Deanb44

I can't help but notice that most off-road rc cars use rear a-arms. Why do you think that a-arms are used over trailing arms?

Ahab

my guess would be that it is to do with suspension geometry, A-arms keep the wheel angles/cambers Etc the same throughout the stroke.
older ('70s) off roaders are often pictured with trailing arms - esp on the front end.

ultimately I think it is that the technology has moved on.

Deanb44

The camber is constantly changing with a-arms and this tire scrub cause excess tire rear. Trailing arm have less camber change but more caster change.

That is just what I can't figure out. Why do rc cars use a-arms but most full scale buggies use trailing arms?

Johnboy Walton

Two words baby - "Ride Quality!"

RC's are unmanned, so ride quality is no concern. Furthermore, we don't particularly mind if the superlight RC chassis is bouncing all over the place - we can still see where we're going.

The reason is that (assuming it begins below level) when a trailing arm cycles upward to absorb an impact, it also moves rearward. This helps the obstacle to "slide" under the tire as opposed to forcing its way through as it would have to if the arm couldn't slide backward a bit (like an A-arm).

For the real thing, keeping the chassis level is important to seeing where you're going. In RC, even if the nose is 90* in the air, you can still very clearly see where you're going from the driver's stand.

So in short, a trailing arm "gets out of the way" of an obstacle (sacrificing tire contact for chassis stability), while an A-arm forces the chassis over the obstacle, which in general (especially on smoother surfaces) gives better overall handling.

Mike