Lunchbox grinding gear sound?

[junglemonkey 3]

Took my lunchbox out in the garden tonight for its first run. Although I scuffed the paint job already! Grrr I noticed that when it went from a standing start to full throttle the gears sounded like they were grinding or not engaging correctly. Sounds ok once it’s moving and seems to drive fine, it’s just the initial full throttle burst at the beginning that doesn’t sound right. It doesn’t make this sound if I go full throttle with the wheels off the ground, only when they are on the ground. No issues in reverse. Should I strip down the gear box and see if there is anything odd before I do any major damage? If so what should I be looking for? Just a thought, could this be due to too much grease on the gears? I’m a newbie so any help greatly appreciated. I’ve watched vids on YouTube of people’s lunchbox going from a standing start to full throttle and I don’t hear what I’m hearing. Bit disappointed that I’ve hit issues already as I’ve been looking forward to having some fun with it since I got it for Xmas and it looks like it’s gonna be back in the garage for a service already!

[NameUnchanged 21]

could just be the new gears as they are still sharp and have no wear 

it might be a good idea to strip the gear box as in some of my cars I've had bits of debris between the gears which made awful noises as the car went along 

[Juggular 4626]

[1] Check to see if the bolts securing two halves are not loose (but don't overtighten either).  

[2] If two halves are fine, take out the motor, and see if the little grub screw on the pinion might be loose.  

If you look at the motor shaft, it's cut flat on one side.  The little grub screw (BC4 below) must be pressing down on that flat side.  

[MadInventor 3878]

21 minutes ago, Juggular said:

[1] Check to see if the bolts securing two halves are not loose (but don't overtighten either).  

[2] If two halves are fine, take out the motor, and see if the little grub screw on the pinion might be loose.  

If you look at the motor shaft, it's cut flat on one side.  The little grub screw (BC4 below) must be pressing down on that flat side.  

This is what it sounds like to me as well. You could also check the end float on the motor armature (How much the motor shaft moves in and out of the motor), and check the pinion isn't touching the motor bush under load.

[junglemonkey 3]

Excellent thanks guys. Yes the little grub screw wasn’t attached to the flat side, it was on the round side! Haven’t tested it outside yet as it’s a bit dark now to give it a try but I think that was the problem. Before if I held the lunchbox down on the floor and kept hold of it and gave it full throttle it made the sound but I’ve just tried that in the garage as I can’t give it a proper try outside until tomorrow and there was no sound like before, just an angry car that wanted to pull away and go! 😀