I'm kind of late to the party, but you do a really nice job of explaining complicated subjects like this. Well done, and thank you for all of your posts!
Jason, it seems like your videos always have been inline with similar issues I am experiencing at the time I view them. Thank you for all the useful information contained in them.
Great video Jason, one of those topics that probably won't be explicitly covered in my engineering program at university, so it's great to hear about it now :)
I watch this guy all the time. This is probably one of my favorite channels to learn things about car components from. I may not understand everything, but I end up figuring it out. Thanks man, keep up the awesome work.
Hi mate, Love the info, but (as a challenge) can you please touch on all this for solid axel setups. Trailing arm. 4 link. 4 link with panard rod etc. thanks
So strange was just talking about this in the canyons and I come on UA-cam today and you have a video on it. Always learn a lot from your videos! I'm just the test driver and can comment on feel and how the car reacts but always fun to see the math/science behind it!
I always go through your old videos to make sure I don't forget stuff, but I think I've never stopped and say thank you for the knowledge. btw, there's no link for the anti roll video on the description.
In interest to the front of the suspension , wouldnt the COG be behind behind the front wheel ? just my head is seeing this as the cog being the point of measurement looks like its in front of the front wheel
Xcellenet video and explanation. We run a dirt late model and i notices the upper and lower control arm points dont really ever intersect. Now the cars have been like this for years , but after watching this video i noticed a brand of car that just came out the upper has about 5 degrees of angle which raises the anti-dive. This is prolly a very good thing. But i wanted to know what your thoughts would be if there isnt any intersection for the uppers and lowers. Basically, there parallel.
Shouldn't the 100% anti-dive line run from the front contact patch to an imaginary intersection of the center of gravity with the rear contact patch, so directly above the rear axle?
I don't see how antidive makes the suspension stiffer; seems to me that it just applies a preload, which doesn't alter the spring rate. It might seem subjectively stiffer on a bumpy road where varying arm loads due to changes in traction can cause oscillation/chatter.
Hello, I'm not sure about the increased stifness with an anti dive setup. To me with this kind of setup, you can use a more compliant suspension because you don't have to control body movements under acceleration so much. So the more compliant suspension allows better small bump sensibility... There is a vey similar system on mountain bikes with buit in anti squat (see Dave Weagle patent), where low anti squat design use heavily damped shocks, thus not giving the best sensibility. Some idea for your next videos, anti roll bars, and then hydraulic and mechanical coupling of suspension elements. And then active suspension. Torque vectoring is interesting too.
Can you explain how this relates to motorcycle geometry? Possibly the Hossack suspension. Could this effect be applied to the rear wheel to prevent wheelies?
+Engineering Explained: Why did you choose to use this method of calculating the anti dive? The method you use seems to be what is described in "Tune to win" of Caroll Smith on page 35. In "Race car vehicle dynamics" by Milliken & Milliken, on page 617 (chapter 17.3) another way of calculating is proposed in which the longditudinal position of the CoG does not influence the Anti-features.
Is there software available that finds the optimum control arm connection points based on some input parameters. More anti-dive, more caster etc. Could this optimization be applied when you have a specific racetrack and have all the underlaying data to develop the "perfect" car for a certain track?
Would a certain angle of the upper control arm directly determine the angle of caster, keeping it perpendicular to the arm, or am I not really understanding the effects of this..??
Hello! Very good, this vídeo show me efficiently and rapidly how to discover the porcentage of anti-dive! Can you give some bibliography where I can find this? I'm doing a work that envolve this concept, and I like to use some book or reference! Thank you in advance.
is there any measure on how much anti dive percentage is best for passenger cars or any other vehicle ? have you also made video on pitch and bounce centres?? thank you.
I think accidentally achieved a very high anti dive percentage. Rides great. Doesn’t dive much at all. But it all the road imperfections travel straight into the truck. Speed bumps are terrible.
