350 Track Falling Off

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JDCI
40C crawler
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350 Track Falling Off

Post by JDCI » Thu Jul 19, 2012 10:06 pm

Hi, my friend has an original JD 350. The machine will frequently throw the right track during operation. Basically, the track stays on the teeth of the sprocket, but it gets on the outside of the bottom rollers/idlers. This is causing wear on the inside edges of the sprocket teeth.

The sprockets seem OK, they are not worn to a point yet. I'm not sure about wear on the rest of the undercarriage.

Does anyone have ideas about what may be causing this? Is it fixable, and are replacement parts available for reasonable prices?

Thanks for the help!

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Willyr
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Post by Willyr » Fri Jul 20, 2012 4:22 am

Check the rollers underneath. The rollers should be H shaped. If the sides have broken off you need to replace them.

Other items that toss tracks. Improperly adjusted tracks. Tracks should not have more than 2 inches of sag in them. Place a board across the top of the track and measure under the board to the top of the growser (the pointy tip of the track plate).
Also having a loose front idler. If the front idler no longer holds onto the carriage. Or if the idler is now pointing on a angle (no longer parallel with the under carriage). Or if you have a bad bearing on the front idler. When I say the front idler, I mean the lead wheel at the front of the carriage.

Start the dozer. With the blade. Press down on the ground so it raises the front of the tractor as in depicted in the picture. You can then check out the rollers and idler.

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former owner of a 1956 420c
All help is greatly appreciated.

Proud owner of a project 1952 JD 60

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JDCI
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Post by JDCI » Sat Jul 21, 2012 7:45 am

Thanks for the help! Unfortunately the hydraulics aren't hooked up right now. My friend broke the cover of the hydraulic reservoir when he was taking it off.

I inspected the rollers as best I could and they all seemed to be intact. I'm not sure if they or the idler have any wobble in them, but we may try jacking the machine up to see.

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digitup2
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Post by digitup2 » Sat Jul 21, 2012 8:32 am

If the chains are to the point of snaking or derailing then there isn't much can be done but turning the pins that will stop that snaking besides new chains .Digitup.

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Lavoy
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Post by Lavoy » Sat Jul 21, 2012 9:37 am

Even turning really won't do much for snaking, all the wear is still there, the rails will just be shorter. I will help some because the rails will be back in pitch, and not climb the sprocket so bad.
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Parts and restoration for antique and late model John Deere crawlers.
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digitup2
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Post by digitup2 » Sat Jul 21, 2012 1:16 pm

Yes I am not a fan of turning pins the best fix is new chains but check the sprockets and rollers as well no sense putting new chains on and the sprockets and rollers being worn out .I saw new chains and old sprockets last week and after 500 hours the new chains are wrecked with the old sprockets pounding the chain at the wrong point .Way she goes!! .Digitup.

JDCI
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Post by JDCI » Sat Jul 21, 2012 8:37 pm

Thanks for the replies.

I actually took a close look at the machine today. The bottom rollers on the problem track don't seem to be tight and look like they could wobble. One of them actually looks broken. They seem much better on the track that doesn't fall off.

How hard are new rollers to get? What kind of money do bottom parts go for on these things?

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