The Stovebolt Site Forums The Parking Lot Big Bolts 2-Ton GMC 350-24 King Pin Questions

I asked these same questions over on the OldGmcTrucks forum as well, but thought it might help to ask here too. Hopefully I ask these question correctly.

I've been searching for a new king pin set for my 2-Ton GMC 350-24 project, and I'm finding two types. On one set, the thrust bearing at the bottom of the axle boss seems to be made up from what looks like two thick steel washers with a bronze washer in the middle. The second type (which is more familiar to me) uses a ball type thrust bearing at the bottom of the axle boss. Any thoughts on why there are two styles?

Also, I ordered a long Sunnen honing mandrel so I can size the bushings to fit the king pins. Is there a preference on stone grit for finish? I can hone it to whatever finish needed. I'm just not sure if there should be a courser finish in the cross-hatch pattern for holding grease? Or something smoother. I'm concerned too course of finish would not provide enough bearing surface for wear. I also don't want it to be too smooth if that's not right either.

Anywho, thanks in advance for your thoughts.

Take care.

Thrust bearing or washer is your choice.
I like the bearing because they might turn easier and might get by with a little less frequent greasing. The thrust washer probably caries more load.
Just my thoughts/opinions.

The bushings have grease grooves, I ream them as smooth as they can be, would not try for a coarse or cross hatched finish. Bronze is soft and any texture I think would be pressed and burnished flat by the hardened pin resulting in slightly increased clearance, so keep it smooth to start with.

Grigg

Any honed finish will be smoother than the reamers that were standard procedure when the truck was new can produce, but a close fit and as smooth a surface as possible will make the job last longer. The ball bearing support will make the steering effort at low speed a lot less.
Jerry

Thanks Grigg and Jerry! I really appreciate the reply.

I purchased a honing mandrel that's long enough to easily hone both bushings at the same time, assuring both bushings are sized in alignment. I will also bring those bushings to size with a very smooth finish. Thank you for that information.

My personal thought was to purchase the king pin set with the ball type thrust bearings. I can also imagine how the whole system would steer easier.

Thanks again for your thoughts. I'm no expert for sure. Just brave enough to get into trouble... Roll Eyes

David

I see in the GMC Maintenance Manual, they are calling for between 6 tenths (0.0006") clearance on the tight side and two thou (0.002") clearance on the loose side. Easy enough for the hone.

I used to fit the bushings so a lightly-oiled kingpin would slide through the bushings of its own weight in a few seconds. That was usually slightly under a .001" clearance.
Jerry