Replacing Inner Track Support on OC3

[jeffesonm]

Hi all - New owner here, just got home a 1953 OC3 with dozer/loader as well as a 1961 OC46-3D.  First tractors so I'm very excited.  46 came with a manual and I ordered the OC3 manual from Zimmerman.  The OC3 runs but the 46 has the aux trans at Zimmermans getting new bearings.  Hope to use both for a bit and maybe sell the OC3 later on and look for a 68 as I really like the wide ones.

Brought the OC3 into the garage to change all the fluids and give her a tune up before I go pushing dirt and noticed the inner track support is missing a bolt and cracked in two spots.  The OC3 came with a bunch of parts so I've got another one here.  Can I just jack up the right side and change it out?  Where do I go jacking this thing up?  First crawler so excuse the stupid questions.  Thanks.

[Doug424]

It's no big deal to change it. The sprocket will support the weight on the track, you will just have to jack on the final housing to get a little play to remove the support, you might not even have to raise it, depends on how the machine is sitting, if there's any weight or twist on the track frame, etc.   Just be careful removing the bolts,, they go into tapped holes in the track frame and if you break a bolt off its a pain to fix.

[jeffesonm]

Well I've got it out okay but I figured out why it's missing a bolt, and probably why it's cracked too.  Last guy broke off the bolt  flush against the track frame.  What are my options here?  Put it back with three bolts and probably crack another support?  Try drilling out the bolt?  Try welding a nut on?

[Robert Barbour]

I have had that problem too.  I drilled the old one out and tapped the it over size for a 9/16 bolt.  On some I installed a stud and nut on the outside. Use an Anti-seize lub on the new bolts when you install them.

[Doug424]

Is there any of the old bolt sticking out? If there is, I would try welding a nut on it. Otherwise, I would drill it out. If you get lucky you'll get on center and maybe the drilling action will drive the bolt out.

[Jack in NB]

If you drill a 1/4 to 5/16 hole clear through (being careful not to get into the threads) you can use an acetylene torch to heat the broken stub red-hot by directing the flame through the hole. Don't take too long - you're directing flame against the final drive housing. (You could put a piece of light steel plate in there to act as a shield.)

Heating it red-hot will cause it to shrink a bit as it cools. After cooling, a squirt of penetrating oil or ATF, let sit overnight, and an easy-out will usually remove it. Might not, if the threads are really welded together. In that case you have to drill out and tap to the 9/16 thread as Robert suggested earlier.

But this is quick, and worth trying first.

I have a vague recollection of using a 1/2" bolt with a nut on the inside at one time. Can't be sure, but that may be an option if there's enough clearance between the retaining rail and the final drive casting.
.

[jeffesonm]

Thanks all for the suggestions.  The bolt is sheared off flush with the frame so I think I will try Jack's hole/torch/lube/easy-out trick first, and then the full drill/tap if that doesn't work.

[Blake Malkamaki]

Get a piece of bee's wax to put on the broken stud when it's hot. Capillary action will pull the hot wax into the tiniest space between the threads and it will not burn off like petroleum based oils. Always handy to have some around for freeing frozen bolts.

Blake

[Jack in NB]

Another gem added to my memory bank. Now if I can retrieve it when needed,....... !

Thanks, Blake!

[Robert Barbour]

I have used the hole and torch trick too, and to often works very well.  However, it that bolt was a grade 8, it will be very hard after the heating and rapid cooling so that you will not be able to drill out the rest of it with a regular high speed steel drill.   You will need a solid carbide drill, they are very expensive.   I know because I have had that issue!!