I have researched this a lot, but I'm finding conflicting info, both on this forum and others.
First, stock gearing: It's 14/68, right? When researching that, I'm finding supposedly "stock" numbers all over the place. One guy even swore stock was 12/58. I don't think so!
Next, I have found that, supposedly:
Hot Motor, Cool ESC = Undergeared
Cool Motor, Hot ESC = Overgeared
Cool or warm Motor and ESC = They are happy!
Finally, I found that the following should fix gearing problems:
Undergeared = Add teeth to pinion or remove teeth from spur
Overgeared = Remove teeth from pinion or add teeth to spur
Are the above true, or have I misunderstood something?
Based on a hot motor, my Summit is apparently undergeared.
Last week, my Summit stripped the spur gear, so I decided that was a good time to disassemble, inspect and clean everything. I have so much to learn about this hobby, but I'm all in.
When I took things apart, I found that the previous owner installed a 17T pinion, but left the Spur at 68T. Therefore, I left the pinion at 17T, but replaced the stripped spur with a new 65T to help with the undergeared condition. I used the "strip of paper" method of spacing the teeth when meshing the new gears. A quick throttle test felt and sounded great.
I went out and ran hard for about 20 minutes. The truck was noticeably faster and could easily pull wheelies in high gear. It could not do that before. Unfortunately, the motor became too hot to touch! I had to yank my finger away after about a second. That totally surprised me since I thought my gearing change would make the motor run cooler.
All I can think of is that I must have misinterpretted something. I'll buy some different spur and pinion combinations and do some experimenting. Until then, I'd love to get your feedback on what I might be doing wrong and how to correct it.
FYI: I run Proline Trencher X tires and use dual 2S Lipos from SPC rated at 8200mAh and 50C.