Ahhhhh ! SS was a term I could have used but I was looking for a 4X4 DOH !
Thanks !

Yeh I ran an aluminum idler in my brushless maxx. I hadn't got around to getting and idler for this trans yet. I'll have to pick one up for sure. I thought it was really off the ends of the teeth just broke off too!

UE still has them. CLICK

Yeh it's hard to justify spending $10 for shipping on something that can be put in an envelope for $1 though.

Don't buy it then. Or order some other cool stuff while your at it.

Yeh I could spend a lot of $$$ on that site :lol:

3905 trans is on the way. Figured it wasn't much more to just get a new trans that already has a steel idler and wider gears. I'll have to make new trans mounts but no biggie. I'm hoping it's narrower overall than the old trans' motor plate. Anyone know that for sure?

I know for certain the newer tranny is narrower than the older version, not sure how much but about 5-10mm maybe. The motor mounting plate is another question though, its a rather odd shape compared to the old symetrical design- I think it may actually be wider on one side (one motor on top and the other to one side of the tranny). Dremel on standby.... :mdr:

That is correct.

Worst case scenario the transmission gets mounted higher up in the chassis. My drive line angles were fine before so I have some room to play. Probably not a bad idea to keep the motors up out of the way anyhow. I really should get some outerwears for them though.

Well the new trans came in today. I started drawing up the mounting template and was bored so started messing around with how it might fit in the chassis. The drawing isn't extremely accurate since I didn't have anything to take the transmission apart with here at work.

Here are the sizes compared to the old 3906 transmission

http://i736.photobucket.com/albums/x...Comparison.jpg

I'll need to make new mounts and probably raise the new transmission up slightly. That motor hanging off the side is horrible.....

http://i736.photobucket.com/albums/x...mbly_Front.jpg

Should clear pretty good.

http://i736.photobucket.com/albums/x...embly_Side.jpg

You have far too much free time at work... :D

I agree about the offset motor though, really kills the looks department if you are using 2 motors.

That said, I have seen a 'clocked' tranny before, done with a TXT-1 using the stock tranny- that might make the thing look a bit more balanced, though I imagine its more hassle than its worth for most applications.

It was a slow day :lol:

funny you mentioned clocking the trans. I had it setup like that in the drawing but the mounts would have really been a pain. It would fit inside the chassis plates that way though. I was going to work on it last night but the clod project was getting close to running so that took priority. Maybe this weekend I'll get this trans mounted up. I found some aluminum angle that should work for the mounts.

While doing a little researching today I stumbled across something that looks like it could have saved me a lot of time and some money.

Obviously as seen earlier in thread the idler gear in my older (3906) trans was done for and I didn't want to purchase a steel idler from UE since it was $26 shipped. Ended up getting a new 3905 trans for $55 shipped which is supposedly brushless ready and all that jazz. I'm in the middle of changing mounts and what not and not all that pleased with the way it'll be mounted in the chassis. Oh well, give and take right?

Well I noticed that the mounting bolts for the new trans are larger than 3mm so I downloaded the exploded view from traxxas. I can not for the life of me find a view of how the trans mounts to the chassis? There are some 3mm hardware that hold the bottom braces to the chassis that look like they are supposed to go through the chassis into the trans but that won't work since they are 3mm? Any insight?

Ok back to my original reason for posting. What I came across was interesting. I seen this exploded image here.

http://i736.photobucket.com/albums/x...905_tranny.jpg

The part number for the idler gear looked REALLY familiar. Why? Because it's the same exact number without the "X" used in the older 3906 transmission.......

http://i736.photobucket.com/albums/x...906_tranny.jpg

So it turns out traxxas has two different idlers with very similar numbers.

3996X Steel Idler

3996 Plastic Idlers

Do you think it's safe to assume the 3996X will fit in the older 3906 trans? They're $5 new. For that price I'll pick one up and try if my LHS has one.... Looking critically at the drawings it looks like the new idler is wider.

yes the two different idlers are interchangable.


3996 is plastic
3996x is steel.