The Stovebolt Site Forums The Shop Area General Truck Talk Kingpin in axle fit

A standard kingpin (not oversized) has a slight movement on my truck, but no movement when I put in the locking pin. This truck will be a daily driver when finished.What kind of fit should the kingpin have in the axle? Should I just go ahead and hone the axle for an oversized kingpin? Thanks in advance.

49,

Reaming the axle for the oversize pin would be the proper way to do it. On the other side of the coin, it takes special tools to do that, and for general driving, you might not notice the difference if you just assemble it the way it is now.


Stuart.

i would recommend getting the oversized king pins and having new bushings pressed in and reamed to the correct size. putting all the load of a loose fitting king pin on the locking pin (especially on a daily driver) is not a good idea. aside from handling problems it could also cause excessive wear on the bushings and eventually on the castings.

it does require special tools but i found a shop to press and ream the bushings when i replaced my king pins. it was pretty inexpensive and well worth the effort.

I thought it was the axle eye that had worn oblong/oversize...this isn't bushed, and is attached to a heavy truck. Am I confused about how this works? :confused:


Stuart.

atomarc,
The truck in question is a 49 Chevy 3100 1/2 ton truck. The axle eye HAS become oblong/oversize. I think P.J. was talking about pressing in "custom" made bushings into the spindle/knuckle and then reaming the bushings to the size of the kingpin. The people I have talked to have recommended doing this. (Not that there is anything wrong with the floating bushing design that Chevrolet uses). Any opinions?

49,

I understand what P.J. was saying, but the crux of the issue is this; oversize kingpins are used when the axle eye, which isn't bushed, becomes oblong and worn. This is reamed oversize to fit the new pin diameter. This is done on the truck, or off the truck...it does take special equipment. After all this is addressed, the bushings are installed in the spindle and machined to fit. I sort of thought the bushings supplied with a new kit were actually pre-sized for the pin and didn't need to be reamed or honed, but I am not sure. Any spindle work is easily taken to the gararge or to a machine shop.

I'm sure I'll catch holy hell for this statement, but I have reduced the size of a worn axle eye by installing a kingpin, heating the eye, and gently "re-forging" it around the pin...with a BFH I might add. I did this after it was suggested to me by a crusty old front end man..I think he died in a wreck when his front axle busted!!

Anyway 49, that's my take on the situation..what say Ye?


Stuart.

my bad.

i was under the impression that the spindle was the part that was still loose, but your axle ends are where you're getting too much play. i have heard that you can bore out the axle ends and install larger diameter pins to compensate but i have not done this with my truck. i just replace king pins and bushings in the spindles.

atomarc- as far as the bushing that are supplied with the new king pin sets, the do fit over the pins most of the time, but after they are installed in the spindles they are supposed to be reamed to make sure there is a straight line from the top of the pin to the bottom to avoid binding when the steering wheel is turned.

atomarc,
Your take on the situation is correct.

I thought that all Advance-Design 1/2 ton trucks used king-pin sets that do not need the bushings to be reamed for the king pin to fit. I think that on 3/4 ton trucks and larger the bushings had to be reamed.

If I am correct, if you find that you have to ream the bushings (standard or oversized) on a 1/2 ton Advance-Design truck, something is out of alignment and the fit of the kingpin in the bushings will be looser than is appropriate (it has to be - the pin fit properly in the kit and material has been removed due to the reaming).

Most likely I am misreading and/or misunderstanding something here (a distinct possibility - sorry)?

As described above, an oversized kingpin kit has a kingpin that requires the axle be reamed. If the axel is reamed properly (I have had this done), there is no need to worry about alignment of the bushings in the spindle (unless the bushing-seats in the spindles are wallowed out, requiring some sophisticated surgery and special kingpin/bushing kit(s)).

Tim

Tim,

The reference to honing the spindle bushings might be misleading. During the process of pressing the bushings into their bores, sometimes they get dinged or slightly mashed if the correct driver isn't used. I have used oil/lapping compound to get a sliding fit. I suppose if it were done perfectly this wouldn't be needed. Using the new pin as a guide can really help get them in straight.


Stuart.

