Steering Axis Inclination - Explained

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  • Опубліковано 1 лют 2025

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  • @michaelskalecki3073
    @michaelskalecki3073 9 років тому +138

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

    • @tasi3mi3c
      @tasi3mi3c 7 років тому +1

      Same here dude :D

    • @bansi64
      @bansi64 7 років тому +6

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

    • @DigitalBathInAZ
      @DigitalBathInAZ 5 років тому +1

      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
      @Agbahizzal 2 роки тому

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

  • @EngineeringExplained
    @EngineeringExplained  13 років тому +11

    @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!

  • @EngineeringExplained
    @EngineeringExplained  12 років тому +13

    [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
      @jonahkinoshita632 5 місяців тому

      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
      @jonahkinoshita632 5 місяців тому

      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
      @jonahkinoshita632 5 місяців тому

      Positive caster would be like a motorcycle with monkey bar handles

  • @EngineeringExplained
    @EngineeringExplained  12 років тому +4

    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.

  • @drahkas8526
    @drahkas8526 9 років тому +8

    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!

  • @EngineeringExplained
    @EngineeringExplained  13 років тому +2

    @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
    @rafaelrego6482 10 років тому +2

    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

  • @rsn9394
    @rsn9394 4 місяці тому

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

  • @EngineeringExplained
    @EngineeringExplained  13 років тому +1

    @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
      @ronvaliquette8798 4 місяці тому

      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
    @EngineeringExplained  12 років тому +1

    You are quite welcome, thanks for watching!

  • @mojtabakomeili
    @mojtabakomeili 11 років тому +1

    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.

  • @CR604
    @CR604 7 років тому

    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

  • @hasanimam3102
    @hasanimam3102 Рік тому

    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

  • @EngineeringExplained
    @EngineeringExplained  12 років тому +1

    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.

  • @EngineeringExplained
    @EngineeringExplained  12 років тому +3

    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
    @EngineeringExplained  12 років тому +1

    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
    @EngineeringExplained  11 років тому +2

    Seems sound, glad you enjoy the videos!

  • @EngineeringExplained
    @EngineeringExplained  12 років тому +1

    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.

  • @EngineeringExplained
    @EngineeringExplained  13 років тому +1

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

  • @LordAlexis
    @LordAlexis 9 років тому

    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

  • @EngineeringExplained
    @EngineeringExplained  11 років тому +1

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

  • @EngineeringExplained
    @EngineeringExplained  13 років тому +1

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

  • @peteflynn3923
    @peteflynn3923 4 роки тому

    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"?

  • @Nicosh1471
    @Nicosh1471 13 років тому +2

    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
    @patricksquires77 Рік тому

    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
      @patricksquires77 Рік тому

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

  • @JeromeDH92
    @JeromeDH92 11 років тому +4

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

  • @EngineeringExplained
    @EngineeringExplained  13 років тому +1

    @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.

  • @EngineeringExplained
    @EngineeringExplained  12 років тому +1

    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?

  • @tips4truckers252
    @tips4truckers252 3 роки тому

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

  • @subnigra
    @subnigra 9 років тому

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

  • @RecordnRtist
    @RecordnRtist 4 роки тому

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

  • @naf546
    @naf546 11 років тому +6

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

  • @dumplingsquads2674
    @dumplingsquads2674 8 років тому

    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!!!

  • @EngineeringExplained
    @EngineeringExplained  12 років тому

    My answer was in response to your original post.

  • @surdsvortices6304
    @surdsvortices6304 11 років тому

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

  • @EngineeringExplained
    @EngineeringExplained  11 років тому

    Yes, this and caster.

  • @TheSilverwolf19
    @TheSilverwolf19 11 років тому

    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

  • @jvraghav14
    @jvraghav14 12 років тому

    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?

  • @sonVason
    @sonVason 4 роки тому

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

  • @ericohman
    @ericohman 12 років тому

    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

  • @TheOnlyRaceEngineer
    @TheOnlyRaceEngineer 6 років тому

    Fantastic explanation ... you are the best.

  • @spartanity
    @spartanity 8 років тому +1

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

  • @VeganCorie
    @VeganCorie 13 років тому

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

  • @jvraghav14
    @jvraghav14 12 років тому

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

  • @Salazar518
    @Salazar518 13 років тому

    Very great informative video man!! keep them coming.

  • @TheReapero
    @TheReapero 13 років тому

    awesome explanation! Your videos are fantastic!

  • @pankaj51281
    @pankaj51281 13 років тому

    Such a nice and explicit explanation thank you sir so much

  • @Mcarlsonnr
    @Mcarlsonnr 13 років тому

    Love your vids man. Keep it up.

  • @ronvaliquette8798
    @ronvaliquette8798 4 місяці тому

    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).

  • @Degr8n8
    @Degr8n8 13 років тому

    Very informative video, keep them coming!

  • @karosasify
    @karosasify 11 років тому

    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.

  • @Carrera911Fan
    @Carrera911Fan 13 років тому

    love the vids keep up the great work man

  • @ConTejasMusic
    @ConTejasMusic 11 років тому +2

    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?

  • @JOSUELITOlive
    @JOSUELITOlive 13 років тому

    are you going to do a video on torque steer?

  • @jin5632
    @jin5632 5 років тому

    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 ?

