Amp Spur Gear Issue

RC_Noob

Active Member
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36
Today I upgraded the electronics in my Amp MT.

Dynamite 60A ESC and Spektrum SR310 receiver.

I did this as I wanted LIPO cutoff and to be able to safely run a 15T motor, which I also installed.

I had a few problems initially where the throttle on the esc would not work, the ESC flashed the LED to show it was getting the signal but no power to the motor, or it would run briefly then cut out. Re-binding and ensuring the throttle was not cut on the TX seems to have (mostly) solved that problem.

I had the Amp running for about 5 mins before a loud clicking noise started, especially pronounced when the motor slowed and I seemed to lose all braking power.

The motor seemed to be running very hot and the Nylon spur gear seems to have gotten pretty mashed.

Any thoughts on what caused this? Too much power? Running too hot, Not having the mesh set correctly?

I can't find a replacement nylon spur so I've had to order a Steel one from eBay. Though I could only get an 83T, will that be OK with the Stock 18T pinion or am I going to damage that? I did also pick up a 16T and an 20T steel pinion to try some different gearing options.
 
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Looks like gear mesh is to blame. Looking at the spur you only see that some of the spur is fine but the other parts of it are stripped. The spur usually doesn't spin very true around so when you set your mesh you need to rotate the spur around and check different spots on the spur for the mesh.

When you use steel spurs make sure to use hardened steel pinions. Start with the stock 18t and monitor heat if the motor doesn't get hot (more than 170F) then you can try and gear up (bigger pinion).
 
Thanks, I figured it was the mesh - I'm a damn fool.

I guess there is little point running the stock 18T pinion as a benchmark since the steel spur has a reduced number of teeth, 87T stock to 83T replacement. The motor has also been changed from a 20T to a 15T.
I should have ordered a 17T hardened pinion. that would have pretty much given me the stock ratio. I guess the 16T would be safer to try first?
 
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It doesn't hurt to start with a smaller pinion and work your way up. The 15t will be a hotter running motor but I think the 18t pinion would be fine but I haven't run brushed in a while. The only thing I have brushed is an old Duratrax Evader that's using the 20t motor I took out of the Circuit (mine is an Electrix Circuit before ECX).
 

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