With spec Slash class racing, most off-road track race directors will outlaw the ball diff, however, most will accept tuning to the gear diff.  Out of the box, the gear diff is packed with light weight grease and for the most part the gear diff action is too quickly, which unloads too fast while the truck is cornering and at the same time does not allow power to be put down effectively coming out of the corner.  The diff action of the gear diff needs to be slowed down.  Reading several online articles, racers have been trying thick vicosity silicone diff lube (like those used in nitro vehicles).  While this method works great in the beginning, but because the Slash’s gear diff is not a sealed unit, the silicone diff lube will leak out eventually because it is a fluid.  And because of the heavy viscosity, once it is out in the gearbox, it tends to slow down the transmission causing extra drag for the Titan 550 12T motor.

We tried several grease and fluid, and found one that seems to work the best.  The super grease from Mugen Seiki racing seems to have just the right thickness and tackiness for the Slash gear diff.

For those that have not done this modification before, it is a fairly simple mod that can be done in about 25 minutes that delivers a significant performance advantage on the track.  Simply remove the gear diff from the transmission and remove the 4 screws that holds the side plate together to the main diff gear/housing

Then take the Mugen super grease and coat the internal gears liberally

Now reinstall the side plate and the screws back on and you’re all done!

A side note:  A great tool that helps in disassembling your Slash (or any R/C vehicle) is this great powertool from Hitachi.  It runs on 3.7 volt Li-Ion battery that makes this tool very powerful (high RPM) and the battery last a long time.  You can get this tool (with two batteries) for about $70 from Amazon.com  The hex wrench bits are from OFNA Racing.  This tool set makes working on your vehicle a breeze.

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