I am on step 81 and just realized that the small parts have a wavy and straight side and that I have to put them a certain way, I’m not sure if all of them are the correct order will this affect my build? If it shows that the wavy side is on the inside and I put it on the outside?

  • Could you please clarify which set number you are referring to? LEGO has produced at least 6 Technic/Racers sets over the years with two (42125 and 42143) in just last 2 years.
    – Alex
    Dec 26, 2023 at 7:23

2 Answers 2


Assuming you're talking about Technic Bush :

enter image description here

The wavy side is such that it can interface with studs. For example using a Technic, Plate 2 x 4 with 3 Holes :

enter image description here

As long as the bushing isn't sitting against studs (like the example above), the orientation doesn't really matter.


I assume your set is Ferrari Daytona SP3 (42143).

The step 81 you refer to looks like this:

enter image description here

In this particular case and most of the time it doesn't really matter which side you place Technic Bush within the model. Well, maybe for reasons of aesthetics you may want to keep symmetry. Modern sets have a tiny ring around both end to reduce surface friction. As long you don't push bush too much it will allow rotation no matter which side you place it.

"Wavy" feature isn't really used that much these days. But the reason one of the ends is wavy is illustrated in answer by Sander De Dycker.

  • Thank you so much Dec 26, 2023 at 10:18

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.