Steering Axis Inclination - Explained

[@michaelskalecki3073]

University is where I go for my engineering degree, your youtube is where I go to learn what I'm really interested in

[@tasi3mi3c]

Same here dude :D

[@bansi64]

Uni isn't the best place to learn stuff so YT is where I go.

[@BPoweredLove]

I hear ya. I say it slightly differently though and will offer my refinement of your sentiment: "University is where I go for my engineering degree paperwork, the Internet with its instant-access information is where I go to research what I'm really interested in." :-)

[@Agbahizzal]

Exactly. In UTI right now and they mention this, but no one explained it better than this.

[@EngineeringExplained]

@yamenad When you're looking at the diagrams on the board, imagine that you are sitting behind the front right tire at looking parallel to the ground at it. The dotted red line is the line about which the wheel/tire rotates. The dotted green line is the center of the wheel/tire. The closer these two lines are at the bottom of the tire (scrub radius) the easier it is to turn, and less wear will occur. Hope this helps!

[@drahkas8526]

Dude, thanks. I have been noticing a slight *bump* in my WRX when I reverse and lock the wheels in one direction or the other and was worrying that there might be something up with the wheels or axles. You've saved me some embarrassment asking a mechanic about it at the shop!

[@rsn9394]

These videos introduced me to vehicle dynamics. This channel is legendary.

[@EngineeringExplained]

[1] No, having a large scrub radius will make it more difficult to steer. However, at high speeds little effort is required to steer. [2] Scrub radius is the distance between where the center line of the tire meets the road, and the line of the steering axis meets the road. By changing the camber the tire's center line moves closer to the steering axis. [3] It doesn't heavily depend on caster. Caster moves the steering axis in a different plane, making the scrub radius change minimal.

[@jonahkinoshita632]

So Negative camber = less scrub radius right? And Caster is true vertical with the adjustment being strictly lateral (forward backward) from top of the strut tower ?

[@jonahkinoshita632]

So just to be clear Caster= forward backward position of the wheel base mounted from the strut. Negative Camber bottom of tires stick out.: creating tighter scrub radius because of contact to the innermost surface of the tire? Positive camber: top of tires stick out keeping the cars ride alignment toward center ? What's the point for Posicam?

[@jonahkinoshita632]

Positive caster would be like a motorcycle with monkey bar handles

[@EngineeringExplained]

Bigger scrub radius means more tire wear when turning, and by altering the camber they're also going to change the tire patch, likely making it smaller. The trend goes, smaller tire patch = less overall grip, as there's less surface area of the tire "meshing" with the pavement.

[@EngineeringExplained]

@PhilTheBroatian Because there are things between the steering axis and the center of the wheel. Brakes, suspension components, the wheel itself has an axle in the center obviously, from which it is driven. These components make it difficult to decrease that distance, though it would be beneficial if possible.

[@rafaelrego6482]

Excellent videos. I'm watching one by one, since the firts one. I'm almost an mechanical engineer (graduating at the end of the year), and this videos are such a precious thing for motorsport and cars in general interested. Congratulations

[@EngineeringExplained]

Seems sound, glad you enjoy the videos!

[@mojtabakomeili]

I have teaching experience in engineering. But what you are doing is awesome dude.Keep it up and thanks for making such an effort in amazing videos.

[@EngineeringExplained]

Yes, many people have requested this kind of idea. I've started to incorporate real examples in my latest videos. It's difficult to pair with some topics though, but thanks for the feedback!

[@EngineeringExplained]

Well, negative camber can be beneficial in corners where the tire will sort of even out with the ground and hold the car better. If you move the pivot of where the tire rotates you can also reduce the scrub radius.

[@EngineeringExplained]

Oh my. Well, I don't really know. You can read on forums or just test things out. Make slight variations in each, and then see how the car performs. Make minor adjustments, and see how it changes. Work in small steps until the car behaves the way you want. Though I'm assuming there isn't time for all this, so I would check out forums and see what setups people like to use.

