How Anti-Roll Bars Work - How To Improve Car Handling
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- Опубліковано 12 вер 2024
- How do anti-roll bars (sway bars) work? This video looks at how anti-roll bars can improve the handling of your car, and prevent a vehicle from excessive roll.
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I love how Jason went from awkward nerdy teenager to nerdy middle-aged man in the short span of 7 years.
Read too many youtube comments.
atlucas1 😂
Dude that's actually super funny lol
InstaBlaster
Why are u wearing a helmet
lmao
@ west wood - What a jerk.
Dick head
He's always ready to race
Rick King it’s a joke Asshat
That's one of the great things about Forza! And another benefit is understanding the effects of varying these things without worrying about damaging your own car. Find out how it acts based on Forza's physics engine (which is pretty darn accurate) and build a better understanding for when one day you can apply it to the real world.
this is just NOT a good explanation. Delete this video and try to make it again.
Ask someone who doesn't understand the component and test them after your video.
If they don't understand, think of ways to remake your point.
That YOU UNDERSTAND DOESN'T MATTER. You did when you started, & used your own metaphor to judge it.
The last 30 seconds was gold. That 30 seconds made everything clear to me. Thanks!
Tagging this ancient comment to say: many explanations of swaybars neglect to mention what Jason shows at the end, which is that the bar is _fixed_ to the chassis inboard of the suspension. This constrains the motion of the bar (or that central section) to only rotation, meaning it can only rotate (when both wheels hit a bump) or twist (when one wheel hits a bump).
Anti-roll bars reduce body roll under applied lateral acceleration (i.e. in cornering), which DOES reduce the static WEIGHT transfer (i.e. weight transfer due to lateral movement of the body CoG). However, an anti-roll bar will increase roll stiffness on the axle that it is mounted to which will increase LOAD transfer (i.e. the reaction load, at the outside tyre contact patch, of the vehicle lateral accelertion). Due to tyre load sensitivity this reduces overall grip of the axle. Thus in order to dial out (for example) mid-corner understeer on a vehicle you would tend to soften the front anti-roll bar to reduce lateral load transfer across that axle, decrease the delta in tyre loading and thereby increase overall grip across the axle.
Will this anti-roll bars can be used in off-road vehicles is this necessary for off-road vehicles??
You have answered a question I thought I was going to have to research, thank you good sir
Word
This was a very young Jason, who now knows that reducing body roll does NOT reduce weight transfer. That can only be reduced by either lowering the center of gravity (CG) of the car, or by increasing the track width.
So remove sway bars to maximize roll for most traction?
Thank you for pointing this out, the wiki statement is logical. However, as a body rolls, the CG of the car also moves with it, so I believe a rolling body (if extreme enough) could slightly alter the CG, therefore altering the weight distribution. If the roll is minimal, then certainly your statement would hold nearly true. Interesting to think about, thank you for challenging my video.
Well, the goal is to keep the car level, so yes. But if your roll bars are too stiff, you could pick up an inside tire off the ground when cornering.
The green control arm is mounted to the frame and can move the tire vertically. I explain the torque reaction in the blue bar using my hand and arm, in the video. As one side is lifted, it causes the blue bar to twist, making the other side lift as well.
The effects of the ARB would remain the same. The difference is since the Porsche is one of few vehicles with a rear mounted engine (behind the drive axle) it has a tendency to oversteer since there is weight at the rear. Porsches in general seem to be pretty well balanced and not in need of adjustments unless you simply want to eliminate understeer completely, but that makes the car more difficult to drive.
watching in 2019, wondering why there's a child on my screen? Keep it up
I'm actually working on a website right now, and one of the articles I've written is a comparison of going to school for mechanical engineering, automotive engineering, or a technical education in mechanics. The website is taking longer than it should, but when it's released I'll be making a video on it, and so you will surely know.
Woops! You are correct. Assuming the travel is the same (which it would be) a shorter arm would mean a greater angle change of the ARB, thus transferring a greater torque to the opposing side.
