Lunchbox Problem

[Rcfreak363]

i keep stripping this gear in my tamiya lunchbox, the first one had about 50 runs with the stock motor, and then i felt the need for more power. the motor i put in it was a yokomo twisters motor, and on the first gear, i got 5 runs, and then i gave it full trottle from a dead stop, and it partially lifted the fron end, and just stoped, then the same thing happened on the second gear, but this time it was on the 10th run.

is their a solution, im tired of stripping gears. here is a video of my lunchbox with that motor in it.

http://www3.towerhobbies.com/cgi-bin/wti00...=LXGN41&P=K - the part were the pinon touches the gear is were it stripped

- video

[markbt73]

Do you have ball bearings in it? If you're still using bushings, they could be worn enough to mess up the gear mesh.

If you have bearings, it almost has to be something assembled wrong and not lining up. You should be able to run just about anything short of a small-block Chevy in that gearbox and not strip anything.

Maybe if you post a picture of the stripped gear, we can point you in the right direction.

[terry.sc]

Is the pinion gear worn? As it wears it creates sharp points that will just rip into the spur gear. And if there are the kit plastic bushings in there instead of bearings if they are worn they will move the gears apart and again damage the gear teeth.

[mymonsterbeetleisbroken]

Nothing really to add other than the gearbox should take a lot more punishment.

I've been running mine with a castle creations brushless motor that revs at over 45,000 rpm and the gearbox sounds sweet - and is working fine. Before that I had a 19 turn motor installed, again with no issues.

Could it be a fault with the gear box casing, or motor mount plate?

[Rcfreak363]

Do you have ball bearings in it? If you're still using bushings, they could be worn enough to mess up the gear mesh.

If you have bearings, it almost has to be something assembled wrong and not lining up. You should be able to run just about anything short of a small-block Chevy in that gearbox and not strip anything.

Maybe if you post a picture of the stripped gear, we can point you in the right direction.

im running full ball berings, idk how to post pics, but the gear is missing 3 teeth

Is the pinion gear worn? As it wears it creates sharp points that will just rip into the spur gear. And if there are the kit plastic bushings in there instead of bearings if they are worn they will move the gears apart and again damage the gear teeth.

the pinon looks brand new

Nothing really to add other than the gearbox should take a lot more punishment.

I've been running mine with a castle creations brushless motor that revs at over 45,000 rpm and the gearbox sounds sweet - and is working fine. Before that I had a 19 turn motor installed, again with no issues.

Could it be a fault with the gear box casing, or motor mount plate?

how would i tell if it is a fault in the gear box, or motor mount plate

[mymonsterbeetleisbroken]

do the gearbox halves fit together properly? Also check that the shaft that the counter gear runs on is fitting ok.

Make sure the motor mount plate looks ok too, and that the shaft of your motor isn't bent.

[Rcfreak363]

every thing looks and lines up great. what else could it be?

[kontemax]

Probably you land after a jump at full trottle and when the wheels touched the ground again the motor torque did strip the gear.

No slippery clutch and a torquey motor and this is the result.

Max

[markbt73]

I don't know what to tell you now... I've had half a dozen of those gearboxes over the years and never stripped anything, and I've done some truly stupid things to them. If anything breaks, it's usually the axle tubes where they attach to the housing.

Maybe it's overheating the motor, and the excess heat is causing the gear to weaken or softening the motor mount and changing the gear mesh. Old motors weren't nearly as efficient as newer ones, and heat was sometimes a problem, especially if the motor is worn. That's about all I can think of. Try a newer motor, and see if it holds up better. There are a lot of cheap mod motors around that will outperform "vintage" motors.

[Rcfreak363]

Probably you land after a jump at full trottle and when the wheels touched the ground again the motor torque did strip the gear.

No slippery clutch and a torquey motor and this is the result.

Max

when i jump, i let go of the trottle compleatly

I don't know what to tell you now... I've had half a dozen of those gearboxes over the years and never stripped anything, and I've done some truly stupid things to them. If anything breaks, it's usually the axle tubes where they attach to the housing.

Maybe it's overheating the motor, and the excess heat is causing the gear to weaken or softening the motor mount and changing the gear mesh. Old motors weren't nearly as efficient as newer ones, and heat was sometimes a problem, especially if the motor is worn. That's about all I can think of. Try a newer motor, and see if it holds up better. There are a lot of cheap mod motors around that will outperform "vintage" motors.

the motor runs cold

[mymonsterbeetleisbroken]

It's seriously unusual!

If you like, check out my brushless pumpkin

I've driven it on and off road with that motor installed, and the gears are totally fine.

Is everything greased up well? I'm really running out of ideas as to why your gearbox keeps breaking.

My pumpkin is about 17, 18 years old. I've replaced the counter gear once, and that was only because I'd installed a new pinion gear and wanted both gears to be new. It had years worth of use with a mechanical speed controller too, which is harsh on the gears compared to an ESC.

Are you certain the motor is ok? If the output shaft is bent or damaged it will send the pinion out of line.

I think every other possibility has been suggested, we're truly stuck!

[Luke_87]

maybe the mounting collar is bent/loose? have you tried tightening it up?

is it fast enough for you?

you could swap to a hornet pinion, and do away with the collar mounted adapter, this should tighten up your motor mounting and hopefully stop the pinion jumping and breaking gears,

Luke

[Rcfreak363]

here is a picture, its a little blurry

[markbt73]

Well I still can't really see what's going on, but from the looks of it there's a lot of residue from the pinion gear on that spur, all the dark yellow/gold deposits. At the very least, there's a lot of wear going on in there.

I'd say get a new spur and pinion, and replace them both at the same time, so you're starting with fresh teeth on both gears. Take the whole gearbox apart and clean all the old grease out and rebuild everything exactly by-the-book, and see how it does. That's about all I can think of. Good luck...