BMW ZF5 Shift Pin Drift Punches

prusaprinters

These punches are used to drive new shift detent pin bushings to the correct depth in the ZF5 transmission case. These are BMW special tools 232360, 234022, 234023, 234021, and 233110These punches are based on the drawings from the excellent DIY guide at https://web.archive.org/web/20161019184449/http://webspace.ringling.edu/~dplassma/bmw_diy/shift_pins/shift_pins.htmlI did resize the handles, based on the dimensions of the aftermarket punches from Thayer Motorsports. These punches are intermittently unavailable from Thayer, and entirely unavailable from BMW from what I can find. Custom machining quotes were in the realm of $150-$200 per punch, so I set out to print my own. However, Thayer ran another production run and I was able to get a set of metal punches before I found a material that would work for this high impact application. I still believe these can work, but I didn't get a chance to try PLA, and the PETG I was using was not stiff enough (looking back, PETG is possibly the worst material for this application…). Regardless of print settings, the material would deform due to the small working surface area of the punches.I don't have another good opportunity to try them since my transmission has been serviced now. I'm posting them in the hopes that the models can help someone out that can't get their hands on the Thayer punches. I believe PLA might work with the right print settings, but even better would be some sort of fiber reinforced PLA, PC, or Nylon.These should work for any ZF 5 speed manual gearbox, which were in many BMWs in the 90s and 2000s, including E36, E46, E34 and E39 models. Measurements and testing were done on the ZF S5-31 from my early 2003 330i.The dimensions are very exact, they're extremely critical for this application. Your printer should be able to recreate better than 0.1mm dimensional accuracy, ideally closer to 0.05mm.Recommended print settings:0.2 layer height5-7 perimeters (you want the diameters at the tips to be solid)5-7 top/bottom layers40+% cubic (or similarly structural) infill throughout100% infill for the top portions could help strength, but it's probably better to use more perimeters throughoutNo supports