Modern RC cars are increasingly offering options for "flex" adjustments, particularly for on-road racing.
Chassis flex
![](https://cdn.prod.website-files.com/5e5ae7175a542c69f8e338b4/635e72fcc9179330544366d5_chassis%20brace%20screws.png)
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](https://cdn.prod.website-files.com/5e5ae7175a542c69f8e338b4/635e7008618e0abe85b7c6d9_x4%20chassis.jpg)
Arm flex
![](https://cdn.prod.website-files.com/5e5ae7175a542c69f8e338b4/635e71eff51427c3918d0112_FireShot%20Capture%20885%20-%20%20-%20www.mugenseiki.com.png)
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.