Notorious Grease in diffcase turned into black dust

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Double Apex

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So I opened my rear diff today and noticed the grease I used on the ring and pinion gears tuned into a black, compact, dust like, substance. Am I using the wrong grease or is this normal.

I used this grease (multipurpose grease for those who can’t read German)

image.jpg
 
Your grease there is NLGI #2... is fine. (y) Any automotive NLGI #1 or #2 is ok for RC gears.

You had other issues causing this. It's not because of the grease you are using.;)
Perhaps just needed more maintenance. (Neglect)
Or you just simply wore it out. Normal. Especially if you are hard on your rig in dirty terrain. How many runs did you have on these gears?
Time to do both Fr and Rr diffs as a set and bash on again. The other gear is probably not far behind this one IMHO.
The Plastic Main gear will simply wear out like this. Especially if dirt/clay/sand migrated into the carrier/bulkhead with use and was neglected. Or perhaps not enough grease was used. :unsure:
Consider a better more frequent maintenance regimen.
 
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Okay thanks, good to hear the grease is fine.

I think ran about 15 packs since the last service. Actually didn’t have any real problems with the Diffs. Was just checking it out because the car was making a horrible noise since I changed the pinion last night. For now I think a worn center diff spur gear is causing the noise (and chew up my previous pinion yesterday). Should have caught that wile changing the pinion ….
 
15 runs on average and you are do for maintenance. You were pretty much on schedule for a diff failure. These rigs don't run forever. Open and maintain/lube that motor also.
Many wait till their rigs fail, then replace parts, preferring to drive mostly, while others are more proactive with maintenance at set intervals. Parts last a bit longer this way. Pick your poison.
Eventually many drivetrain parts will wear out at some juncture. Fix then repeat.:cool:
Although expensive, consider a steel main gear as an upgrade option
 
Grease turning to black dust usually means it got hot for an extended period of time and lost the oil component to evaporation/oxidation/carbonisation. I'd check to make sure the ring/input gear mesh isn't too tight and generating excess heat.
 
^^Either that, or you're picking up a lot of dust through gaps in the diff case/covers/chassis... I'm using MoS2-Langzeitfett from Liqui-Moly or "red grease" like Red-N-Tacky.
 
Thanks for the tips, relative new to this. I was still relying on the manual which advises maintenance every 20 packs. But since I mainly run in dusty conditions and temps are usually in the high side I will open the diffs every 10-12 runs from now on.
 
Try Reefs diff grease. It's the best I've seen. It stays liquid or at least emulsified after hard use. I was using the Red and Tacky also but noticed it would turn almost solid after a few runs. Probably was still working good but I like the Reefs better because it seems to stay more viscous longer which helps with the smoothness of the gears. I've heard marine grease works well also.
 
R & T turns thick and pasty. It is very tenacious and stays put.
Attracts dirt instead of expelling dirt from the teeth.
Some don't like that on diff gears. Doesn't mean it won't work well enough for gears. IDK.
I use it mostly on other things around the house. My car. Trailer hitch etc.
I would not use it on RC BB's for example. The balls and races would probably gall out fast....
 
I just checked the front diff, dry but not completely dry like the rear one.

In the rear diff the new pinion I put in about 15 packs ago is now completely worn out (small sharp teeth). Front one is still fine.

QUOTE="@9G, post: 741633, member: 21577"]
Try Reefs diff grease.
[/QUOTE]

Unfortunately I can’t seem to find it in Europe.
 
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