So, if I understand correctly, it would not be beneficial to have a high % anti-squat/anti-dive in the suspension of an offroad vehicle like an ATV, right? Because they don't have a high power-to-weight ratio, but they do need to have lots of suspension movement.
can you tell exactly how much anti dive percentage i have to keep.. i mean any equation ot Mathod to find how much it affects amount of load on spring and how much it affects the calculations for spring stiffness?
reycon13 There's no such thing as ideal anti-dive, it depends on multiple other factors. It all depends on the balance of things and what you want to achieve with the design. In general designing the suspension is extremely complex and there is never an ideal piece of design or something to go for. If that was the case, all cars would have identical suspension design because there would be one ultimate and best design. But that's not the case. There are literally hundreds of things to think about, various conditions in which the car will be used, at which speeds, how it should feel, etc. That's why suspensions keep constantly improving, no matter how good a system on a current car is, new generation will be better, because some little things will be changed again to improve it.
I'm kinda confused anti dive suspension systems are meant to enhance the performance of the vehicle right? So why doesn't the system act in a way of decreasing the inertia momentum instead of just simply controling the body of the vehicle? Am I misguided in some way?
I know about roll ceter but... How anti-dive suspension geometry works on an independent suspension? Does this consept works only for a rigid axle?? pd: sorry my bad english
so, it seems to be technically possible to achieve >100% anti-dive when the intersection of the CG with the green line lies above the CG. does this affect the behavior while braking, and if so, how? also, do all race cars (e.g. F1 or LMP cars) have a high amount of anti dive or do they achieve this anti dive mechanic in a different way?
0chriser0 Well, F1 used a special system for a few years until mid last season called FRIC. (Front-Rear-InterConnect). Basically it was a connection between the front and rear dampers, that aloud the rear damper to soften up and the front damper to stiffen up under braking so it reduced diving a bit. As far as i know Audi has a very similar system now in there LMP1 Car. It's said that Porsche also use such a system, but instead of using a hydraulic connection like Audi does and the F1 did, Porsche uses a mechanical linkage.
So If I have aftermarket coil overs can't I just adjust the damping and stiffen the suspension and lower the car ride height and this should reduce nose dive under heavy braking right??
spoon games yes you can and it will reduce diving, but you'll still have the drawbacks of stiffer suspension and lower ride height. What Jason explained is how you can counteract diving without stiffer suspension or lower ride height, so you don't get as much of the drawbacks as you do when you just stiffen your suspension up.
spoon games without the right geometry you can't reach 100% AD. Unless you weld the suspension... which is less than desirable. Finding the happy medium between stiffness and geometry is the key to success.
If your control arms are not exactly paralell (in a side view), wouldnt this create some kind of a mechanical lock that prevents the wheel from moving up/down? Any Input on this is highly appreciated!
When the nose dive during decelerate, which is at the corner turning, the shift of extra weight will help to increase the traction onto the front wheel to ease the turning of the wheel...effectively avoid under-steer. Correct me if i 'm wrong.
Chin P.S. When too much weight shifts to the front, rear wheels can actually lift from the surface. This is especially true in front wheel drive cars. Also, that weight will initially transfer when braking, before the turn in. You still have to worry about getting through the turn without suddenly transferring that weight again, but in some other direction.
The lines must be drawn through where the wishbones attach to the spindle, not through the wishbone's rotation axis, great video though Also, the green line passes through contact patch (most usual case) or though wheel center depending on whether the brakes are inborad or outboard (most usual case)
For cars with big aerodynamic effect, anti-dive is mandatory unless active suspension replaces the anti-dive with artificial anti-dive, or you have active height aerodynamics (either actuated or unsprung suspension-linked splitters and wings)
This thing doesnt even take into account the percent break force on the front. you will get two different values if you use this method versus the method taught in the race car vehicle dynamics textbook ( the god of race car textbooks ).
can you please help me and tell me what if i have parallel a-arms what will happen ? IC will contract on infinite what does that mean ? do i have unknown anti-dive ?
