The Stovebolt Site Forums The Shop Area Driveline 1/2 ton kingpin bushings

I know that the 1/2 ton kingpin bushings are referred to as floating bushings, install them in the spindle and they are already sized for the kingpin, no reaming necessary. My question is, how tight of a fit are they supposed to be in the spindle? I can push them in my '53 by hand. They don't seem to have any slop at all, but are loose enough to get in by hand and they can spin, yet snug enough that there is no slop. I don't know if this is normal or if they should be a slight press fit and not be able to spin. To me, I'm not a fan of them being able to rotate in the spindle. If this is a normal situation, I'm wondering if there isn't something like an epoxy that can be used that isn't too permanent (for ease of future replacement) to keep them from rotating and causing unwanted wear to the spindle. Any input?

"My question is, how tight of a fit are they supposed to be in the spindle? I can push them in my '53 by hand. They don't seem to have any slop at all, but are loose enough to get in by hand and they can spin, yet snug enough that there is no slop."

Press-fit by hand.

If there is no looseness/wobble, you are lucky. I would just install them and use them.

I am interested, as you are, in other opinions.

Or maybe a removable loc-tite could be used to hold the bushings in position, yet allow for a relatively easy future replacement. Think about it:)

We did what Lemmm117 suggests on my 1954 3104 (this scares me).

A word of caution on which Loctite you choose.

I was doing the same task a few months ago and read of others successfully using Loctite 660 on their bushings when there was a little bit of slop to keep them in place so I decided to use it on my bushings. Mine were in the same shape as yours. There was not much if any slop in them but they were pretty loose and spun in the bore when I turned kingpin. When I put the loctite 660 on them and pushed them in I could not get them to go 100% of the way in (even with some hammering and a press) and they seemed to lock up in the bore once they got to about 90% in. They were frozen in place and I could not get them completely in the bore and I could not get the kingpin in to align them. Maybe I am wrong, but I attribute this to the fact that the loctite 660 is for larger gaps and maybe should not be used for tighter gaps like I had.

I dry fit the bushings and the kingpin in before putting the loctite 660 on them and made sure that they were put in the same direction and bore as the dry fit was done. I did both spindles and had the same results.

I read of others using red loctite and that is the method I would use if I was redoing mine, which I may have to end up doing.

I have used red loctite for years on the bushings with no problems.
I make sure to have a pin in place through both bushings while it sets up to keep them inline.

Loctite 660 is a high strength, fast setting formula, made for larger clearances. That does sounds like trouble in a hurry. I did a little research and talked to my fastenal guy, and I ordered a bottle of loctite 609. It's a medium strength, slower setting concoction that is made for situations like this. I'll try it when it shows up Monday and see how it works.

"Full Floating" means just that!!!! That the bushings float on
the kingpin and in the steering knuckle. They should be a
light press fit into the steering knuckle, which should be
very clean and free of any burrs and the bushing should be
wiped lightly with oil. The bushings Should not be locked in
place with LOCTITE in the steering knuckle of the 3100, period.
It the steering knuckle is worn then and only then should it
be align honed and an over size bushing SLIP fit to it. what
is meant by a slip fit is when it can just be pressed in with
light finger pressure, NOT A SLOPPY fit.

The 3/4 and 1 ton trucks are different and don't have full
floating bushings. The must be pressed into the steering
knuckle and line honed to fit the kingpin.
dg

Well, mine are gonna get a nice little introduction to loctite. The fact that the bushings are allowed to "float" inside the spindle is, in my opinion, why they wear out the spindle bushing bore in the first place.

Uh oh. I will have to give it a read when I get a chance. The loctite might hafta go back on the shelf. Haha.

Lack of grease is what wears out the old 1/2 ton king pins. Not the movement the factory engineered into them.

