Technical king pin inclination

Been searching but can't find an answer.

I have a dropped '40 ford I beam axle to install in my '40.

How do I tell the front and rear to the axle?

 

There is no front or back, your caster is set in your front crossmember. The axle can go either way.

 

Is the axle new? If so the above "may" be true. If it is used it may have been bent to line it up at some point. Lay it on a flat surface to try to see if there is any caster built into it.

 

Wedge straight rods in the kingpin holes and the perch holes, up against one face, front or back. Sight down these rods from one end of the axle to see if they are all on the same plane.

 

Technically, 'king pin inclination' is a different factor of the front end geometry. I think you are referring to the 'caster angle', the tilt of the axle/ king pin when viewed from the side.

'King pin inclination' is the degrees to which the king pin is inclined, closer at the top, when viewed from the front (or rear), similar to the tilt of negative camber angle.

On ball joint suspensions it is the imaginary line through the upper and lower joints, same idea when discussing caster angle with ball joints.

Ray

 

To follow up with what Hnstray said
King Pin Inclination (KPI) is the inward tilt from vertical in degrees.



On the axle you might look around the holes that the tapered pin that holds the kingpin in to see if there are marks from the nut or lock washer that held the pin in as those are almost always on the back side.

 

I think he is refering to Caster

 

The caster is determined by the wishbone unless they did something with the axle when they dropped it. I have a CE dropped axle in my 40 with split bones. Some dropped axles will be a bit narrower than the stock axle To give more fender clearance and it's not uncommon to have to heat and bend the bones for tire clearance to keep the turning radius and also if you split the bones the spring hangers will need adjusted accordingly too.

 

Check the kingpin locking pin, I believe it is tapered hole, nut/travel limiter in the rear. That'll tell you front/back of axle.

 

Nope. Not supposed to be tapered. If it is, somebody after Henry Ford has messed with it.

 

HOLE is not tapered- LOCKING PIN is. It also has raised sharp edge "cuts" in it that bite into the axle as it's drawn tight. You may see evidence of this in the locking hole, unless someone has cleaned it up, made the hole larger, and basically messed it up. I don't know if they make oversized locking bolts?? Anyone??

 

Wow. the poor guy asked one question,"how do you tell the front from the back on a 40 dropped axle" and he he got one answer, "there isn't any difference" and all the rest talking about everything under the sun to do do with front suspension set up and so on. He did title it"Kingpin inclination" which was not mentioned in his question.