Differential Troubleshooting-Need Help!
 

At the end of last season a friend of mine and myself purchased the Losi RTR 8ight 1.0. We were able to run the vehicles for about 2 hrs, before putting them away for the winter. Over the winter both of us replaced the grease with Losi's recommended diff oil weights for front, center and rear. We both throughly cleaned the differentials of all of the existing grease before adding the oil.

My buddy's car is smooth, however my rear differential has a "crunchy" feeling to it. Similar to how wheel bearings get when they have dirt in them.

My center diff feels normal as does the front. This "crunchy" feeling causes the car to make a tinging noise when you roll the car back and forth. I believe it is cause from the drive shaft vibration as it come into the center differential housing.

Does anyone have any suggestions as to the cause? And how I might be able to correct it?

I would greatly appreciate any help.

ethier its a little chip in the gears or maybe they are worn down and just need to be replaced thats my guess

sounds like improper diff shimming might want to check into that.

Are you using the upgraded aluminum "inserts?" The ring and pinion DOES need to "wear in." The Losi is very tight from the factory.

Also, check to make sure the CVD hasn't loosened up on the pinion shaft. If it has, be sure to get it put back with no slop.

Did you grease the teeth of the ring gear? You should every time you take the diff out... just a thin line around the gear tooth surface.

And the comment about worn teeth on the rear ring and pinion could be right. I replaced my rear ring and pinion 3 times on my Losi buggy... then I replaced the buggy. If the ring and pinion in the rear have gone bad, replace them, AND the bulkhead.

the rings are good to have but should not be the problem since it is so new - when you reinstall the four gears in the diff cup, check to make sure you installed the correctly. there are 2 different notches on the sides of the diff cup, one slot goes to the bottom of the cup and the other goes half way down. You must install the bottom set of gears in the long slot

hope this helps

the ringing sounds like the center diff and the engine are not meshed right are you sure its from the rear of the car

No upgrades. I checked the CVD, and appears to be tight. After I cleaned out all of the factory grease, I just added in the correct amount of oil. These gears look brand new, no evidence of any wear at this time. I have yet to run the car, that's the good news, but I do plan on running it on Sunday at the track. The other good news is that when Amain dropped the price on the RTR to $374.00 I purchase another one, for a backup/spare parts.

Thanks for all the great information.

I am going to take it apart tomorrow night, so I will definetly check that out.

Thanks

Funny that you should mention that, because I originally thought that it was coming from the center diff, but when I pulled it off, that's when I could definetly tell that it was not there.

I also thought the noise was coming from an improper gear mesh, but I have checked that as well, and all appears to be fine.

Thanks for the info.