BRCC blown rear diff after 3 hours runtime

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, and others.

thegunsmith

Member
Messages
176
Reaction score
60
Arrma RC's
  1. BigRock 4x4
I have had literally nothing but problems with this car since I received it, first it was the motor and pinion gear, next is was the slipper clutch hub and now my rear diff is blown the car won't go any faster than 10mph. The car has a little over 3 hours runtime on it now. So I Install my new motor and all new parts and take it out for a run, about 10 minutes later it won't move, I take it home disassemble and find the problem. It turned out to be the slipper clutch hub had been stripped. So I order the parts, get them a few days later and install them. Once again about 10 minutes in YET ANOTHER drivetrain problem, this time the rear diff is making a horrible sound and won't go any faster than about 10mph. Haven't hit LVC on the car since one of my first runs, I don't do anything crazy, in fact I take it super easy on the truck as I do not want to break anything. This thing is crap, honestly I don't know if I received a bad truck but mine definitely is not "Arrma tough" and at this point it seems like my E-revo was a better and more reliable car. Long story short don't buy the BRCC unless you enjoy being pissed off or you need a $300 door stop. This is for anyone thinking about getting into RC or even Arrma for that matter, I wish I would have seen something like this on here before I purchased mine.

Sorry for the rant, but I do have 2 questions:
1. What would cause a diff to fail so soon after purchasing it?
2. Does anybody want to buy a BRCC?

Everyone here has been super helpful and that is one thing I do appreciate about Arrma, so thank you all for that.
 
Have you changed the bearings? The stock bearings can fail rather easily and what happens is things start to spin out of round and then boom there goes the diff. That is how I lost one of the diffs in my Outcast anyway.
 
This is certainly not they way to introduce someone new to the Arrma brand. I am sure that someone on here will gladly assist you in your troubles and have you back on the road with a big smile on your face and you can see just how tough these Arrma rigs can be. Good luck and keep us updated ? chin up mate
 
Have you changed the bearings? The stock bearings can fail rather easily and what happens is things start to spin out of round and then boom there goes the diff. That is how I lost one of the diffs in my Outcast anyway.
I checked every bearing inside and around the diff and all of them spin freely. Does anyone happen to know what weight oil needs to go in the diffs? I have 20wt silicon oil i'm wondering if that will work?
 
I think it was 10,000cst. 20wt is way to thin that is like 200sct.

If you tightened down the slipper hub nut all the way that is most likely the cause of the problem. If you set the slipper too tight something in the driveline will let go.

Also not sure if you jumped it or not but landing while on the throttle will also cause diffs to strip, even off a small jump if you do it enough times.

Not saying that you did these things but just trying to narrow down the causes of what the issue is.
 
I would suggest you warranty everything that you possibly can, get the truck back together and sell it. You will never be happy with it and everything that goes wrong in the future will have you pulling your hair out. Time to cut bait. Sorry for the poor experience.
 
I would suggest you warranty everything that you possibly can, get the truck back together and sell it. You will never be happy with it and everything that goes wrong in the future will have you pulling your hair out. Time to cut bait. Sorry for the poor experience.
Yeah that's the plan, thanks for the input. At this point I have spent about 10 hours working on the thing for a grand total of 3 hours drive time.
 
Yeah that's the plan, thanks for the input. At this point I have spent about 10 hours working on the thing for a grand total of 3 hours drive time.
I understand your frustration. I've seen this once before with a guy and a Senton. No matter what he did, something else broke. I've beat the crap out of my BRCC and it keeps coming back for more.
 
Man u are just having horrible luck with your rig. I am not easy at all on my 3s rigs, and have not blown a diff yet. What part of the diff went out? I've told u before to not give up on it, still don't think u should.
 
Man u are just having horrible luck with your rig. I am not easy at all on my 3s rigs, and have not blown a diff yet. What part of the diff went out? I've told u before to not give up on it, still don't think u should.
When I took it apart the HD input gear was pretty damaged(stripped) and the differential case main gear is missing a piece off of one of the teeth. Based on the sound I was hearing when I was driving it I was expecting there to be a lot more damage than that. To my surprise the planet gears were all perfectly fine but I am still very confused. I put it all back together for now because with my luck I'd probably loose all of the screws or something. Now when I spin one of the wheels the other doesn't spin at all, I can see that it wantsto move but it doesn't. I'm at a loss I have no idea what to do to fix this thing.
 

Attachments

  • IMG_20190407_164633.jpg
    IMG_20190407_164633.jpg
    221.4 KB · Views: 51
  • IMG_20190407_170326.jpg
    IMG_20190407_170326.jpg
    348.4 KB · Views: 59
When I took it apart the HD input gear was pretty damaged(stripped) and the differential case main gear is missing a piece off of one of the teeth. Based on the sound I was hearing when I was driving it I was expecting there to be a lot more damage than that. To my surprise the planet gears were all perfectly fine but I am still very confused. I put it all back together for now because with my luck I'd probably loose all of the screws or something. Now when I spin one of the wheels the other doesn't spin at all, I can see that it wantsto move but it doesn't. I'm at a loss I have no idea what to do to fix this thing.
I can tell you from experience, that just doesn’t happen, lol. Driving around doing nothing and those big plastic gears just shear off? Something is f@cked up. And those internal gears aren’t easy to reassemble. If one wheel turns and the other doesn’t, there is probably an assembly error.
 
I can tell you from experience, that just doesn’t happen, lol. Driving around doing nothing and those big plastic gears just shear off? Something is f@cked up. And those internal gears aren’t easy to reassemble. If one wheel turns and the other doesn’t, there is probably an assembly error.
When this happened all I was doing was driving up and down a dirt road doing wheelies. I think I assembled the internals correctly but then again I probably didn't. Took a picture of it before I took it apart and reassembled the exact same way.
 
When this happened all I was doing was driving up and down a dirt road doing wheelies. I think I assembled the internals correctly but then again I probably didn't. Took a picture of it before I took it apart and reassembled the exact same way.
Is your slipper locked or too tight?
 
Is your slipper locked or too tight?
I did run my slipper fully tight for about 2 batteries. It was after I replaced a spur gear I tightened it all the way up and forgot to loosen it. However when this happened I had already set the slipper to what the manual says which is 1.5 turns from fully tight.
 
Does it look like I put the diff back together correctly? As far as I can tell I did but maybe I am wrong. I am also wondering if I used too much grease on it? After seeing other pictures of the diff case they weren't nearly as lubed up. @bicketybam
 

Attachments

  • IMG_20190408_142559.jpg
    IMG_20190408_142559.jpg
    270.1 KB · Views: 58
  • IMG_20190408_203316.jpg
    IMG_20190408_203316.jpg
    277.9 KB · Views: 61
  • IMG_20190408_203420.jpg
    IMG_20190408_203420.jpg
    301.8 KB · Views: 60
Old Thread: Hello . There have been no replies in this thread for 90 days.
Content in this thread may no longer be relevant.
Perhaps it would be better to start a new thread instead.
Back
Top