On my bobcat 331, we are going through and fixing all the leaking cylinders and fixing it up and after cleaning we found this crack. Anyone have any recommendations on best way to fix this?
You will get lots of advice, but I would like to point out that this is one of the most stressed points on the machine, and they did an insanely poor job of welding sequence here. Couldn't help but crack out from the factory welds. I would take it off of course, vee out all the old welds, heat and beat it back in shape, vee that cracked area on top all out enough to get a backer inside and tacked in, weld it all back in in passes using 7018, or if you can afford it, Eutectic 680 or a near substitute. Then grind the lengthwise middle welds top and bottom flat for several inches and lay a 1/4" or better high strength low alloy steel doubler on top and bottom, five or six inches maybe, coming back and bent down to connect with the tube, welded all around. The doubler should have mitered corners and if possible a couple inches of taper at the front so you're not welding straight across. Install matching doublers on the other side so they're more or less equally strong and rigid. YMMV
You think he will need to plan on line boring that after all that heat and beat?
In my experience and opinion only, no. Dust the bore with a flapper in a die grinder if it picks up any rust or shrinks a bit. Line it up and drive it home. Oh, and ignore the last bit in my first post about matching doublers, I had a brain cramp and thought we were looking at the load arms of a skid steer, LMAO!
First thing, get it clean and get that paint off there and see how far it goes. That's a real common fail we so on utility machines they beat on pavement and concrete with. IMO those sides should go all the way down and be bored for the pin boss not coped out and welded to it up I know that they usually do that for clearance.
It has doublers on the sides. It looks like the problem started with lack of fusion between the reinforcement and the pin bushing. IMO you will need to cut part of the reinforcement off the crack side so you can reweld the main beam to the pin bushing. Then patch the reinforcement and weld to the pin bushing. When you are done, cut out the weld between the reinforcement and the pin bushing on the other side and reweld. Proper fusion to the pin bushing may shrink the pin bushing enough to need some work before the pin will fit. It depends on how loose the pin is currently.
Thanks for the replies, I will probably start breaking it down tomorrow if time let's me. I'll post some better pictures after I get it all apart.