Suspension Alignment, Part 1 - Intro and Roll Center

This is the first video in a series where we address the overall complexity of a suspension system and how to align a cars suspension and wheels. There is an introduction to the alignment series, and a first topic called "Roll Center" or Roll Point".
Simulation tool can be found at : www.vsusp.com

[@duncangrainge]

Very interesting Steve. Well explained. I bet most car enthusiasts have little or no true understanding of the various parameters and inputs that are critical to set up of your car. I certainly learned new things. Thanks.

[@D3Sshooter]

Thanks for the comments, I know and I just scratched the surface in this video. But it is importend IMO to have a good understanding why we do things in a certain way

[@tiitsaul9036]

Thank you. You’ve explained RC differently from other explanations I’ve heard and it made sense to me.

[@D3Sshooter]

Glad it was helpful!

[@gshort4707]

Thank you for explaining everything so clearly. I love your in depth thinking.

[@D3Sshooter]

Glad it was helpful!

[@mrvanT]

Good morning Steve, this is very good, I’m going to do it on my VW golf mk1 that I’m restoring. Greetings from the east of the 🇳🇱.

[@D3Sshooter]

Good idea, what I have shown can also be done on struts... like on you VW, if they are adjustable

[@mrvanT]

@@D3Sshooter I did some upgrades to have more adjustments. Since the restoration is on a small budget, I love it if I can do it myself. As always I look forward to your videos and hope to see old rusty again soon. Thank you Steve!

[@cumbob]

@@mrvanT just remember setting ride height on a MacPherson front end too low will hurt camber curve under load. General rule is to have control arms flat at ride height

[@mrvanT]

@@cumbob that is good advice, I will remember that. Thanks

[@nils5005]

I am building a modernized replica of a 1955 Ferrari 500 Mondial and this will be my perfect guide to my suspension design.

[@dalamar6228]

Looking forward to this in depth series so that I can setup my TVR properly. Thanks!

[@JPB90]

Brilliant video. Makes you appreciate the setup that goes into high level race cars, downforce, average speed of the track, driving style, tyre type, weather conditions all factored into making changes to suspension setup for that extra bit of lap time.

[@D3Sshooter]

Thanks for the comments

[@johnscott8592]

Another great video Steve, looking forward to seeing you put this theory into practical work.

[@D3Sshooter]

Thanks for the comments

[@tomgraham6833]

Wish I had this back in 1969 when after 3 years of racing a fully race prepared Triumph TR4 I purchased a Sports Racing car called a Bobsy SR3, a made in USA car raced in SCCA Sports racing class. Being an Engineer I had read all I could find on the subject you are discussing and went so far as to modify the TR front suspension by changing the inboard upper A arm inboard pivot location. Lowered it about 1" Negligble effect. I purchased and re-engined. rebuilt the Bobsy using a British, Holbay mofified Fromula III engine of the time except that the rules I raced under placed no restriction of Carburation so it was fitted with 2 downdraft Webers. I think it dynoed at about 130 HP. at 9500 RPM. Class rules set max displacement at 1150CC. Car weighed about 1100# The objective was to win races that included various types of cars but restricted to more or less equalize performance. My main competition was a 1967 Porsche 91`S, race prepared and a veteran, placing well at the Daytona 24 HR race. I needed about a5% lap time improvement over my best TR-4 time. The car was mostly raced at Mt Tremblant/St. Jovite track just north of Montreal. The reason I am writing is that during my first track time I crashed at a quite high speed LH bend as a result of some roll induced, rear suspension steering effect that while at slower speeds just slid a bit and self corrected but as I pushed for better lap times it became an accelerating uncontrollable slide. The suspension was all fully adjustable and similar to Formula cars of that period. After reparing the crash damage I more carefully adjusted the rear suspension according to my own analysis and information available at the time which was limited. Hard way to learn about such things but the car was eventually a winner and probably still holds the Lap record for its class. The track is now owned by Lawrence Stroll.

[@D3Sshooter]

Thank you so much for sharing that information, it is always a pleasure to read what people did to make their cars better. Practical experience is still the best school as you just explained and demonstrated.. As for your crash, bumpsteer on the rear wheels is devastating as you experienced. That is why I always measure the bumpsteer.... and should be zero...anyhow , its a pleasure to read you text. take care

[@davidyendoll5903]

I really enjoyed your video Steve as I have enjoyed all your previous work . The subject is so complex and interrelated that most of us cannot fathom it out without a lot of help from a guru . Well done ! Please tell me more .

[@D3Sshooter]

Glad you enjoyed it, I have tried to keep it understandable. Yet we just scratched the surface. As the suspension on a car is a 3 D model with many interworking forces...it complex. So I try to take step by step.

[@TheObserver567]

Excellent information. Thanks

[@marchutchings8834]

Your video's Steve are very informative, keep working on them, you will build up a strong following. I love your education. Thanks many times over. Marc.

[@D3Sshooter]

Thanks for the comments

[@stevepearce6689]

Thank you Steve for explaining the dark art of suspension tuning. I think of you as a Renaissance Man.

[@D3Sshooter]

Thanks for the comments

[@OvertravelX]

Great topic, thank you!

[@D3Sshooter]

My pleasure

[@paulwhiteman3625]

That was a really interesting and informative video! Thank you sir and I look forward to watching the rest in the series.

