Kingpin fit

[oj]

I am learning myself how to do the kingpins. The bore for the kingpin is larger at top and bottom than the middle, i have one set of bore gages taht read to .750 and the next set begins at 1.25 so i can't tell you how much it is out.
My procedure has been to heat the axle to red and quech, repeat about 3 times. It has shrunk enough so that i cannot slide the kingpin thru.
Heres my question, should i now ream? the pinch is in the middle where it was tighter. the ends still have a thou or so of play.
I did one end like this, the pin fits tight and has no play but i know there isn't 100% support of the kingpin, it is lacking at the thickness of the shoulder ring on each side of the axle - if you know what i mean.
Do continue heat and shrink? or am i there?
Thanks, oj

[Mikeinnj]

OJ- Why are you heating the axle? If anything you will weaken the metal doing that. The spindle is what holds the bushings for the kingpins. The bushings should be reamed or honed to fit the kingpins Be sure to use a reamer with a pilot guide through both bushings. Most front end alignment shops are able to do this proceedure and it's cheaper than buying a reamer for a one time use.

Bratton's kingpin reamer.

http://www.brattons.com/prodtype.asp...ageHistory=cat

[oj]

The axle has slop in it. I have already done the spindles with a Lempco reamer and it has an alignment fixture for the spindle - i got that part dead nuts.
The kingpin in the axle feels very good, i may go back to the first one i did and do it one more time. I did the search thing and read about how if the kingpin isn't 100% supported in the bore of the axle that when the lockpin goes in the kingpin will still move around some at the top even though the pin has it locked.
thanks, oj

[James Rogers]

The bolt that holds the kingpin is what tightens them in the axle. You should NOT heat the axle ends to shrink them.

[Special Coupe Frank]

I have seen kingpins get sloppy in beam-axles themselves due to years /miles of spindles pounding in worn knuckle bushings...

Worked on a few front ends where the kingpins and bushings had been replaced, but the spindle still rocked on the axle due to the axle bore being worn.

The "correct" fix with other makes was to ream the axle bore and and use an oversized kingpin & bushing set... or replace the axle.

Is there another approach with Model A 's ?

SC Frank

[Cool Hand Lurker]

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How about reaming out the axle bore and installing a sleeve to bring it back to stock diameter?

[oj]

What is wrong heating and shrinking for pin fit in the axle?

[Kevin in NJ]

Axles are cheap and common.

You have ruined the axle bad axle beyond safe use in a car you plan on driving, it will work fine for a trailer queen. The axle gets VERY soft once it has been heated up beyond 400 or 500 degrees. You would be amazed how how little effort it takes to bend a heated axle when compared to a good axle. I would imagine after a few years of driving the hole will have moved from the normal forces of driving.

The worn end can be fixed, but is it really worth the effort? Bore it out and insert bushings, but you must always check the axle for straightness.
Axles are cheap and not very hard to find if you look. Take a good spindle and make sure it does not look like someone has heated the perch holes. You need to check and straighten every axle. This is not hard, but you need to make up a tool.

Here is a link to my Axle Straightening Hints.

[Pete]

Originally Posted by oj

What is wrong heating and shrinking for pin fit in the axle?

Two things.
1-You have taken the heat treat out of the axle. It's not safe to use now without re-heat treating.
2- By the time you hone the scale from heating out of the hole, you will be back to the same problem size or larger.

It is common practice to sleeve axle eyes. Most truck machine shops can do it.

[dave in australia]

Originally Posted by Cool Hand Lurker

How about reaming out the axle bore and installing a sleeve to bring it back to stock diameter?

This is how I repaired my axles. I had 11 to chose from. Six were bent and five were straight. Of the ten ends, nine required bushes. I ended up turning down some old axles that were beyond repair to use as bushing material. After installing the bush, the bore was honed to size, and then the taper pin hole was re-drilled. If you do bush the king pin bore, be aware that the taper pin is just that, a taper. It is 1 degree included angle, I ended up making a tapered slot drill to do this job in my mill.

[oj]

Thanks, i learned something new - i was not aware that the axle was heat treated.

[Marco Tahtaras]

Originally Posted by dave in australia

This is how I repaired my axles. I had 11 to chose from. Six were bent and five were straight. Of the ten ends, nine required bushes. I ended up turning down some old axles that were beyond repair to use as bushing material. After installing the bush, the bore was honed to size, and then the taper pin hole was re-drilled. If you do bush the king pin bore, be aware that the taper pin is just that, a taper. It is 1 degree included angle, I ended up making a tapered slot drill to do this job in my mill.

If I understand you correctly you are suggesting there is a front and rear to the axle. That is not the case.

[dave in australia]

Marco, I checked each axle taper pin bore with a parallel bar, and it would only go in from one end about half way through. This was after measuring all the axles I have, and the results were the same for each axle, I realise you have some blue prints, thanks for printing them, but as I did not have access to these, I can only go off my own measurements. I can only draw conclusions based on a majority of sameness, and then pass on any assumed correct information to others, and then others will add to correct any misinformation, to build a greater knowledge base.
This also raises another question then, is the pin of a significant greater hardness to cause all the axles I have to have their taper pin bores to become tapered over time in use?

[JoeWay]

Originally Posted by dave in australia

Marco, I checked each axle taper pin bore with a parallel bar, and it would only go in from one end about half way through....

This also raises another question then, is the pin of a significant greater hardness to cause all the axles I have to have their taper pin bores to become tapered over time in use?

Sure sounds like a good theory to me.

Joe

[Special Coupe Frank]

Originally Posted by dave in australia

...This also raises another question then, is the pin of a significant greater hardness to cause all the axles I have to have their taper pin bores to become tapered over time in use?

I think it is possible; that type of "distortion" is sometimes referred to as "plastic deformation".

It would be interesting to "mike" an NOS locking pin at the major and minor diameters of the taper, and compare that measurement to the bore specs from the print that Marco posted.

Now, having just looked at that print again, I notice inside the red circle, the dimensions: .561 Ream
.563

And then just to the right, the distance from center-line of spindle-bolt bore to CL of lock-pin bore is listed as: .561
.564

Now, I am not a machinist or a draftsmen, but does that indicate a tolerance range for a straight bore, or dimensions for a tapered bore / reamer ?

?

Regards,

SC Frank

[Fordors]

Frank, section AA on the drawing shows the tolerance of the center line of the through hole for the lock in relation to the c/l of the king pin. It is a tolerance range for a straight bore.
In checking a NORS Moog pin, in fact one each from two different k/p sets I get a diameter of the pin as .5605. The taper is machined onto the pin at a 3* angle with a form cutter; a shape is ground onto the diameter of the cutter just like a profile might be ground on a cutter for a router. A fixture that has the correct angle designed in clamps the pin and the form cutter mills the wedge onto the pin.
The straight pin goes into a straight hole, it is the wedging action on the angle-milled taper that holds the king pin. A Ford print of the pin would show a tolerance for the diameter, as well as other dimensions of the pin. Of particular importance would be the dimension at the wedge, if too much material were machined the lock pin will go deeper into the bore through the axle until it is tight against the king pin.

[Special Coupe Frank]

Fordors,

Got it !

Thanks for the additional explanation !



SC Frank