Reducing slop in the RC4WD AX2 transmission

[fyrstormer]

(reposted in the SCX10 subforum because the AX2 transmission also fits the SCX10)

Several years after buying my Wraith and installing a RC4WD AX2 transmission in it, I finally decided to modify it to reduce the slop in the shifter assembly. Here's what I came up with:



I bought a piece of 4mm solid brass rod, cut some pieces off it, epoxied them into the slots on the sides of the gears, and then sanded the sides of the gears smooth so there would be no protruding edges for the shift puck to get stuck on and rip the brass inserts loose. (not that I don't trust the strength of JB Weld, but why tempt fate?) I could've gone further and filled-in the other side of each slot as well, but I would've needed to grind away some of the round profile of each brass insert to leave enough room for the shift puck to engage properly, and I just didn't care that much...this time around. Maybe next time I have to take this transmission apart, I'll finish the job.

Hope this helps someone.

[Voodoobrew]

Man I must have not been paying attention at all when I tool mine appart. I was thinking all that smop was from the teeth.

Hindsight this makes much more sense. Lit us know how it holds up. And what Epoxy you used.

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[HumboldtEF]

That's a great idea, nice work!

[Xx Losungen xX]

Nice homebrew solution!

[fyrstormer]

Originally Posted by Voodoobrew

Man I must have not been paying attention at all when I tool mine appart. I was thinking all that smop was from the teeth.

Hindsight this makes much more sense. Lit us know how it holds up. And what Epoxy you used.

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JB Weld -- the stuff that comes in two separate tubes and needs to be mixed, rather than the stuff that comes in a roll and needs to be kneaded together. Also I thoroughly washed the gears and- degreased them with CRC Electronics Cleaner before epoxying the brass bits into the slots, to make sure the epoxy would stick as well as possible.

Yep, I'll post a followup in a few months, or sooner if I hear unpleasant loose-metal sounds coming from the gearbox.

For the record, these brass inserts reduce the slop by about 60%.

[Voodoobrew]

60% nice, how's the shifting?

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[fyrstormer]

Shifting works the same as before, perhaps slightly smoother thanks to the polished surfaces. I wish I could put a servo-saver on the shifter servo to reduce strain on the shifter assembly when the puck is misaligned with the selected gear and the shift can't finish immediately, but there's no room under the RTR Wraith body for a servo saver. That's never actually caused problems though, it's just something I fret about.