Loose sprockets and idlers on HG-42

[pasochris]

I have an HG-42 serial number 13GA998.  It had been sitting for about 20 years before I got it.  I have it running and driving very nicely now, but I recently discovered a problem.  The sprockets and front idlers are very loose.  I can easily wiggle them around by hand.  The tracks and rollers look pretty good as far as wear goes, but it seems like some bearings must be worn out.  I checked the sprocket mounting bolts and they were all very tight, I'd read that they often come loose.  Are there any adjustments I could make to tighten things up, or do I need to take the tracks off and start replacing bearings?  I would greatly appreciate any advice before I start digging into it.

Thanks

[walter hudson]

the front idlers are a shaft and bushing ,you will probably need  to replace both. if you can move the sprockets and the nuts are tight you probably have some bad bearings in the final drive or the stub shaft is loose in the housing. the bearing adjustment is made by using shims where the trunion fits on the stub shaft.
                             walter

[pasochris]

Thanks for the info Walter.  I was out of town for a couple of days, but now I'm back and ready to take on this project.  I think the first step will be to take off the tracks.  I found what look like the master links on each side, but after removing the retaining clip, about 1/4" or so thick, I couldn't drive out the track pins.  Is there any special procedure for removing the pin, or do I just need to get a bigger hammer to pound them out with.  I'd really appreciate any advice on this, as I would like to avoid damaging anything in the process of removing the tracks.

Thanks

[mtncrawler]

Make sure you back up the inside of the track chain so when you hit the pin you don't spread the chain. It took alot of pounding with a sledge hammer to get mine out.

[walter hudson]

spin the tracks until the master is on the back side of the sprocket . remove both lockpins so you can work it both ways or find which way will move the easiest . first try penetraiting oil ,brass drift and a large hammer. if that does not work ,use a torch to help brake it loose.

[pasochris]

Well, I finally got my tracks off, but unfortunatly I damaged one of the rails in the process.  The first pin I tried to remove put up quite a bit of resistance, and all the heating and sledge-hammering bent out and cracked one side of the rail.  The crack isn't too deep, so I'm hoping I can weld up the crack and move on.  Any suggestions on how to deal with this problem?  Of course the second pin came out in about a minute with no trouble.

With the tracks off I have removed one of the front idlers.  The shaft was loose inside the wheel, so I removed the shaft and bushings.  The shaft does not look too bad, but from what you said it seems like it would be wise to replace the shaft and bushings.  Although one side of the wheel is worn thinner than the other, I think that it is still in pretty good shape so I am planning to re-use it.  Does this sound like a good approach for the front idlers?

I have not yet dug into sprockets/finals to see why they are loose.  I believe that the sprocket is loose on its shaft and that the shaft itself may be loose as well.  I hope that nothing is damaged inside the final drives and the looseness is confined to the sprockets.

I have my fingers crossed that the three bottom rollers on each side are ok and will not need any attention.  Overall the undercarriage seems to be in exceptionally good shape.  The rails, sprockets, and rollers all seem to be doing very well as far as wear goes.  The master pins I removed show a minimal amount of wear as well.  I believe the undercarriage to be all origional, so I am surprised that the sprockets and idlers seemed to wear loose while everything else is in great shape.

Thanks again for the advice, I'll post an update next time I get a chance to work on it(hopefully saturday or sunday) and see if I can put up a couple of pictures.

[pasochris]

I took one of the final drives apart this morning.  The tapered roller bearings seemed to be fine, and the gears themselves looked excellent.  Should I replace andy of the bearings while I have it open, and is there any good way to check them?  I think I may have found the cause of the looseness.  The large shaft that supports the larger final gear seems to be loose, but will not come out of the housing.  It seems to me that this shaft should be rigidly mounted to the final drive housing.  It also appears that someone attempted to weld it in place by the inner truck frame pivot, but this weld is broken.  How is this shaft supposed to be attached to the housing and should it be rigid.  I think that if I can get this shaft properly attached and tighten up the tapered roller bearings with new shims the looseness problem will be solved.

[walter hudson]

if the bearings and races are not pitted you are probably ok. your shaft problem is common . it should be a pressed fit and welded. if the shaft is very loose in the housing , you will need to have the housing bored and a bushing installed and true the stub shaft. if it is fairly tight you can get by  with welding it in but be sure it is clean and use the right rod for cast iron.