have properly adjusted tracks with them being broken. I'm beginning to see why your machine was pulling to one side. It sounds to me like you need to do a complete assessment of your undercarriage and maybe the entire machine. What is okay and what needs to be replaced.

As for whether or not to put new sprockets on with new rails? You should never put new rails on old sprockets. The only way I would is if the old sprockets gauged out to be close to the same as new and as long as they were wearing normally. The reason is an old worn sprocket will wear new bushings out before the pins wear. Once that bushing wear starts then there is no going back. A new sprocket is cheap when it comes to the rest of the undercarriage. Change out what is badly worn or broken. It is the only way to fix it right.
40 plus years working on JD 350s, 400Gs, 450s and other equipment both Ag and Construction.

original possum
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Re: 350B Final Drive Gearing

Post by original possum » Wed Sep 23, 2020 10:03 am

Here's the conundrum: Repair the bad side and it will change the direction it pulls to, assuming the other side has at least some wear. Both sides need to have the same amount of wear. Either fix it right or put up with it. As long as you can adjust the tracks it will work for you. There should be one spring on each side. If that spring is broken you should not be able to adjust (worn) tracks. Replacing that spring is a bear.
Early 40C w/Yakima toolbar and homebuilt ripper: 350 w/6-way

Kaiverol
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Re: 350B Final Drive Gearing

Post by Kaiverol » Wed Sep 23, 2020 5:38 pm

I’m starting to understand the undercarriage quite a bit more now. Had thrown the track a few years ago but never really knew why. Just thought it was loose. Today I had to use the loader for a bit to move a bucket full of soil a few hundred feet. Was going slowly in second gear and constantly adjusting direction since I only have one steering clutch (what a pain), when the track started to sound worse than usual. Looked at the bad track and saw that the guide (chain) had popped over the Outside lips of the five lower rollers. That’s when I realized how important it is to have good parts and proper adjustment. Did a field repair and drove it back.

Before this happened I had already ordered a brand new chain and sprocket.

Will likely get new springs, but the repairs are still at least a month away before I start. Was hesitant to replace springs because the breaks are close to the end of the spring and there is no misalignment. In other words the break is not separating on the one spring. The other is worse and on the fourth wrap and has separated about 1/4”. Plenty of time to convince me.

I do believe that the other track chain is in good shape, maybe close to new for pitch. Will need to find all specs to know..
I am optimistic that it will steer a whole lot better than right now.

At least I had some fun today.

Jim B
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Re: 350B Final Drive Gearing

Post by Jim B » Thu Sep 24, 2020 4:30 am

Stan Disbrow posted a very good article called "Understanding Undercarriage" on the FAQ Board, you might want to study. It includes info on how to measure an undercarriage. The JD 350B service manual (TM1032) should include most of the specs you need to check your undercarriage components for wear. If you can't find them folks here can likely help you get them. The internal wear is a major one to check. How tracks look to the eye can be far from the actual condition, when measured.

Here is a link to Stan's post: viewtopic.php?f=2&t=10123

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Stan Disbrow
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Re: 350B Final Drive Gearing

Post by Stan Disbrow » Thu Sep 24, 2020 4:40 am

Hi,

Why they are called rails goes back to trains: folks laid rails to form a road for the train to ride on.

Early crawlers were called Tracklayers. They lay their own tracks, ride on them, then pick them back up, send them forward, then lay them down again.

Yes, they are actually chains with pads, but the term Rail sticks. ;)

Stan
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Kaiverol
430 crawler
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Re: 350B Final Drive Gearing

Post by Kaiverol » Thu Sep 24, 2020 10:50 am

Good piece of history. I can really visualize that. I know I need a service manual, but can’t decide how/where to get one. Wondering if some are different with less info, or poor quality printing. I also see that I can get a digital copy straight from John Deere.

Jim B
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Re: 350B Final Drive Gearing

Post by Jim B » Thu Sep 24, 2020 12:13 pm

Contact Lavoy about manuals before you go to JD. He sells manuals. I understood one of his posts a while back that he changed supplier/publisher to get a better quality manual line than his old supplier/publisher had. If he can't supply you with what you need, post back and there may be other options. That applies to not just manuals but parts as well, in the quality and fit. And he doesn't just sell parts, he works on JD crawlers so he can help you with problems if needed.

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