Non-Zero King-Pin Angle

[DrJB]

With either the current 57515 or old 32195b control arms, the King-Pin angle is forced to be zero, as seen on many vehicles (8880, 8488, 8644, ...). But how about mixing the control arms? Granted, the offset is 1M and thus might be too large, but nonetheless still feasible. Of course this would have all sorts of implications on the various tire angles and the balloon tires might be the best fitment.

Has anyone tried this? If so, what's your experience?

Edited February 3, 2014 by DrJB

[Thirdwigg]

I have been trying for the last month. I can't seem to get it to work. If I get the bottom arm to the outside, and the top arm to the inside, I am unable to get the steering lock that I would like with wheel 44772. But it does work to get the King-Pin angle better.

I do like how the two arms are a different length, so I can get a long/short A-arm setup.

[radioactive28]

Hi, I'm a recent lurker just signed up.

I've been wondering about this for a while too. Thought about using axles and bushes to create variable length arms (sort of like a Technic turnbuckle), although the obvious drawback is that the solution will be very bulky. Additionally, bushes cannot guarantee non-slippage, so arm lengths can change inadvertently with usage.

[nicjasno]

The kingpin would still be zero.

The problem are not the controll arms, but the hubs.

If you use long and short arm wishbones, you can get a caster change in curves when the car leans to the outside of the curve, which is good for road holding. And you can even make a caster angle.

But the kingpin is not doable if you use stock wheel hubs with ball joints.

[Zerobricks]

Also lego tyres are too hard, even if you add a king pin angle the ruber doesnt bend enough, but instead the car 'drives on edge' od the tyre.

[nicjasno]

It does so on a normal car aswell if the car is not cornering at the time.

[DrJB]

The kingpin would still be zero.

The problem are not the controll arms, but the hubs.

If you use long and short arm wishbones, you can get a caster change in curves when the car leans to the outside of the curve, which is good for road holding. And you can even make a caster angle.

But the kingpin is not doable if you use stock wheel hubs with ball joints.

It seems you answered quickly before reading the entire post. Think about it again, a non-zero king-pin angle IS possible, but because of the limitation of tire spindles (x873c01 or 32186) this will also force a negative camber and that is why I hinted you'd need a balloon tire.

But, all is not lost as THERE IS a solution (and that is why I started this thread). You can use the new spindle 11949 and offset the top ball joint so it is 'closer' to the vehicle on the top. The problem here is that friction alone might not be sufficient, so you'll need to glue together few parts. You'll then need to add the short A-arm on the top, and the long one on the bottom, and Voila! You have a tire/wheel WITH non-zero king-pin AND zero camber.

I only have few 11949 and not ready to glue 2 of them 'permanently' ...

Also lego tyres are too hard, even if you add a king pin angle the ruber doesnt bend enough, but instead the car 'drives on edge' od the tyre.

You're correct if you're limited to flat crown tires (eg Unimog or 8421). Balloon tires should be no problem though.

Edited February 3, 2014 by DrJB

[DrJB]

Here is an LXF to illustrate the non-zero king-pin. The part in red should be replaced with the LONG A-arm.

King-Pin.lxf

Edited February 3, 2014 by DrJB

[Zerobricks]

Here is an LXF to illustrate the non-zero king-pin. The part in red should be replaced with the LONG A-arm.

This is gonna fall apart in real life...

[nicjasno]

You never mentioned gluing in your first post. :) Everything is possible once you start supergluing parts together. With stock lego gubs it isn't possible.

Also, if going that route, using my turntable hubs is a better idea :)

Edited February 3, 2014 by nicjasno

[DrJB]

True, though gluing is not an absolute must. The main 'weakness' is securing the half pin to the spindle. I'm thinking a friction half-pin with some paper ... might be able to do away with the glue. I should try it on an actual car.

This is gonna fall apart in real life...

Of course it'll fall apart as is ... What you should really do first is attach it to a vehicle and see what happens ...

Edited February 3, 2014 by DrJB

[nicjasno]

King-Pin-2.lxf

[DrJB]

Nice, how do you attach a wheel+tire?

[nicjasno]

You use my rotor.

[AndyCW]

You could also use the 6.5 arm on the bottom and the 6 on the top. This would give both negative camber and a camber curve. Offset the top arm aft of the bottom arm and you would also get caster.

v/r

Andy

[nicjasno]

All combinations are possible. And more.

[Alasdair Ryan]

I am not a car builder but I messed around a bit In LDD.

I am sure you have seen all these designs before.

[Marcel1980]

Maybe you should check this one as well ; http://www.eurobricks.com/forum/index.php?showtopic=74356

Edited February 3, 2014 by Marcel1980

[nicjasno]

All good possibilities, but not good in practice. You do not want an axle/rim connection, and you certanly don't want to use the 2 stud cv joint axle. :)

[Marcel1980]

Well, to be honest i really dont know what the benefit is of a setup like this... You can you explain easy english?

[nicjasno]

Of a kingpin+caster angle setup?

Handling.

Even if you just have a hand of god steering, the fun and better handling of a car equipped with this is so worth it.

[DrJB]

Well, here it goes. For improved handling (how fast a vehicle responds to steering inputs, without overshooting), you want as small as possible a scrub radius. The scrub radius is the distance, measured on the ground, between the intersection of the king pin line and the center of the tire's footprint. That distance needs to be as small as possible. Since typically you cannot put the pivot (king pin) line inside the wheel, you want a king-pin that is inclined. Some upper-scale European vehicles achieve such small scrub radius by using multi-link suspensions. Also, while 'vehicle handling' is not something you can really 'experience' in a lego vehicle, all this discussion it to essentially mimic realistic suspensions/kinematics.

My explanation above is very simplistic and there are more in-depth interactions between the various tire angles and vehicle handling ... I may have to wear my 'vehicle dynamics' hat, but it'll become very mathematical in no time :)

Edited February 3, 2014 by DrJB

[nicjasno]

Kingpin isn't just for that. It also is responsible for the steering to return to center in cars (if you ever wondered why your steering wheel returns to the center position).

[Alasdair Ryan]

Would this be any better?

[Lipko]

Kingpin isn't just for that. It also is responsible for the steering to return to center in cars (if you ever wondered why your steering wheel returns to the center position).

Isn't that the Caster?

Also it's a bit disturbing that you only use "kingpin" when you really refer to "Kingpin inclination". King pin (according to wikipedia) is something old cars had.

Or am I the only one who didn't know that "kingpin" is the synonym for "kingpin inclination"?

Edited February 3, 2014 by Lipko