Big Rock Help a Newb - My Big Rock Won't Go

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jbjtx81

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Arrma RC's
  1. BigRock 4x4
  2. Kraton EXB
  3. Vorteks
I haven't started disassembling it yet but I'm pretty sure something in the transmission is broken. When I hit the gas I can hear a slight whine from the motor. But nothing turns. There is now power at all. Not even a slight or interment delivery of power. I've probably run a total of 16 batteries through truck so far over roughly 2 weeks since I purchased new. This will be the 5th breakage requiring new parts. I'm really not feeling/seeing the the Arrma is so tough reviews I read before the purchase.

Any one have links to videos or threads with step by step directions on how I break this thing apart to diagnose the problem.

Any help will be greatly appreciated
 
With the power that rc cars have now. Even back in the day
Spur gears should be something one should have on hand at all times.
they’re a wear part IMO. So many things can cause them to strip. A crash at a precise angle changing the mesh etc.
with cars just getting more and more powerful. Failures should be expected. Especially with hobby grade rcs. It’s part of it
 
I'd suggest saving the headache and time of replacing the stripped plastic spurs and invest in a steel spur. Besides checking your pinion isn't loose or spur is chewed see if the motor shaft has any play as it could be a bad motor bearing. The Vorteks I recently won from the forum destroyed the motor bearing on the 3rd pack which chewed up the spur and now motor is unusable until motor bearing is replaced.
 
A whining sound is most likely a stripped spur or a loose slipper. A loose pinion is also a possibility, but if you have a newer Big Rock, it's less likely.
 
Steel pinion is an alright idea. But having the spur as a weak point is a cheep fix if it strips out for whatever reason. Possibly saving the axle shafts etc
 
Slipper too loose. Will not engage. Pull motor/transmission from truck-adjust slipper to fully tight then 1&1/2 turns opposite direction from fully tight. I loosened mine and it did the same thing
 
Tore it apart this weekend. It was a stripped spur gear. I can but 3 or 4 plastic ones. and change them out as needed in the future (time consuming and a PITA when wanting to drive vs repair) or I can get get one of the metal ones from Hot Racing or Integy linked below. What are the Pros an cons? Money isn't an issue. Durability is. Will the metal ones last longer? With the metal ones change the focal point of future damage from the spur gear to some other part as @MarioTwins stated? Just looking for the least long-term headache.

Does anyone make an entirely enclosed metal assembly and cover with all metal gears as well. That seems like that would be be best way to go. Something where the plastic gear isn't exposed at the bottom of a plastic assembly?

https://www.amainhobbies.com/hot-ra...MI_sKCsqCT8gIVBmpvBB0rtwDoEAQYASABEgL8ePD_BwE

https://www.activepowersports.com/i...MI_sKCsqCT8gIVBmpvBB0rtwDoEAQYByABEgJkxPD_BwE
 
1st of all, that Integy gear is for the older V1&V2 versions, 2nd, don't order anything from Active Powersports. They show that they have items in stock and when you order they take your money, but a little bit later they will send you a Email saying that the part is out of stock. The one time it happened to me I got my money refunded but there are others that said they didn't get a refund or had to fight like hell for a refund.
 
Thanks for the heads up on active powersports. Any one give me pros and cons of metal spur?
 
Pros: A metal spur is definitely more durable. You should also make sure your motor mount plate is straight. Bent motor mounts are one reason plastic spur gears get stripped. But even with a metal spur, if your motor mount is bent, the spur ends up stripping the pinion.

Cons: Price. But if you have to replace several plastic spur gears, it may be worth it. It also adds a little weight and is a bit noisy, but that's not a big deal.

Keeping dirt out of your power module also helps save the spur gear. With an upgraded motor mount and sealed power module, I'm able to run the plastic spur gear without stripping it. I actually have a metal spur, but no reason for the extra weight if the plastic holds up. But different driving styles and conditions can be rough on spur gears. If you're stripping them, a metal spur is a good upgrade.
 
GRC said:
Pros: A metal spur is definitely more durable. You should also make sure your motor mount plate is straight. Bent motor mounts are one reason plastic spur gears get stripped. But even with a metal spur, if your motor mount is bent, the spur ends up stripping the pinion.

Cons: Price. But if you have to replace several plastic spur gears, it may be worth it. It also adds a little weight and is a bit noisy, but that's not a big deal.

Keeping dirt out of your power module also helps save the spur gear. With an upgraded motor mount and sealed power module, I'm able to run the plastic spur gear without stripping it. I actually have a metal spur, but no reason for the extra weight if the plastic holds up. But different driving styles and conditions can be rough on spur gears. If you're stripping them, a metal spur is a good upgrade.
Click to expand...
How do I validate my motor mount is square/straight? Do you have examples of better motor mounts and sealed power modules you can share? I'm totally new to all this and really don't have a clue.
 
Arrma coming out with a 6mm plate. Hot Racing says irs an upgrade but imo I didn't think so. Also have an m2c motor plate and mount. Super pricey 70$ and mixed reviews due to the mount possible making a stress point on chassis. Wait on arrmas new it hot racing most seem to go that route. Then hammer it straight when needed.
Steve38 said:
Arrma coming out with a 6mm plate. Hot Racing says irs an upgrade but imo I didn't think so. Also have an m2c motor plate and mount. Super pricey 70$ and mixed reviews due to the mount possible making a stress point on chassis. Wait on arrmas new it hot racing most seem to go that route. Then hammer it straight when needed.
Click to expand...
Lay it on a flat surface. If it's laying flat ur good
Steve38 said:
Arrma coming out with a 6mm plate. Hot Racing says irs an upgrade but imo I didn't think so. Also have an m2c motor plate and mount. Super pricey 70$ and mixed reviews due to the mount possible making a stress point on chassis. Wait on arrmas new it hot racing most seem to go that route. Then hammer it straight when needed.
Click to expand...
Lay it on a flat surface. If it's laying flat ur good
 
As GRC said, if you clear out debris from the motor area, especially after running on gravel etc, you'll noticeably increase the life of your spur gear - takes 5 mins to do and it's free. If mesh is set correctly as well, you'll have little problem. I've had to change mine once in just under a year but that was my own fault for driving like an idiot!
 
Well after I finally got got a few spur gears in and had time to sit down and replace it. It appeared to be more of a mesh issue. the tips of the spur were stripped but still lots left on the gear. I think maybe an impact misaligned the motor/pinion. After I tore down the slipper clutch to replace the gear, I broke one of the meatal pieces of the slipper then tightening it back down. So then I just went and bought a whole freaking assembly. While I had the change I also adjusted the alignment of the front wheels and and put locktite on the back of the hex and the the wheel nuts. I threw in a 25Kg servo from amazon and replaced the the little drive shaft brace that really doesn't appear to do much as it ran fine without it. I put 2 packs through it last night and it runs like a champ. I also DIDN'T break anything. I think I'm starting to get the hang of things!
 
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