How Anti-Roll Bars Work - How To Improve Car Handling 

I love how Jason went from awkward nerdy teenager to nerdy middle-aged man in the short span of 7 years.

The last 30 seconds was gold. That 30 seconds made everything clear to me. Thanks!

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.

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.

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.

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.

Why are u wearing a helmet

Glad to hear, cheers!

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.

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!

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.

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.

Thanks for sharing, truly appreciate it!

Thank you for explaining how the anti-roll bars work so well!

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.

Thank you! Best of luck with your engineering!

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

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!

Jason..this man right here is a living legend. Theres no nonsense. just pure knowledge here

This guy explains stuff so well.

fantastic channel. just what I've been looking for! thank you

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.

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

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.

Great video! It's quick, direct, simples, and highly informative. Well done!

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!

Now I understand. Thanks for the explanation!

even after 10 years, very informative video for sway bars. 10/10

Hey man, thanks, been dreaming for this particular tutorial and again, I appreciate it sooooooo much.

amazing explanation, came here after Rosberg's anti-roll bar problem in the 2013 Chinese F1 Grand Prix.

This guy just made me understand something I've been trying months to do in just 3 minutes, thanks :)

You make it so simple with just hand drawings. Kudos.

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.

Thanks a lot man, appreciate the easy explanation:-)

Another great explanation. Good to see some real-world examples in the video, too!

Wow... something so subtle.... Thanks for explaining this. been wondering for years.

Wow...Congratulations on your achievements! Well earned.

THANKS, BEST EXPLAINED ON RU-vid SO FAR!

I really enjoyed your videos and you looked so young in this video (not saying you are not anymore!) Thank you and great work.

Beautiful, intelligent and quick lesson. Thank you my brother

Thanks for the videos man, great job! definitely subscribing to your channel

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?

No, it's just an illusion that I've added in to my 100+ videos. :) Haha, yes, yes I do.

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

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

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.

Great video though! learned a lot for such a short amount of time :D

Good explanation

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.

Good job on the video! Very informative, thanks!

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 .

Really nice explanation! Thanks! :)

Excellent explanation! Thanks.

Thanks!

Great job and great explanation!

Good clear explanation. Just subscribed.

Different materials, different thicknesses; there are also some that are adjustable.

Brilliant thanks! I learn better with demonstration, so this was awesome help for my curious self! Cheers!

Perhaps eventually, thanks for watching!

Seeing the actual thing visually... Rather then diagrams will always be king.

What I mean by increase is basically replace with a stiffer sway bar. Or, in the case of racing roll bars, some are adjustable.

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.

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.

Hey Jason!Thank you very much for the easy explanations!Your videos are truly inspirational. I have a small doubt that needs to addressed in order to understand the Sway bars. You said that the Sway bars bring the tire closer to the car when the car tries to roll. So, suppose if the car is cornering to the left(as shown in your video), the sway bar tries to bring the right tire nearer to the car thereby risking the loss of contact with the ground .So, How can it be advantageous when there is a loss in contact?

Thanks for subscribing!

Thanks dude! Im learning two in a once: english and mechanics here (Im from Brazil) ;D

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.

Glad to hear, appreciate you watching!

thx dude. My 1999 f150 sway bar links went out awhile back

I have been watching your stuff for the last two years, but this is glorious!

Very good explanation.

thanks for the knowledge. -Car Guy

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...

Great explanation best one on utube.

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

Thanks for the explanation

Dude you really explain well.

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.

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.

I would agree, yes.

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....

very nice explanation! thx

You are welcome!

Debating if I should buy a rear sway for my '07 Eclipse GT. Completely stock suspension, understeers like a giraffe on rollerskates.

Hey man, awesome video, wondering if you could do an explanatory video on third spring configurations, or on j-dampers in F1. Both are tricky topics, would be nice to see and hear your explanation :)))

Thanks for the video, i haven’t seen any anti-pitch bars. Ie to limit the back to front motion.

Great video, thanks

you explained that perfectly thank you

before this video i didnt even know what swaybar was Now i even know how to change the handling of car By changing them

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.

Great explanation

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.

Nice explanation

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.

Lol, was looking for sway bar info.. what a young man!🤣👍

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.

I like your older vids better than the new ones

Correct, the movement of the CG is minimal thus weight transfer is fairly insignificant.