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Going to change both king pins on my front axle tomorrow. Got all parts and a big puller,but need some information about this job. Do i have to pull the old pins down or up? Very thankful for an answer to this question. 

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bjornebraten...The typical kingpin has a uniform diameter from top to bottom.  Measure the diameter of your new pins, top to bottom.  If the notch for the lock bolt is tapered, be sure to install the new pin with the taper matching the bolt's taper.  Otherwise, the lock bolt will not fit properly.

Kingpin work begins with supporting the beam axle and 1) removing the brake assemblies, 2) removing kingpin lock bolts and driving out the old kingpins to remove the steering knuckles (from the top or bottom, whichever is easier) and 3) removing the upper and lower kingpin bushings. This requires the correct driver or press tools for removing and then installing the new bushings.  Bushings require careful reaming (both bushings reamed together to maintain proper alignment), using a kingpin reamer to size each pair of bushings until the inside diameters fit the new kingpins. This should be a lightly oiled, close fit without binding.  Bushing grease holes must align with the steering knuckle grease fittings!

Traditionally, many mechanics sublet kingpin bushing replacement and sizing to an automotive machine shop.  After removing the brake assemblies and backing plates, they would knock out the pins and take the loose steering knuckles and a kingpin/bushing repair kit to the machine shop.  The shop pressed out the old bushings, pressed in the new bushings, then reamed the bushings to fit the new pins.  Some machine shops use a connecting rod bushing hone to finish the bushing surfaces and provide a finished pin fit.

If this is done crudely, or with a choppy reamer, an initial fit of no play can quickly deteriorate in service to a loose kingpin fit.  As far as trying to get by without reaming, the later kingpin bushing kits sometimes have hard nylon bushings that do not require reaming.  (Ford is noted for this.)  I-H kits have bronze bushings, and driving/pressing them into place can flare the bushing end.  This is reason enough for reaming.  Many new bushings are "undersized" and require reaming. 

Check the fit of the new bushings onto the new kingpins.  Keep in mind that pressing the bushings into place can shrink the inside diameter slightly.

Moses

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Hi Moses. Thanks a lot of your description. I have had the same thoughts about the pins. Read somewhere that a guy got trouble because the pins were too tight. I have taken the axle off the car and will get some help from an old skilled bus mechanic at work in our workshop. I also have outfit to hone the bushing after fitting. Bought two sets to be on the safe side. Have to be extreme careful when pulling in and out to not damage the surrounding iron. I`ll try.

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You're on the right track...Make sure you ream and hone both bushings together.  If you ream and hone the bushings individually,    This results in additional material being removed to allow the pin to pass through.  The bushing bores become oversized even if the pins seem to fit without any play.  Bushing bores are offset, contact with the pin is not complete, the bushings wear quickly, and pins become loose prematurely.  This is why reamers and pin bushing hones are long enough to cut and hone upper and lower (both) bushings at the same time...

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Typically, if your repair kit has parts that match the OEM parts for thickness, you should be able to restore the fit by using the same thickness of new shims as the original shim stacks.  This is often just a place to start, however, especially if there is wear or distortion involved.  Here is a sensible service guideline for Stemco kingpin installations.  These kits are for larger commercial vehicles.  This information is only for a better understanding of the process and to get some ideas:

http://www.stemco.com/f/qbin/ qwik-kit-king-pin-installation-training-instructions.pdf

Your specific application is different, and if you want pinpoint accuracy and specifications, you need to invest in a copy of the I-H factory service manual for your specific truck.  A used copy should be available at eBay or through automotive used book outlets.  You're doing a lot of detailed work on the 1210—I personally would not do any of this work without an official I-H factory service manual within reach.  For service and restoration work, I always purchase a factory shop manual for the make, model and year vehicle involved.

Stemco provides a test fit formula that sounds practical for most kingpin installations.  Read the palm and finger tests described (Step #7) and how Stemco suggests adjusting the shims.  These adjustments and the guidelines of others would suggest a maximum clearance around 0.005".  You want the thrust bearing to move freely through its range of travel with only slight up-and-down knuckle to axle beam clearance.  Again, I would check and follow the specifications recommended by International-Harvester for your '73 I-H 1210 2WD and the FA12 front axle.

  

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