Obviously lack of grease will lead to the early demise of the kingpins and bushings, but I wasn't talking about the kingpins wearing out, I was talking about the bushing bore of the spindle wearing. To me, if the bushing wasn't allowed to move inside the spindle, the spindle should never wear at all. But since the bushings are able to move inside the spindle, logic tells me that after time this would cause unwanted wear to the bushing bore, creating unwanted slop, properly greased or not. What is the advantage of the bushing being able to move inside the spindle?

And that is why the bushing were available in standard and .010” oversize.
The king pin is not supposed to move in the axle. But In some cases it has and the I-beam
axle needs to be reamed for an oversize kingpin. I don’t think the service manual goes into
enough detail about the availability of bushings and kingpins. If the axle had to be reamed
then an oversized internal bore bushing is used with the oversized kingpin. If the steering
knuckle is worn and had to be reamed, then the .010” over bushing was used. If both the
steering knuckle and I-beam were worn and needed to be reamed, then the bushing would
have been oversized on both the ID and OD. This is the point that is lacking in the service
literature. And it’s not perfectly clear in the parts manuals. The call-out for the bushing is
010” oversize but it doesn’t define if that is ID, OD or both.
Being an ex-Chevrolet parts man, I could imagine there being some confusion at the
parts counter when the mechanic came looking for parts.
If you haven’t read the service manual, here’s all you get from it:

“REPAIRS
Kingpin Floating Bushings---1/2 Ton Trucks
Bushings used on all ½ ton vehicles are the
floating type and when replaced in service, either
standard of .010” oversize, they need not be
reamed to size as all service bushings are machined
to finished dimensions.”

dg

It would be nice if someone came up with MOOG part numbers for:

47-55st GMC 1/2 ton truck king pin kits:
1. standard king pin and standard bushing diameter
2. 0.010 oversize kingpin and matching bushing
3. standard king pin and 0.010 oversize outer-diameter of bushing
4. 0.010 oversize kingpin and matching bushing with 0.010 oversize outer-bushing diameter

Much too much is being made about the bushing floating in the spindle.
I do not know why Chevrolet tried this design for a few years,along with other designs only the engineers of the time understood.
At the time when new spindles were available it may have made sense to just replace a worn spindle, or buy oversize bushings (which I doubt are available any more).

I can tell you not every manufacturer used this design.

I have been running a vintage Chevrolet repair shop since 1985 and have done many king pin jobs. I can't remember ever replacing a spindle because of the wear from the floating bushing.
I have always Loctited the bushings in place, with a king pin through both bushings, to keep them inline while the Loctite sets. I have yet to see a comeback from this process.

According to the parts books, the floating kingpin bushing design was used on many of the
GM vehicles from 1934 to 1962. Corvette used them from its inception in 1953 to 1962, the
½ ton light trucks at least until 1959, I don’t have any documentation beyond that and the
passenger cars thru 1954.
One thing that comes to mind is that allowing the bushing to float doubles the bearing
surface in rotation, which in theory would double the life of the bearing.
So about all I’ve got to add is that there must have been a reason the GM engineers
thought so highly of the design for all those years and millions upon millions of vehicles and
miles driven.
Just so this doesn’t take off in the wrong direction I’d like to say for some of our new
comers, Dave is one of our much respected and highly regarded contributors to the forum,
so I’m not trying to get into a pizzing contest with him. But…for the sake of discussion, is it
possible Dave, that the vintage cars that you’ve restored are not chalking up tens of
thousands of miles in daily use and that’s why you’re customers aren’t experiencing
excessive wear in their kingpin bushings?

Denny Graham
Sandwich, IL

It would be hard to document the millage on all I have worked on. I can say though, through the years some were daily drivers.

Discussions like this are great. That's why these forums exist. I see nothing wrong with a good conversation/debate and trying to understand past practices and trying to improve upon them. Everyone has their own unique opinions and ideas, and that, to me, is what puts a lot of enjoyment into these old trucks.