What a perfectly timed question, I just posted a video on strut bars an hour ago! :) Yes, they are different.
I was familiar with your other videos and I searched for this question. It was cool see you from 2012. Keep up the good work!
An ARB is not necessary, and depending on your spring stiffness/shock damping they can be eliminated. There may be a weight difference between the auto/manual, or a different spring/shock set-up that is the reasoning behind not having the sway bar in the manual. Or possibly to reduce understeer in the manual, since manuals are more of driver's cars than autos.
I have learned so much from watching your videos man! I now understand so much more about my car and truck and how they work. I have been doing my own repairs to my 77 gmc sierra grande, and now I know what most of the parts do. Thanks a lot!
Dear Jason, thank You very much for explaining anti-roll (balancing) bar! I was watching every your video from 2017 onward, but this one dates back to 2012. You look like a kid here, what a discovery :D
This guy explains stuff so well.
Glad to hear, cheers!
The result is fairly small indeed but the pneumatic tire does not develop grip linearly to the applied load. The load sensitivity of tires actually make even the small amounts of weight transfer affect the grip levels noticeably and as a whole the "rubber grip" is more complex phenomenon than often realised. The mentioned wheel posture, camber changes for example, can be dealt to an extent in the suspension geometry itself, though it is of course affected by the roll nonetheless.
Stu, if you are just looking at the front end of the car, the ARB will reduce understeer by controlling tire camber. The driver likes it because the car is responsive and takes a set quickly. However, anytime you transfer weight from one side of the car to the other, you reduce the total traction the tires develop. So a really stiff front ARB transfers a lot of weight to the front outside tire (and the inside rear tire from diagonal weight jack). Continued in next post...
Debating if I should buy a rear sway for my '07 Eclipse GT. Completely stock suspension, understeers like a giraffe on rollerskates.
@Down Shifts too late, it's fully built now lol
@Down Shifts nah.
Part 2: Camber does not fix balancing issues, it changes cornering ability so be careful with that, you might make your car better in corners, but if you get it wrong you might make it a lot worse and also it will increase your tire wear.
Shocks don't affect tire balance, but you might get a similar effect (shaking) if your shocks are bad, but this usually is noticeable only when taking corners, but not if you drive in a straight line.
Hope this helps, cheers
Different materials, different thicknesses; there are also some that are adjustable.
They are all made from a similar alloy steel. And you don't significantly change the weight transfer by adding more roll stiffness, a lower CG and wider track will do that.
No, it's just an illusion that I've added in to my 100+ videos. :)
Haha, yes, yes I do.
Note to Stu continued... this describes the Mechanical grip portion of traction. EE discusses the importance of controlling roll (with stiff ARBs and good suspension geometry) to keep prototype and formula cars "flat" to the road in order to maintain their Aerodynamic grip. A good laymens book on all this comes from Carroll Smith called Tune to Win - Smith was Carroll Shelbys head mechanic for the GT40 program winning Lemans from 1966 - 1969. The recent SAE textbooks go over the top with math
Jason..this man right here is a living legend. Theres no nonsense. just pure knowledge here
Yes, they basically do the job of a solid axle, which is fine on flat pavement, but if they're too stiff and you're on a bumpy road, it's definitely not ideal. Hence most road cars have fairly light ARBs.
Glad to hear, appreciate you watching!
Great explanation! I wanted to learn about this component and this video was straight and to the point without being any longer than it needed to be.
Thank you
i must say, the way you explain is really really simple and good! thanks a lot man.
one more thing to appreciate - at the end of the video you show the component (the one you explain in the video) in real life eg. Roll Bar in this one. that really helps man!
