How many King Pins shims?

[Larry Jenkins]

I'm getting ready to reassemble the right hand spindle after rebuild.

Is there a good way to determine how many king pin shims there should be to ensure the weight of the car is on the front king pin bearings?

Thank you!

Larry Jenkins.

[Fullraceflathead]

I needed to add three on each side when I did mine.
If you put a floor jack under the spindle to put say 100lbs force or more on it. The bearing will no longer turn IF you have enough shims in place.

[Marco Tahtaras]

Originally Posted by Fullraceflathead

I needed to add three on each side when I did mine.
If you put a floor jack under the spindle to put say 100lbs force or more on it. The bearing will no longer turn IF you have enough shims in place.

That confuses me! Placing a jack under the spindle has the same effect as having the car on the ground (weight on the wheels). I've never heard of a car messed up enough that the bearing shell will turn under these circumstances.

By contrast, if the car is on the ground and you raise a jack under the axle the bearing shell SHOULD be able to be turned. If you use a enough shims to prevent it from turning then you are creating friction between the top of the axle and the spindle flange which will certainly inhibit steering.

With everything shimmed and the car back on the ground, you MUST be able to get a feeler gauge between the top of the axle and the spindle flange all the way around.

[Mikeinnj]

Originally Posted by Marco Tahtaras

That confuses me! Placing a jack under the spindle has the same effect as having the car on the ground (weight on the wheels). I've never heard of a car messed up enough that the bearing shell will turn under these circumstances.

By contrast, if the car is on the ground and you raise a jack under the axle the bearing shell SHOULD be able to be turned. If you use a enough shims to prevent it from turning then you are creating friction between the top of the axle and the spindle flange which will certainly inhibit steering.

With everything shimmed and the car back on the ground, you MUST be able to get a feeler gauge between the top of the axle and the spindle flange all the way around.

What size feeler gauge ?

[Larry Jenkins]

Thanks to all. But my question still is, to put it another way, how do you know when shims under the King Pins are needed?

Larry Jenkins

[Tim B.]

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I follow Les Andrews guidance to use one or 2 shims that is based upon the reproduction thrust bearings being thinner than the originals. I found I could turn the thrust bearing with one shim installed when the weight of the car was on the axle. With 2 shims I couldn't turn the thrust bearing so the weight was on the thrust bearing where it belonged and not on the on the felt washer and cup.

[Brobrian]

I'm with Tim, here. Usually, at least one is needed, but as Andrews says, most cars using new parts require two. The test for whether you have enough is similar to what flathead described. When the locking pin is in so that the spindle is secure to the axle and the weight of the car resting on the spindle by way of a jack under the spindle, the bearing should not be able to be rotated. If the bearing housing can still be turned by hand, you have to put in another shim. (Les Andrews Red Book p. 213)

[Fullraceflathead]

Here is a Link from my Youtube account showing how to check the Shim stack on the Spindle. This is the last step, I do show the entire Process on installing new King Pins and bushing.
https://youtu.be/5Ozx3kVDpFI?list=PL...gvqn60A_JPvFda

[colin1928]

Originally Posted by Mikeinnj

What size feeler gauge ?

0.005"-0.015" Repair Manual
I try for 0.005"-0.008"

[Bob Bidonde]

Assemble the spindle to the axle using the king pins an no shims. Be sure that the locking bolt is tight. Measure the gap between the king pin bearing and the axle. It should be zero. Add shims to zero the gap.

Any gap between the axle and the bearing negates the purpose of the bearing and will overload the locking bolt.

[Larry Jenkins]

Thank you, Bob. Very clear and makes sense.

Larry Jenkins

[Marco Tahtaras]

Originally Posted by colin1928

0.005"-0.015" Repair Manual
I try for 0.005"-0.008"

What exactly is the "repair manual"? I suspect it was written based on the modern .010" shims that are available. Of course that means it should have been written as .005"-.014". if .005" was the preferred minimum. It would certainly help if someone had .005" shims made to allow for more suitable tolerances. .015" is too loose.

There are several side effects to too much clearance between the top of the axle and the upper spindle flange. For example, besides added noise from the front end, .015" clearance is more than enough clearance to make the brake pedal pulsate when stopping on all but the smoothest roads. Also, for those that have brake issues that require adjusting the brake rod length for function with the axle on jack stands (spinning the wheels), when putting the car back on the ground the brakes will tighten up. Often they will tighten up to the point of dragging. There are other issues as well but mostly not noticeable over the short term. Of course larger clearances magnify ALL side effects.

I've posted numbers before but I went out and measured the clearance again on my car. It has all original parts with no wear which also means no modern shims added. I can only get a .0025" feeler between the top of the axle and the spindle flange. That is with using only Ford parts.

It's clear from a couple of posts above that the focus has been simply to make new king pin sets function with the thinner new thrust bearings and the resulting interference with the steel felt retainer below the axle. I've never worked with that "stuff" so it never occurred to me. Unfortunately there is more to making it right than just making it work. Nobody will know just what they have until they measure the clearance as described with the car on the ground.

In reality the proper shimming would be faster if the steel felt retainer was initially left out. Install everything else including one shim under the thrust bearing. Carefully jack up the spindle just enough to lift that end of the axle off the jack stand. Then measure the clearance between the top of the axle and spindle flange with the largest feeler that will slide in to the king pin from any angle, with slight to moderate drag on the feeler. From there you can do the math so the number of shims to be added results is no less than .002" clearance i.e., .012"-.021" (feeler) clearance add one additional shim, .022"-.031" clearance add two additional shims. The reason I suggest installing one shim before measuring is that the shim will tend to bridge any worn spot or pocket on the top of the spindle. Without it the bearing will sink into that pocket and provide a less than ideal measurement and the math will no longer be accurate.

When this topic came up a month ago I was asked about the thickness of the original thrust bearings for reference but I couldn't get to it then. I pulled out a couple NOS bearings I made several measurements of each squeezing as tight as possible between my thumb and fingers (to create a MINOR load). They were consistently .522"-.523". I also pulled out a couple felt retainers (steel cup washers). These were far less precise and varied from .103" and .113' thick. Unfortunately we have no idea if the current king pins are within spec or not.