+Mahdi G No. Draw a green line from the contact point between tire and road, parallel to the a-arms. The anti-dive will be where the green line intersects with the CG line. Usually it will result in negative anti-dive.
+Heitor Cicoti thanks for replying but what you saying is ill have 0 anti-dive which means all the longitudinal forces will be transferred through my coilover, but i dont get the negative antidive part may you explain it further ?
Thanks man. Been getting into car restorations lately and your channel has the education to back up my interest. If only I had the capacity to be a engineering major I'd take it:)
Engineering Explained Why did you draw that center of gravity line where you did? That appears to be in front of the car so how do you determine how far to put it?
I know this is an old comment but to the right of the wheel is an arrow pointing to the right, indicating the direction of travel. To find the fore/aft and left/right location of your CoG, you would put your car on corner weights to see the load on each wheel. To find the height of the CoG you then raise one axle (preferably the highest loaded axle) as much as you can, note down the angle of tilting and the measured load on the corner weights of the remaining wheels. The book "Race car vehicle dynamics" by milliken and milliken has a section on this.
you lost me, forces typically more forward with motion and braking brings the centre of gravity lower with motion so how can it be reduced without increasing ride harshness
Not sure if less aerodynamic a bad thing when you trying to slow down. Doesn't that make you stop faster by a fraction of a second? Also, the dive compresses front spring which theoretically gives you more traction?.....until it bounce back Lol. Just saying. But I can see how bad it is if you dive so hard and the rear tires loss traction.
Is is good to have an anti-dive geometry in a race car and if Yes, then how much is the optimum anti dive % Are there any examples of race cars that use anti-dive geometry ?
TokiWartooth6666 "Deceleration is the term used for acceleration that causes an object to slow down." What do you mean it's not a real thing? Language is a real thing. Deceleration is a real word, with a real meaning.
I thought acceleration was a change in velocity. Weather that be speeding up or slowing down. I truly don't mean to come off as an ass. Genuinely curious.
Who else is here to know about ANTI-DIVE after the 2023 F1 season started?
Not me
Always a plain and simple explanation for complex issues !
Great video !
Thanks !
I'm kind of late to the party, but you do a really nice job of explaining complicated subjects like this. Well done, and thank you for all of your posts!
Thank you very much for this explanation! It was far more helpful and intuitive than all the articles I have read.
Jason, it seems like your videos always have been inline with similar issues I am experiencing at the time I view them. Thank you for all the useful information contained in them.
Great video Jason, one of those topics that probably won't be explicitly covered in my engineering program at university, so it's great to hear about it now :)
I watch this guy all the time. This is probably one of my favorite channels to learn things about car components from. I may not understand everything, but I end up figuring it out. Thanks man, keep up the awesome work.
Hi mate,
Love the info, but (as a challenge) can you please touch on all this for solid axel setups. Trailing arm. 4 link. 4 link with panard rod etc.
thanks
This is such a crisp explanation thank you!
Great explanation! I got a reference to just "anti-dive geometry" and this video explained it beautifully.
übel gut erklärt bre küss dein herz
So strange was just talking about this in the canyons and I come on UA-cam today and you have a video on it. Always learn a lot from your videos! I'm just the test driver and can comment on feel and how the car reacts but always fun to see the math/science behind it!
Interesting, keep up the good work.
I always go through your old videos to make sure I don't forget stuff, but I think I've never stopped and say thank you for the knowledge. btw, there's no link for the anti roll video on the description.
Can you do a video on mechanical grip loss from stiff swaybar use?
impressive,thank you my friend for your explanation
I saw this anti-dive suspension in the Porsche cayenne and Audi Q7, and it looks so cool.
You have used a double wishbone setup up as your example, how would anti drive be accumplished with a macpherson strut front suspension please.
The upper dashed line must be drawn in that case perpendicular to the strut and through the mounting point itself, check the roll center video.
Engineering Explained please make a detailed video about suspension tunning like explaining damping ratios,damping factors etc their effects.
Is it possible to do this on a macpherspn suspension?