OK. Right off:
Anti-roll bars DO NOT reduce weight transfer by more than a tiny, tiny smidgeon. Weight or load transfer is an unavoidable consequence of the vehicle's centre of mass being above ground level, where the lateral forces are applied. All anti-roll bars do is to get you to the amount of roll that will equally oppose the torque created by those lateral forces at a smaller total roll
+Alan Baker i see u have read race car vehicle dynamics :P
+08yannch More than a time or two, yeah... :-)
ARBs do, however, contribute to either front or rear roll stiffness.
ARBs increase roll stiffness of the end they are mounted on. Increased stiffness causes increased load transfer on the end that becomes stiffer, in a curve. Load transfer decreases across the other end, so that the net transfer is the same (except for some very minor effects from CG migration).
Think "stiffness attracts load transfer" and you'll have it right. If, say, you stiffen a rear swaybar, you'll increase the load transfer between the rear wheels and decrease it between the front ones. This has the effect of giving less traction in the rear and more in the front. There are also other effects from the reduction in body roll including improved camber, that can affect vehicle balance in other ways.
Millikan (the younger) was my vehicle dynamics teacher. Awesome guy.
dude there is no weight transfer in a car
@@DasKloputzer ....... Can't be serious.?
You make it so simple with just hand drawings. Kudos.
Hakan - you must look at the front pair of tires and the rear pair of tires vs. any single tire to understand over/understeer balance. A CanAm car I studied had 540 pounds of force on each rear tire going straight. In the turn, it transferred 328 pounds to the outside tire. The coefficient of friction does increase with wait, but relatively less and less with each additional pound of force added to the tire. In a straight line, the tires had 1.4G of grip, but in the turn, now only 1.3G....
You are correct, the stronger the ARB the less independent your suspension becomes. The independence is sacrificed for reduced roll. On a track, it can be worthwhile. On the street I'd question having an ARB that was too heavy.
Well it would vary, but generally cars are set-up for understeer since it is typically more safe. So the set-up would likely follow my descriptions and create a light amount of understeer.
On the "yes to lifting" part, you can see this effect if you have unbalanced ARBs. For example a car with soft springs, and a very stiff front ARB combined with a very soft (or no) rear ARB can lead to not having enough total roll resistance to prevent body roll, but since the front suspension is tied together the inside front does indeed lift off completely.
Both can achieve it, though typically ARBs are a cheaper way of doing it. The downside is your wheels start to lose their independence with heavy ARBs.
I’m getting the opposite effect with my car. RWD Dodge Magnum RT. I have the Touring Suspension as was looking at upgrading for less roll and less float. I got the Bilstein B6 shocks and struts, which are awesome, kept factory springs, and was going to swap in a 30mm sway bar from a Performance Suspension model or SRT8. Mine has a 27mm ARB. But while going through LKQ to get a 30mm I saw a police spec Charger. All of my suspension is the same except for the 32mm sway bar. It made a significant difference. The car is far more settled especially at highway speeds. But one particular thing I always wanted my car to be able to do it now can do. And I was t expecting this. I like the ability to spin a car around on the tightest axis possible, basically leaving the inside front tire on one pivot point and rotating the rear. Well now, that’s a breeze after putting that sway bar in. Why? It’s supposed to reduce oversteer, but now it’s easy to oversteer it from a standstill, and at speed I ca. break the rear end loose, the front end is incredibly tight, and the car has transformed into more like an M5 kind of ride and handling. But why did my much stiffer ARB increase oversteer AND reduce understeer considerably?
Thank you for explaining how the anti-roll bars work so well!
Thank you for the video, current studying mechanical engineering and they have really helped. Also I love the way you explain things visually- you're a fresh take on lecturers :P x
1. Body roll makes little difference to toppling over in steady state situations. The COG does not move much laterally. It is dynamic situations where a lack of roll control can result in toppling, but the skill level of the driver plays a large role here.
2. The crux difference between fitting stiffer springs versus anti roll bars (or stiffer anti roll bars) is double bump stiffness, like when you go over a speed bump or expansion joint in the road. Everything else is the same or similar.
Slip angle is the angle between the direction a tire is traveling and the direction the tire is pointing. When the tire is *slipping* there is a difference in these two directions.
