Click on image for the lowdown. 
====
| | | Forums66 Topics128,088 Posts1,056,114 Members48,434 | | Most Online14,466
Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
Lots of work on Brad's part ... pure enjoyment (and references) for you!
| | THANKS!
For helping keep this great
old truck web site
on the Internet for over 30 years! and not clogged down
with Ads!  Again, thanks!
| | | | Joined: Jan 2014 Posts: 3,685 'Bolter | | 'Bolter Joined: Jan 2014 Posts: 3,685 | Bear with me, I understand what a king pin is and what it does, but having never replaced them myself....the following questions might be dumb.
I've read the shop manual and tech tips. Sounds like on the bigger AD trucks, you actually ream the bushings to fit the oversized king pins. Whereas the 1/2 ton AD are "precision fit" (floating?) bushings.
Looking on rock auto, you can buy standard size or oversized king pin sets for not a great deal of money. Although it's not on my immediate list, I can tell there is some noticeable play in mine....so this job is in my future.
So when you buy an oversized kin pin set for a 1/2 ton, what are you really buying? Bushings with standard OD and a larger ID to accommodate the larger pin? And then you ream the axle bore accordingly?
Last edited by JW51; 09/20/2017 2:10 PM.
1951 3100
| | | | | Joined: May 2005 Posts: 8,878 . | | . Joined: May 2005 Posts: 8,878 | This thread is like a tech tip on replacing the king pins and bushings in a 1/2 ton AD truck. See if it answers all your questions? King pin replacement thread | | | | | Joined: Jan 2014 Posts: 3,685 'Bolter | | 'Bolter Joined: Jan 2014 Posts: 3,685 | Thanks.
Were you reaming the axle in the truck, or remove the axle?
1951 3100
| | | | | Joined: Mar 2010 Posts: 10,280 Renaissance Man | | Renaissance Man Joined: Mar 2010 Posts: 10,280 | You will not know if you need an over-sized king pin until you take everything apart. The only time you would need an over-sized king pin is if there is slop between the original king pin and the axle. That occurs very rarely. What does occur all too often is excessive wear between the outside diameter of the spindle bushing and the spindle. An over-sized king pin kit won't fix that.
Carl
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
| | | | | Joined: Jan 2014 Posts: 3,685 'Bolter | | 'Bolter Joined: Jan 2014 Posts: 3,685 | Thanks. Understand better now. I was thinking maybe the oversized kit also had oversize OD bushings that allowed for correcting the spindle wear.
1951 3100
| | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | I think someone posted a part number for a 47-55 3100 king pin set that had over-size outer-diameter bushings (with/without oversized king pins) that might save a "wallowed-out" spindle/knuckle and axle. The spindle/knuckle would have to be drilled/reamed to match the outer diameter of those bushings.
Maybe someone can find that post with the part number?
My observations have been that the bushings/pins get loose and eventually wallow out the spindles, while at the same time wallowing out the king-pin holes in the axle. Poor maintenance/inspections is the obvious cause of the often irreparable damage.
As stated above, over-sized king pins are readily available (sometimes in two over-sizes). | | | | | Joined: May 2005 Posts: 8,878 . | | . Joined: May 2005 Posts: 8,878 | Thanks.
Were you reaming the axle in the truck, or remove the axle? Out because that's how I received it, without truck, but it doesn't matter. | | | | | Joined: Jan 2014 Posts: 3,685 'Bolter | | 'Bolter Joined: Jan 2014 Posts: 3,685 | I think someone posted a part number for a 47-55 3100 king pin set that had over-size outer-diameter bushings (with/without oversized king pins) that might save a "wallowed-out" spindle/knuckle and axle. The spindle/knuckle would have to be drilled/reamed to match the outer diameter of those bushings.
Maybe someone can find that post with the part number?
My observations have been that the bushings/pins get loose and eventually wallow out the spindles, while at the same time wallowing out the king-pin holes in the axle. Poor maintenance/inspections is the obvious cause of the often irreparable damage.
As stated above, over-sized king pins are readily available (sometimes in two over-sizes). Was this the thread you were thinking of? https://www.stovebolt.com/ubbthreads/ubbthreads.php/topics/977880/2.html
Last edited by JW51; 09/21/2017 7:24 PM.
1951 3100
| | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | | | |
|
|
