kingpin question

[fosh69]

Does anyone have the tech manual for trucks with the 2800 lb. axle? I need to know the kingpin reaming tool size. Thanks in advance!

[D300]

My 68 supplemental service manual says the 2800 lb axle has a king pin diameter of .872" with a clearance of .0005"-.0025".
I had mine honed and am very pleased with the results. Hope this helps.

Dan

[HEtkind]

I am trying to remember where I ordered my adjustable reamer from...I found once I have pressed the new bushings in, reaming was a 10 minute job!

[fosh69]

Thanks for the info. Does anyone have a copy of the procedure? I'd like to read up on it before tearing into it.

[Codger]

Do you mean the procedure for removing the king pins?

From the factory service manual:

Block the brake pedal so it doesn’t accidentally get pushed and blow the pistons out of the wheel cylinders.

Remove the backing plates with brake shoes, lines and anything else still attached and hang it from the
frame with a wire.

Remove the steering arm from the knuckle.

Remove the pivot pin (king pin) locking screw or pin. (some models have two locking screws)

Remove the upper pivot pin oil seal plug (steel disc) and drive pivot pin down forcing the lower seal plug
(steel disc) from the assembly. (Some have a lock ring, others have caps with hold-down screws)

The pivot thrust bearing is also removed at this time.

It calls for a special tool #C-328A to remove the bushings but you could probably do okay with a flat ended
punch. It doesn’t say how to install them except to make sure the grease hole lines up with the fitting.

Heres the important part — “Line ream both bushings with reamer C29.” (If you have one of those laying
around)

The bores have to be inline with each other like line boring a block. You need a reamer with flutes at each
end and spaced just right to ream both bores at the same time —or some kind of bushing to put in one hole
after you ream it to hold the reamer straight for the other bore.

If the bores aren’t inline with each other, they can be the correct size but the king pin won’t go into both at
the same time. You’d have to “wallow out” the bores to get the kingpin to fit. I’ve seen machine shops do it,
but if you had a microscope with x-ray vision, you could see that the pin is only hitting on two tiny spots in
each bore. In 1000 miles it will be more loose that the bushings you are replacing because it only has to
wear down those two tiny spots.

For the same reason, you have to have a reamer that is the exact correct size for your set-up. If everything
isn’t perfect, a reamer can make a hole that is larger than the reamer. But if you buy one a little small and
happen to get everything perfect, you have to then figure how to get the .001 out that it left in the hole.

It can be a pain in the keister or it can work like a dream. Or half and half.

[HEtkind]

a single sized reamer won't work, you need an adjustable reamer, so you can set the pins to a tight sliding fit...

the worst part of doing kingpins in my opinion, is getting it apart, if it hasn't been kept greased. On the town wagon, it was heat and pound, then I even took the axle out and tried to press out the pins, and bent my 12 ton press, took it down to the local machine shop and they tried the 50 ton press, finally two torches, one on the top and one on the bottom and it came apart in a giant mess.

The 68 came apart MUCH easier, with a few good whacks with a hammer

[Codger]

I see what you mean now. Go to the very last post here:

http://tinyurl.com/3cgwjt

for a picture of this:

http://tinyurl.com/2n67tc in action.

You can nip & tuck it if you’re lucky but it would be safest to have a micrometer to set the reamer size with.

An air-impact hammer works well for driving out most king pins.