My UDR is making a strange noise.

[jjabe]

The Traxxas UDR I recently purchased used makes a low-pitched "buzzing" sound. This sound becomes significantly worse when the throttle is opened more than 50%.

To eliminate this noise, I removed the play from the shaft, replaced some bearings, replaced the motor with a bent shaft with a new one, and filled the differential with fresh oil, but it shows absolutely no signs of disappearing.

I have uploaded a video of the noise coming from my UDR to the YouTube link below. What could be the problem?

 

[KnowAir]

I have heard the same from my UDR. Also is in need of it’s 3rd rear ring and pinion gear set.. my guess is it’s from the rear axle. Mine is broken more often than running. Not my favorite rc. Too fragile. Awesome in action but also rarely in action.

 

[BashingBrian]

In the second video, why is it only 2wd.??

 

[RustyUs]

... and the rear wheels/tires have a weird stutter to them when they slow down.
Yeah, no. This is where you get to know your used RC. Gonna have to open 'er up and do some investi-ga-shee-on.

 

[Cranberry Juice]

The Traxxas UDR I recently purchased used makes a low-pitched "buzzing" sound. This sound becomes significantly worse when the throttle is opened more than 50%.

To eliminate this noise, I removed the play from the shaft, replaced some bearings, replaced the motor with a bent shaft with a new one, and filled the differential with fresh oil, but it shows absolutely no signs of disappearing.

I have uploaded a video of the noise coming from my UDR to the YouTube link below. What could be the problem?

Could be dirt stuck in places it shouldn't, could be cogging or incorrect gear mesh.