RC Car Roll Center Explained

What is Roll Center?

   One of the least understood settings on RC model cars is concept of roll center. The simple definition of roll center is a point in space that the chassis rolls from side to side as the car maneuvers around a corner.

The Calculation

   To calculate roll center you have to consider things like the height of the axles, the inside and outside camber link positioning, the length of the suspension arms and the location of their inside pivot point. Sounds complicated doesn't it - and in truth - it is.

Center of Gravity and Roll Center

   On all RC model cars, most of the cars weight is above the chassis and the center of gravity of the car is not only from front to rear, but also from top to bottom. This point is called the "true" center of gravity and is the point around which the weight of the car will want to roll from side to side, but it is the roll center of the chassis that the chassis will actually roll around, not the center of gravity.

Roll Moment

   Once you have determined the positions of roll center and center of gravity, you can calculate the "roll moment". It is this that determines how easily the chassis will roll from side to side.

What Does This Mean?

   But what does all this mean? I hear you ask. Well, it gives you some insight to what changing the position of your camber links can do to the way your car handles.

How to Adjust for Roll Center

   Lowering the outside camber links, lowers the roll center, so conversely, raising the outside link position raises the roll center.

   Lowering the inside camber link position raises roll center and raising the inside camber link position, lowers the roll center.

Adjustment and Affect

   Any of these adjustments will affect the "roll moment" and therefore you have some control of body roll.

   The length of the camber link bars affects the speed of roll center change as the car driver around corners. Longer links increase the rate of change. Shorter links decreases the rate of change.

   Adjustments to the roll center will change the way the car reacts in a number of ways.

Front Roll Center

   Lowering the front roll center gives more steering under acceleration, but the car is less responsive. Ideal for smooth high grip tracks, with long sweeping corners.

   Raising the front roll center provides less steering when accelerating out of the corner, but the car feels more responsive and is less prone to traction roll. Best for high grip twisty tracks.

Rear Roll Center

   Lower rear roll center improves grip under acceleration, but reduced grip when breaking. Helpful to avoid traction roll as you enter the corner and tracks with low grip to increase traction.

   Higher rear roll center gives you less grip under acceleration, but the car is more responsive. Works for high grip twisty tracks to reduce traction roll.

   At present, the RC Model Manufacturers, Brands and Distributors covered by us are: ABC Hobby, Academy, Acme Racing, Agama Racing, Amewi, Ansmann Racing, ARRMA, Team Associated, Atomic RC, Axial, AYK, Bolink, BSD Racing, Capricorn, Carisma, Carson, Caster Racing, Cen, Corally, Custom Works, Durango, Duratrax, ECX - Electrix, Exceed RC, FG Modellsport, FS-Racing, FTX, Fujimi, Gmade, GS-Racing, Harm, HBX, Helion, Heng Long, Himoto Racing, Hirobo, Hitari, Hobao, Hong-Nor, Hot Bodies, HPI, HSP, Intech, Integy, Jamara, JQ Products, Kawada, Kyosho, Losi, LRP, Maisto, Mardave, Marui, Maverick, MCD Racing, Megatech, Mugen, New Bright, Nichimo, Nikko, Nkok, Ofna, Pro-Pulse, Protech, PTI, RC4WD, Redcat Racing, RJ-Speed, Robitronic, Schumacher, Seben, Serpent, Smartech, Sportwerks, Step-Up, Tamiya, Team-C Racing, Team Magic, Thunder Tiger, Tomy, Top Racing, Traxxas, Trinity, Tyco, Vaterra RC, Venom, VRX Racing, WLToys, X-Factory, Xmods, Xpress, Xray, XTM, Yankee RC, Yokomo, ZD Racing and Zipzaps.

   This is an ongoing project, with new and "lost in time" RC Models and Brands being added as they are found and although most of those listed above have been covered in relative detail, some are still being researched and will be completed in the near future.