King/Link Pin vs Ball Joint

[Zach Gomulka]

What advantages/disadvantages are there between the two?

Which one handles better?

Which one rides better? In my experience, lowered K/L beams ride better. Is this just from ball joint bind, or?

Why did VW go ball joint? Just ease of manufacture? Easier to align? Or?

Is there a driveability difference?

[AirCooledCurtis]

On a ball joint pan head there is less road-to-panhead clearance than a link pin, so you can get the link pins lower without hitting a man-hole and end up with a shortened wheelbase VW  .  VW stopped making the link pin to minimize and speed up production simplicity, or at least that is what I heard   

[Neil Davies]

Ball joints were used as they are lower maintenance than link pins for the average man in the street. As you said, they do reach a binding point whereas link pins don't, which is why they seem to be better at lower heights. I've only had one link pin car on the road 15 years ago for four months, so I couldn't say how much better or worse the handling is.

[roland]

Disadvantage: can't modify camber on a k/l spindle. Needs greasing every 5000km.

[Mike Lawless]

The freedom of movement throughout the range is in linkpin's favor. If everything is set up correctly and nothing is bent, there is no alignment issue with a link pin. Also, a well maintained and properly set-up (proper shocks)  LP will have a much better ride quality.

The Blue Car has a ball joint pan. I built a custom CroMo beam that uses link pin spindles.

For road racing, perhaps the BJ beam has the advantage because of the ability to put in some negative camber.

[Zach Gomulka]

Why do off road cars use K/L? More robust, freedom of movement or ride quality?

If you were to build a fun street car (all around use, think daily driver) that you wanted to go around the bends as best as possible, what would you use?

[roland]

For road racing, perhaps the BJ beam has the advantage because of the ability to put in some negative camber.

Exactly.

Why do off road cars use K/L? More robust, freedom of movement or ride quality?

I'd say the 3 but mostly 1 and 2.

If you were to build a fun street car (all around use, think daily driver) that you wanted to go around the bends as best as possible, what would you use?

Definitely ball joint.

[65bug]

Mike made some great points! And most older link pin front ends I'll bet are bent! I have removed 2 and both had bent tubes from the pan where they bolted in out to the ends! Hitting curbs over the years I am sure does a number on them. CIP1 sells braces you can purchase that bolt from the tubes to the pan, stiffening the entire front end substantially. I have been told they make a big difference in handling.......
     
     

[Zach Gomulka]

CIP1 sells braces you can purchase that bolt from the tubes to the pan, stiffening the entire front end substantially. I have been told they make a big difference in handling.......

I used the CSP ones on my last car, very nice pieces. I made a couple other suspension changes at the same time so I can't say exactly what they did, but the end result was spectacular.

[hotrodsurplus]

Ball-joint parts are easier/cheaper to manufacture and assemble. Plus ball joints make it possible to compensate for manufacturing tolerances. If a kingpin arm comes out a little bit out of spec you can make up the difference with shims; however, if a kingpin spindle comes out a little bit out of spec you can't realign it without binding the link pins. That reduces tolerance issues and makes it easier to compensate for parts damaged lightly in a collision.

Ball joints can articulate in more than one axis. This was exploited in the Type III. If you dissect a TIII beam you'll notice that the upper and lower control arms don't pivot on the same plane. I believe that the lower arms pivot just a tiny bit off axis. That moves the bottom of the front wheel out when the suspension compresses. The negative camber that the design generates has the net effect of lowering the roll center which improves handling. But that's only specific to the TIII.

Off-roaders like the kingpin beams because of the theoretically limitless travel. Only the damper length limits travel (to a point). But to get that advantage you can't really use stock VW spindles. The spindle spuds are skinny and weak. The spuds on the Porsche 356 units are far bigger and stronger but also way more expensive. The common route is combo spindles, or basically a combination of the kingpin carrier and knuckle with the ball-joint spud dimension.

If there's a ride-quality difference between KP and BJ then it's in the spring rate and damper tune. The rest is just motion ratio and both designs can be tuned to ride identically.

A kingpin will maintain almost all if not all of its ride quality if you pull leaves, cut the snubbers, and run stock dampers. A ball joint will ride like stock if you pull only the intermediate leaves, trim the snubber, and run stock dampers but it will bind if you try to lower it a bunch by pulling leaves or installing adjusters. A ball-joint suspension will maintain its stock ride if you run dropped spindles, stock dampers, and either pull a few leaves or install adjusters. I know this because I've made all of the aforementioned modifications/mistakes.

Someone mentioned that the frame head hangs down a bit more on a ball-joint car. A common thing in the Class 5 circles is to start with a ball-joint pan. Instead of replacing the frame head with a KP head they just section the beam-mounting spread to lower the top beam mount. That makes the lower beam fit in the ball joint head's lower mount which gives the cars an extra inch of ground clearance.