  • @antoniskaloterakis7996
    @antoniskaloterakis7996 4 роки тому

    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

  • @ReubenMRU
    @ReubenMRU 13 років тому

    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

  • @adityapareek2840
    @adityapareek2840 9 років тому +2

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

    • @EngineeringExplained
      @EngineeringExplained  9 років тому

      Aditya Pareek I have a lot of videos on the subject; check out this playlist! ua-cam.com/video/JjCcFsGLpaM/v-deo.html

    • @adityapareek2840
      @adityapareek2840 9 років тому

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

  • @alexbarquin9
    @alexbarquin9 8 років тому

    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 👍

  • @Jron45the_pimp
    @Jron45the_pimp 13 років тому

    I know there's probably an explanation for this, but my first though about the scrubbing axis was, wouldn't the decrease in tire contact mean the car puts down less power?

  • @EngineeringExplained
    @EngineeringExplained  12 років тому

    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.

  • @RicardoSS85
    @RicardoSS85 12 років тому

    So when people make the camber more negative, what they're actually doing - if they don't change the steering axis inclination - is creating a bigger scrub radius, right? How can that bigger scrub radius negatively affect the dynamic properties of the car?

  • @colekasanke1115
    @colekasanke1115 2 роки тому +1

    This was way before the "hello everyone and welcome"

  • @samiralim95
    @samiralim95 9 років тому

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

  • @Jerkwaad
    @Jerkwaad 11 років тому +2

    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
      @EngineeringExplained  11 років тому

      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
      @Jerkwaad 11 років тому +1

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

  • @ilkermersinlioglu
    @ilkermersinlioglu 7 років тому

    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...

  • @JamboS93
    @JamboS93 11 років тому

    Nicee vidd much easier to grasp the concept

  • @mikec3201
    @mikec3201 3 роки тому

    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
      @mikec3201 3 роки тому

      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?

  • @moonhue5304
    @moonhue5304 9 років тому

    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?

  • @billsoult3149
    @billsoult3149 8 років тому

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

  • @vaibhavkalamkar4290
    @vaibhavkalamkar4290 4 роки тому

    Well explained!

  • @stateisflow-c6f
    @stateisflow-c6f 9 років тому

    This helps a lot. Thanks.

  • @automaintenancesupplyalfon7022
    @automaintenancesupplyalfon7022 9 років тому

    Really appreciate your video thank you

  • @punarvasusharma2296
    @punarvasusharma2296 6 років тому

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

  • @dannylarsen635
    @dannylarsen635 4 роки тому

    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,

  • @wawancakra5926
    @wawancakra5926 7 років тому

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

  • @VeganCorie
    @VeganCorie 13 років тому

    You have a great observation

  • @chrisknechtel
    @chrisknechtel 10 років тому

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

  • @akashbyju844
    @akashbyju844 7 років тому

    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...

  • @dknc7393
    @dknc7393 5 років тому

    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?

  • @matiaspedraza4072
    @matiaspedraza4072 7 років тому

    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

  • @EngineeringExplained
    @EngineeringExplained  12 років тому

    I have a video if you're interested.

  • @jvraghav14
    @jvraghav14 12 років тому

    'm designing the steering sub-system of my BAJA team..
    Now, i need to know the Caster,camber,SAI,scrub Radius in order to proceed..
    HOw do i decide on these parameters??
    I know the safety ranges for angles specified..
    How do i come at the exact value of these??

  • @MrRishabhmukesh
    @MrRishabhmukesh 9 років тому

    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.

  • @satishgummadi6022
    @satishgummadi6022 9 років тому

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

  • @RGHTBrainDesignDrive
    @RGHTBrainDesignDrive 8 років тому

    I don't think you understand this fully. This isn't even half of what SAI does and how it effects vehicle dynamics. I'm amazed to see that you're putting more of an emphasis on scrub radius than it's effect on the geometry as the suspension travels through stroke. That's where the real SAI negativity shows up.

  • @banxify
    @banxify 8 років тому

    I like this guy

  • @bahy-amir
    @bahy-amir 13 років тому

    if i want to get -ve cambers and small scrub radius ,could i increase the steering axis inclination to ease the return of the wheels back to the center ?

  • @yudhasutanto3773
    @yudhasutanto3773 6 років тому

    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.

  • @Islander39er
    @Islander39er 12 років тому

    great video! thanks!

  • @fanoflakespeed9460
    @fanoflakespeed9460 6 років тому

    What is the difference in caster to steering axis inclination?

  • @AkashGupta-no2ef
    @AkashGupta-no2ef 11 років тому

    can u please explain that when steering turns about its axis then how come tyre experiences a downward force..??

  • @chaitanyaanish8103
    @chaitanyaanish8103 8 років тому

    do u have any videos on upright??

  • @ftwgigaspace
    @ftwgigaspace 11 років тому

    Thank you! I finally understand it now :)

  • @jvraghav14
    @jvraghav14 12 років тому

    yea, we have the theoritical values of all those...
    i need to know, how exactly it changes with these values.. 'm asking the behaviour of SAI,scrub radius.. a graphical cur
    ve probably...

  • @CaptainPillows
    @CaptainPillows 12 років тому

    thank you..really useful

  • @Nicosh1471
    @Nicosh1471 13 років тому

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

  • @NipunaGunathillake
    @NipunaGunathillake 9 років тому

    Shouldn't the line connecting the wheel to the axis with an inclination be at an angle to the ground?

  • @jrheavyduty
    @jrheavyduty Рік тому

    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

  • @PhilTheBroatian
    @PhilTheBroatian 13 років тому

    To decrease the scrub radius, why cant you just decrease the distance from the wheel to the axle?