Modding the Cup Racer for a Front One Way, part 2

Success! Just a bit of grinding, some bearings and there's a TT-01 one way in your Cup Racer.

I wanted to keep costs relatively low on this project, reusing parts where possible. The stock ball diff bevel gear is a near perfect ringer on the TT-01 one way. Start with the stock diff and use a Dremel to grind down the inner race lip-amajig. Once smoothish, plunge down and enlarge the opening to fit. ~12mm center bore is the goal.

The ball hole seats on the diff need to be hogged out a bit, they're set a hair too far apart. These are what are going to center the diff ultimately, the center hole only need to be mostly round and allow you to get an even fit on the screws. Reuse the three stock screws that came with the one way. Yes, they're phillips head..

Upon test fit, the gear mesh was too loose for my liking. Servicable, but needs work. Grind the diff on mounting ring slightly, you should have a good feel for this by now. I didn't measure, but it's less than 1mm.

Add blue Loctite and re-assemble. Keep one plastic washer on the driver's side (US standard) between the custom bearing and diff cup.

 




 

And that's how to mod a tt-01 one way to a HPI Cup Racer bulkhead. Of course the dog bone pins don't fit the diff cups. Part 3 - Grind the drive cupes.




Click for part1 if you missed it..