we used to have a good industry in NZ , Trackweld , not around any more . Used to build up rails , plates , rollers the whole lot . What seemed to limit the life of the tracks was the ability to hold pins after a turn or replace . I had tracks on a D4 with new pins and bushes with rebuilt rails ,trackbar on the plates to . Back of the plates was so sharp you could near shave on them , the odd pin that worked loose could be sorted by welding on the flat bit on the link , hammering tight , then a few runs with the welder over it again , soon pulled up tight when it cooled . Fiat (AD7 ?) next door was spitting its pins regularly with them welding the pin to the link to hold it , bad news for the next bloke wanting to squeeze some more life from the tracks with a new p/bush group and a squirt on the rails . It must have had a few pin and bush groups changed as the bolts were good on both sides .