Your blackboard videos will help on our racing car improvements! thanks! Suscribed,
In interest to the front of the suspension , wouldnt the COG be behind behind the front wheel ? just my head is seeing this as the cog being the point of measurement looks like its in front of the front wheel
Can you do a video on velocity stacks
Puede alguien por favor subtitular a este pana que hace videos tan brutales?
Good job men!! Could you please make sub titles in spanish?
Xcellenet video and explanation. We run a dirt late model and i notices the upper and lower control arm points dont really ever intersect. Now the cars have been like this for years , but after watching this video i noticed a brand of car that just came out the upper has about 5 degrees of angle which raises the anti-dive. This is prolly a very good thing. But i wanted to know what your thoughts would be if there isnt any intersection for the uppers and lowers. Basically, there parallel.
In case of a McP strut suspension, how do you draw the lines? There's lower control arm, but no upper arm?
Shouldn't the 100% anti-dive line run from the front contact patch to an imaginary intersection of the center of gravity with the rear contact patch, so directly above the rear axle?
hey!! is it not like that stiffness of suspension is good...
I don't see how antidive makes the suspension stiffer; seems to me that it just applies a preload, which doesn't alter the spring rate.
It might seem subjectively stiffer on a bumpy road where varying arm loads due to changes in traction can cause oscillation/chatter.
quite useful
Should have a look at the Koenigsegg Triplex system. I believe there's a video on the /Drive channel about it
Hello,
I'm not sure about the increased stifness with an anti dive setup. To me with this kind of setup, you can use a more compliant suspension because you don't have to control body movements under acceleration so much. So the more compliant suspension allows better small bump sensibility...
There is a vey similar system on mountain bikes with buit in anti squat (see Dave Weagle patent), where low anti squat design use heavily damped shocks, thus not giving the best sensibility.
Some idea for your next videos, anti roll bars, and then hydraulic and mechanical coupling of suspension elements. And then active suspension. Torque vectoring is interesting too.
Can you explain how this relates to motorcycle geometry? Possibly the Hossack suspension. Could this effect be applied to the rear wheel to prevent wheelies?
+Engineering Explained:
Why did you choose to use this method of calculating the anti dive? The method you use seems to be what is described in "Tune to win" of Caroll Smith on page 35. In "Race car vehicle dynamics" by Milliken & Milliken, on page 617 (chapter 17.3) another way of calculating is proposed in which the longditudinal position of the CoG does not influence the Anti-features.
Is there software available that finds the optimum control arm connection points based on some input parameters. More anti-dive, more caster etc. Could this optimization be applied when you have a specific racetrack and have all the underlaying data to develop the "perfect" car for a certain track?
Ah, that explains it - very cool.
Would a certain angle of the upper control arm directly determine the angle of caster, keeping it perpendicular to the arm, or am I not really understanding the effects of this..??
How does this apply to McPherson type suspension?
Hello! Very good, this vídeo show me efficiently and rapidly how to discover the porcentage of anti-dive! Can you give some bibliography where I can find this? I'm doing a work that envolve this concept, and I like to use some book or reference! Thank you in advance.
is there any measure on how much anti dive percentage is best for passenger cars or any other vehicle ?
have you also made video on pitch and bounce centres??
thank you.
Thank you
I think accidentally achieved a very high anti dive percentage. Rides great. Doesn’t dive much at all. But it all the road imperfections travel straight into the truck. Speed bumps are terrible.
So, if I understand correctly, it would not be beneficial to have a high % anti-squat/anti-dive in the suspension of an offroad vehicle like an ATV, right? Because they don't have a high power-to-weight ratio, but they do need to have lots of suspension movement.
Can loss of tire to surface contact be one of the main drawbacks?
Been done on motorbikes for years,
My 1986 Gpz 600 has this.
Hi could you do hub steering motorcycle and motorcycle geometry please
thanks again!
can you tell exactly how much anti dive percentage i have to keep.. i mean any equation ot Mathod to find how much it affects amount of load on spring and how much it affects the calculations for spring stiffness?
