RC Hopefull 7 Posted March 30, 2020 I have a DT-03 Racing Fighter. After a jump and crash the back wheels no longer spin. They move freely by hand. The engine revs when the throttle is depressed but nothing. I have pulled the engine and gearbox apart and cant see anything that appears to be wrong. Any suggestions. I have a attached a video after I inspected the inside of the gear box thanks IMG_6992.mov Share this post Link to post Share on other sites
ThunderDragonCy 7878 Posted March 30, 2020 Check the differential internals. Something is rattling in there by the sound of it and brokrn diff internals is the only thing i can think of. Otherwise, is the pinion definitely clamped to the motor? 2 1 Share this post Link to post Share on other sites
Mad Ax 9313 Posted March 30, 2020 Can't view the vid from current network but when something doesn't work, work through logically. Start with the obvious bits: Are both driveshafts still in place? If not, the diff will spin freely and you'll get no drive. Are both wheel nuts still tight and the hexes intact? They can break. Are the drive pins in the wheels still in place? If the wheel nuts come loose they can get lost. If you spin one wheel, does the other turn in the opposite direction? Do the driveshafts turn as they should? Is the pinion definitely clamped to the motor shaft? Pop the motor out and check - after the external checks, it's the quickest job to do and is step 1 for most other jobs anyway. Are you absolutely sure the motor is installed in the correct position? It's easy to reassemble with the wrong pinion holes so there's no mesh between pinion and spur gear. If it's none of those then it's time to open the gearbox. As @ThunderDragonCy says, the diff is a likely culprit. If other gears had failed it would probably be more obvious but a blow diff can fly around in its own contained space without affecting the rest of the gearbox. 2 Share this post Link to post Share on other sites
RC Hopefull 7 Posted March 31, 2020 Thanks guys. It was the Pinion gear. The 3mm grub screw wasn't even there to hold it to the motor. Can tell I'm a rookie Thanks for showing me where to look. Now to find some 3mm grub screws 3 Share this post Link to post Share on other sites
markbt73 5316 Posted March 31, 2020 If you still have the leftovers from the kit, there might be a spare screw in the bag. They often include an extra of really tiny parts like that. When you do source a new screw, put a dab of thread-lock on it before you install it. It'll stay tight for good that way. Share this post Link to post Share on other sites
Jonathon Gillham 4606 Posted March 31, 2020 9 hours ago, RC Hopefull said: Thanks guys. It was the Pinion gear. The 3mm grub screw wasn't even there to hold it to the motor. Can tell I'm a rookie Thanks for showing me where to look. Now to find some 3mm grub screws If you don't have a spare grub screw, check banggood or aliexpress. I got about 100 of them of various sizes for about NZD7 delivered. Really. I paid that for a pack of 8 M4 grub screws in a LHS Share this post Link to post Share on other sites
No Slack 454 Posted March 31, 2020 RC Bearings in the UK as them too I noticed. Share this post Link to post Share on other sites
Bromley 681 Posted April 1, 2020 Make sure the old grub hasn't dropped in the gearbox. Could be crunchy crunch time if it gets dislodged and jams something up. Share this post Link to post Share on other sites