[@CR604]

wow your channel blew up... good straight forward clear information... this is one of the very few channels that are actually useful for the world

[@EngineeringExplained]

@Nicosh1471 It is also due to positive caster, which will be another video posted shortly. Positive caster plays a very important roll in keeping the tire straight. Glad you enjoyed the video!

[@ronvaliquette8798]

In your explanation of turning, you're confusing the differences between SAI and CASTER. To compare caster, I use the straight-ahead value of the fork of a chopper motocycle. Having to turn the wheel left or right, it causes the need to cause a "lifting" of the bike causing the weight of the bike to want the direction of the front wheel to want to go straight. Drawing a staight line between the upper and lower ball joints or strut tower pivot point and lower ball joint and where that line meets the road surface and where that point is inside or outside of the center of the tire surface will determine the totque angle of rolling resistance of the tire (left or right). I studied mechanical and electrical engineering and was a field rep for Hunter Engineering for several years before owning a front-end shop for years. Ron Valiquette

[@EngineeringExplained]

Because of the angle of the SAI, as the video describes. It forces the tire downward.

[@EngineeringExplained]

Well for racing purposes you may use negative camber, at the sacrifice of tire wear. But when you're racing negative camber isn't going to be the major cause of your tire wear. It's the fact that you will frequently be hitting 1g of deceleration and close to 1g in the corners. Put's quite a beating on your tires. So for racing purposes you might ignore things like the scrub radius. Probably didn't make that too clear in my camber video.

[@hasanimam3102]

Wow, you made this eleven years ago and still helping automotive students like us. Thank you. You've come a long way. I've been watching your videos for more then five years now. Keep the good work up. And please make more tutorial videos as many new techs have arrived since you moved on to car reviews and explaination videos

[@Nicosh1471]

I never knew this is what caused the steering wheel to return to centre. I always presumed it worked by some kind of elastic or spring operated mechanism! Thanks! :)

[@patricksquires77]

Great Excellent video from 11 years ago. Additional benefits- -Better aligns the force on the wheel along the camber angle of the tire to by increasing & decreasing camber as the wheel turns. -Further aids toe in and out for optimal alignment of wheel to pavement for inside and outside tires. This is in conjunction to length & angle of steering knuckle to axle.

[@patricksquires77]

Right Now - Finding out that this channel has videos going all the way through today! ❤ Awesome 🤩

[@EngineeringExplained]

@HawaiiJackJr The amount of contact between the tire and the ground is almost identical in both scenarios. Regardless, power would not be affected.

[@EngineeringExplained]

You are quite welcome, thanks for watching!

[@JeromeDH92]

Just for completeness, the angle of the steering axis on the y-z plane (the board in the video) is called King Pin.

[@tips4truckers252]

I remember watching this when it came out you came a long way

[@LordAlexis]

hey you look really young in these videos but you explain things very well its a shame teachers are well paid to motivate more children to seek knowledge like you do. we need more people like you in this world

[@subnigra]

You sir are awsome. Simple, accurate explanations. Keep up the good work. Thank you.

[@RecordnRtist]

This video puts my textbook and professors to shame. A thousand thank yous!

[@EngineeringExplained]

My answer was in response to your original post.

[@naf546]

"And that's steering axis inclination" - And that is awesome. The things we take for granted...

[@EngineeringExplained]

@yamenad Well, possibly, but the camber angle is very small so it won't make a huge difference.

[@peteflynn3923]

I can't believe that more people aren't watching this. It's incredible to see cars being driven around with huge amounts of negative camber, stretched tires, no suspension travel. And these are regarded as "performance improvements"?

[@EngineeringExplained]

Hmm, interesting. Could be a difference in the tires, or perhaps the SAI since it's off. What did your mechanic say after looking at the alignment?

[@dumplingsquads2674]

brother thank you for these videos its a great inspire for me, I'm a future engineer in automobiles....n I'm seeing your videos since months ......... I insist u post a video what nitro does to an engine to have such a suddent boost!!!