Okay, now I am confused :confused: . I am about to show my ignorance on this subject. Also, it only applies to 47-54 1/2 ton 3100 series trucks (maybe others, I dunno) It is my understanding that the kingpin is about .002 smaller in diameter than the inside diameter of the bushing. The knuckle is about .002 bigger than the outside diameter of the bushing. I also thought that the outside diameter of the bushings that came with the kingpin set (standard OR oversize) was the same and only the inside diameter changed. When using the bushings that come with kingpin kit (standard OR oversize), no press fit (or tool for that matter) was required and no reaming was required as it was "pre-reamed". Aren't these bushings supposed to "turn" inside of the knuckle? (dumb question: How can they be reamed inside the knuckle if the bushings are turning?)
Just to muddy things up some more, several of my buds have recommended making a one-off custom bushing that HAD to be press fit in the knuckle and HAD to be honed to fit the oversized kingpin as they do not like the floating bushing design. (Of course, they all drive f***d's, so what do they know )
Any opinions about the one-off custom bushings?
I won't be responding to this thread any more as I may be in over my head!! So, Thanks in advance.

49,

Unless things have changed in the last 40 years, here is how it works. The bushing presses into the spindle and is held mechanically...tight.

The bushing bore USUALLY has to be honed for a palm press fit.

The axle holds the kingpin tightly, the bushings are held tightly in the steering knuckle, when you turn your wheels, the movement is between the fixed pin and the ID of the bushings. I am sure you understand this..even though I have done everything I can to confuse the issue.

I haven't heard of a "floating Bushing" on a truck like yours. Tell your Ferd friends the Chevy already comes with a custom, press fit-hone to fit setup.

Stuart.

atomarc,
I think that if you check the shop manual, the 1/2 Ton used a floating bushing in the spindle and the larger trucks used the setup that you describe. I am talking about the Chevy and GMC shop manuals.

Just had my king pins on my 52' pressed out. It took 20 tons of pressure on a forty ton press! The bushings were even tougher.
I'm thinking about going to a stainless pin with needle bearings in lieu of the bushings. Classic Trucks at classictrucksweb.com has a Royal King pin kit with such. Patrick's has something simular for around $160.
Anyone tried/used one of these updated assembly?
-jeff

truckernix,

The shop manual is something I really want, but don't have yet. I should make a pact with myself not to post anymore until I get one...just for this very reason! Although I DO have a 4400, I recall doing 1/2 tons before and thought we pressed the bushings in. I stand corrected.

Rattletrap,

Do a search using "king pin replacement"..the Royal set is discussed at length.


Stuart.

49. I think you have it right. I,ve never used that o-sized set but it stands to reason if the standard size float the o-sized will too. If it,s just a little loose in the sxle I would just lock it in with the lock pin. You could use some Permatex shaft & bearing lock but you would have to grease it right away because some is going to get on the bushings. That,s just my $.02.

I swore I wasn't going to get into this again, but what the hell is a "floating bushing". Why would they put a bushing in a precision machined bore (the knuckle) and let it move around? If the bushing is greased on it's ID through a hole in the king pin, what the heck greases the fit between the bushing and the knuckle...what, two zerks...what, NO grease. I am almost out of Prozac and I need answers or else!!! Wrenchbender, Rattletrap52, truckernix, tclederman...help. :confused: :confused:

Stuart.

for that matter, what does oversized, but retains the same diameter mean? if i need something oversized, wouldn't it need to be bigger to fit tighter? i'm so confused...2

Stuart,

The Shop Manual states:

1/2 Ton Trucks
"Bushings used on all 1/2 ton vehicles are the floating type and when replaced in service, either standard or oversized, they need not be reamed to size as all service busings are reamed to finished dimensions....... These bushings should be free on the kingpin, but might be somewhat snug in the steering knuckle."

3/4 - 1 - 1 1/2 - 2 Ton Trucks
1. a special driver is needed to remove bushings, or in place of the driver, a special technique is described, using a coarse tap as a driver.
2. the same driver (not the coarse tap) is needed to press the bushings in - A HAMMER IS A NO-NO.
3. These bushings have to be reamed to the size of the kingpin.

Tim

Over-sized refers to the diameter of the king-pin.

old-blue,

The bushing for an oversized kingpin has an over-sized inner diameter (an over-sized hole for the over-sized kingpin) and the bushing has the same outer diameter (to fit into the holes in the spindle/knuckle).

The kingpin hole in the axle must be reamed to a larger diameter to allow the oversized kingpin to fit. This hole in the axle must be reamed at the proper angle.

