Are my differentials working properly?

[ninnon]

Hello, I am a bit of a newbie to the nitro RC hobby and I bought a second hand car, I broke it in and am running 20% nitro, works great. BUT...whenever I spin one wheel the opposite wheel doesn't really spin at the same rate, if at all, sometimes it acts confused and doesn't know what to do at all! This also happens with the four wheel drive system... I've searched everywhere and can't find anything...PLEASE HELP!!

P.s I have a 2012-13 HPI trophy 3.5.

 

[Snook Man]

Sounds like the diff(s) is/are low on oil/grease or the oil is too light wt.
Light wt oil = less positive effect on the opposite wheel.
Heavier oil = more positive effect on opposite wheel.

Oil wt depends on how you want the diff to react.

 

[ninnon]

So if I put a thicker oil in the diffs they would react faster? if so how do you change it? thanks for replying this forum is epic

 

[Snook Man]

Yes, heavier wt oil will increase the positive effect on the diff.

To change oil you will need to remove the diff from the rc. When in hand you will then remove the ring gear from the diff cup. Clean the internals and then add the oil. Fill the cup (with spiders installed) to where you will have no squeeze out when you install the ring and beveled gear on the cup.

You should also look at some threads on shimming diffs as it will greatly improve longevity if needed.