I actually felt like my axles were "crunchy" since I got mine together a month ago. I haven't driven it much though since I need to find a place to do so, about 30min. total so far. I did recently install an STR rear lock-out (straight rear axle). I was sure it became louder afterward. In part because I wasn't terribly impressed with inconsistent dimensions of the STR setup. Holding it up to my ear and running it with each axle alternately, by my ear, I thought it was the rear making grinding or crunching noise. It was consistent, like every 4th tooth on the ring gear was a little bigger than the rest or something.
One entire rear axle disassembly, inspection (nothing found), reassembly later, I needed a different explanation. With one half of the drive shaft connected to the rear (disconnected from motor), I spun the rear end, with wheels on, by the drive shaft. It was smooth and quiet, incapable of the noise I had heard. I did the same with the front, smooth and quiet! I hooked it all back up and crunch and grind.
My noise, which seems similar to the noises I've read about from many others' new setups, was coming from the transmisssion. Given how completely silent my axles actually are, I think this may be the culprit for most of us. I dropped the motor/trans carrier, removed drive shafts and ran and sure enough, it's loud as hell. It was however different sounding disconnected from the load of the axles, less crunchy. I disassembled down to the planetary trans level to check for an improper assembly there (by me) only to find nothing wrong, that I could see.
After reassembly of the trans, the only thing I had left was to check the adjustment of the motor on the motor plate. I backed out the two screws holding the motor in, just enough to make an adjustment but, tight enough to still test run the new position. What I found is a lot of room for change in the amount of noise from different positions. I reinstalled both "inboard" driveshafts so I could slide the two driveshaft halves together, connecting the rear and front ends to the motor to check the overall noise. With the motor still able to be adjusted and set far away from the trans gear, I ran the motor. While running, I gradually squeezed the motor toward a tighter meshing of gears.
Soon, I found the best alignment possible and locked my motor in at that position. I reassembled the motor/trans carrier back in the chassis and it has made a signifigant difference in the noise issue. Ultimately, the noise is a result of the planetary transmission, I believe. I hope I can save somebody the journey I took to get here! Start with adjusting the motor, at the "motor plate".
I hope I have been clear in my description. This cr-01 is my first rc "anything", so I'm not exactly a natural in this topic of discussion. I'll post some pics of my Landcruiser soon. Man, this thing is really cool!