[@sonVason]

Still watching your vids sir. these are awesome (Y)

[@EngineeringExplained]

@JOSUELITOlive I want to eventually but to be honest I'm not quite sure yet of the cause. I know the root of the problem is apparently unequal shaft lengths, however I'm not sure why this angle difference creates a problem since the joints are "constant velocity." I'm gonna have to spend some extra time on that one.

[@surdsvortices6304]

Would you create videos about fuel efficiency or some vehicle modifications (esp. engine modification)? Thanks. I'm learning a lot from you.

[@EngineeringExplained]

Yes, this and caster.

[@colekasanke1115]

This was way before the "hello everyone and welcome"

[@VeganCorie]

And your good at rectifying on how to solve a problem with steering axis

[@TheReapero]

awesome explanation! Your videos are fantastic!

[@TheOnlyRaceEngineer]

Fantastic explanation ... you are the best.

[@TheSilverwolf19]

SAI is what allows the wheel to straighten out after a turn because of the downward force during turning when you release pressure it moves back to straight position

[@spartanity]

Can you explain the difference between zero/ positive / negative scrub radius? Thanks a lot!

[@pankaj51281]

Such a nice and explicit explanation thank you sir so much

[@Salazar518]

Very great informative video man!! keep them coming.

[@ericohman]

If you still make videos then I have a request. What about making a video about wheel base and the difference between for example a limo and a toyota ae86, honda crx or something with short wheelbase. IF wheelbase=length between fron and rear wheels. I hope that's called wheelbase. Would be really interesting to see the angles and radius happening for the front L/R and rear L/R wheels depending on wheelbase. Best regards from Sweden. PS You are really good with teaching. All those 3D animations

[@Degr8n8]

Very informative video, keep them coming!

[@antoniskaloterakis7996]

Hello , great video explains things clearly . May i ask , I am designing a tricycle that due its small wheels (18in) and the distance that a non dished wheel has from centerline , I have to incline kingpin 20 degrees , is that too much ? Is there any limit in kingpin inclination ? Does it make steering heavier ? Shifts weight too much ? Etc Thanks in advance

[@jvraghav14]

sorry about my last post. :) i realized i made a blunder in my 2nd question... Thanks a lot mate :)

[@Mcarlsonnr]

Love your vids man. Keep it up.

[@jin5632]

After doing wheel alignment, the front left camber is -0.15 degree and front right is -0.25 degree, and the car usually pull left. Do you think that difference in camber might cause that pull ?

[@jvraghav14]

Hey, just got a couple of questions.. [1] In order to get a low steering effort at high speed, shouldn't the scrub radius be higher?? [2] How does it depend on caster?? Camber decides right?

[@vaibhavkalamkar4290]

Well explained!

[@ilkermersinlioglu]

Hi, thanks for your work, I am a fan. I have a question. What is the MAIN reason that a car pulls to the direction of road inclination? I know that a car must drive straight despite of inclination on the road. I have a BMW F11 with double control arm, the lower one is new on the car.. The mechanic says that hte other ones are OK....!!! The ShockAbsorbers are also OK...

[@EngineeringExplained]

Not too good. I would say fixing the SAI would be the fix. I don't really know though. It's unfortunate it was in an accident, and you don't know how well it was actually repaired.

[@JamboS93]

Nicee vidd much easier to grasp the concept

[@banxify]

I like this guy

[@Carrera911Fan]

love the vids keep up the great work man

[@automaintenancesupplyalfon7022]

Really appreciate your video thank you

[@stateisflow-c6f]

This helps a lot. Thanks.

[@alexbarquin9]

Im planning to upgrade my wheels on the fiesta st. I would like to keep the wheels as stock as possible so that the handling doesn't change. but the wheels that im after has an of ET38 and will protrude 10mm towards the outer fender. Would a 10mm extra track width on each wheel affect the handling of the car or the longivity of the suspension/ball bearings etc? Thank you and keep up the good works 👍

[@chrisknechtel]

Lv Yr Vids, Thx. Question: If designing your own steering, Is the objective to set the Scrub Radius to zero?

