I've been reading that the 3996X idler is wider than the 3996 meaning it's not a direct replacement.

Just shave down the width a bit then. Or buy a RCM idler if Mike has them still.

If you purchase a RCM idler it'll be the last idler you buy period. No mods,inexpensive and worry free.

Shaving down the 3996X isn't as easy as that (I don't think). If it's wider then I'm guessing the bearing seats would also need milled out to make up for the narrower gear or else the bearing would stick out.

I've already spoke with Mike about getting an idler and it's hard telling when they'll be in stock again. With the new 3905 trans out people aren't as interested in beefing up the older 3906.

I'm going to pick up a 3996X idler for my old trans since they're only $5. Since I converted my trans to single speed I'm thinking I should have room to fit the stock 3996X idler in there somehow. There is a fork style plastic spacer in there that separates the idlers from each other when it's a two speed so there should be some room I can make there.

Nick, I dont know if you've looked at it, but the 3905 tranny has a different output ratio than the 3906. Not sure whether you we using first or second gear in the 3906 tranny.

3906- 1st: 2.76
3906- 2nd: 1.72

3905- 2nd: 1.833
3905- 1st Wide: 5.09
3905- 1st Close: 2.96

nitrostarter - I was using 1st gear in the old trans (smallest gear on the input and largest main gear). What's the difference between that 1st wide and 1st close? I definitely don't want that 1st wide ratio........

Got the trans mounts done. Offset to the one side as far as I can go. I'm going to mount the motors before drilling the holes in the mounts. I'd hate to drill them to find out they don't clear the chassis plates.

Sorry for the cell pics

http://i736.photobucket.com/albums/x...s/IMG00027.jpg

http://i736.photobucket.com/albums/x...s/IMG00028.jpg

http://i736.photobucket.com/albums/x...s/IMG00029.jpg

Looks good!

The difference in gears is on the top and bottom gears, completely different. Traxxas used this to provide the option of installing a "more true" first gear, like the Summit has. My Summit was a real brute in 1st gear...

So which ratio comes in the transmission stock? I never paid attention to how many revolutions it has. 5.09 is some serious reduction.

Well the stock 3905 tranny doesn't have the 2 speed in it. It is a single 2nd gear. Ratio is 1.83333

Interesting. So you have to buy the 2 speed kit to get the other gear ratio? This thing is going to be fast with that ratio. I'd like to have the 5.09 for a second gear. That would give me a big range.

Got the mounts done and motors in. Seems to all be fine. Top motor sticks up higher but not by a whole lot.

http://i736.photobucket.com/albums/x...d/IMG_0043.jpg

http://i736.photobucket.com/albums/x...d/IMG_0044.jpg

Electronics tucked back into place

http://i736.photobucket.com/albums/x...d/IMG_0045.jpg

Looks like whoever was driving last got a little muddy

http://i736.photobucket.com/albums/x...d/IMG_0046.jpg

While waiting on the two speed to get here I started looking into something else I've always wanted to do with an RC. It's been done before so it's nothing amazing but I wanted to approach it differently.

This is just too cool right?

Stopped at the local Harbor Freight and found some inner tubes that fit inside the Jumbo Kongs. 8" OD x 2.5"w wide for a 4" rim. I'm running 3.2" rims but that's ok.

Deflated inner tube

http://i736.photobucket.com/albums/x...s/IMG_0112.jpg

Added a little air to see how the fit would be

http://i736.photobucket.com/albums/x...s/IMG_0113.jpg

Not to bad. A little narrow.

http://i736.photobucket.com/albums/x...s/IMG_0114.jpg

Drilled a through hole for the valve stem

http://i736.photobucket.com/albums/x...s/IMG_0118.jpg

Put the tire on.

http://i736.photobucket.com/albums/x...s/IMG_0119.jpg

Added about 10psi to see what would happen.

http://i736.photobucket.com/albums/x...s/IMG_0120.jpg

Since the tube was too narrow it didn't stay centered.

http://i736.photobucket.com/albums/x...s/IMG_0121.jpg

I took the stock foam which is 4" wide and cut 2" out of the center. Then I used the 1" rings left over on either side of the inner tube inside the tire.

http://i736.photobucket.com/albums/x...m/IMG_0124.jpg

Inflated to 20psi (on mistake, thought the gauge said 10psi) next to a jumbo kong that has nothing inside it.

http://i736.photobucket.com/albums/x...m/IMG_0125.jpg

http://i736.photobucket.com/albums/x...m/IMG_0126.jpg

You're probable wondering the size difference? The stock Kong measured 8.4". The inflated Kong?

http://i736.photobucket.com/albums/x...m/IMG_0128.jpg

Yes, it's insanely big!

http://i736.photobucket.com/albums/x...m/IMG_0129.jpg

However, 20psi was too much and the inner tube blew sometime over night. :lol: I have to pick up another one at lunch today. I built the 3 other tires and they have all held at 10psi so far and measure around 9" OD

That is so awesome! Big fan of the build! I hope you find a way to make the pneumatics work!

you should be able to float your truck over mud now!

SICK!

very nice addition