What is the Kingpin?

[ralphdig]

I saw several references to Kingpin Inclination for the 240SX alignement,what is the kingpin?

[GhostDriver]

It's got something to do with the scrub radius. Do a google on it.

[cdlong]

if you are looking at the front suspension from the front of the car, it is the angle from vertical of the axis that the wheel rotates about when turning the steering wheel.

basically draw a line from the upper shock mount to the lower ball joint and extend it through to the ground. the angle that it tips in towards the center of the car is the kingpin inclination.

the point where it hits the ground (dave point) to the center of the contact patch is the scrub radius.

you can't change it so don't worry about it. maybe if you had camber plates, but not much, i'm not sure.

fyi, the same thing but from the side of the car is the caster.

[ralphdig]

I saw several references to Kingpin Inclination for the 240SX alignement,what is the kingpin?

I found this definition:

The kingpin is the main pivot in the steering mechanism of a car or other vehicle. Originally this was literally a steel pin on which the moveable, steerable wheel was mounted to the suspension. In more modern designs, it may not physically exist as an actual pin, but the axis around which the steered wheels pivot is still referred to as the kingpin.

Suspension, showing tie rod, steering arm, king pin (axis) ball joints

[Exar-Kun]

woute! someone reseached it beofre I could reply. awesome!

-Chet

[McRussellPants]

KPI - KING PIN INCLINATION

[Exar-Kun]

distance from where the KPI hits the ground to the tire C/L...

Scrub radious

-Chet

[vvaffle]

So then caster is looking at those same lines but from the side of the car? Ok, but how do people change that then? seems like a pretty set thing to me. Can someone quickly remind me what kind of effect caster has on handling again?

EDIT: actually, lets keep chet happy. found this on wikipedia (a great site if you ask me) http://en.wikipedia.org/wiki/CasterQuote »Excessive caster angle will make the steering heavier and less responsive, although, in racing, large caster angles are used to improve camber gain in cornering.[/quote]But what I still don't know is, does lowering the car effect caster and what is the stock caster angle on a 240? Also, if you don't mind taking a quick look at that article Chet, or anyone else, they talk about the mechanical trail and how setting it is independant of setting castor. I am not sure how this would work so some clarification would be great. They also say that trail adds more feel to the steering but I am not sure if they mean a longer trail or a shorter trail adds more feel.
Modified by vvaffle at 1:17 PM 10/13/2005

[cdlong]

you can change caster if you have adjustable tension rods. i think the only way to adjust trail independantly of caster is to have an adjustable upright.

lowering the car will affect caster, but not much. unless you are racing the car, i wouldn't worry about it

[grimple1]

I ran a search on yahoo.com and found this.



I hope it helps.

[Exar-Kun]

I'll be doing a write up on various basics of suspension gemoetry as well as tires once I get a break...I'll probaly clarify that for you this weekend

EDIT: no break in sight, going to be out of town for 4 days :/

-Chet