I have one loose spindle/king pin. Not so bad it causes any issues. But a jack placed on one side will reveal a little wheel movement top to bottom if the Tech is big enough. I put a set of new ones in and, it was still loose. The "pin" is snug and secure in the axle. No wobble there. I was looking for a spindle but the Loctite solution seems a good one to me. Pulling a used spindle and finding it as worn as the one I need to replace sounds like no fun to me. Good information on the difference between the 660 and 606 Loctite. Thanks.

Happy birthday Steve.

And that's the point of discussion Lem. To bring to light methods
that have evolved by necessity due to lack of parts or the
introduction of faster easier techniques.
I've often admitted that I'm a 98% purist so, if the
repair/upgrade doesn't effect the original look and improves
on what was originally available at the time of manufacture
then it's okey doke with me.
That said, this is an instance where if I were making the
repair and needed oversize, I'd stay with the factory design
for the reasons I mentioned. If I couldn't find a bushing to
float, I'd simply spin a set up on the bench lathe. Bushing
material is readily available from sources like McMaster Carr
and that is about as simple of a machining job as they
come. An auto machine shop could ream your steering knuckle
and hone it to a slip fit for the bushing. Now need looking
for another one.

Oh, and this discussion has done gotten me off my duff and
out to the garage, grease gun in hand to lube up those
kingpins. As Ken says, lack of grease is a death
sentence for them.
dg

I can see how having full floating kingpin bushings would double the life of the kingpin setup. And since it appears to me that they never got lubed, "twice as long" would be very valuable.
If you lube them every 10,000 miles, I doubt if they would go bad whether you glued the bushings to the spindles or left them loose as GM designed them. Its all about the grease.
BTW, has anyone ever pulled a kingpin that had any wear what so ever on the hardened pin?
I wish a vender would offer just the bushings. We are discarding too many perfectly good pins.
Carl

Yer living to much in the present Carl, try every 1,000 miles
With me, that's about three times a year.
Time for my mid-summer lube job. I was just telling sweetie
face, that I was looking forward to crawling around under the
old gal in the morning and getting all greasy. Took care of
the WB a couple of weeks ago when I was de-glazing those
squeaky brakes.
Then I'll juice her up again in the fall when the roads start
to get messy.
dg

Denny,
Did you ever put the springs on your drums?

Oh yeah, thanks for remembering. No, they didn't do any good.
Tried them in all three groove of the drums but they didn't
stop the screeching.
http://www.pbase.com/dennygraham/image/161091402
Only thing that stops it is if I take some 80 grit to the
shoes every couple of weeks, and as you can imagine, that
gets old real fast.
At this stage I'm pretty well convinced it's the compound
that was used in the lining. Shoes look fine, not really
glazed, just nice even wear over the entire face of the
shoe. I've seen some that was flat arsed shinny.
The drums look fine also, nice even wear pattern, no grooves
and no sign of glazing or hot spots.
Got some neat video with the GoPro but can't get it uploaded
to youtube to demonstrate the problem, so I'm the only one
that can see/hear it.
dg

Thanks for the update Denny! I guess crossing my fingers did not help you then.

Had mine crossed also Dave, but that's no substitute for
actually knowing what's causing the problem.
Since it seems that I'm the only one, out of 37,208 Stovebolters
that keeps coming up with squealing Huck brakes, it's gotta be
the compound.

dg

I feel your pain!

I'd try some loctite on those brake pads! Haha, I couldn't resist.

Denny, do your shoes have pins and springs midway to keep the shoes against the backing plates?

Totally stock 3/4-ton Huck brakes front:
http://www.pbase.com/dennygraham/image/114877862
and rear:
http://www.pbase.com/dennygraham/image/114877868
That's not rust on the break parts, just the reflection
of the trouble light.

There is no mid-point hold down springs on the '50, 3600
Huck brake. Here's the backing plate showing no holes for
mid-point hold down and there is no stud on the inside:
http://www.pbase.com/dennygraham/image/161099734

dg

I used to wonder about the mid point hold downs that I saw in some illustrations. My 38 Master has those hold down springs. The difference is that those two sets of guides on the upper assembly are not used on my 38. My 51 1 Ton looks just like Denny's.

