King Pin Question

[Frank]

Frank, your kind of twisting BobW's words. What he is trying to tell you is on '49 and earlier you use shims on the bottom and top and on '50 and newer you only use shims on the top. �

I understand that,

I asked if it was improved machining, of which the answer was "Yes" that brought about this change, There is no word twisting, as far as this splitting the shims evenly from top to bottom,

Dont add up,

The shims vary in thickness,  So if you tear apart a axle and it has 4 shims, you throw them in the pile and do not keep track of the thickness and simply put 2 on the bottom and 2 on the top,

Its going to be out of wack, more then likely,

[ventport]

Like I said, divide the total thickness of the shims top and bottom added together and put half of the total on the top and half of the total on the bottom.  If it does not come out even buy some shims that equal the old total but that can be divided by two.

[Tumbleweed]

Okay so now I have backtracked a bit on the shim stacking. I am putting the shims in tonight, top and bottom, evenly split.

[Gunslinger]

Make sure you have the right pre-loading on the King Pins, on the 3A they should be between 15 and 18lbs.  You measure this by taking everything including the axle out of the housing, I used a fishing scale, hooked it into the eyelet for the tie rod end, and pull, the scale should read between 15-18 lbs at the point the housing starts to turnn.  If its too light or too heavy you may have to adjust the shims to get the right pre-load.

[Frank]

Like I said, divide the total thickness of the shims top and bottom added together and put half of the total on the top and half of the total on the bottom. �If it does not come out even buy some shims that equal the old total but that can be divided by two.

Okay, So I know for sure the rational on this because its a recipe for "Out of Wack" The last axle I did had a .050 and a .030 shim on the bottom for a total of .080 and the top was .040,

So according to the evenly split theory I take the grand  Total of 1.020 and divide by 2 and put a .060 on the top and on the bottom,

putting the knuckle housing, .020 off of what it was from factory,  No this just dont add up, Now I dont mean to be a trouble maker but really there is no sense to that,

The shims vary in thickness, best bet without some sort of alignment tool is to keep the same thickness @ the bottom and dial in the pre load from the top, The evenly split theory is a guessing game, @ best,

[Bob W]

Okay so now I have backtracked a bit on the shim stacking. I am putting the shims in tonight, top and bottom, evenly split.

That is correct for your vehicle. �:)

[Bob W]

Frank,

Please answer the following question with a yes or no.

Let's say we are setting up king pin bearings a Willys front axle. The knuckle is perfectly centered to the axle and there is preload on the king pin bearings. We have determined more preload is needed to meet the turning torque specification. Removing 0.010" of shim from the upper cap gives us the proper preload. By removing 0.010 of shims from the top only, did the knuckle move off center?

[Frank]

Frank,

Please answer the following question with a yes or no.

Let's say we are setting up king pin bearings a Willys front axle. The knuckle is perfectly centered to the axle and there is preload on the king pin bearings. We have determined more preload is needed to meet the turning torque specification. Removing 0.010" of shim from the upper cap gives us the proper preload. By removing 0.010 of shims from the top only, did the knuckle move off center?

No Bob,

What I have been saying all along, without some sort of alignment tool, leave the lower shims the same, and adj pre-load from the Top,  This for sure is not fool proof if they had been lost track of in a prior service, but when working with a axle that has functioned well for years, leave them the same,

Now this is not as critical for these Dana axles, the axle seal position in the housing allows for more of a margin of error, but still you dont want the axle in out of whack, and housing off center,

[Bob W]

No ....

So with the same initial setup, if we remove 0.010" from the lower cap only, will the knuckle move off center?

[Frank]

No ....

So with the same initial setup, if we remove 0.010" from the lower cap only, will the knuckle move off center?

Yep, by .010,

The lower shims Center the knuckle, adding a .010 would send it the other way, by .010, I really dont understand how this could even be a question, you take out the .010 shim, tighten up the trunnion cap bolts and it sucks it down that .010 that you removed,

Are you just messing with me ? the trunnion Stud pin, whatever you want to call it bottoms out against the bearing inner race and down comes the knuckle, by .010

Same thing on the top when you removed the .010 to snug up the preload a bit more, the pin squeezes into the bearing adding the additional desired "Squeeze"

Squeezing AKA bearing pre load,

Do not just split up shims evenly, the bottom center the knuckle, adj the "Squeeze" from the top,

[Frank]

Perhaps this picture will help,

With the centering tool installed and the spindle flipped around backwards the knuckle is centered with the axle, inserting the lower trunnion cap as far as it will go there is that .040 gap, of which the shim takes up,

Take .010 �away from that shim �then when the bolts are torqued it will pull the housing down, .010 off centering it by, .010

A alignment tool like this here, slides into the axle housing, slotted to expand , and machined out to the ID on the spindle, and since there is a machined ridge on both sides of this spindle, the knuckle is centered to the housing,

and wouldnt you know it after fiddling around with building and having this center tool made, the shim on the bottom was just right, re used it, but if I would take .010 off of it,

It would not fill that .040 gap and Down would come the knuckle,

[Bob W]

Why would the knuckle only move off center by changing the lower shim and not the upper shim? What is the difference?

[Frank]

Why would the knuckle only move off center by changing the lower shim and not the upper shim? What is the difference?

Bob You must not be reading this,

Yep, by .010,
 
The lower shims Center the knuckle, adding a .010 would send it the other way, by .010, I really dont understand how this could even be a question, you take out the .010 shim, tighten up the trunnion cap bolts and it sucks it down that .010 that you removed,
 
Are you just messing with me ? the trunnion Stud pin, whatever you want to call it bottoms out against the bearing inner race and down comes the knuckle, by .010
 

Let me try this again,



Now with the knuckle centered , the lower trunnion cap will only go up so far, till is stops against the bearing, then there is that gap there, of which you select a shim that thick, it takes up that space,

Now if I where to not install that shim, or take .010 off of it, It would draw the knuckle housing down that far, when you tighten the bolts, Off centering the knuckle housing,

This rather easy for me to picture, but must be hard to explain,

[Frank]

Why would the knuckle only move off center by changing the lower shim and not the upper shim? What is the difference?

Bob, May bee this would be easier to picture if you think of the vehicle sitting on the ground , the weight of the vehicle on the axle, the lower is set, not going to change, whatever that is,

The lower shims center the knuckle, you can take away shims from the top to add the pre load,


Or If you think of it like this, to move the knuckle housing up by changing just a upper shim, you would have to take away the same amount from the bottom,

[Bob W]

Frank, You really need to take a step back and think about what you are saying.

For everyone else, just use the appropriate Willys service manual for your vehicle and you will be fine. On pre-1951 Jeeps the front knuckle will be centered on the axle when the shims are equally divided between the top and bottom. Unequal shimming will cause the knuckle to move one way or the other slightly. Of course there is a lot of leeway in these axles so it probably won't matter much either way.

Here is a cut from a 1950 Willys service manual.