[@dknc7393]

If using an adjustable top camber plate and adjust the strut to move out to keep as closed to 0 camber as possible due to lowering of stock height, will that affect the scrub radius?

[@dannylarsen635]

can you make a similar video using a 4x4 block thats 6'' long and a piece of 3/4 '' pipe please, its the best way ive been able to visualize what is happening. the pipe being the ground and the block placed on the pipe being the tire for caster adjustment, tire turning, and the reactions of positive and negative camber. then explain the gripping benefits or loses with that. i realized i can see the idea better this way but dont understand the concept of what is ideal for grip. this made me understand why my tire wanted to take a hard right like a motorcycle but my other tire stayed flat like when you have a passenger on a motorcycle who doesnt lean when you do.......sorry thats the best example i can give. I just want to get it right. so i can drive safely to get an alignment. also does any of this affect the wiggle in a idler and pitman arm? Thanks in advance for the help. I maybe over thinking everything but my favorite saying is perfect is good enough, thatll do pig thatll do. Thanks again,

[@matiaspedraza4072]

Hi . I'm designing a Mac Pherson suspension for an electric car with 54% weight distribution ahead and 46% back. Which kingpin angle do you recommend I use? Where can I find kingpin angle values used in city cars? Thank you very much for your response. regards

[@VeganCorie]

You have a great observation

[@samiralim95]

Can you please explain everything about Scrubradius? I need to know why we have it and sooo on!??

[@ReubenMRU]

Oh so that's why the wheel spins back on it's own!!! But I've got a 4WD ... hmmm does that mean that the 1998 Rav 4 has positive camber? Or is it just the Steering axis that's inclined? I noticed two things: 1. My wheels appear to get worn uniformly... 2. My car makes an awful lot of screech when I turn the front wheels in the work parking lot - Polished Cement Flooring - Even if I'm not accelerating... - Of course couple that with acceleration and I've got everybody looking at me always :-P

[@ronvaliquette8798]

In your explanation of turning, you're confusing the differences between SAI and CASTER. To compare caster, I use the straight-ahead value of the fork of a chopper motocycle. Having to turn the wheel left or right, it causes the need to cause a "lifting" of the bike causing the weight of the bike to want the direction of the front wheel to want to go straight. Drawing a staight line between the upper and lower ball joints or strut tower pivot point and lower ball joint and where that line meets the road surface and where that point is inside or outside of the center of the tire surface will determine the totque angle of rolling resistance of the tire (left or right).

[@EngineeringExplained]

I have a video if you're interested.

[@punarvasusharma2296]

Please also explain Steering errors like toe-change, roll steer etc. Kindly Resolve Thank you.

[@Nicosh1471]

Ahh wow! I never knew that this is what causes the steering wheel to return to centre. I always presumed it was on

[@mikemills9279]

Hi ive made a reverse trike..and made the wishbones lower and higher same length..how much would be a good axis incline ..i can shorten top wishbone but by how much? id would post pic but dont know how...ive set caster to 81 degrees do you think this be good place to start for axis incline ..

[@Islander39er]

great video! thanks!

[@karosasify]

A little remark on reduction in turning effort. Yes, axis inclination reduces scrub radius, but it creates that additional lifting force that driver has to overcome when turning. So finally you gaining nothing but less tire wear.

[@simplelife87]

its a trade off

[@akashbyju844]

I don't really understand why the vehicle body moves up. Okay the wheel can't obviously plow into the ground. So I'm guessing the road exerts increased reaction force on the wheel when it's turning. But how does this reaction lift up the vehicle body? Also wouldn't the suspension spring absorb this force and keep the body steady?Or does the reaction get transmitted through some other path? Confused...

