Front Axle

[captain marty]

What is the angle in degrees of the front axle where the king pins go through.
Camber right?
I've heard 5 degrees and 9 degrees. I'm not sure which is correct.
I am having a hard time finding this one specification and want my axle looked at.
Thanks
Marty

[Reds34]

I believe that is caster. 5 degrees sounds familiar, but I am probably wrong.

Red

[BrianT]

Using specifications from the blue prints, the Kingpin inclination is 7 degrees (it is possible some axles could be 8 degrees) , this will give 2 plus degrees camber at the wheels, the castor on AA trucks will be 3-4 degrees plus, after checking there is no twist in the axle beam.
I was lucky enough to find a unused axle last year, after using alignment pins and angle gauges I found it to be as above and the truck tracks well, in addition a slight pre load on the front bearings and 1/4 toe is also recommended.

[SHELBY MESSER]

Somewhere in the previous post there is a chart posted on how to set or check the caster, I look but did not find it. Someone my know where it is Shelby, Louisiana.

[spectria]

I have alignment info I can send you.

Ford Sch align 1 cropped.jpg (165.54 KiB) Viewed 7149 times

[BrianT]

Somewhere in the previous post there is a chart posted on how to set or check the caster, I look but did not find it. Someone my know where it is Shelby, Louisiana.

Hello Shelby,
Other than bending the axle beam at the wheel side of the perches there is no way to adjust the caster, a sagging spring or bent radius rods are the primary reasons the caster is out of limits, for every inch the cross member moves up when changing a front spring the caster will change 1 degree, Les Andrews shows a simple way to check caster but does not explain what to do about it, typical of his writings.

[spectria]

What is the angle in degrees of the front axle where the king pins go through.
Camber right?
I've heard 5 degrees and 9 degrees. I'm not sure which is correct.
I am having a hard time finding this one specification and want my axle looked at.
Thanks
Marty

7 degrees King Pin Inclination. Castor is 3-4 degrees. A straight axle, tight king pins and straight radius rods needed, as well as preload on tapered roller bearings.
On a straight axle the caster is set by the radius rods.
pm me for the book...

Mis-statement corrected, along with caster angle addition.

[captain marty]

I've purchased a video from Deablo showing a complete front end rebuild. One section has a guy straightening an axle.
He does quite well with the set up and tools he uses. What usually bends the end of the axle back is parking against curbs.
I want to straighten that and then adjust so that the king pin holes are as they should be. Now I've heard ot this angle from 9, 5, 7.5.
I would like to find this angle and do it right once.
Marty

[spectria]

I've purchased a video from Deablo showing a complete front end rebuild. One section has a guy straightening an axle. He does quite well with the set up and tools he uses. What usually bends the end of the axle back is parking against curbs. I want to straighten that and then adjust so that the king pin holes are as they should be. Now I've heard of this angle from 9, 5, 7.5. I would like to find this angle and do it right once. Marty

Once you find a print with an exact angle It might be worthy to consider this info. I'm going to post 3 pages of the book (I'll take a chance). The relationship of the angles, Caster, Camber, and Toe-in, as well as Spindle inclination is what matters. Caster can be off by 25% with little effect, as long as it's equal on both sides. Positive Caster makes the wheels return naturally to center, more caster the more they will, but will be harder to turn static, ie; at the curb.
Moving the radius ball up or down changes the caster, as does load on front springs or sagging springs or a twist in the axle. If the axle is straight and identical side to side, bending to straighten the radius rod can correct caster.
This aligns with the training I received in my Auto Tech program... 42 years ago...

Ford Sch align 4 shrunk.jpg (195.11 KiB) Viewed 7088 times

Ford Sch align 5 shrunk.jpg (193.49 KiB) Viewed 7088 times

Ford Sch align 6 shrunk.jpg (199.55 KiB) Viewed 7088 times

You need the whole book...

[BrianT]

It is well documented in Ford Motor Company documents that the specs are as I posted, --- in addition caster should not be changed by raising and lowering the radius ball at its attachment point at the flywheel housing, lowering it 5/8 would be needed to gain 1 degree of change, attempting do so will offset its function and will require some reengineering, those familiar with this will know.

In addition NO WHERE in Ford Motor Company factory literature does it say that bending radius rods is a prescribed way to adjust caster, it would serve as a farmers fix only if the caster was severely out on both sides.
This statement is obviously a misquote ---- On a straight axle the king pin inclination/caster is set by the radius rods.

[RustydoubleA]

Hi all, to throw another wrench into the pot; on page 392 of the service bulletins (Nov. 29) it states "The length of the truck front radius rods has been increased by 3/16". This change makes for easier handling of the truck by giving the front axle a 3 degree caster". It continues with " care must be exercised not to mix the old design rods with the new ones". Why do you think it would matter if one were to put the newer longer rods on an older axle, unless the writer was unaware that the "rods" were welded together? Good luck, Steve.

[spectria]

It is well documented in Ford Motor Company documents that the specs are as I posted, --- in addition caster should not be changed by raising and lowering the radius ball at its attachment point at the flywheel housing, lowering it 5/8 would be needed to gain 1 degree of change, attempting do so will offset its function and will require some reengineering, those familiar with this will know.

In addition NO WHERE in Ford Motor Company factory literature does it say that bending radius rods is a prescribed way to adjust caster, it would serve as a farmers fix only if the caster was severely out on both sides.
This statement is obviously a misquote ---- On a straight axle the king pin inclination/caster is set by the radius rods.

Yes, a mis-statement. It should read "On a straight axle the caster is set by the radius rods."
I didn't suggest adjusting Caster by moving the radius ball, I only stated it's position affects caster, nor did I suggest adjusting castor by bending a straight radius rod, (bent radius rods are a common problem with Ford straight axles) only that bending a bent radius rod can correct caster. Fords Alignment literature is there in Black and White.
As I said, you need the whole book...

[spectria]

Somewhere in the previous post there is a chart posted on how to set or check the caster, I look but did not find it. Someone my know where it is Shelby, Louisiana.

Hello Shelby, Other than bending the axle beam at the wheel side of the perches there is no way to adjust the caster, a sagging spring or bent radius rods are the primary reasons the caster is out of limits, for every inch the cross member moves up when changing a front spring the caster will change 1 degree, Les Andrews shows a simple way to check caster but does not explain what to do about it, typical of his writings.

I highlighted your statement on bent radius rods.

[spectria]

Using specifications from the blue prints, the Kingpin inclination is 7 degrees (it is possible some axles could be 8 degrees) , this will give 2 plus degrees camber at the wheels, the castor on AA trucks will be 3-4 degrees plus, after checking there is no twist in the axle beam.
I was lucky enough to find a unused axle last year, after using alignment pins and angle gauges I found it to be as above and the truck tracks well, in addition a slight pre load on the front bearings and 1/4 toe is also recommended.

There is a difference as Brian T points out.