What I mean by increase is basically replace with a stiffer sway bar. Or, in the case of racing roll bars, some are adjustable.
There is also wheel droop: the opposite of the compression action you described. A bar will also lessen a wheel's ability to droop if it's opposing wheel is compressed. Some cars can lift the inside wheel during hard cornering caused at least some of the time by the anti roll bar.
Thanks for the explanation. A driving instructor just told me to disconnect the rear bar to lessen under steer and I had to double check that that is wrong.
I wanted to put stiffer sway bars on my fwd car. Now I realize that it is probably not a good idea. Thank you Jason, for showing me the light.
Hakan (cont) - You are right, the outside tire is developing more grip, but the rear pair of tires develops less overall grip. A stiffer rear roll bar increases outside rear tire grip, but results in less total rear tire grip* (*see comments below regarding Camber control) - an adjustment toward oversteer.
even after 10 years, very informative video for sway bars. 10/10
Basically you just increase (or decrease) the length of the lever arm. The longer the lever arm (where it connects to the control arm) the greater the torque which passes to the other side, essentially making the ARM more stiff.
I would agree, yes.
THANKS, BEST EXPLAINED ON UA-cam SO FAR!
the primary reason for ARBs is to control tire camber on the outside tire during a turn. You could achieve the same with very stiff springs; however softer springs give better tire compliance and grip; therefore, we use ARBs to control car roll in turns. You only want bars stiff enough to control tire camber at the speeds you drive - slow speed = softer ARBs
Note to Stu continued... and if there is no rear ARB, the rear tires have more overall traction than the front which is the definition of understeer. Lateral Load Transfer = Lateral acceleration in G's * weight * Center of Gravity height / track width. A sports car cornering above 1G transfers 70+% of its weight to the outside tires. Having that outside tire flat against the road ends up to be more important that anything happening with the inside tire. Continued...
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They're not totally necessary if the suspension is good enough as is, but it's cheaper to make a good suspension with roll bars than it is with different shocks/links/springs. Hence why some supercars can get away without using them (for a price, of course).
Quick question: Wouldn't an ARB defeat the purpose of independent suspension? One consequence of installing an ARB is that what happens to one wheel will happen to the other and thus a suspension system such as a double wishbone isn't truly independent. Am I thinking about this the wrong way?
Thanks for the awesome videos by the way! I've learned more from you videos than from talking with all my wrench head buddies.
I don't know the full reasoning, but I know that the suspension in the MP4-12C isn't conventional, it uses hydraulic controlled suspension and dual-chamber shocks that bleed excess pressure from one side of the shock to the other... Some people explain it as adjustable spring ratios, which is also why the car rides so comfortably when its in normal and is so stiff in track mode. The hydraulics manage the body roll as well.
Good explanation, but I think your diagram would have made more sense if you'd shown that the anti-roll bar is clamped along its main length in order to only allow it to rotate.
Exactly. And most people forget to point this out in their videos
I have been watching your stuff for the last two years, but this is glorious!
amazing explanation, came here after Rosberg's anti-roll bar problem in the 2013 Chinese F1 Grand Prix.
They would reduce the roll of the car significantly, however the suspensions would lose some of their "independence" as well. It's fine if the track is perfectly smooth, but for bumps, holes, imperfections, it's more of a balancing act of getting it just right.
This guy just made me understand something I've been trying months to do in just 3 minutes, thanks :)
Correct, the movement of the CG is minimal thus weight transfer is fairly insignificant.
Ahhh I understand now. I used to think a roll bar was a small roll cage type thing for convertibles/karts that would go directly behind the seat headrests. Thanks dude.
