Gear Replacement for Mixing Motor

This part replaces the gear that tends to break in the mixing gate motor (OEM part number a1638200108). It is unlikely to be suitable for non-original engines.

Before disassembling the product, turn the engine over and mark the position of the protrusion on the metal shaft. You want to gather everything in the same place. Four screws hold the engine together, remove them, and the assembly will split in two. The upper tension roller will come out easily.

Next, you will find a metal shaft with a replaceable gear. The plastic gear will need to be carefully squeezed out. Compare your equipment with the original. The tolerances on this part are VERY tight; you may need to adjust the size. I printed this from internal ABS plastic, and the design takes into account the normal shrinkage of ABS. PLA is not recommended for this part. Print with 100% infill.

Replace the hardware you just printed with the flat side facing up. You should be able to manually push the gear halfway and will need a press or socket and hammer to install it all the way. If not, adjust the center hole size in the openscad file.

Reassemble the engine assembly, ensuring the metal tab on the bottom aligns with the mark on the bottom of the housing. Lubricate the gears, reinstall the screws, and you're done.

This uses the gear library, which can be found at the provided link. I've included the current version in case the library changes. There are reports that this gear will fit other GM vehicles including the 2004 Blazer and 1998 Saturn SL2. Shout out to thall320578 for reporting his success.