BT 571 backhoe on B21 TLB, repairing

[joea]

While taking things down to remove boom cylinder for reseal, took on replacing some bushings in that area as I felt there was "too much slop" as I moved the boom. Seemed like the pivot and such were a bit free.

I found two bushings, or "inner rings" on the swing frame where the boom pin goes though almost "fell out". They do not seem worn hardly at all, but do kind of "float" in their hole, when I would expect them to be a press fit. Like the difference between a "floating" piston pin and a press fit in a IC Engine.

Seems to me they could be free to rotate with the pin, inside the swing frame, where there is virtually zero lubrication is going to find it's way in, eventually causing a problem. As now discontinued part, at a cost of almost 3 grand, nothing to sneeze at, allergy season or not.

The WSM does not seem to go there as far as installation is concerned, so question is, should I try to fix those 2 rings in their bores, using some Lock tite sleeve mount or something, or am I being too cautious?

 

[#40Fan]

I wouldn't want them spinning in their bores. Is there enough of a tight fitment that anything would help?

There is a product that I have had good success with call Bearing Mount. Once set up will take quite a bit of abuse and usually requires lots of heat to remove the part.

 

[joea]

Lock Tite or Permatex? They both offer stuff with similar name and function.

Any experience or opinion with the "wax stick" version?

 

[joea]

On another note, I am pondering replacing the two main pins, already replaced the "bushings" they ride in. That was fun.

I found the set/lock screws loose when dissembling and right away was concerned. The wear on the pins seems withing "factory spec" but I get a bit squishy about putting them in new bushings.

To add to that, the threaded holes for the set screws are pretty much shot, "hogged out" apparently by movement against the loose screws. Nothing holds when screwed in. I guess that is reason enough to replace them. Welding up and re-tapping those holes won't so easy. Or free.

Once installed, I guess "red" thread locker would be wise? I did not find a torque spec for the screws, beyond the general spec by fastener size, of 30-40 ft lbs.

 

[#40Fan]

Permatex Bearing Mount is the stuff I use.

Might look into a thread insert for the wallered out holes. You'll have better luck with those versus trying to weld up the cast iron.

 

[joea]

On another note, I am pondering replacing the two main pins, already replaced the "bushings" they ride in. That was fun.

I found the set/lock screws loose when dissembling and right away was concerned. The wear on the pins seems withing "factory spec" but I get a bit squishy about putting them in new bushings.

To add to that, the threaded holes for the set screws are pretty much shot, "hogged out" apparently by movement against the loose screws. Nothing holds when screwed in. I guess that is reason enough to replace them. Welding up and re-tapping those holes won't so easy. Or free.

Once installed, I guess "red" thread locker would be wise? I did not find a torque spec for the screws, beyond the general spec by fastener size, of 30-40 ft lbs.

View attachment 103701

Wondering if those pins are not actually supposed to be threaded and the apparent threads are impressions from the screw threads from the pins moving around a bit under strain.

 

[#40Fan]

I thought you were talking about the threads in the casting (part 010), not the pins themselves.

 

[joea]

I thought you were talking about the threads in the casting (part 010), not the pins themselves.

Oh, sorry, the swing casting is fine. Except maybe for the original question about the slip fit rings.

The pins are the question. Now I think the screws should just bottom out in the holes to lock them in place, as having threads would seem to present problems, like getting the threads started correctly. Seems unlikely that would work well, once I bothered to actually think.