RC Tank Warfare community hobby forum

Jarlath wrote:

General Jumbo01 wrote:They all have a geared output but it's useful to know what the gearing is. I doubt that you'll cook the electrics if used sensibly BUT if you use on grass or long pile carpet and then perform sharp turns, due to the high degree drag you may cook motors and / or mfu.

All depends on the current draws at stall loads.
Jam up a track and you can burn up nearly any motor/MFU.

Excuse my ignorance , but what is an MFU?

Multi function unit, the box that controls all the functions on the vehicle.

General Jumbo01 wrote:Multi function unit, the box that controls all the functions on the vehicle.

Ok, thanks.

MFU = Multi Function Unit. It is the electronic board that controls all the tank function and it sits between the rc receiver and the various motors and servos. In the main, off the shelf RTR tanks have a combined receiver and MFU.

General Jumbo01 wrote:Remember, the gearbox names misleadingly do not refer to their final ratios. Why retailers do not publish the true ratios is beyond me.

You weren't around when this went down, but it all started when a vendor, I believe it was schumo, came out with a gear reduction setup for Tamiya tanks that was supposed to be a 3 to 1 reduction. Then when they added a fourth reduction shaft they started calling those 4 to 1, but those gear ratios have never been accurate. I believe the 4:1 gearboxes have an actual final drive ratio of 39:1 but that might be the number for the three shaft gearboxes. Anyway, the point is that you can't use those numbers for actual ratios, they're only good for identifying the different types of gearboxes.

And when those 5 to 1s cooked my mfu there was no hang up and I was not on grass. I started out in a straight line, got about two feet, and that was it. I highly recommend the four to one black steel, ball bearing gearboxes from IMEX. I have never had a set of those fail on me, and I've never heard about a set of those failing on anyone else.

Thanks, interesting. I've been doing RC hobbies for over 20 years but only for the last 5 with tanks. In all those hobbies, car racing, drifting, trucks, boats and drones, variable gears and toothed belts are used in variable sizes providing users to tune their vehicles to suit conditions, being changed in real time at events.

Tanks are not used for racing or hauling variable loads so once you get it right you can leave things as they are but if you are buying a motor and gearbox combo, again peculiar to tanks, you should expect to be able to choose your motor size and winds, and your gear box by final ratio. This hobby is still aimed at ignorant RTR customers who just need to fit the batteries, turn on and go.

Those of us who want to improve, modify and even build our models are just not catered for BUT those with experience from other hobbies can bring their knowledge and skills to tanks and share it, which is what we all try to do here

Max-U52 wrote:And when those 5 to 1s cooked my mfu there was no hang up and I was not on grass. I started out in a straight line, got about two feet, and that was it. I highly recommend the four to one black steel, ball bearing gearboxes from IMEX. I have never had a set of those fail on me, and I've never heard about a set of those failing on anyone else.

Henglong 3:1 is a 29:1 ratio
Taigen 3:1 is a 39:1 ratio
Taigen 5:1 is a 46:1 ratio
Tamiya are 59:1 ratio (For the most part)
Mato are 69:1 ratio
Taigen 4:1 is a 90:1 ratio

All are approximate and assume the standard motor mounted pinion (Usually 10 teeth for non 5:1)

It is always the sudden current requirements that is the issue as well.

So... Keep those gears clean and properly lubricated, same for the motor and gear shaft bearing and all the wheels that rotate. Take care with oil by making sure it's plastic friendly. Try using a silicon based grease on the gears. All this will reduce drag and current draw.

Heng Long's CNC sealed gearboxes come in 1/39 and 1/56 ratios with both short and long shafts.