Arrma Nero w/ diff brain maintenance

LtGhost08

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Hello everyone. I have been reading a lot of the posts on this forum, love it here! I traded for a used Nero and I think I will be doing some service soon (shocks, diffs). My question is what are the stock shock weights and diff oil weights? and from there what should I use? I feel like this question is all over the board so its hard to make a decision. I basically run in grass, on some gravel, and in the woods (leaves, branches, loose dirt), I also jump occasionally (tend to either nose drive or land on the lid, sort of inconsistent). So I guess what are your recommendations?

Diff weight front, center, rear?
Shock weight front and rear?

Do you also recommend using the diff and shock maintenance kits?
 

craig72

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Arrma RC's
  1. Kraton EXB
  2. Nero
  3. Talion
  4. Typhon 6s
Hey Ghost,
I have been looking for info on rebuilding my diff-brain Nero differentials as well, but have not received any feedback. I have my center pulled and completely disassembled on the bench. On teardown, I realized the two end O-rings (AR716014) inside the diff were destroyed, so I have new ones on the way along with some shims/washers (AR709034, AR709036).
From what I have read, we will use grease, not oil, inside the diff because it is not sealed. The oil would just eventually seep out. From the factory, mine seemed pretty low on the amount of grease inside the diff. With the O-rings gone, I had a lot of lateral play which was causing a grinding noise. Luckily, none of the internal gears showed any damage.
I also ordered the other internal O-ring AR716019 because it no longer wanted to lay in its groove (a bit stretched).
Like I said, I did not order the rebuild kit because my gears/rods were fine. I ordered all of the parts from Tower and I have enough to do all 3 diffs for < cost of one rebuild.
Hope this helps! I'll let you know how my rebuild goes. Once the center is done, I'm going to do the front and rear because of the o-ring issue.
 

LtGhost08

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Thanks for your input. What grease will you be using? Are there different grease weights? Do you use the diff gaskets on tower too? I thought these diffs were sealed
 

craig72

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  3. Talion
  4. Typhon 6s
From what I gather, the grease type is not all that special. I have read that some folks use a Lucas Green (marine type?) which you can find in most auto parts stores. I did not order the gaskets because mine were intact. I cannot answer whether the grease is available in different weight. I think it is pretty easy to seal the diffs but with the “brain” in there, I did not see the need at this time.
 

craig72

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  3. Talion
  4. Typhon 6s
I spoke with Arrma Support and he said the type of grease is not critical. I picked up these today at the auto parts store. Waiting on the remaining items from Tower and I’ll commence with the rebuild. The green is for inside the diff, the white is for the casing.

ACBABCCD-C0BF-406D-969B-B4E01613986C.jpeg
 

Mboss

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I have the non brain version and used 50k/300k/30k and sealed the diff case with screws and red loctite. Diff case hase held up great with no leaks. Performance is also great for all around bashing...limits front wheel ballooning.
 

craig72

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  3. Talion
  4. Typhon 6s
Agreed, I think they are pretty much the same. The only reason I have not (yet) sealed and used oil vs grease is because of the change in behavior of the diff with the oil. From what I have read (if I have it right), the heavier oil acts as 'somewhat' of a locking mechanism. So if I were to do that in one with 'the brain', I would go from having 'locking/unlocking' behavior to 'locking/somewhat unlocked' behavior. I might eventually get there, we'll see.
 

VerticalChallenge

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  2. Kraton 4s
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  4. Typhon 6s
To fill the diff with oil you plug the holes that the diff brain prongs insert into, with tiny screws, and then fill with oil. I don't see how this would work with the center diff brain installed, I think it would all leak out. I recently did that to my "brain-less" Green Nero to counter the front tire ballooning under hard acceleration, using Associated 100k oil, and have been really happy with the results. I suspect I may need to replace with 50k or thinner as the weather turns colder... Can anybody corroborate this?
 
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