I have just had a revelation in my RC racing career. I think I finally understand roll centers a little. I must admit, I’m not an engineer, and I really don’t understand all engineering aspects of the cars. I’m a driver, and I go all by feel. It’s worked well, and I can normally get my cars pretty good for me, but there are disadvantages as well.
Roll center adjustments I have always struggled with, mostly in 1/10, as it’s a very easy adjustment. I never really know what I’m doing in this area. I try asking other engineers what does what, but I normally get a novel answer that left me more confused than before. All I want to know is what makes it roll more, or less. Somehow I got it painted in my brain that if you raise the inner link, that makes it roll less. I would always have that in my head, and my feeling on the track would be confused.
In the winter, I spend much more time at my local track, Fastlane Raceway, than the rest of the year. We have a pretty good group of racers and some pretty fast guys running Mod. There is one guy there that is just all into setup. For years, he has driven me nuts, he’s always talking all sorts of setup ideas and telling me what I should try. Haha. Now he is running all Kyosho, I thought this was going to be a total disaster with him just talking my ear off. It was actually quite the opposite. I took the “annoying” label off him, and actually listened to what he had to say. We were both up there testing 4wd. I am always all over the place with my 4wd setups. I’m really hit and miss, and just not as consistent as I should be. He started to tell me that I’m going the wrong way with my roll centers. He then proceeded to get all engineer on me, but I was trying to really pay attention.
After that, I just went for it, I went drastically the other direction. WOW, he was correct!
Here is the none engineering guide to roll center adjustments.
Lowering the inner link = less roll
Raising the inner link = more roll
Lowering the outer link = more roll
Raising the outer link = less roll
A lower “roll center” rolls more
A higher “roll center” rolls less
I know a lot of people are confused about this. Hey, after 13 years of racing as a professional, 15 national championships, 2 world championships, I was still confused about it. Haha
Thanks Wayne for the help!! Sometimes those crazy hardcore club racers might actually know what they are talking about. Not always, but hey, even the squirreliest squirrel gets a nut 🙂 Anyways, hope this might help guide you guys a little bit and help you get all dialed into the track. Thanks for reading and God Bless.
Setup has always intrigued me. I will never be the best driver. As a rule of thumb, there is always someone better on any given day. Setup is what separates us. I’ve had similar issues with roll center because of how much it effects and how it changes between driving styles. Never thought of it as the link position determining how much it rolls but at what direction the force is applied to the tire. Is the weight transferring towards the center of the wheel or more towards the top…etc.
Hey Jared great info i agree roll centers are always confusing,with all the testing you have done with these can you give some explanation to where you find what the difference in having more roll vs less roll effects the car on the track?
Haha, I knew that was Wayne right when I read the topic. The hardest part after knowing that is when it is right to change roll centers.
Hi Jared, have a read of the suspension section of this website. http://users.telenet.be/elvo . It explains the method for working out ‘roll centre’ as used by vehicle dynamics engineers. A higher roll centre will actually mean less roll…. I agree with your comments about moving of links though. Anyway, it is cool that you post comments about your thoughts on setups, most top drivers wouldn’t admit to not knowing everything!
Yeah I thought it was backwards when I typed it. It’s fixed now. Thanks
OK, now I am really confused … all I want to know is, if I want more rear traction (i.e., a dry dusty track), do I want to lower the inner camber link, or raise it? Jared, please settle this once and for all so I can sleep at night 🙂
It’s not quite that simple. The factory sets your cars main roll center. You can just adjust it. Some have a higher roll center or lower when they are designed. For me when I want to gain grip I want my car to be a little softer and move the weight of the car around more to get the grip.
Wayne is a great source of info. He has helped a lot of people on RC Tech understand roll centers. I always use his video to show people what I’m trying to describe to them in what it does. You’re lucky to have someone like that at your track who can break it down for you, I like talking to him about setup stuff on RCT. Good stuff!
Thanks for the mention Jared! I definitely love me some setup, and I switched to K cars recently just so I could learn another platform. We all enjoy when you get to race with us locally—its like Christmas in more ways than one with great tips/info from the champ. Plus, we all get to test our skills on the track like we turned the CPU player’s difficulty to max and figure out where we’re losing tenths! It is definitely funny that people knew me from RCTech just by first name and subject matter—roll center and camber curves have definitely been my favorite drum to beat as of late.
Jared, any chance you could describe what you’re trying to achieve when making a rc change? Or what the various changes do in terms of handling?
BTW, your “testimonial” was very good, thanks for sharing
I’ll try to go some posts like that. Sometimes I have a hard time explaining the feeling I get with changes. I’ll try though. Thanks about the testimony, it’s not my work though, all the glory is Gods!
Thanks for sharing this Jared. I raced for many years before taking some time off from the hobby. During that time I also struggled with understanding roll center adjustments. Joe Pillars had some good advice about this. He was saying to go ahead and make a big adjustment to really “feel” what the change does. You know, rather than a just single thin washer under a ballstud which can be hard to feel, go with something bigger instead, like 1.5, or even 2mm and then go drive the thing. It really makes sense, as a learning experience. He credited Greg Hodapp with the original idea.
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how less or more roll effect the car handling. i’m still confuse a bit.
what i mean is if the car have more roll than i’m facing u turn how should i run the car. and when the car have less roll than i’m facing u turn again how should i run the car???
wich one is faster. and wich one is easier thanks guys
Good post Jared!
I learned a basic way to think of roll centers a long time ago. Think of a broom stick standing on end. If you grab the very bottom of the stick(low roll center) it will be very easy to tip over the stick(more roll). If you grab it in the middle(higher roll center) it will be much harder to tip over (less roll). Learning and experimenting with vehicular dynamics is what I love the most about racing.
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