Back to the floating king pin discussion.
I can see why they originally floated and that's fine, a good system when fixing worn parts is as simple as just pulling new spindles off the shelf.

Fast forward to today, those parts shelves are pretty empty of new spindles.
I am very much an advocate for the loctite bearing retaining compound as used to fix the bushings in the spindles. Doing this with the spindle in place to line them up will result in a tighter fit overall then even a new truck had.
When things wear it will only be the bushing and pin, and can be replaced without machine work or a new spindle.
Also compare the 1/2 ton spindles, king pin, and relative bushing size to that of a 3/4 or 1 ton. They are all similar in size, the 1/2 ton does not have undersized bushings for the application or anything unusual about them beyond full floating. Therefore I'll argue that if the larger trucks do well with fixed bushings then so can the 1/2 tons these days.

The corvette article linked about the floating bushings is about NOT using a center punch to rough up the spindle bore to hold the bushing in place, which I agree is bad practice. The bushing may not have turned but there will still be just as much slop after the two pieces worked together, still nothing filling the gap.
There is no mention of using loctite to firmly fix the bushings in the bore, the article is not quite applicable to the discussion at hand.

Grigg

Been tryin' to get this posted since sun up and I keep getting
interrupted, so all what I wrote is probably out of date by
now. But, here goes anyway.
Unless I miss understood the article Grigg, the crux of it was
that the bushing should be full floating, which the owner was
completely aware of, and that was what he was upset about.

Do as you may, but I'll still stick with the factory design
whenever possible. Now if you came up with a needle bearing
replacement instead of the bushings, that's one mod that I
would agree with, because it would improve on the design
instead of detracting from it.
It's true, that today in order to keep the floating bushing
in many instances, one may have to ream/hone the steering
knuckle. Along with that necessity you would need OS bushings
which are probably not available. Meaning you would have to
have access to a machinist or have a lathe available to make
your own new OS bushings. So....yep, the easy way out would be
to glue the bushings into the wobbled out steering knuckle and
simply rotate the load on the king pin alone.

Which brings to mind a problem I had when I re-bushed the
steering knuckles on my 3600. Reaming is not the best choice
for this kind of a fit. Honing to the finish fit to the king pins would be
my preference. I do have piloting adjustable reamers that
allowed me to come close to the ideal slip fit, but the last
bit I took to my local auto machine shop and had him line-hone
them on his Summen hone. I'm looking for an alternative to the
auto shop, that is, some way of final honing two bushings
that are 6" apart at home in the shop.


There were lots of variation over the years. One that was the
subject of a discussion just a couple of weeks ago was the
thrust bearing vs the thrust washer. I'd much prefer a thrust
bearing over the washer on my truck, but perhaps the reasoning
was the physical dimensions. Where the thrust washer is
capable of supporting more weight than a thrust bearing.
Of course now that my '50 is retired and doesn't do any
hauling anymore, I could get by with a bearing now. But from
what it sounds like, the kits are not shipped with bearings
any more, just thrust washers.

Denny Graham
Sandwich, IL

Thanks for the Birthday greeting. That day was good. The information on the king pins is helpful and yes, I have a relationship with my grease gun. Sorta love/hate, but the floor in the shop is not getting any softer. I have found a skill I never looked for. Rubbing skin off the back side of both shoulders. Good stuff.

Denny, I thought there was an aftermarket needle bearing king pin kit available. Only problem is it needs spindles with the bores in good enough shape to machine to fit the bearings.

http://www.speedwaymotors.com/Deluxe-1949-54-Chevy-King-Pin-Set,9650.html

Grigg

Didn't know those were being offered Grigg. Not enough dimensional
information given in the instructions, but I don't think they
would work in the 3/4-ton trucks. I noticed that the
replacement king pin is turned down to a smaller diameter then
the original. Wouldn't be as strong as the original bushing
setup. Wonder how they are greasing them??
Thanks for the link, I'll have to look into that a little
deeper.
Denny Graham
Sandwich, IL