I bought a maximum st 2 months ago just rolling chassis as just getting into the hobby of rc nitro. i rebuilt the whole truck. i went with a OS max .18 cv-r for the powertrain...love the motor...very powerful (i think), but i keep breaking the teeth off the spur gear, went threw 6 plastic ones and said why not metal...now with the metal ones im chipping the spur and tearing up the clutch bell. ive gone threw $150's worth the gears this month alone. am i doing something wrong. everything is lined up right. the gears are close together, and centered this is the only problem im having with the truck. i had one occurance with rounding out the diff gear but a new one solved that. i finally got a hardend steel clutch bell made by robinson, and before i go out and buy another metal spur gear i was hoping someone could tell me what im doing wrong or a easy solution.

Not only do the gears have to be close, they have to be sort of seperate too. It is called meshing, or mesh. There has to be a minor space between the gears or else they will bind, if too far away, they won't transfer power properly and the power will go to the tips of the gear teeth and snap them off. You can try a few things: Your diff may be too tight, your slipper may be too tight (when you land the wheels spin at a different speed than the clutchbell is spinning, and you can shred gears if your slipper doesn't slip!) or it might be your meshing.

When do they break? What surface are you driving on? Does it break immediately? Do you know how to check your slipper and diff?
If you replaced a diff gear before, you may have it too tight (which would be why you had to replace the last one most likely) So I am goingto say that is your problem, but give us a little more info.

If you have every thing set properly a plastic spur well hold up fine! I run plastic in my Savage, which is about 11 pounds with well over 6 gallons of fuel through it and only replace the spur one time, do to the poor stock clutch shoes slipping so bad when new it meted the spur. I put alloy shoes in and now have well over 6 gallons on this spur and still looking good. First make sure you run good clutch shoes and the clutch is not slipping. Make sure your CB bearings are good. If you are running a Steel spur you have to run a hardened CB made to run with a steel spur. All so you have to know how to set mesh properly!
Good Luck

thanks for the reply's!!! i think my slipper might be too tight cause i run the slipper pretty tight thinking that it will put more power to the ground in the higher rpm. my gears are meshed pretty good, not to close where there pressed together, but spaced out enough where they spins freely. my rear diff spins fine, i replaced the old diff gear when i got the truck due to the fact it was shot to start with. i drive the truck stricly street...no jumps, off road...none or that, just whipping it around the parking lots, and drag racing it agains my friends aftershock and rc10gt. (im the fastest...lol) i got a hardend steel clutchbell last weekend so if my slipper is correct i should be good to go with another steel spur gear......could chassis flex have any thing to do with it cause it only seems to chip the spur when i spin out or accerate really fast when the road get bumpy.....let me know what you'll think and thanks for the help so far.

Do not know much about your truck but on my Savage and HPI MT I run my slippers tighten up all the way. I cannot do this on my Rush or it mess up the gear box. I run plastic spurs on all of them.