sc0rch

i'm fairly new to the nitro scene so bare with me.. The other day i trashed a spur gear..it was the stock setup..so i go to hobby town and get a new stock replacement and 12 friction pegs..i get everything on and adjusted (tightened all the way the backed off between 1/4 and 1/2 turn) and it runs fine for a few minutes.then all of the sudden i can hear it trying to shear the teeth off again..it looks as if the teeth arent meshing as well as they should but other than that i have no idea what going on..the gear attached to the engine is metal (the smaller one that i dont know the name of)
I'm affraid of messing with it before i have some kind of an idea of whats going on cause hobby town is a good distance away.

cooldriver385

Check if the clutch bell (the smaller gear) and the spur gear are meshing with a very slight looseness. When I mean slight, I mean VERY VERY LITTLE. I believe the reason for this is because if it's completely meshed with the spur gear, then it can cause it to strip when there's more than normal load on the engine, ESPECIALLY when landing with throttle applied. If I am wrong, though, someone correct me, I do remember reading somewhere.

sc0rch

almost forgot..i got the gears adjusted so that they mesh better but it still seems to shear off teeth on just one part of the spur..

cooldriver385

When you mean mesh better do you mean you put them right with each other so they're like really tight?

sc0rch

no not tight....before i adjusted it they were barely meshing at all but i put them so that they were about "half" meshing if that makes any sense

cooldriver385

Not too sure on what it is.

sc0rch

so i think my bottom chassis is bent..the aluminum part..i cant get the smaller gear i bought to mesh at all..and the other one seemed to wobble and not mesh good in one spot..so i'm going to try and straighten it tommorow and see what happens

joeseif

What size is are both gears? like how many teeth? Make sure you use blue locktite on all bolts so they do not walk out and allow the motor to move away. When you tighten the gears roll a dollar bill between them then tightn them then remove the bill and you mesh will be text book right. Not all gear combo's fit so make sure you got the right gears. If your spur is stripping maybe you should try backing it 1/2 a turn out. Check and make sure there are no little rocks stuck anywhere in the drive train or in the wheels. the small gear on the bell is a pinion gear or clutch bell gear, at least that is what i would call it. good luck

cooldriver385

So should the dollar bill be like crushed in between the two? Or should it be completely straight?

joeseif

crushed but not ripping

sc0rch

its a 68 tooth spur..seems too small..i ordered the stock 70..thats what was on it the 1st time it stripped

quix

A 68 tooth gear will work just fine. Just make sure it's the proper pitch of 32.
Here's a very straight forward video on how to properly set gear mesh...

1QwkSport2.5r

I use regular inkjet printer paper (standard 20lb computer paper) to set gear mesh. Dollar bills are thicker paper with cloth imbedded into it - this will not crush the same as regular paper.

One other thing I've noticed a lot of people do when setting mesh - they may use the paper trick and get the mesh right but still shred spur gears.. The problem is when setting the mesh, oftentimes the engine is meshed at at an angle to the spur. Before tightening all 4 motor mount screws, ensure there is the same gap in the slots of the motor mount on all 4 corners.

a 68t spur gear is going to give better top end than a 70t spur. If you're running a 2.5 engine, I'd run the 70t personally. Anything bigger than a 2.5 I'd run a 68 or 66.

I got a 70t spur to last me over 2 years, and that was a plastic stocker, too!

mattjavorsky

i was shredding a lot of spur gears on my Nitro Rustler until I found one of the Pinion gear Bearings was broken. Replace the Pinion gear bearings and see if that helps. If that pinion wobbles even a little bit under load it will shred your spur gear no matter how well you think your mesh is. Good Luck

1QwkSport2.5r

The trick here is not to use cheap junky eBay bearings. Use good bearings. While it’s good advice to keep an eye on clutchbell bearings, it’s usually quite obvious if a clutchbell bearing is bad and causing problems. I actually got away from using just the standard two clutchbell bearings and started using 3 on the bells that will allow it. Also, using the right lube in the bearings helps prolong their life somewhat, but don’t expect to get a long life from them. Plan to replace them twice per gallon of fuel give or take.

mattjavorsky

I agree that it’s usually obvious, but this person said they were pretty new to Nitro so it’s something they should check. In the case of My Nitro Rustler, The Bad bearing was Not obvious until I took everything apart. And the bearing quality is Super Important; not something to try and save money on. I bought a sleeve of high end ABEC 5’s and the difference in performance is staggering compared to the EBay Junk bearings.