Multiple issues regarding toughbox minis used with kit chassis.
This is our 5th year using the kit chassis and have had no issues with it. But this year, our toughbox mini gears seem to be sticking and are difficult to turn manually, as well as making a lot more noise than usual.
I have already drilled out the motor mounting holds slightly to allow the CIM to sit better. We have also noticed that the half round boss that lies between the two CIMs on the outside of the TB was interfering with the CIMs, causing them to sit at a slight angle. We ground down the boss a bit and the gears got better, but are still tight.
Is anyone else having these issues this year?
In the years past, we have swapped to the 5.95:1 gear ratio. But this causes serious drain of the battery and brownout issues before the match is over. Wondering how we can get the same speed out of the TB Mini with this gear ratio, but avoid the Brownouts. What are we doing wrong?
As for the sticking issue, it might be solved by running the gearbox for 10? minutes before adding the lubricant. I am pretty sure 10 minutes is the recommended amount of time but you might want to check the manual.
As for the gear ratio, I would not recommend using anything lower than 10.71 for standard 6 inch wheels. To understand gearing choices, you have to know that acceleration is proportional to gear ratio (because it depends on torque) and top speed is inversely proportional to the gear ratio. The lower the gear ratio, the higher the current draw.
So the switch from 10.71 to 5.95 will increase your top speed, but decrease acceleration while increasing current draw. This is probably why you had brownout problems. To fix this, you would have to implement a current limit to prevent brownouts. We went through the same thing last year because he had a wrong gear ratio.
If you want to learn more about drivetrain calculations, I’d recommend the ilite drivetrain calculator. You input the specs of your drivetrain and it models sprint distance time, lowest voltage, wheel slip, how much current limit you need, how much battery is used per match etc. It is a great tool.
…for standard CIM motors. (Which it sounds like OP is using, but you know some newbie is going to read that as “never go below 10.71 ever even with 20 Falcon 500s” or something like that.)