How do you find the CG (height and planar location) of the vehicle?
Can I tilt the lower one to positive angle rather than doing this on front end?
Does anti dive depends on ball joint position?
Which wouls you say is the ideal anti-dive percentage for a regular car?
reycon13 There's no such thing as ideal anti-dive, it depends on multiple other factors. It all depends on the balance of things and what you want to achieve with the design. In general designing the suspension is extremely complex and there is never an ideal piece of design or something to go for. If that was the case, all cars would have identical suspension design because there would be one ultimate and best design. But that's not the case. There are literally hundreds of things to think about, various conditions in which the car will be used, at which speeds, how it should feel, etc. That's why suspensions keep constantly improving, no matter how good a system on a current car is, new generation will be better, because some little things will be changed again to improve it.
Do inboard shocks effect anti dive/squat?
I'm kinda confused
anti dive suspension systems are meant to enhance the performance of the vehicle right?
So why doesn't the system act in a way of decreasing the inertia momentum instead of just simply controling the body of the vehicle?
Am I misguided in some way?
I know about roll ceter but...
How anti-dive suspension geometry works on an independent suspension?
Does this consept works only for a rigid axle??
pd: sorry my bad english
Sir, I want too ask that what % Anti Dive is best for ATV for Baja??
so, it seems to be technically possible to achieve >100% anti-dive when the intersection of the CG with the green line lies above the CG. does this affect the behavior while braking, and if so, how? also, do all race cars (e.g. F1 or LMP cars) have a high amount of anti dive or do they achieve this anti dive mechanic in a different way?
0chriser0 F1 has very stiff suspension and very minimal suspension travel, that's how they mostly achieve it.
0chriser0 Well, F1 used a special system for a few years until mid last season called FRIC. (Front-Rear-InterConnect). Basically it was a connection between the front and rear dampers, that aloud the rear damper to soften up and the front damper to stiffen up under braking so it reduced diving a bit.
As far as i know Audi has a very similar system now in there LMP1 Car. It's said that Porsche also use such a system, but instead of using a hydraulic connection like Audi does and the F1 did, Porsche uses a mechanical linkage.
shi01 this is also how the McLaren mp4-12C suspension works. No roll bars.
How does one determine CG height?
So If I have aftermarket coil overs can't I just adjust the damping and stiffen the suspension and lower the car ride height and this should reduce nose dive under heavy braking right??
spoon games There are certainly other ways of reducing nose dive, yes.
spoon games yes you can and it will reduce diving, but you'll still have the drawbacks of stiffer suspension and lower ride height.
What Jason explained is how you can counteract diving without stiffer suspension or lower ride height, so you don't get as much of the drawbacks as you do when you just stiffen your suspension up.
spoon games without the right geometry you can't reach 100% AD. Unless you weld the suspension... which is less than desirable. Finding the happy medium between stiffness and geometry is the key to success.
If your control arms are not exactly paralell (in a side view), wouldnt this create some kind of a mechanical lock that prevents the wheel from moving up/down?
Any Input on this is highly appreciated!
+jakob k
No, it would just make the caster to change with suspension travel. If you have any CAD software, you can try it yourself.
How to find instantaneous centre
Well,since 100% anti dive has a drawback,what is the best amount of anti-dive for design of a racing car.
Isn't that nose diving is beneficial for sharp/speedy cornering for race car?
Chin P.S. Why?
When the nose dive during decelerate, which is at the corner turning, the shift of extra weight will help to increase the traction onto the front wheel to ease the turning of the wheel...effectively avoid under-steer. Correct me if i 'm wrong.
Chin P.S. When too much weight shifts to the front, rear wheels can actually lift from the surface. This is especially true in front wheel drive cars. Also, that weight will initially transfer when braking, before the turn in. You still have to worry about getting through the turn without suddenly transferring that weight again, but in some other direction.
Isaac Dover true and i am agree on that fact. In real sport racing,speed and design have to be compromised to optimised the track race.
