Turns out I had a spare diff from my LSP and that diff assembly practically drops right in to replace the XTM diff. I didn't have a pinion I could try so I'm thinking about trying to get a complete LSP2 diff and pinion and see if I can get it working. Those diffs look a lot more stout.

How about a little mud? :yipi:

To bad the fun didn't last long


Chevy Monster Muddin video

Dead in the water :neutral:

http://i736.photobucket.com/albums/x...n/IMG_0007.jpg

Good effort from my buddy's 2.2 to get it out.

http://i736.photobucket.com/albums/x...n/IMG_0010.jpg

Electronics stayed nice and dry. I think I'm going to line the top of the rear fenders with a foam weather stripping so that when the cover is down it seals up better.

http://i736.photobucket.com/albums/x...n/IMG_0018.jpg

Look at that little feller

http://i736.photobucket.com/albums/x...n/IMG_0015.jpg

Found out it was the idler gear in the maxx trans that gave up

http://i736.photobucket.com/albums/x...n/IMG_0020.jpg

Every time I check out your thread I get inspired to look for a similar truck and can't find one or any info. This truck must have ben out a while. I'v found a Hummer but would rather not :-(
Good to see your getting a lot of use out of it ! Keep posting.

It has been out for a while but the body is really hard to come by. New in the package they are lowered with big rims on it. I THINK this is one but it doesn't mention the scale. There is a 1/10th version out too which I why I'm reluctant to say it is the larger version.

JJ Silverado SS on ebay

You can find the body only on the crawling sites sometimes for sale but they still aren't cheap. Most people strip them down and get ready for a build but don't follow through. I think I paid about $50 shipped for the body only to get mine.

Heh, thats how my output gear looked when it striped- I find it strange though that the teeth sheer off like that, rather than just grinding down or melting through friction etc. I would say either chuck a steel idler from Mike in there, or consider an 3905 tranny- they have a steel idler and wider gears as standard.

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.

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

Thanks guys! Nice thing about the inner tubes is I don't have to worry about gluing in the valve stems or the tires. That was something I didn't want to do. Plus I can easily let the air all the way out for driving around on land and still have some of the foam inside for damping. They had a larger 10" inner tube that I think would fit better but it has a straight valve stem which I'm not sure will fit inside the rim. I'm going to pick one up just to try though.

Now you just need some belting.... duct tape!

If it works for high speed ballooning it should work for no speed ballooning right?

I wonder if it would just make the tires wider though... just a thought.

Good stuff!

Ya know, my friend mentioned the same thing on the phone the other day. I think the only reason the inner tube popped was because the inner tube had expanded so much. With some duct tape limiting how much it can expand that might help fill the tire up with the inner tube instead of it stretching the tire out.....

One thing that I've been finding out I don't like is that the inside of the tire isn't sealed perfectly. I haven't sealed where the valve stem goes in the rim so water can get inside. Obviously only so much water will get in there since the inner tube will still hold air but I'm wondering how much of a buoyancy difference that'll make.

I'm ordering in a different set of wheels that are wider so if this setup doesn't work I'm going to glue a set of tires to the rims and glue in a valve stem too.

yep, I think sealing the tire would be a good idea. Not just because of the loss of buoyancy when the foams get soaked, but also because of the weight and inbalance this water would add to your tires.

We're going to see how it does today at lunch time. Brought the truck, a video camera, the tire pump and a good length of rope. If I keep it in water under about 12" deep I don't have to worry about electronics getting wet so if it sinks in about a foot of water I know I failed and it should still drive out without using the rope :lol: