Still looking at straight trucks as I see them for sale locally. Two of the trucks I recently looked at the owners both told me that they sidelined the truck because the king pins need repair. I am not familiar with front end work on big trucks so I don't know if this is like replacing a ball joint on my pickup or really serious and loose your butt expensive. Both were class 8 trucks. A freightliner and an international. Other than the king pins, both trucks were claimed to be in good condition. The freightliner has an N14 Cummins, and I think the chassis is long enough to swap our box right on to, asking $7000 for it. We've had one truck on our farm that needed front end repair. We took it to a shop, they replaced whatever (I don't remember what, it's been awhile), got an alignment, and paid the bill. Wasn't over $2000, I remember that.
We replace king pins for about 1000 bucks not including our labor, 300 bucks a side to bore and sleeve the axle eye if it is beat out and 400 bucKS approximately for a kit. Stemco Kaiser quick kits have a steel spiral bushing that is pretty easy to install. It isn't as good as a reamed brass bushing but seem to have reasonable life. If you put a new kingpin about 1/3 of the way in the axle eye and can move the top much the axle eyes are beat out. Sometimes the draw key that holds the pin from spinning can be hard to get out, when you reinstall the new one torque it to what they recommend. If you google axle surgeon you will probably find a number of guys that can machine the axle in your area with the axle in the truck at your shop. Plenty of videos of how to tear them apart and put together. It ain't a horrible job and you get a close look at everything else related to the front axle when you do it. The guy that does our machining will install and ream brass bushings for free if we buy the kit from him.
I've installed several sets of Kaiser Spiral Stainless kits that worked and lasted a fair amount of miles. It depends on how often the pins get greased on any of the bushings spiral or brass. But JPV is right on that axle eye, make sure there in good shape. And a good thing to check while servicing a truck is check the king pin draw bolts, make sure those are tight. Truck Shop
If the thrust bearings between the axle and spindle are hammered out or collapsed/missing/broken. Plan on some fitting there. That's why the kits include shims. The bore in the axle ends are usually in good order. The wedge locks usually hold the pin tight , in turn , no wear. You just don't want something where axle is in contact with the spindle.
Awesome information, thanks guys. Now I have a better understanding of what they are and what it entails to repair them. I also did a Google and YouTube search for more information. I'll have to check the king pin draw bolts on our other trucks at service. They do get over greased though. We typically grease entire truck every time we chop forage, which is every 28 days during the summer, but they only see about 16-20 hours run time over 2 or 3 days. Then they sit parked for the rest of the month. Over greased, probably, but a little extra grease is cheaper than non productive time incurred plus cost to repair whatever has failed.