JD 420c crawler

[tonypis1]

Hi I am having trouble with my track I was cleaning out a ditch line and the right track off the back and I can not find the master track pin. They all look the same oh by the way it is in the mud. How do I get the track back on without braking track and the bolt that holds the blade arm on broke off can I fix that what size is the bolt.

[boaterri]

On my 450C, I can collapse the track tensioner and with come-a-longs, steel tooth picks and swearing I have successfully remounted a track without breaking it.

Good luck, you will find new and creative combinations of "special" words.


Rick

[Jim B]

Welcome to the Board, too bad your first post is a problem like this.

On a 420C you have manual adjusters on the inside and outside of the track frame that push the idler out to tension the track. Have you ever adjusted the tracks? You will likely need to back the nuts off (Turn them closer to the spring) to allow the idler to move to the rear as far as it can. I believe you will need a couple 1-1/2" wrenches. At least one will need to be open end crowfoot wrenches were used at times. If you have never moved them it likely won't be much fun. If you have to have the blade up to access and work on the inside adjuster, secure the blade from falling by chaining it up or blocking it, It is not safe to work under a raised implement no matter how good you think the hydraulics are. And there is always the chance someone could bump the lever and cause the blade to drop. You will need to align the track as part of the idler adjustment after you get the track back on.

Hard to say what size bolt you need without knowing what blade you have (there were several different ones used on 420Cs) and just which bolt you are referring to.

Your 420C falls in the Early Model category here, so don't be surprised if this post gets moved to the Early model JD crawler technical support Board.

[fundytides]

I have had this happen a few times with my 40c before I finally took it apart and fixed the problem(s). The following is a summary of my experience. Others may vary. The track coming off is usually the result of one or more of the following factors plus interference from an immovable object (rock, stump, etc.) and typically will happen in the worst location on your property (mudhole, side-hill, etc.): incorrect track adjustment, worn or damaged sprocket, idler, roller(s), idler and roller shafts and/or bushings, idler shaft, etc. I have found that, in most cases, if a track comes off, it will go back on with the use of every tool that you have plus those you can borrow from your neighbors. During this process, children or your pastor should not be within hearing distance. The first thing to do is attempt to lift your machine out of whatever hole it is in (I had to hire a guy with an excavator in one case) and free it from any obstructions. Then try to get the machine level with the offending track sitting on 1 or 2 rugged planks. Then you can jack the track clear of the planks, get the track over the idler and attempt to start it over the rear sprocket. If during this process you can manage to loosen the track adjusters, all the better. Once the track is started on the sprocket, the very careful application of power may wind the track on to the sprocket. If this is repeatedly unsuccessful, you will have to find the master link pin and remove it. If it has the original pin, it should have a clip on one end. If it is a replacement, drive in pin, it should have a divot in one end. I have had cases where all of the above was unsuccessful but I managed to get the pin out, couldn't get the track back close enough to get the pin in but was able to insert a smaller piece of rod, bend the ends over and the crawler hauled it self far enough to get on solid ground. In one case, all I could get in the hole was a piece of heavy wire and this worked too. The most important thing in all of this is to "STAY SAFE". Do not put any part of your body, that you do not want to loose, under 2 tons of crawler or between any parts that may turn or slip. After doing this a few times, I replaced a track with a better used one, repaired the idler brackets and shaft, freed up the adjusters, put in new idler bushings and seals and replaced my rollers with the correct ones. Make sure that you have a Service Manual (the John Deere one) and, a parts book is very useful as well. Lavoy, who manages this site) is a great source of quality parts and advice. Listen to him! Good luck, have fun and again STAY SAFE!