ring gear teeth chipping off

[blueb8llz]

i replaced my diff oil last night and noticed that 3 of the ring gear teeth on my 3905 emaxx was chipped. i dont have a camera but, its 1/4 of a teeth and its the outer edge that broke off. two of the teeth was right next to each other, and the third broken teeth was like 8 teeth away and it had the smallest breakage. so what causes this anyways so i can be more careful next time.
wot from a standstill? shimming needs to be done? constant braking...?

and why didnt i notice anything wrong with the truck with 3 broken teeth? does it take more damage for me to hear or notice something? and what usually are the signs of broken teeth on a ring gear?

[BrianG]

If it's the ring gear, you need to do some shimming to make a better mesh. It could also be the case that is flexing, which causes the mesh to vary under heavy load. Assuming everything is shimmed perfectly, aluminum cups helps prevent spider gear stripping, and an aluminum case helps keep the pinion/ring gears meshed since Al flexes less.

No matter what, even steel can only take so much power - gotta remember that there is a LOT of power concentrated on such a small contact area.

Originally Posted by blueb8llz

i replaced my diff oil last night and noticed that 3 of the ring gear teeth on my 3905 emaxx was chipped. i dont have a camera but, its 1/4 of a teeth and its the outer edge that broke off. two of the teeth was right next to each other, and the third broken teeth was like 8 teeth away and it had the smallest breakage. so what causes this anyways so i can be more careful next time.
wot from a standstill? shimming needs to be done? constant braking...?

and why didnt i notice anything wrong with the truck with 3 broken teeth? does it take more damage for me to hear or notice something? and what usually are the signs of broken teeth on a ring gear?

my guess would be extreme abuse such as going off jumps where you would have an action of the gears slamming into each other while not being shimmed properly

[blueb8llz]

stock doesnt come shimmed at all on my 3905. i hope it was just a fluke or something. i replaced the ring gear without shimming. i replaced the diff cup too..but with a stock one.
btw, i dont do any jumps at all.

[bl-is-future]

it comes down to power and shimming. I would hear people constantly complaining about going through savage diffs. I have had mine for over 2 1/2 years and 1/2 year was with BL in it. I have yet to replace a diff. If you shim it correctly it will last. But as Brian said it can only take so much even if you shim it correctly. Me running a 1y i doubt your power is too much just think you should shim the diffs considering you said stock isn't shimmed at all.

[blueb8llz]

greaaat. so this prolly means ill be chipping teeth constantly untill i do the shimming. which i have no experience of.
hey when you guys have the diffs fully assembled, when you spin the pinion (holding the shaft) does it spin smoothly? mine will spin kinda smooth but every once in a while, it would get stuck, and then itll spin again. does this mean that its not meshing good. im thinking the ring gear needs to be pushed up.
which is why the edge of the teeth were chipped , becuaes it was barely meshing. and now its stuck every so often when i spin cus its getting caught between the edge of the pinion tooth.

[bl-is-future]

could be a number of things. ex. bearings, bent or warped drive shafts, bad housings for gears to make them crooked. So many variables. The best way is start at the transmission, if it is smooth got to the front or the rear, and so on. OH and shimming is jsut making sure you have a tight mesh with the ring and diff gear. Not so tight it can barely move but tight to where the gear cannot move to creat slop in the mesh thus creating broken or chipped teeth.

[bdebde]

Always check the bearings on the diff pinion, they should probably be replaced any time you open up the diff. My Muggy has TiNi diff gears shimmed properly in Al cases, the next weakest link is the diff pinion bearings, it just tears em up. I wonder how ceramic bearings would hold up there? I may have to try it.

[George16]

http://monster.traxxas.com/showthrea...=diff+shimming

[blueb8llz]

thanks all for the helpful replys. i will be sure to check these things the next time i open them.