Somewhere after 4.5.1 upto 4.7.6, It became impossible to add a child volume to a Wheeled Vehicle BP and have it set to a different Collision Type than the inherited root mesh.
Such as adding an overlap collider to the outside of a vehicle.
Since this forced inheritance doesn’t exist in other blueprints like Character, I can only assume this is a bug?
Hi KWS,
I’m not running into this issue when I try to reproduce it. To be thorough with what I did, I created a Wheeled Vehicle BP and placed it into the world. I then selected it in the World Outline and clicked ‘Add Component’ in the Details window to add a box collision. After this, I set the mesh’s collision to ‘Overlap All’ and then set the Box Collision’s collision preset to ‘Block All’. After doing this, I was able to collide with the Box Collision but not the Wheeled Vehicle’s Mesh. After this, I tried the same with adding the Box Collision inside of the Blueprint Editor instead to the same result.
Was there something that I did differently?
Hi Mathew, Thanks for responding.
I followed a tutorial on the Wheeled Vehicle, twice, and both times I hit this problem, then I noticed that the tutor was using 4.5, so I installed that version and the problem was gone. yet in 4.7.6 and above, I just can’t find any way to make this collider act as an overlap.
I did notice something odd though.
Setting the Box Collider to “NoCollision” works, but any other setting such as the various Overlap types are ignored and the root meshes collision type is used instead.
Here is the project, and a video illustrating the issue.
Project: Vehicle3PS. (25 MB)
Video: Wheeled Vehicle Test (1:33)
Test Phase 1:
Car: BlockAllDynamic (Working)
Box: NoCollision (Working)
Test Phase 2:
Car: BlockAllDynamic (Working)
Box: OverlapAll (FAIL, Acts like a BlockAllDynamic instead)
Test Phase 3:
Car: OverlapAll (Working)
Box: OverlapAll (Working)
So, in conclusion, the Box can only be an Overlap when the car is also set to Overlap.
Is it perhaps the “autoweld checked by default” issue…
It looks like dcyoung is correct. After turning off ‘Auto Weld’ in the PlayerInteractionTrigger’s details, the issue stopped occurring. Could you please test and see if this fixes the issue for you as well, KWS?
Where would this “Auto weld” be? I searched all over the details but don’t see it.
Searching “w”, this is what I get:
http://i.imgur.com/uIh5Ian.png
I even clicked the “Show all Advanced Details” option, but that didn’t seem to add anything new.
Searching the Doc’s or the web in general turned up nothing useful either.
Hi KWS,
Here is a screenshot of my editor with a border around the option. Could you be possibly running some type of UI plugin that could be affecting this? Your UI does look a bit different.
Oh, silly me, I accidentally loaded the 4.5 project in 4.5 without thinking, which doesn’t have the Auto Weld option or the bug.
I just tested in 4.8 and indeed, disabling Auto Weld solved the problem, and I see that it has been fixed but didn’t make 4.8, so all is well.
Thanks guys 