[@moonhue5304]

I've always enjoyed your videos and I've been watching them for awhile. They are helpful, but I've always been wondering. What is your name?

[@jrheavyduty]

I’m installing a rack n pinion on a car that had box idler setup. If you drew a line from tie rod to tie rod at the spindle, should the rack be installed fore or aft of that line

[@JOSUELITOlive]

are you going to do a video on torque steer?

[@SzymekCRX]

Cool ! I didn't know about that !

[@ConTejasMusic]

I'm a bit confused on how the steering and suspension systems work when the wheels turn and roll. How do the wheels turn left and right but also roll these ways too?

[@CaptainPillows]

thank you..really useful

[@MrRishabhmukesh]

Hey, What is the difference in SAI for a AA joint and a MCpherson strut? I mean, I understand that Mcpherson strut has one control arm and AA has two, but is there any other difference with regard to the orientation of the SAI for the two? Thank You.

[@Ale_775]

Thanks, thanks, thanks, thanks!!!!

[@AnkitKumar-sr3zp]

You are awesome

[@prerakvaishnav7512]

Thank you

[@mikec3201]

so it's actually a combination or a delicate balance between axis inclination, caster, and toe in that keep the steering wheel straight and bring it back to straight after a turn, right?

[@mikec3201]

and those are also dependant on whether it's a front or rear wheel drive car too correct? don't front and rear wheel drive cars react oppositely to positive/negative axis inclination?

[@Nsatiro]

Academic level here.. Good job

[@ftwgigaspace]

Thank you! I finally understand it now :)

[@billsoult3149]

since the return to center effect can be acheived from the steering axis inclination why is positive caster angle used in cars?

[@Jerkwaad]

I understand well what you are explaining, but I can't relate this theory to the tie rod steering, as we have on most modern day cars. If we are dealing with the antique "King Pinn" steering, I CAN contribute to you're lecture. I however want to ask: Is the scrub radius, the distance at the "ground point" between the camber axis and the linear axis that would cross both the upper and lower ball joints on a "Double Wishbone" suspension?

[@EngineeringExplained]

I think you've got it right.. via wiki "The scrub radius is the distance in front view between the @wiki/Kingpin_(automotive_part) axis and the center of the contact patch of the wheel, where both would theoretically touch the road."

[@Jerkwaad]

Engineering Explained Ok I see. Thanks for replying. You've a whole bunch of good videos by the way.

[@adityapareek2840]

Can u please add vids about cornering power ; understeer and oversteer in this playlist jason.

[@EngineeringExplained]

Aditya Pareek I have a lot of videos on the subject; check out this playlist! kzbin.info/www/bejne/gJumlHmpfLGjl68

[@adityapareek2840]

hey thanks alot.. your videos were of great help when we were appearing for our automobile engineering exams..keep up the good work!!

[@wawancakra5926]

which is the true inclination?degree between steering axis and positif chamber or degree between steering axis and true vertical?

[@sourabh19911]

I m making a go kart so should I have any camber angle n if yes can I provide steering axis inclination to negative camber

[@satishgummadi6022]

What's the difference in steering axis,kingpin inclination, caster angle and camber angle

[@RicardoSS85]

Thank you.

[@mikemills9279]

just realised i cant just shorten top a arm ...is it possible to engineer my stub axle carrier to keep wheel vertical or slight camber...but keeping steering axis to say 81 degrees..

[@yudhasutanto3773]

I didnt really get the explanation, why the wheel goes straight when steering is released. Why does it force the tyre to go downward? I couldn't really understand the experiment. On the white board the shaft going to the tire is horizontal. However, in your experiment with the markers it's inclined and orthogonal to the steering axis.

[@chaitanyaanish8103]

do u have any videos on upright??

[@majdalmohamad4091]

I have a positive camber on left side of my car ,its not too much ,mabey 1 digree but I feel like the steering is much harder especially to the right, is it because of the positive .camber on left side ,????