first post. looking at a 2017 Deere 135G, 4,100 hours, private seller near Willmar. he says "60 percent undercarriage left" and i nodded like i knew what that meant. i dont. what do i actually put a tape on? i have a tape measure, a depth gauge from harbor freight and a saturday.
how do you actually measure undercarriage life before you buy
"60 percent" from a seller means "i looked at it and it did not look terrible." here is what you measure, and write every number down because you will forget.
grouser height. put a straightedge across two grousers and measure down to the shoe plate with your depth gauge. new single grouser on a 135 size machine is right around 26 mm. worn out is about 12 to 13. do three or four shoes on each side, not just the clean one he points at.
link pitch. this is the real number. measure across 4 link pins center to center with the track tensioned, divide by 4, compare to the book pitch for that chain. once it is stretched about 3 percent the sprocket starts eating itself. deere will tell you the nominal pitch if you call parts with the serial.
bushings you cannot measure without pulling a pin, but look at the sprocket teeth. if they are sharp and hooked like a shark fin the bushings are gone and the sprocket is next. rollers, measure the tread diameter with a big caliper or just look for the flange getting thin. idlers same.
then you take those numbers and the deere wear charts and you get a real percentage. if it comes out 40 and he said 60, that is 8 to 10 grand of undercarriage on that machine and you bid accordingly.
what luis said plus one cheap trick. walk the machine forward ten feet on hard ground and look at the track chain from the side while it is moving. a stretched chain sags and slaps between the top rollers even when the tension is set right. a good one runs flat. you can see 3 percent stretch from 20 feet away once you know what to look for.
also ask him if it has ever been turned. if the pins and bushings were turned at 2,500 hours that is a different machine than one that never was.
went and measured today. grousers 17 to 19 mm depending on the shoe. link pitch came out 2.4 percent over what the deere parts guy told me on the phone. sprocket teeth are starting to hook on the left side. he had not turned the pins. so not 60. i am guessing 35 to 40?
he did not love me crawling under it with a tape for an hour.
35 is about right, and the left side is worse than the right which usually means it spent its life spinning one direction on a slope. that is a chain and sprockets inside 800 hours, figure 9 grand installed at a dealer in your area or 6 if you do it in the yard. knock that off his price and see what he says. sellers who do not like the tape measure are telling you something too.
offered him 7,500 under asking with the numbers written on a sheet of paper. he said no. two weeks later he called back and took 6 under. picking it up next saturday with my uncle's tag trailer. thanks to both of you, i would have paid full price and found out in the spring.
for whoever finds this thread later, the manufacturers publish the wear tables. cat has them in the undercarriage guide, deere in the parts catalog by chain part number, komatsu in the shop manual. do not use a generic chart off a parts website, the numbers move with chain size. deere.com will get you to the dealer locator and the dealer will pull the table for your serial if you ask nice.