First, thanks for the videos. They are very good and I have learned much from them. However, anti roll bars ALWAYS INCREASE weight transfer in roll. In racing this can be seen when the inside wheel is completely pulled off the circuit by the stiff ARB, in which case, the outside wheel is carrying all the load. Ultimately the ARB is good by maintaining good wheel camber on the outside wheel - leading to maximum tire contact patch size/traction and increasing the cars transient responsiveness
Wish I could answer your question better, but I don't have any experience with it. I'd try searching for forums for your car, where people who have used various set-ups explain the pros and cons. Best of luck!
Wow...Congratulations on your achievements! Well earned.
You can make diy adjustable roll bars by making adjustable droplinks. Usually when a car is lowered with coilovers or lowering springs the antiroll bar turns too much "upwards" when car's weight is on suspension. Therefore you'll need shorter droplinks to make the wheel lifting effect faster on the inner curve side. If you know what I mean..
You are welcome!
Sure, for now you can check out my video "stability control." I go over it in that video.
Could be but I'm not sure. I'd check forums and see what set-ups others have done.
You are so yong back then
Siqi Zhu not sure this counts as a compliment. You looks so young!... in your old videos
Young and just starting out on his videos. Seems like he was just recording with a smartphone first before adding microphones and camera for better video quality. Engineer explain has come a long way for sure
Why do I feel like I'm getting "Deja Vu" reading this comment..
He is 65 or something. Its insane
Continued:
If you get added grip from increasing total roll stiffness (without changing tlltd) it will be due to minimizing the movement of poor suspension geometry. More likely though, you will lose grip due to minimizing the movement of *good* suspension geometry, and you will be much more likely to lose grip driving over a bump in the road as you've taken your independent suspension and then linked it up again (assuming you used a ARB to increase roll stiffness) left to right.
Well yes, the alignment is much cheaper and it can be done very fast (basically it takes 10-15 minutes). But it won't solve the camber issue, it will only reduce the tire wear as much as possible.
The springs themselves are only used to raise or lower your ride height, the camber depends on your wishbones...and how they are constructed.
Google "camber adjusting kit porsche 997 tt" - it could be the best solution for you if you can afford it.
fantastic channel. just what I've been looking for! thank you
You're very welcome!
Perhaps eventually, thanks for watching!
Search my channel for "solid axle suspension," should clear things up! But no, I can't see a reason why you would use both.
I really enjoyed your videos and you looked so young in this video (not saying you are not anymore!) Thank you and great work.
Adding an ARB when it is unneeded is generally counterproductive. A lot of effort goes into making independent suspensions actually independent, and sticking in an ARB in ruins a lot of that work by coupling them when one hits a stone etc.
The McLaren probably achieved its roll stiffness targets with single wheel springs alone, and achieved under/oversteer tuning through other methods. An ARB is often merely a bandaid for a problem that would preferably be fixed in a different way, but wasn't.
Anti-roll bars will actually not reduce weight transfer. Weight transfer is not a function of anti-rolll bars, springs, or suspension geometry. Here is the equation: Weight Transfer = (Weight*Ay*h/t) Where Ay = Lateral Acceleration, h = height of CG, and t = track. From this you can see that roll bars play no effect in weight transfer. The reason why they help you go fast is b/c they reduce body roll which helps your tire stay in a better part of the camber curve for better traction.
I would use newer images but don't feel like chasing copyright permissions. All the images I use are pictures I took, thus have copyright for.
Part 1: As far as I understood you have a problem with your tires being unbalanced (car and steering wheel starts shaking as you speed up).
First you should start with the simple things that could cause your problem....take your car to a tire shop and ask them to balance your wheels - this is the cheapest thing you could do.
If the problem is still there, check if your rims are straight (hitting a large hole can bend your rims, affecting their balance)
Bought my car in high school, in cash. Type R was not an option, though it's an awesome car.
Thank you for explaining this so clearly. Also, what a trip seeing you ten years ago, well done sir love your channel and that whiteboard.
I'm curious about how you change your slip angle with an anti-roll bar?
What you should had say is when you change the anti-roll balance (front/rear) you change the load transfer balance (front/rear). Where you have the stiffer anti-roll bar you'll have the more load transfer so the opposite track will have more grip.