Did only i misread "anti-drive suspension"? :)
Your suggestions what would it be anti-drive suspension?
Eugene Hvorostyanov Anti-dive*
The lines must be drawn through where the wishbones attach to the spindle, not through the wishbone's rotation axis, great video though
Also, the green line passes through contact patch (most usual case) or though wheel center depending on whether the brakes are inborad or outboard (most usual case)
hey, for racing car like f1 cars is it good to have anti dive suspension
For cars with big aerodynamic effect, anti-dive is mandatory unless active suspension replaces the anti-dive with artificial anti-dive, or you have active height aerodynamics (either actuated or unsprung suspension-linked splitters and wings)
Wouldn't this put more stress on the control arms, causing them to be more prone to breaking?
yes, that's also why too much anti-dive is not good
neaterino!
This thing doesnt even take into account the percent break force on the front. you will get two different values if you use this method versus the method taught in the race car vehicle dynamics textbook ( the god of race car textbooks ).
can you please help me and tell me what if i have parallel a-arms
what will happen ? IC will contract on infinite what does that mean ?
do i have unknown anti-dive ?
+Mahdi G
No. Draw a green line from the contact point between tire and road, parallel to the a-arms. The anti-dive will be where the green line intersects with the CG line.
Usually it will result in negative anti-dive.
+Heitor Cicoti thanks for replying
but what you saying is
ill have 0 anti-dive which means all the longitudinal forces will be transferred through my coilover, but i dont get the negative antidive part may you explain it further ?
So if I have more than 100% anti dive, will my car squat under braking? XD
Yes!
what do you mean by suspension?
LiqCharles ua-cam.com/video/jOiOO7qloXQ/v-deo.html
Thanks man. Been getting into car restorations lately and your channel has the education to back up my interest. If only I had the capacity to be a engineering major I'd take it:)
Engineering Explained Why did you draw that center of gravity line where you did? That appears to be in front of the car so how do you determine how far to put it?
+dbeckMSP I think it should be at CG height Usually 4-6 inches above the camshaft) at center of rear tire?
I know this is an old comment but to the right of the wheel is an arrow pointing to the right, indicating the direction of travel. To find the fore/aft and left/right location of your CoG, you would put your car on corner weights to see the load on each wheel. To find the height of the CoG you then raise one axle (preferably the highest loaded axle) as much as you can, note down the angle of tilting and the measured load on the corner weights of the remaining wheels. The book "Race car vehicle dynamics" by milliken and milliken has a section on this.
Othe ytbr with your voice 90%
RB19
you lost me, forces typically more forward with motion and braking brings the centre of gravity lower with motion so how can it be reduced without increasing ride harshness
Engineering Explained can u plzzz explain about the ecu of magnetic suspension and how does it work ...I look forward for your reply
how do you ads on your videos? Sorry I know it's irrelevant.
Not sure if less aerodynamic a bad thing when you trying to slow down. Doesn't that make you stop faster by a fraction of a second? Also, the dive compresses front spring which theoretically gives you more traction?.....until it bounce back Lol. Just saying. But I can see how bad it is if you dive so hard and the rear tires loss traction.
Is is good to have an anti-dive geometry in a race car and if Yes, then how much is the optimum anti dive %
Are there any examples of race cars that use anti-dive geometry ?
Who came here because they want to know why RB19 and RB20 does what it does?
Say " basically" a few more times
how can I calculate the Anti-dive is there a law or any way to do it??
+Engineering Explained
Huh?
As long as my car stops and turn is fine!...I'm cunfuzled!😫😑😐😕
I hate that you use the word deacceleration since it'snot a real thing. Say it dives when you abruptly slow down.
TokiWartooth6666 "Deceleration is the term used for acceleration that causes an object to slow down." What do you mean it's not a real thing? Language is a real thing. Deceleration is a real word, with a real meaning.
I thought acceleration was a change in velocity. Weather that be speeding up or slowing down. I truly don't mean to come off as an ass. Genuinely curious.