Mercedes W126 560SEC Digital speedometer pinion gear (12 tooth)

thingiverse

Shear age weakens and destroys the plastic drive pinion in the W126 speedometer (Mine is out of an Australian-compliance 1989 560SEC). A replacement 12 tooth pinion is difficult to obtain in Australia, so I resorted to printing a spare one on my Mendel Prusa II. Design was based on the Openscad design file “parametric_involute_gear_v5.0” by Greg Frost (2010). Gregs original design was fiddle, fudged and stripped until the pinion looked “right” and printed correctly. The modified Scad file has been included so anyone wanting to try for a different configuration can have a go. I printed it direct from the STL file provided. So far the odometer is still working with the new pinion. The original printed pinion is a trifle “small”, so the current STL file has got a slightly larger gear profile so it should mesh better. (Update 1/8/15 - new slightly larger gear printed and fitted. No problem with bore size, and much better mesh than original design - STL file in "downloads" was always correct version) Thanks to Greg Frost for his original work.