Axial 27T and 2S

[LamChop]

I toasted my 27t today on a 2s. Looking around it doesn't seem like it's uncommon, but I was at a slow crawl when it happened. I have 2.2 tires on it and i honestly haven't looked to see what the gearing is, but is it normal for a motor to fry in a situation like this? Or were the 2.2 tires a factor? They're rc4wd roklox. My dilemma is whether to get another one or not. I was planing on putting it in a 1.5 scaler still with the 2s. Will this prolong the life of it especially if i optimize gearing?

[struhall]

If you didn't change your gearing that could have been the problem because it got too hot. I had the same 27t on 2s and it got too hot to touch in just a few minutes then I changed the gearing enough to keep it cool and it lasted a while.

[Thechewmaster]

Throw away motors are throw away motors

[LamChop]

Lol screw it then. I rather burn down one of these than a 1:1 any day. Made me laugh when I saw the smoke lol

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[new2rocks]

Originally Posted by Thechewmaster

Throw away motors are throw away motors

X2. And changing tire size has the same effect as changing gearing. If you swap for bigger tires, you need to gear down to compensate or risk overheating your motor. Conversely, if you drop your tire size, you will lose top end unless you gear up to compensate.

[LamChop]

Here's a total noob question. When talk about rear ratio on here is the ratio determined by the motor gear and spur gear or does one account for every gear in the drive line?

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[Eric0424]

Originally Posted by LamChop

Here's a total noob question. When talk about rear ratio on here is the ratio determined by the motor gear and spur gear or does one account for every gear in the drive line?

Depends on what you're asking for, I'm assuming "rear ratio" is a typo for "gear ratio". The spur/pinion has a ratio, the transmission diff-gear/top-shaft has a ratio and the axle ring/pinion has a ratio. All three together are called the Final Drive Ratio (FDR for short) and all three can be altered with optional gears and after-market transmissions. The / indicates which gear (tooth count) is to be divided into the other, 87t spur / 18t pinion, 52t diff gear / 20t topshaft, in a gear reduction drive system.

Tire size changes your tire/gear roll-out ratio, it's similar in effect to changing the gear ratio and changing the spur/pinion or axle ring/pinion ratio may be necessary to compensate for a drastic change in tire size. But tire size doesn't actually change your gear ratios.

[new2rocks]

Originally Posted by LamChop

Here's a total noob question. When talk about gear ratio on here is the ratio determined by the motor gear and spur gear or does one account for every gear in the drive line?

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What ultimately matters is the final drive ratio -- i.e., the number of times the motor has to spin to move the truck a given distance -- which takes into account all the gear changes at each stage (spur/pinion, tranny gearing, t-case if you have one, axle gearing) plus tire size.

When talking about gearing, people usually talk only about spur/pinion because it's the easiest to change and provides the greatest flexibility for changing the final drive ratio in either direction. But talking only about spur/pinion ratio ignores differences in tire size and axle gearing (on rigs where axle gearing can be changed), both of which impact the final drive ratio. And 2-speed trannies add yet another gearing variable into the mix. So when you're looking at spur/pinion on your own rig or comparing to other people's setups on similar rigs, it's important to know the rest of the setup to get the full picture. And if you are even thinking about comparing spur/pinion gearing across platforms, you'd also need to take into account differences in tranny and axle gearing.

Here's some fun reading on gearing:
http://www.axialracing.com/blog_posts/1073905374

Hope that helps!

[new2rocks]

FWIW - Eric and I are saying the same thing. Some people use the term "final drive ratio" to refer to gearing combined with tire circumference, and others use the term "rollout" to refer to the combination of gearing and tire circumference. Either way, the concepts are the same.

[LamChop]

Thanks guys, I've built and worked on a bunch of 1:1 vehicles and even though concepts are the same the lingo is something to get used to and also the electric motor side of things

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