flex

What is "flex" and how does it affect an RC car's handling? Read on!

Modern RC cars are increasingly offering options for "flex" adjustments, particularly for on-road racing.

Chassis flex

On the RC10 B74.2, you can tune the flex by leaving some screws out of the braces.

Some ways to adjust chassis flex:

Alternate chassis or top deck - some cars offer alternate chassis or top decks that provide more or less flex than the kit chassis
Braces - some cars offer extra braces that can be added or removed or changed to a different type (plastic, aluminum, graphite, brass) to alter the flex
Stiffening screws - some cars will provide multiple screws to attach a brace (or a motor mount) to the chassis, and you can use more screws to reduce flex or fewer to increase it

More flex

More lateral traction
Less consistent line
Worse handling on jumps

More stiff

Less lateral traction
More consistent line
Better handling on jumps

Image of chassis flex options for XRAY X4 '23 — XRAY X4 '23 Chassis Options. Their solid aluminum option is the most rigid and ideal for high-grip carpet. The "flex aluminum" chassis is good for medium- to high-grip, and the graphite chassis is intended for asphalt of all grip levels.

Arm flex

Mugen MBX8R setup sheet showing plastic inserts for added stiffness.

Some cars offer alternate suspension arms that are stiffer or more flexible, and others offer arm inserts (aka stiffeners) that let you fine-tune the arm flex characteristics. See our article about suspension arms for more.