This has been something that's been on my mind ever since the 400EX came out. The manufactures seem content to put aluminum swingarms on their quads, yet all I see in mags (print and online) is people putting on after market steel ones. I have no doubts that the steel ones are stronger, but is it necessary? Has anyone here had or has seen a aluminum swingarm break? I never have. Yet the mags continue to say "race worthy" when replacing the aluminum swingarm with a steel one even though, IIRC the Z400's were breaking the frame not the swingarm.

The pros seem to be the ones doing this the most, but I have a feeling it's more to do with displaying their sponsors products than the fear of breaking one. Of course I could be wrong, since I don't pound or jump as hard as they do. Nevertheless, the only time I would switch materials would be for desert racing were I'd rather not have a broken swingarm in the middle of nowhere.

Personally I'd much rather have the lightweight unit even if my sponsors wanted me to run their arm.

But, have you seen one break?

 

I think someone on this forum had one break clean in half but dont remember who. Other than that, nope.