March 7, 2026
Description
This is a bracket designed to be epoxied to the back of the trunk cover on the BMW X3 or X4 to retrofit the trunk strut that was removed in 2019. Took design cues from the OEM part and revised it so that it'd be durable as a print. Should actually be more durable than the mold-injected OEM part, which has been known to crack over time.
Square recesses were added to the bottom to add more surface area for the epoxy. An M8 heatset insert (M8 x 12mm L x 10mm OD) is required for this print for the 10mm ball stud, use a soldering iron to push/melt it into the hole. Use a 10mm ball stud with M8 threads no longer than ½" or 15mm.
What I used:
M8 Heatset Inserts: https://a.co/d/bS4e5r1
10mm Ball Stud: https://a.co/d/cfI7WLw
30lb 11" Gas Strut: https://a.co/d/1WqEKmn
Blind Rivet Nut: https://www.ecstuning.com/b-genuine-bmw-parts/blind-rivet-nut/07147132312/
JBWeld AutoWeld: https://a.co/d/dZG84pZ
Use a 30lb strut that will extend out 10.5-11". An M8 blind rivet nut or M8 wing nut will be required to affix the ball stud to the floor of the trunk. There is an opening/hole designed for the OEM blind rivet nut on the trunk floor but you can also use an M8 wing nut. You can either use the OEM parts for this or aftermarket equivalents (significantly cheaper).
OEM Part Numbers:
51477442678 - Strut
41218186446 - M8 Ball Stud (not compatible with my bracket but works for the trunk floor)
07147132312 - M8 Hexagonal Blind Rivet Nut
Print with 100% infill in PETG, ABS, ASA, or other tough engineering grade material.
Tips:
- Be mindful of the orientation of the bracket when you epoxy it to the floor. I've received messages from users that flipped the part the wrong direction which required a lot of effort to remove the part from the floor.
- Be liberal with the epoxy, let it soak through the carpet so that it cures with the carpet and against the panel the carpet is adhered to. Fill the recesses on the bottom of the print with epoxy for more surface area and then clamp the part onto the trunk floor. If you don't have a clamp, place a weight on top while the epoxy fully cures. After curing, it will be on there permanently, stronger than if it was bolted onto the floor with a few rivets.
- If you don't have a blind rivet gun/tool, you can just use an M8 bolt to rivet it on by tightening it.
Bimmerpost: @jinetix
Facebook: David Lee (moderator / group expert of several M40i groups)
License:
Standard Digital File License
9