upgraded or alternative center diffs for the ofna / hobao 1/8 scale buggies?
 

Hi all,

I am looking for options for an upgraded center diff for my older Ofna Nexx8 buggy. Mine failed (bevel gear teeth wore down) and while replacements are available, parts support is kind of thin for this model.

As far as I can tell from exploded parts diagrams the buggy is still mostly parts-compatible with current Hobao 1/8 scale vehicles (although to be honest I get pretty lost in the brand name mess of Ofna/Jammin/Hong Nor/Hobao...).

Anyway, does anyone know if any other manufacturer's center diff is a drop-in fit for this lineup? Maybe Tekno, or Losi?

I will start taking measurements to figure it out but thought I'd see if folks here already new the answer.

Thanks!

Curious if you ever rebuild the diffs and if so what fluid you were running?

IIRC they only use a small amount of grease without any fluid in stock form which can lead to premature wear if not properly maintained. When you use regular diff fluid instead of grease and keep them properly filled by applying fresh grease on the rubber seals, then you should get really long life out of your diffs.

Bill, I was running 7k diff fluid. After some particularly hard bashing I could hear grinding coming from the center diff, and I could see a loss of power on acceleration. When I opened the diff, the fluid was dark gray (not quite black) and there were also a few slivers of metal here and there inside the diff.

The spider gears were all fine, and one of the bevel gears was also ok, but the other had rounded edges on many of the teeth. The damage seems subtle, but that's the only thing I can find wrong in the diff so I assume that's the problem.

Here's a pic showing the two bevel gears - the one on the left is damaged:

https://cimg7.ibsrv.net/gimg/www.rct...a605d586f8.png

Ofna 1/8 bevel gears, left side damaged

Maybe check out the Hyper VS thread for users that could measure HoBao's #87002 sun gears.

That's really unfortunate... glad to hear you were running diff fluids and 7K sounds reasonable, also a slightly greyish color is normal too... I have seen some diffs that need an extra shim placed behind the bevel gears to get the mesh to tighten up. I would give that a try and stick with the HoBao parts for now.

Also curious what fluids you're running in the front/rear diffs as well?

If the center diff is considerably thinner than the front, then you could possibly be cooking your center diff with excessive heat and potentially damage your gears that way too :(

Rustyus, thanks! I will check it out. Those do look like the more up-to-date version of the gears I have. I am looking for some hardened steel gears vs these cast aluminum parts.

Bill, I'm running 5000 up front and 1000 in the back. I think the balance was about right but the damage did occur after two back-to-back packs at high speed and let's just say "aggressive" driving... so there was a lot of stress on the components.