Gearing question

[jimny82]

Hi Mick, Thanks for the info. I'm currently running a standard internal ratio of 2.58.1. I don't think my gearing is in the right area at the moment for my 8.5T motor, as my top speed seem far too low.

When you refer to the ''overall ratio'' to be 9.3 & 7.8, is this what some call the final drive ratio?

So if that overall 9.3 is for a 7.5t & 7.8 is for a 10.5t (im assuming this is approximate and not exact), how can I find out what will be best for a 8.5t motor? Am I judging this purely on how the electronics handle things, i.e don't get too hot? Overall/final drive ratio of 8.5 would be somewhere in the middle of the above, and then I could just play around with a pinion one or two teeth either way to see what works best(?).

Or I may have completely misunderstood this lol

[mattr]

Originally Posted by jimny82

Can anyone explain why I might cook my electronics changing from a 23/83 to a 25/76 ratio. I don't really understand the 'delta' of toot difference, but just thought the motor & ESC would be able to handle either ratio, and it would just be the power delivery that would be affected?

There is a sweet spot for ESC and motor related to load and speed. You get too far one way or the other you'll either cook the motor, or the ESC, as you'll be stressing them. (Too fast/low load, too slow/high load)

Most combos will handle some variation. But you're looking as a massive change, the sort of change you'd see going from something like 8.5T to 13.5T motors........

The proper way to change punch and speed is to get the motor/ESC at the right ratio for the car/motor then to play around with things like EPA, punch, current limits. And others. You can probably get a 8.5T motor to behave like a 13.5T, or a 5.5T by playing with settings (with certain limitations of course!)

[jimny82]

Originally Posted by chrispattinson

I've been looking through my setup sheets, and with a Thunder Power 8.5, I would run a 25/76 when used, so thats quite a move away from where you are at.

So can anyone explain why I couldn't run this gearing ratio (without cooking my electronics) with my speed passion 8.5 if its worked for others?

I don't think the combo's you buy come with recommended ratio limits stated on them.

[mattr]

It's generally the cars that come with the gear charts. And it's not that you can't run them way out of ratio, it's just that most drivers with most motors will find the best trade off between heat, acceleration, top speed, battery life etc with that ratio. A couple of teeth either side on pinion/spur won't hurt, depending on how you drive. But a huge change might.

FWIW i managed on my 2wd for a long time with (almost) stock set up, bang in the middle of the recommended ratio. Gave the car to a mate who is a *far* better driver, he cooked the motor (thermal cut out) as he was able to be "on power" for far more of the track than me. Added about 30 degrees to the hottest i'd ever seen.

[jimny82]

Ah right ok, I see what you mean now Matt. Thanks for your help