Arrma transmission gear ratio.
What is the number of teeth of all of the gears on the Arrma Fury (and all other Arrma vehicles if different)?
I'm talking about the input gear, idler gear, and diff gear. I'm using this website (http://scriptasylum.com/rc_speed/top_speed.html) to calculate the speed of my RC and I cannot find this needed information anywhere.
Maybe JAM can help out here if he is still reading these forums.
Nevermind, I found it right on the Arrma official website. The internal gear ratio for the Fury is 2.8, probably the same for all Arrma models. Strange how they didn't put that rather vital piece of information in the manual!
So, let's say I replace the stock motor on my Raider with a Leopard Skyrc 3930kv 10T motor and new ESC. Should I gear down my car at all? I have no idea how to determine if I need to and if so, what I should gear it to.
My stance is that whern starting with a new motor speedo combo, start geared down (high ratio of pinion to spur) then gear up based on temp at the can. You can always add gearing, but if you fry a motor, your done. :-)
Originally Posted by hawkbug
I agree with slider. Especially if its a nonsensored system its best to just start with a small pinion since this will minimize cogging. If the temps are cool and you want more speed, then you can just bump up the pinion incrimentally. If cogging on a nonsensored system is going to be an issue, you will see it when you you gear up.
Its all a personal preference. I just get super annoyed by cogging so I try to minimize it.
Also, if you are running the stock diff you will likely break it with A 4000 kV motor. That is a lot of power for a 2WD SCT. I run an HPI diff in my Fury. Fits great with a few extra shims over the outdrives (between the outdrives and the tranny bearings). Just an fyi.
Thanks for the info guys. Yes, I have a feeling the diff will go bad quickly with this motor. I'm not going to be running a 3S lipo, so hopefully that will help? I'm not sure. Where can sombody just buy an HPI diff to throw into the chassis on these cars? I have read about how to improve the ones in the car already with thicker washers and thicker pins, but it sounds like a lot of work.
The internal gear ratio for the ARRMA 2wd transmission is 2.6
The diff gear is 52T, the idler gear is 28T and the input gear is 20T.
The standard fury gearing is 87T spur and an 18T pinion.
Start with the standard gearing with a brushless conversion, a 3930kv 2 pole Leopard motor may run quite hot, check your motor temps regularly, if cool go up pinion size or two, if hot - go down slightly.
Gearing all depends on use, a really good tool for helping set up gears is a infared laser thermometer, I bought one for less than $10 and use it all the time.