[@DAVEXR2007]

Brilliantly explained. Thanks Steve 👍🏼

[@D3Sshooter]

Glad you enjoyed it

[@neverendingwinkleface6482]

Been looking for something like this, thank you very much

[@phildem414]

Great tool, perfect to apply this course!

[@alans5187]

excellent video Steve, the best I have come across.

[@D3Sshooter]

Thanks for the comments

[@haideralam1]

Hats off You Sir, you are great in every aspect

[@54mgtf22]

Love your work, Steve 👍

[@D3Sshooter]

Thanks for the comments

[@DaanvanGruisen]

Hahahaha, was enjoying a meal with a glass of wine while watching! 🙃

[@D3Sshooter]

Hope you enjoyed it!

[@oleran4569]

Fascinating! And very cool!! You are a great professor!

[@D3Sshooter]

Thanks for the comments

[@93Martin]

Can't wait to see the next one!

[@D3Sshooter]

Its coming soon

[@turboeero]

THANK YOU for this video!!! Very good. Keep up this good work!

[@zaunkonig3493]

Just an excellent lession again!

[@D3Sshooter]

Thanks for the comments

[@benmarr352]

In that generally soft os good for grip it seems to be that getting rc close to cg would be very much beneficial, then run with softer spirings for same roll and a very fluid car. Also probably means no meed for arbs which are for some reason frowned upon by a number of people (GMA T50 as an example). Does.the above make sense?

[@grideffect1193]

Great explanation, thank you 👍👍👍

[@D3Sshooter]

Thanks for the comments

[@TheGreatDefective]

I haven't had time to watch in a while, but as always a fantastic video. I often wonder if you have professional experience or if you are just a very passionate hobbyist!

[@D3Sshooter]

Thanks for the comments, I have a bit if both

[@PhG1961]

Waw, ferm stukje autotechniek !

[@D3Sshooter]

Bedankt

[@windmill1965]

Solide natuurkundeles. Dank u wel voor deze goede uitleg!

[@D3Sshooter]

Graag gedaan

[@nc-pf3qm]

after locating instantaneous centers of the links ,why do we draw a line from center of contact patch to the instantaneous center to find the roll center/point??? can any please explain?

[@D3Sshooter]

Because that creates the center point, its all about vectors

[@janwall2648]

Great ways of explaining how the rollcenter effects the load of different komponents. But to me thre is still something to be explained. How is the instant center established? In all that i read about suspensions it is an abstract. The best ( only) given value i have found is 1,5x track width. Is this determined by the expected dynamics of the car or other?

[@RoMaN-vy4sx]

Very interesting. thanks for sharing

[@D3Sshooter]

Glad you enjoyed it

[@devonrod]

I love your videos, the one on the DGAS carb was very helpful, can you answer one question please, the top wishbone inner mount, do you lower it or raise it to get a higher roll center, this is the only one I can alter on my car.

[@D3Sshooter]

Thanks for the comments, in principle you rise it

[@koolkat969]

Thanks for sharing. That's very informative. Would it also be possible to explain in a later video, how the addition of wheel spacers on a lowered car also affects the different areas of the suspension and where the stresses are most impacted. Cheers

[@D3Sshooter]

Great suggestion! As it makes a difference on the scrub area. I will try to include it when we look at the king pin inclination and caster

[@koolkat969]

@@D3Sshooter That's great! I'll look forward to it. Cheers

[@Da5idc]

Very thorough - are you going to look at the relationship between the front and rear roll centers?

[@D3Sshooter]

Thanks for the comments, I might do that at the end yes

[@Paulman50]

Good topic 👍

[@D3Sshooter]

Thank you.

[@asciimation]

Great explanation, thank you. This might be a silly question but why is roll a bad thing? Is it because of the camber change it causes and changing camber reduces grip?

[@D3Sshooter]

roll shifts weight and reduces the grip

[@rickden8362]

Very good basic explanation of suspension geometry. But all that usually is set when you get a car, Aren't there recommended specs by the manufacturer? Have you found a forum for this class of car, usually a great source of set-up info.

[@D3Sshooter]

This is a special car with no specs available , so we need to reverse engineer

[@Gma7788]

We're driving the latest futuristic race cars and we're already adjusting them. We're racing them at high speed. You haven't seen these cars in the real world yet. We own over 300 race cars. We own multiple Ferrari race and street cars. We're driving the latest F1 race cars. We're tuning them. We have vast amounts of knowledge you don't have.

[@D3Sshooter]

Sure, and I don't claim that either. Of course you do... I would be very disappointed if you didn't if you play in that upper class... so don't watch my video's as they are not made for your level. And just maybe you explain us what that new stuff is all about. I am sure we all like to hear that ... or is it dark magic ??? Lol

[@Gma7788]

But now we're gamers. We get to adjust everything and then we experience what happens. We learn from in driving simulations. We learn rapidly. We experience what tiny adjustments make in the driving experience. You're talking to old world 🌎 humans. Gamers are given lots of adjustments features. We know which corners get which adjustments. We don't need to think in terms of forces. We're drivers, not engineers. We already have a lot of knowledge that you don't have.

[@D3Sshooter]

i think my friend that you have a problem.... of course you do learn from driving simulations, complex 3-D models... but that is not what this car is about nor do I claim that it is.

[@benmarr352]

Enjoy your virtual world, if the game is good then physics are the same. Hence this is valuable for you. When you graduate to a real car you may wish to revisit the physics as it takes a lot longer to change!