Intro to Racecar Engineering: 11 King Pin Inclination

[@tm9141]

I'm amazed how flawless you are when you explain those subjects, I could watch the videos for hours, best videos ever. This is gold and cannot be lost! Cheers for you and your team sir! All the best!

[@Bluuplanet]

In the 1970's I had a VW Rabbit with what VW engineers called "negative roll steering radius". I'm pretty sure that meant that the kingpin inclination angle was steep enough so that there was a negative scrub radius and the centerline of the king pin intersected the ground outside of the center of the contact patch. The "negative roll" terminology meant that when the car was sitting still and you turn the steering wheel through it's range of motion from right turn to left turn, the right front tire would roll backward on the pavement a very slight amount. On every other car that I know of, the wheel would roll forward very slightly. The way it affected driver experience was that I could point the car straight ahead while going down the interstate, take my hands off the wheel and the car would not wander to one side or the other. It did not matter if I was driving on one side of the crown of the road. It seemed I could go a half mile or more without touching the wheel.

[@kevyt21]

This whole series is absolutely brilliant!

[@thedubwhisperer2157]

I am convinced that kingpin inclination and caster are utterly alien concepts to every single Red Bull Soapbox builder!

[@ancientapparition1638]

fantastic explanation I had a hard time understanding scrub radius and KIA but seeing it on a test rig really makes a difference. Thanks so much!

[@guilhermenovaes9488]

Sir, your classes are amazing! I'm waiting for a online course from you!

[@PetitCorpsSalade]

Your videos are sooo interesting and well-made!

[@Prerunner_xj]

This is an amazing video just came across this series big fan now! Thank you. Translating to jeep in my head 😂

[@Franco_Rothar]

this vid should be nº 10 and the vid about caster is nº11.

[@burntnugget1854]

6:19 i may be wrong but did u mean 79 80? Instead of 80 90

[@northerngannetproject3147]

What about changing theses angles by actuators in realtime ?

[@alfs8]

It's great vid, yet, I confused regarding he said that if decrease the scrub radius, on the vid 10:13, he explains that it'll put more of braking load to the steering axis ( king pin ), but on 11:00, he says the greater scrub radius will put more to the steering mechanism, which way would give more load to the steering axis?

[@Nontas1993]

Increasing king pin inclination and thus reducing the scrub radius will put more of the braking, pot hole, road friction and so on through the king pin. And if you decrease your king pin inclination and thus you increase the scrub radius, then the loads will go through the steering system more. Hope this helps.

[@kulaniscap]

Got it, on a positive Caster angle, the wheel contact patch follows the the “Axis” of the steering pivot point.. and not the pivot point itself.

[@jimjimaco4217]

so if you use a king pin angle which is a bit more than the normal the first thing that you will notice during cornering,is that the car in the entry of a corner will be faster and probably sharper due to the force of the outside wheel to push and lift the front axle...so the less the scrub radius the more sharp the steering..correct???

[@jorgearcos4808]

hello, how about the king pin angle in the heavy weight service vehicles, at what angle is for them the inclination desirable?

[@bonovoxel7527]

There's a Segway vehicle that my friend showed me the upper front arms and they're cool, say the spindles too actually, come out of the wheel, reverse over the tire and joint there with the upper arm. Therefore the virtual kingpin passed thru the tire wheel etc pointing, given the lack of depth of the wheelrims, like straight above the center of the contact patch, or at best they were "reversed inwards" and I thought it must be so, because I didn't see a point in having no scrub radius and a straight KPI. That was curious. Also I spend my time wondering why agricultural tractors (eu here) seem to have a KPI and positive scrub radius but, like, zero caster. And I know they're rigid, but they do look like they are built with less than 2/10 of a degree of caster angle and that's curious. Since they wear very high tires shoulder, so they dive in braking, a bit...

[@bonovoxel7527]

damn he explained it right at the end, the thing why offroaders expecially if not high speeders, don't need that much scrub radius.

[@jrheavyduty]

I’m modifying a 2005 dodge 2500 chassis suspension to narrow it for a 1948 panel truck body. I’ll be changing scrub radius and kingpin inclination. Would love to talk to you

[@yoshyoka]

This classes are amazing! Update a little your video quality and your views might explode!

[@nicjasno]

Very good explanation, i just wish the video wasn't in such a low resolution :(

[@Nontas1993]

Great explanation ! I have one question though about scrub radius. Is it true and logical to expect for example that the braking forces or pothole - road irregularities, when scrub radius is negative ( outside of the tire centerline ) instead of positive ( inside of tire centerline ) are reversed, with positive scrub the wheel will want to toe out with braking force or rolling resistance, potholes. With negative though is it the reverse ( Toe in ) ? Thanks.

[@Bluuplanet]

Imagine the front wheel of a bicycle mounted, not between the front forks, but outside the forks to the right side. While riding, if your front wheel would hit a bump, you would feel your handlebars jerk to the right and you would have a scrub radius of about 5". You could eliminate the problem with a zero scrub radius in two ways: The most obvious would be to put the front wheel back between the front forks. But another way would be to bend the front axle where it attaches to the right fork so that the wheel is now leaning to the right and the tire contact patch is back between the forks at ground level.

[@Nontas1993]

@@Bluuplanet That cleared it up for me a lot more and nice and clear example. Thanks for replying !

[@noochmahh]

Great video. love the explanations.

[@batmikipig]

Hi, I have a question. There is any scrub radius variation in a real working system? I think about how the contact patch could change during a corner, so i guess the SR will follow too. I this a problem? In some designs It could change from a positive to a negative one. Is this something we should think about during the design of the suspension? 404english

[@joanbel4029]

Thank you very much professor

[@douglasfilipack1747]

Damn, what a good explanation. Thank you

[@michealfigueroa6325]

TY I just learned a bunch

[@allanreeling1067]

An explanation of the ramifications of neutral and negative scrub radius would have been useful.

[@johnellison3030]

The video is good and explains a lot, but the camera is too far away for the content to be fully understood. Cheers.

[@mydreams299]

Thank you

[@konichiwa2650]

thank you sir!!!

[@ironguts1097]

Thanks!!

[@thedubwhisperer2157]

This should be compulsory watching for Red Bull Soapbox builders!