The Complete Guide To Suspension Roll Centers - Part 2
ฝัง
- เผยแพร่เมื่อ 31 ก.ค. 2024
- The Complete Guide To Suspension Roll Centers. What are suspension roll centers and why do they matter?
Part 2 - Why do we care about suspension roll centers and what do they do for the performance of the vehicle?
In this video we will look at the effects of roll center height on jacking, ride, and body roll
In part 1 we looked two methods for finding the suspension roll centers. Watch it here: • The Complete Guide To ...
Chapters:
0:00 Introduction
0:41 Jacking
14:03 Ride
15:42 Body Roll
18:04 Wrap-up
Huibert Mees
Suspensions Explained
![อยู่ได้แล้ว - LIPTA feat. Mirrr [OFFICIAL MV]](http://i.ytimg.com/vi/-9-hpntNym4/mqdefault.jpg)
This the best video about explaining what roll centers do, but I think part 3 is needed. How the front and rear roll centers affect car behavior, understeer, oversteer. From my understanding and experimentation, building my own racecar, one would want for a 50:50 weight distribution car to have a higher rear roll center and a lower front roll center so that just enough force would be transferred to the front outside tire as to achieve it's maximum grip for the given slip and camber angles.
Great explaination! Though I'm not sure you the audio is frequently muted.
Great videos. Got yourself a subscriber.
Would like to see a video comparing independent vs rigid axle suspension.
Great explanation! I used to be big into offroading/rock crawling. Lowering roll centers paid huge dividends in building go-fast desert racing rigs (see: King of the Hammers). For dedicated rock crawlers, higher roll centers were much more stable on side-hills etc.
Your demonstration of the contact patch shifting left/right is basically a 90 deg rotated view of the concept of "wheel recession" which also helps in going fast in the desert on solid axles. People found having flat links allowed the front solid axle to move backwards as it goes up in bump and absorbed fast whoops much better.
Most have moved on from solid front axles to IFS, but when I got into auto-x and tracking cars, it was nice to see a lot of what I'd learned translated to on-road stuff as well.
I could be wrong but always thought it's a good practice to keep roll centre migration to minimum (like within few millimeters). I guess my question would be is there a negative effect of excessive migration? And what would be jacking value that we could call under control? Short example of this equation with values would be useful.
Please address this question
I never thought to think about the roll center in the context of the instantaneous center of the contact patch, even though the contact patch is what forces the suspension I never made the connection, thanks for the clear explanations!
Without doubt, the best end to end explanation I have seen. The next piece of the puzzle I am looking for is optimising roll couple (roll axis) between axles... AND how CG would contribute to that decision when full freedom is available at the design stage.
Amazing
These are great. Thanks!
Thank you for these videos! I enjoyed the explanation, graphics, and all the details!
This was amazing!
Thanks a lot very clear explications !
Do the inside tire anti jacking and outside tire jacking combine to create a torque that rolls the chassis?
this is all very helpful, thanks!
Thanks for these roll center videos. They were both enjoyable and educational
Thank you very much.
very interesting!!
Amazing video,, why is the upper control arm shorter, and why is the knuckle tilted. what is the engineering behind that?
Great video I really enjoyed It! Clearly presented and with the correct amount of detail needed... IIf (forthe future) a part 3 is in the planning may I ask to explore some cases in which the roll center is below ground? thank you very much!
Can you make a video of how anti-roll bars affect lateral load transfer distribution, yaw stability, and dynamic behavior of cars on corner entry/exit?
Thank you for the suggestion. I'll add it to my list.
I'm not a child, I swear, but, at 18:23, when he said "WE MUST KEEP JACKING UNDER CONTROL", I laughed so hard.
lol same
Thanks for this great video. After watching this one and the previous one I find myself looking for a third video, one that covers a solid axle rean end. Does anybody know a good video that covers the rear suspension like in the old cup cars and the NASCAR/ Whelen tour type modifieds? Most guys usually run either a three link or a torque arm but other variations are possible.
Thanks!
hello sir can you post a series on DESIGNING A SUSPENSION GEOMETRY FOR A FSAE CAR - DOUBLE WISHBONE, DAMPER TO LOWER ARM TO BODY or PUSH ROD SUSPENSION,
I will be waiting sir
i request you sir
I'm assuming jacking is bad when you're not wanting to break traction. However when you're in a constant state of slip could the jacking be beneficial to planting the tire better?
What's going to happen to the jacking force if the roll center is below the ground (contact patch)?
So when would you go for a high roll centre and when would you choose a low roll centre? It would be good to see two scenarios explored. A race car and road car. Perhaps also a high ground clearance off road car.
What happens if we take the imaginary link to start from a point on the knuckle, so that it is parallel to the ground? With no inclination of the imaginary link, how will jacking occur?
what is the relation between the roll center and the CG then?
Thanks for the excellent videos, I am really enjoying watching them.
One thing I have read about previously is the relevance of the slope of the roll centre axis ie a line drawn along the length of the car between the front and rear roll centres.
So if the front roll centre is lower than the rear, this axis would slope up towards the rear, and vice versa.
I have seen some discussions about this that suggest the angle of this axis should be similar to the mass centroid axis of the car ie if you analyse the CoM of the car in chunks along the length of the car and the centre of mass at the front is lower than the rear ( eh mid engine car) it is preferable to have a roll axis that also slopes up towards the rear.
Is this something you are aware of?
Thanks again.
The idea behind that is that you want to keep the distance between roll centre and CoG small. Otherwise you will get a lot more roll moment at the side of the car where the CoG and roll centre is big. It influences the slip angles (so causes under/oversteer to get worse)
@@stevenvandenbosch5528 ahh, of course, that makes complete sense, thanks so much for replying, that's really great. I've been wondering about that for years!
So, what if one were to add a body mounted Watts linkage to a live axle set up? Would the centre of the body mounted Watts linkage become the effective roll centre? If so, mounting this lower than the axle centre point would lower the roll centre and increase the roll moment. I have seen these systems in the after market but never understood any theoretical advantage compared to an axle mounted Watts linkage (except for a slight reduction in unsprung mass) and now the roll centre moves with the body not the axle but why add the complexity? Asking for a friend 😉
Good explanation, I was wondering about the multi-link style. Does KPI and wheel center-line play a role in roll center? If you have scrub radius (meaning KPI and wheel center line do not line up), which one do you use for calculating Instance of center?
Roll center has nothing to do with the KPI. The only thing you need to know is where the center of the contact patch is. That's where you draw the line to.
Is the centre of the tire where the reference line is or is it where 0 scrub radius is?
The line goes to the center of the tire.
@@suspensionsexplained so it changes with offset?
Yes it does. It goes wherever the tire center is.