There are a few different colors of LEGO Technic axles, but not enough to really use for artistic variation - black, grey, some beige, and recently I have started seeing blue.

The particular color used in different Technic sets seems arbitrary to me. Is there a difference between the different colors aside from just the color, like a slightly different size or tensile strength?

  • The only way to check differences would be to perform torsion tests, I think. A possible way would be to create torsion bars like Sariel used in a recent tank build.
    – Riduidel
    Oct 26, 2011 at 10:00
  • Be sure of the difference between axles and connector pegs (and combinations of both). Oct 26, 2011 at 10:31
  • @BoltClock: Yep, I managed to figure out the differences between connector pegs when I was a kid. :) Which is why I always wondered if the axles had similar practical differences.
    – user23
    Oct 26, 2011 at 11:18
  • Hmmm my comment should have been under Sibbo's answer, since it seemed to be referring to pegs. So I posted in the wrong textarea :S Oct 26, 2011 at 11:20

1 Answer 1


The first LEGO axles were milky white and were probably made in a different plastic than they are now.

Later on, LEGO started making all-black axles when they started doing more serious technic sets. However, the tendancy is now to make sure all difficult technic pieces are "color-coded" so that children can pick them out more easily. As such, nowadays, the following axle lengths and colors are standard:

  • 2: red, notched
  • 3, 5, 7, 9: (new) grey - no 11 yet as far as I know but I suppose it's just a matter of time
  • 4, 6, 8, 10, 12: black
  • 3 with stud: dark tan
  • 4 with stop, 5.5 with stop, 8 with stop: (new) dark grey

Similarly, 2L friction pins are black, non-friction grey, 3L friction pins are blue and non-friction tan, and so on. All that to make sure they're easy to pick. Even gears are being changed now, for example the classic 24T is now dark grey.

That said, there have been other colors used for axles, when the color itself was important. I've seen tan, red, green, brown, but possibly others exists. The long ones (32 and 16) have also been produced in black, white, and yellow (32 only).

As far as I know the plastic used is always the same, so they should all have the same mechanical properties.

  • 2
    Years, later, the 11 axle is a reality <bricklink.com/v2/catalog/catalogitem.page?P=23948>
    – RSchulz
    Jul 6, 2021 at 4:13
  • A near useless factoid is that the colorant added to ABS plastic affects the mechanical properties. For reasons I do not understand the RED colorant weakens any plastic it is added to more than any of the other colorants. The black colorant appears to be the strongest.
    – Dan1138
    Jul 9, 2021 at 1:33
  • @Dan1138 the red probably absorbs most UV/blue light leading to brittleness over time. The black may be/include carbon particles which make for tougher plastics in some cases
    – Chris H
    Jul 19, 2021 at 13:27

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