Big Rock Permanent Fix for Spur Gear Stripping

[TheMightyAtom]

I've had my Big Rock for over a year. Been through almost a dozen spur gears. Yes, I know how to set my gear mesh and slipper clutch.

I send the truck a lot but I almost always land on all 4 wheels. I drive it hard, but not abusively.

I've tried most of the solutions commonly recommended on the internet. My latest attempt was using the Hot Racing heavy duty motor mount, recommended by Funcentric's youtube channel. It seemed to work for a bit, but I just stripped another gear today. On a pretty low jump, too.

The only thing I haven't tried is M2C's $120 motor mount and chassis brace. I don't want to sink that kind of money into the Big Rock.

Does anyone know of any other solutions? I know the spur gear's only $6 but it's still frustrating having to keep replacing them. I'm also worried that using a metal spur gear will just cause the rest of the drivetrain to start falling apart.

 

[MrTitanium]

I've had my Big Rock for over a year. Been through almost a dozen spur gears. Yes, I know how to set my gear mesh and slipper clutch.

I send the truck a lot but I almost always land on all 4 wheels. I drive it hard, but not abusively.

I've tried most of the solutions commonly recommended on the internet. My latest attempt was using the Hot Racing heavy duty motor mount, recommended by Funcentric's youtube channel. It seemed to work for a bit, but I just stripped another gear today. On a pretty low jump, too.

The only thing I haven't tried is M2C's $120 motor mount and chassis brace. I don't want to sink that kind of money into the Big Rock.

Does anyone know of any other solutions? I know the spur gear's only $6 but it's still frustrating having to keep replacing them. I'm also worried that using a metal spur gear will just cause the rest of the drivetrain to start falling apart.

I bought the HR unit. Same principle just a few dollars cheaper.

 

[TheMightyAtom]

I bought the HR unit. Same principle just a few dollars cheaper.

Which one are you referring to, specifically? I already tried this one: https://www.amazon.com/dp/B0BPYQ599Z?psc=1&ref=ppx_yo2ov_dt_b_product_details

 

[Johnny b]

I agree that a metal spur gear is not the answer. Are you landing under power? Are the bearings good on the slipper shaft?

 

[TheMightyAtom]

I agree that a metal spur gear is not the answer. Are you landing under power? Are the bearings good on the slipper shaft?

Bearings are good. I do occasionally land under power, but I do that with my other RCs too, with no issues.

 

[Neelis]

I have good experience with the metal spur and would recommend them. The plastic spurs last a few packs, switched to the metal spur and I don't see it failing anytime soon.

 

[GRC]

A bent motor mount plate can absolutely cause spurs and pinions to strip repeatedly since they are no longer lined up properly. Check if your motor mount is straight. Fix, replace, or upgrade if it’s not. I don’t know about the latest HR motor mounts, but as far as I know, they are not much much stronger than stock. The M2C motor mount is great, but I actually use it without the chassis block, which I think is problematic. CRCU, KC-RC, Oktay also offer 7075 upgrades, and you don’t have to pay for an unnecessary chassis block, but I can’t personally say how durable they are.

If that’s not the problem, I think the metal spur gear is your best solution.

I went back and forth between metal and plastic. The metal has lasted forever. The downside is, the pinion now eventually wears down and strips. Overall, I think the metal spur is still the more durable option. And I didn’t strip plastic gears nearly as often as you. The metal spur will definitely be your better option.

Preventing the spur and pinion from getting out of line will also help. As I already mentioned, a bent motor plate can cause repeated stripped gears. The chassis can flex quite a bit and the motor can get bounced around. These things twist the spur and pinion and cause them to strip. Things like supporting underneath the motor (I use a o-ring) and a chassis brace to reduce flex should also help. If your slipper has too much play back and forth in the power module, you can add some shims, which should reduce wear and tear on spur/pinion.

 

[TheMightyAtom]

A bent motor mount plate can absolutely cause spurs and pinions to strip repeatedly since they are no longer lined up properly. Check if your motor mount is straight. Fix, replace, or upgrade if it’s not. I don’t know about the latest HR motor mounts, but as far as I know, they are not much much stronger than stock. The M2C motor mount is great, but I actually use it without the chassis block, which I think is problematic. CRCU, KC-RC, Oktay also offer 7075 upgrades, and you don’t have to pay for an unnecessary chassis block, but I can’t personally say how durable they are.

If that’s not the problem, I think the metal spur gear is your best solution.

I went back and forth between metal and plastic. The metal has lasted forever. The downside is, the pinion now eventually wears down and strips. Overall, I think the metal spur is still the more durable option. And I didn’t strip plastic gears nearly as often as you. The metal spur will definitely be your better option.

Preventing the spur and pinion from getting out of line will also help. As I already mentioned, a bent motor plate can cause repeated stripped gears. The chassis can flex quite a bit and the motor can get bounced around. These things twist the spur and pinion and cause them to strip. Things like supporting underneath the motor (I use a o-ring) and a chassis brace to reduce flex should also help. If your slipper has too much play back and forth in the power module, you can add some shims, which should reduce wear and tear on spur/pinion.

Thanks for the thorough response, this is great.

I had upgraded to the heavy duty HR motor mount because I was quite sure the stock motor mounts were bending. Maybe I just need a bit of putty or something under the motor to support it.

I'll try the metal spur gear. Better to replace a pinion every once in a while than take the truck apart to replace the spur gear every 2-3 runs.