I accidentally ordered some 4907 diffs recently, and discovered on the web that the 3905/3903/3908 diffs are a bit stronger.

How much stronger are the 3905 than the 4907? This will be going in a 3906 on a 4S brushless setup.

Thanks.

The T-Maxx 3.3 and E-Maxx 16.8/Brushless use the same diffs. No difference.

I'm not so sure. There is a pretty decent sized price margin between the two (which is why I ended up with the cheaper ones).

Here is a quote from a listing:

And then the two different diagrams show some differences:

3908 diff view

4907 diff view


I just want to know if people had any experience with both diffs, and had any insight as to how long each would last in a moderate brushless setup.

Crap, you're right. I forgot the 16.8/EMBE brought about the big crossbar diffs.

On 4S, that's really, really mild. The 4907 Diffs are still pretty tough, and should hold up fine against 4S.

Though, my EMBE (3908 Diffs) runs 5S, and changing over the rear diff case to aluminum has bombproofed it. 6 months and counting. Regular plastic diff cup, too.

Thanks, makes me feel a bit better. Most of the time I am going to be running with the throttle end point dialed back, and the punch level on the ESC down toward the low end. I just wanted to know if I was going to vaporize these in the first BL run, or if they had enough strength to get me 10-12 runs. As you know, these take a little while to change.

Thanks for the help!

the emaxx diffs inthe new 16.8v and up aree the same. my difs are bone stock and ive shattered bearings but never broke a gear running a leopard 4282 2000kv on 4s

I was aware of that, I just thought the 4907 diff was also the same diff used in the 3905, and that isn't the case. What I am getting at is that there are (at least) 4 revisions of the maxx diffs...and I got the second from the top as far as strength goes. I was wondering how much better the top end diff was.

Here is how the progression happened:

1st was the original 2-screw diff on the first t-maxx and first e-maxx models (non-wide versions) this was the diff that couldn't take power AT ALL.

2nd was the 4-screw diff used in the widemaxx 3906 (this diff has 4 silver screws)

3rd was the 4-screw diff with black screws used in the 4907 3.3 (and others)

...and finally they made the newest diff that has the nicer pins and a stronger cup (for the 3905 and up model trucks)


At least that is how I have picked up on the long history of the maxx. It is a lot of data to retain, no wonder I bought the wrong parts.

You should be able to dial a 4S up to full power without killing the 4907 diff. The 3908 diffs were really only heavily reinforced because of the Revo-Spec overhaul Traxxas did to the model lines, and assuming people would throw 6S in a Maxx.

I would run it mine lasted on 4s for 30ish runs, then the cup failed. What I would do after it fails is get the alum cup spider gear cup from FML.

Sounds like a plan. Thanks for the input!