Thank you! Best of luck with your engineering!
Well yes in a way, if you have too much camber, the tire wear will not be even, the inside part of the tire will wear faster and more than the outside.
Adjustable camber kit could solve this problem.
Another (cheaper) way is to compensate with adjusting your "toe", this will only minimize the tire wear, but the tire will still wear more on the inside than on the outside.
What car model are we talking about ?
Thanks again for another cool video. My only suggestion is that you use more up-to-date images and not, for example, pictures of 1989 Ferrari F1 cars when discussing present-day technologies, even if they're evolutionary or were actually in-use in some form 20+ years ago. Just my thought (and an expression of what I would prefer) as a viewer of these videos. Cheers!
I love your channel. Thank you for making this information more accessible to all.
as your ARBs get stiffer, the care will respond faster and feel better to the driver, then they will ultimately become too stiff and you will lose traction / speed in corners because you are transferring too much weight and not fully using the traction available from your inside tires. relative stiffness of the bars front to back is important too. A softer front and a firm rear ARB will get your tail out quickly - good for drifting. Otherwise mild understeer = fastest lap time
ARBs do affect weight transfer and the above equation does not tell the whole story when the vehicle's body rolls. Sprung and unsprung masses must be taken into account separately and we need to also determine roll centers so that the weight transfers can be calculated. Then we can continue to roll resistance where springs and ARBs come into play and get the final distribution of weight transfer in roll.
My god i love engineering. It gets my 🐐 bro if u know what i mean 😏 i could fall asleep to this guy explaining anti-sway bars... he’s so calming. Subscribed bro u got me
Engineering Explained Nice video. One thing though. ARBs do not significantly change the amount of load transfer. They change the balance of the load transfer between front and rear. Even if you have welded tubes for suspension and a near zero roll gradient you are still getting the load transfer within 1% of that of normal suspension. Don't you agree?
ty so much man , i am a fast virtual pilot , but i am terrible and setup , i just test and test ,but normaly i dont know what to do ,This helps a lot to know what i must to change .
Beautiful, intelligent and quick lesson. Thank you my brother
Fairly accurate. ARBs allow a car to run a high roll stiffness without running a high heave stiffness. Obviously individual wheel inputs will act on the roll bar but not to the same extent as rolling.
Ultimately total weight transfer is constant and is dependant on track width and CoG height, the CoG to Roll Centre height dictates how much of this transfer occurs elastically i.e. through springs, dampers and ARBs and how much is transferred geometrical through the suspension links.
I'm a bit confused by the slip angle part. The easiest way to explain how an ARB changes handling balance is by viewing them as a way to modify the amount of weight transfer each axle contributes during roll, the total transfer is unchanged you can just shift the majority forward or rearward.
Having a stiff rear ARB increases weight transfer at the rear axle as the rear axle now has a higher roll stiffness (it resists more of the total roll moment), this reduces weight transfer at the front leading to better load distribution across the front axle, increasing grip on the front axle (due to tyre characteristics) and thus reducing understeer/increasing oversteer :)
It's kind of astounding how much misinformation there is on ARBs out there, isn't it? Boggles my mind at times! This was pretty good overall but missed some significant points.
The CG on most cars (at least sedans,coupes, etc) is indeed quite low, the roll center generally remains significantly above ground, and angular displacement of a car in a turn is quite low also - in combination, yes, the CG movement due to lat acc. is actually quite minimal.
Continued in another post because youtube character limit is silly;
before this video i didnt even know what swaybar was Now i even know how to change the handling of car By changing them
Thank you. I knew it had SOMETHING to do with suspension, but was not certain how it worked. Apparently my sway bar completely broke on my tricycle. (2000 Saturn). I've got to know how things work. I should have been a scientist or something related. Thanks again Mr.
Do you have a video on sway bar disconnects? I understand the concept of how they increase travel but I want to see and hear you explain how it works with the suspension.