Tim
[img]http://chevy.tocmp.com/1942_47shop/files/4247csm313a.jpg[/img]

1 Outer Wheel Bearing
2 Wheel Spindle
3 Wheel Hub
4 Wheel Hub Bolt
5 Brake Drum
6 Brake Wheel Cylinder
7 Brake Flange Plate
8 Brake Bleeder Valve and Screw
9 Brake Wheel Cylinder Hose Connection
10 Inner Wheel Bearing
11 Lubrication Fitting
12 Inner Bearing Oil Seal
13 Kingpin Lock Pin
14 Brake Shoe
15 Brake Lining
16 Kingpin
17 Kingpin Thrust Bearing
18 Lubrication Fitting
19 Tie Rod End
20 Axle I-Beam
21 Steering and Third Arm

Tim,

It is crystal clear now, how could I have been so dumb. A floating bushing is "somewhat snug in the steering knuckle", and I'll bet a non-floater is "just a hair more snug". Where the heck is Mr. Goodwrench when you need him?

Thanks for your efforts in the previous posts, I do appreciate it and hope you know I am being a little silly on this topic.

THE END
Stuart

Stuart,

My understanding of this was the same as yours. After just now reading the manual AND comparing the words for 1/2 ton vs larger trucks (which I had never read), the distinction between floating and non-floating is clearer (by a hair, as far as I am concerned).

The Shop Manual does not refer to the larger-truck's bushings as being non-floating or press-fitted. It just describes a different process for their removal/installation.

There is a lot of unclear, inconsistent, and incorrect information above. I do not think you were being silly - you just wanted a clear answer. That is all anyone can/should ask for. We both learned something on this one.

Tim

Yes, a friend of mine has a 1/2 Ton with the floating bushings and one spindle has worn a little oblong. To me it is a crazy design but I guess easier to change. However the bigger challenge usually is getting the damned king pins out to start with!

truckernix,

You got that right. Koolkar's Tech Tip about kingpins might help removal.

Tim

I just had a look at the Chev and then the GMC manual. The GMC manual describes the 1/2 Ton "knuckle as being equipped with floating type bushings" "whereas the 1 Ton is equipped with bushings which are line reamed after assembly in the knuckle". It is interesting that the two manuals have slightly different writeups on common elements.

Stuart,
Are you refering to the step-by-step in the Classic Truck article?
I ordered them from Patricks today. Philip says they do these kits all the time. He really likes the way the steering feels. Easy to do he says.
-jeff

Rattletrap,

Not sure what you are asking?


Stuart.

it may tighten up when you shot it full of grease

While you guys are on the subject of Kingpin assembly replacement, I have a couple of questions about the Kingpin Thrust Bearings. I have seen two types of Kingpin Thrust Bearings used in these rebuild kits, one looks to be an actual roller bearing and the other type is just a stack of thick brass washers. Which is the better design? My other question is around how well these Kingpin Thrust Bearings get greased by the two grease fittings that are located near the kingpin bushings? I've rebuilt two kingpin type systems in the past and I found that the bushings seemed fairly well greased, but the Kingpin Thrust Bearings were totally dry.

Who supplies an oversize king pin and bushing set??

Stuart,
Classic Truck did an article on the use of aqnd Stainless Steel Brake Corp. 'Royal King Pin set's instructions. That's where I had first seem them. I Googled what you had told me and didn'ty see anything else.

Rattletrap,

As they say...MY BAD! Look in the Engine and Driveline Forum. Do a search using the little "search" icon in the upper right hand corner. It is next to My Profile and Directory. Search for " king pin replacement"..it is in a thread titled King Pin Engineering-1 Ton. I saw a bunch of references to the Royal set.

My own opinion would be a stock replacement set of king pins..properly installed (??) and properly greased, they would work quite well. Spend your hard earned money on some chrome or a 8-ball shifter knob, don't waste it on a goofy roller bearing, USDA approved, NASA endorsed king pin setup.


Stuart.

Cujo8,
the heavier trucks used a bronze and steel washer set for the thrust bearings. The lighter trucks such as the 1/2 and 1 Ton used a ball bearing assembly.

I had the kingpins replaced on my 49 3600 during the ongoing frame up resto. I took the entire axle off and took it to a machine shop. Take the brakes and backing plates off first though. The axle is super easy to take off. You could go ahead and press out the old bushings, and press the new ones in (if you have a press). But to get the proper "slip-fit" you gotta have it honed, don't try to beat the new king pin in, you'll F everything up :p About the oversized bushings... this can all be taken care of by the machinist, he/she will know what you are trying to accomplish.