three bolts enough to hold rear crossbar?

[Scottyb]

my 350b drivers side sprocket was hitting the back roller when i bought the crawler. My new tech manual explains that shims in or out will solve the alignment problem however my cross-member is welded to the track frames so I loosened the caps holding the rear crossbar and with a jack all and chain pulled the cross-member over .25 inch and it might just be in the correct place. My problem is that the drivers side cap only has three usable bolt holes. One of the hardened bolts is broken off inside, two of the other three are stripped out and one is still good. I tried to drill the broken one with no success. I drilled another hole completely out and put two heli coils inside and partially drilled out the third and inserted one coil in. I installed much longer bolts in the three holes as the original bolts were only grabbing on about half the usable threads in the mounting brackets. It seems like it is in there solid. Should I weld something across for the missing bolt? This problem has hurt this crawler before as the front cross member was broken and welded sometime in its past I assume from the same cap coming loose. Scottyb

[Tigerhaze]

Stepping back a minute, were you sure that the trackframe was misaligned and that is your only issue? One of the common causes for a sprocket to come into contact with the rear bottom roller is worn final drive bearings which allow the shaft driving the sprocket to "lean" towards the bottom roller.

[Scottyb]

I will look at that possability first chance. It does not have any leaks that I saw and their seemed to be faint lines on the crossbar where the caps were attached in the past. I moved it back to the lines and it seems to be good on both sides. Good Idea to check thoose bearings. I haven't changed the oil in thje finals yet. I wi do it next and hopefully everything will be ok.scottyb

[JWB Contracting]

It is best if you remove all the broken bolts. This can be very time consuming but I am assuming you only want to fix the track frames once. You may want to cut the welded from portion off as this may be causing further stress for the track frame to move back into the old position. This again will take more time and more drilling of the most likely broken cross member bolts.

You may have to disassemble your machine even further so you can drill the bolt holes out. Worst case scenario is removing the final drive and clutch housing.

I would also suggest buying new high quality bolts for reassembly. On our widepads that we work we even go as far as locking the bolts in place by welding a small piece of round bar accross the bolt heads so they cannot come loose.

[Scottyb]

Jason you are likely correct in that I am going to have to get the bracket off on the problem side to get the broken bolt out. I looked it over pretty close and there does not seem to be an easy way to get the bracket off with the broken cap bolt in it without taking a lot of parts off. However it is not going to fun to operate if I have to worry about bolts breaking off every time I use it so I will plan to do it. I see after looking at the parts book that on adjusting my rear crossbars that my retainer plates, shims and bolts are all missing and the cross bar is welded to the brackets on the track frames as you might have figured out already from my earlier description. This is why I thought I had to move the whole crossbar over to make it line up. This actually did help as it had slipped since it was originally welded due to the missing-loose and broken bolts on the cap.(the bolts are fine on the other side but they were not tight at all) Lucky it is more of tacked than a good weld so I should be able to grind the ends of the crossbar free and re install retainer plates and shims.
Also.... After a closer inspection, I think I do not have to worry about the bearings, the sprocket is square and no leaks or wobble so thankfully I wont have to do that job. Although, That is yet another good thing I know to watch for that I learned from this forum. Thanks for your help. Scottyb