The slipper parts are from a Duratrax Evader EXT, and are made for a 5mm top shaft like on the MIP SP-1. As is, the slipper sticks out too far, but with a small file (what I used) or a dremel you can extend the notch for the drive pin like this...
...and push the plates in enough so that they can mesh with the motor pinion.
Right now the slipper is temporarily held on with the 6-32 screw and spring from the MIP Torq Control Hub that came with the transmission. The MIP spring moves around too much since there's only a washer between the spring and the bushing in the spur gear. The thrust bushing, and spring, that came with the Duratrax EXT slipper parts are too small to fit over the 6-32 screw so I still need to find a replacement for those. The Associated Stealth thrust bushing and spring do just barely fit over 6-32 screw but the fit is tight and I'm thinking they'll interfere with smooth slipping. I could sand the inside of the Associated bushing to make it smoother or probably find a thrust bearing from Avid that works so that shouldn't be a problem, and if I can't find a spring maybe I can find some cone washers.
The only other thing I may need is a small spacer for between the 6-32 screw and the inside the spur bushing since the end of MIP top shaft only sits about half way into the spur bushing.
I think it should work...but how well who knows. I'm hoping at least better than no slipper. I got the slipper parts and spur from a new kit pull on eBay for under $8 so it's no loss if it doesn't work.
