Caster angle checking

[elhongotom]

Hi Guys and Gals,  I'm wanting to determine what angle of wedges I need for setting Caster on my Dana 25 axle.
I'm too far from an alignment shop for the current condition of my front end, so want to check caster angle with an angle gauge.  Does anyone know if the differential cover mating surface in the same plane as the King Pins?  If it is, that sure would make this project simpler, and I believe more accurate than relying on the king pin bearing cap surface.
Thank you for reading, and responding with any info.
Tom

[Rus Curtis]

Tom,
The Service Manual, Section O STEERING, indicates the Caster is preset.  Any deviation would indicate a problem - possibly damage.  But I did find guidance that does allow for shims to be added if needed:   Para. O-13. Axle Caster.

On the last page of that section there is a table, O-19. STEERING SPECIFICATIONS.

There is a listing of the Caster at 3 degrees.

[Mark W.]

The castor can be measured with a magnetic protractor placed across the two round donuts on either side of the Diff cover they can be seen here in this photo of a Dana 30 https://upload.wikimedia.org/wikipedia/commons/5/56/Dana30HP.Dana35.jpg

The tool I have that works though a little hard to read is a Craftsman Magnetic Angle Locator  http://www.searshometownstores.com/product/Craftsman-39840-Magnetic-Universal-Protractor

Any number of variations of this available Home Depot has one from Johnson tools for like $11.00

A little extra caster doesn't hurt. If you have changed your front shackles to a longer version it will reduce the caster. I used shackles approx. 1" longer then stock and will be adding 2° of shim. The fat end goes towards the back.

[Bruce_W]

Mark, your method might be good for measuring pinion angle, but I would not rely on it to measure caster angle. Pinion angle is not going to be the same as caster, I don’t think. A positive caster angle would result in a “nose down” attitude for the pinion if it was.
BW