6G Bronco Bump Stop

I used Gemini AI to write the openSCAD code using my measurement requirements. While this is my original work, I was inspired by the Quadratec Jeep forms which I paid for two sets and never could get them to cut perfectly.  The resulting shape is very simple.  The bottom that goes against the Bronco tailgate is flat.  I used 25% in fill and slowed down the print because of the TPU 95A.  The TPU give it a nice rubbery feel and allows for some compression against the sidewall of the tire.

Overview

These extended bump stops are designed to stabilize the spare tire on the Ford Bronco tailgate. When moving to a different rim and tire combination the factory rubber stops were too short to reach the tire sidewall, leading to vibration and potential tailgate fatigue. These are designed to bridge that gap and provide firm, vibration-dampening support.  This specific version was for the 2023 Ford Bronco Big Bend (6G) non-SAS that had switched from the stock rims to the Black Diamond Steelies with the Big Bend Dueler tires.  The result is that the original bump stops no longer provided any support.

I've included the SCAD code generated by the AI so that you can use it to fit your combination of tire and rim.  I imagine when I upgrade my tires later this year I will need to spend another 14 hours printing out a new set. LOL

Materials & Hardware

• Filament: Overture TPU (95A).

• Hardware: OAUTOO Ford Mud Flap Retainers 6.3mm Dia. (45mm Length).

  • Note: These specific "Christmas Tree" style pins are used because I couldn't find the nearly 30mm long push pin that Ford only seems to include with their bump stops.  These offer a much longer reach than factory Ford push pins, ensuring a secure hold through the printed part and the tailgate mounting hole.

  • Source: Amazon - OAUTOO 30pcs Mud Flap Retainer for Ford W707889-S300, 45mm Length 6.3mm Holes Size, Xmas Tree Type Clips

Print Settings (Optimized for TPU)

To ensure these are firm enough to support the spare tire without being too rigid, use these PrusaSlicer settings for the Core One+:

• Profile: 0.25mm STRUCTURAL @COREONE HF0.4

• Scaling (Critical): 101.43% (X and Y), 100% (Z).

  • This compensates for some TPU shrinkage to ensure the 6.3mm pin fits the internal bore perfectly.

  • Note - I actually had to drill out the pin hole to enlarge it as it was too tight.   

• Perimeters: 4

• Infill: 25% Gyroid

• Infill/Perimeter Overlap: 25% (Under Print Settings > Infill > Advanced)

• Fan Speed: 50% Min / 80% Max (Ensures clean overhangs and prevents heat creep in TPU).

• Extrusion Multiplier: 1.00 (Default)

• Temperature (Nozzle): 230°C (All layers)

• Temperature (Bed): 40°C (All layers)

• Max Volumetric Speed: 2.0 mm3/s suggested

  • This setting for TPU; it prevents the printer from outrunning the filament's ability to melt/extrude.  I actually printed at 2.5nmm3/s and there was some stray fine strings changing to 2.0 mm3/s would increase the print time to 17 hours 5 minutes, I figured I could live with some stray strings.

• Fan Speed: 50% Min / 80% Max

Installation

1. Remove the existing factory bump stops (if present).

2. Align the new TPU stop with the factory mounting hole on the tailgate.

3. Insert the 45mm OAUTOO pin through the center of the bump stop and press firmly until the "Christmas tree" ribs lock into the tailgate. 

4. Install the spare  and lug nuts and torque to Ford specs.

5. Sadly no gummy bears to celebrate.