Is it worth continuing to upgrade a 3906?
 

Okay, I've been away from the hobby for several years now. At the time, I was working on upgrading my 3906 E-Maxx. I have installed quite a few upgrades like the Proline PowerStroke shocks and Servo Saver; RPM bumpers, skid plates, A-Arms; and a High speed and torque/metal gear steering servo. I also bought but haven't installed Integy aluminum bulks (F/R); diffs with aluminum cup and hardened gears; steel CVDs (F/R) and center dogbones; and UE idler gears.

I figure that I'll need to get a RobinsonRacing Slipper kit, brushless ESC/motor combo, and LiPo batteries at a minimum, which I estimate to run me upwards of $300-400.

Is it worth it to continue upgrading this outdated platform? or should I cut my losses, sell it on eBay for what I can, and just buy a brand new rig? I've seen some 1/10 brushless trucks with 2.4GHz radios selling for around $200 RTR. Sure, they may not be of the same quality of Traxxas, but at a fraction of the cost, I could buy a lot of replacement/upgrade parts and still come out ahead.

I thought about upgrading it with the 3908 chassis, but then I'd have to replace the entire tranny, and I'm not sure if the front and rear assemblies could be moved as-is or would need to modified, too. Seems like I could throw a lot of money at that solution, too.

Or maybe I'll just keep it as a brushed rig and use what I would've paid in upgrades to get a new truck.

Here's what I'm considering as an alternative to continuing the upgrade path: http://www.nitrorcx.com/16c553-red-rtr-24g.html It looks like a pretty decent setup, and its wheelbase is only 9mm shorter than the 3906, so I could even re-use the HumVee body I painted for it. The other option is to move to a 1/8 scale, which is tempting as well. I'm not a racer, so whatever I end up with is only going to be for bashing around.

Any opinions are welcome.

Well, first off I would not buy that truck you linked to. It would "work" but as soon as you started bashing hard or gearing up at all it would break and the sub-par electronics would fail. I would steer clear of anything but the big names in r/c, cheap knockoffs are cheap knockoffs.

If it were me, I would keep it and go the 3908 route. The 3908 gives you a solid brushless ready tranny, extended wheelbase and more room for lipo batteries. Your current front and rear ends are direct swaps.

Fastlane Machines makes a couple of really nice aftermarket 3908 chassis if you really want to bling the truck out.

It may be more money, but you will end up with a better truck, better electronics and the satisfaction of building it yourself the right way.

Here is a 3906 I upgraded to a 3908 with a custom carbon fiber chassis I made and a custom center differential instead of a trans. It also has LST diffs in the bulkheads: http://rc-monster.com/forum/showthre...&highlight=pif

Good luck and happy r/c-ing!:yes:

Thanks for the input. After I posted, I found a review of that truck and its 1/8 version, and both reviews found them to be lacking in the durability department, so I've pretty much written them off as options.

Since the front and rear assemblies are direct swaps, I may give that some consideration, although that just adds to the list of things to buy. Fiscal responsibility sucks...

You could certainly build it as a 3906 and save money. The only bad point is the tranny, but you've already addressed the idler issue. The next weak point in that tranny is the roll pin that holds the second gear (small top gear) on the input shaft snaps. Replacing the roll pin with an allen wrench or drill bit of the appropriate size, either pressed in or held in with green loctite fixes it. With brushless it is recommended to put it in second gear and leave it there. First just heats up the electronics from not having enough load, and there is enough torque you don't need lower gearing.

A robinson slipper isn't necessary. Just lock the stock slipper tight.

Any original MonsterGT spur gear is a direct gear swap for the 3906 slipper. http://www.ebay.com/itm/Associated-S...#ht_3330wt_907 The benefit to using this as a spur gear is that you step up from 32p gears to Mod1 gearing. The bigger teeth are obviously stronger.

I've changed my mind, build up that 3906!!!!!:yes: And post pics!:intello:

Yeah, after some more thinking and consideration of your inputs, I've decided to just stick with the original project of upgrading the 3906. I went ahead and got the RobinsonRacing Slipper -- found one for $33 shipped -- with the steel 65T spur. I figure that should be pretty tough. Thanks for the heads up on the roll pin. I'll definitely take care of that while I have the tranny open. Any idea what size to use, or just trial and error? Also, are the 3908 diffs direct replacements for the 3906? Just wondering in case I have issues with these aluminum diffs I built way back when.

At some point I'll need to make a decision on ESC/motor. The vehicle setup guide recommended the Tekin RX8 1700 combo, but it's no longer available. I did find it on another site, but it was like $380, which is a bit rich for me. The only recommended combo that's available is the Castle Creations Mamba Monster 2200 combo, but I still have a tough time getting past the $320 price tag. I also can't help but think it's really overkill for what I'm wanting. I found this combo over at HobbyPartz, and it looks like a good compromise: http://www.hobbypartz.com/07e-c-combo-m3a.html. Another site I saw said that the Traxxas Velineon VXL-3S would be a good replacement for the E-Maxx (http://www.rcsuperstore.com/Traxxas_...p/tra3350x.htm), but if that's the case, why isn't it actually used in the E-Maxx? I'd love it if it would work, since it's only like $155 and waterproof....not that anything else is...

On a side note -- I dug out my NiMH batts and threw them on the charger. When the charger indicated they were fully charged after only 15 minutes, I figured something was up. I put them in the Maxx, and sure enough, they lasted only about 30 seconds. Apparently their shelf life is somewhat less than six years. :whistle: Meanwhile, the other set was still on the charger, and one indicated full charge, and the other blew a cell. Fortunately, I was able to clean it up off the floor before the wife came home. Reminder: the WWII ammo box isn't just useful for storing batts.

When I get a chance, I'll take some pics of the upgrades and post them up. The truck could use a good cleaning to be perfectly honest. Here's a pic from when I first got it. I bought a Proline Humvee body and painted it just to see how hard it is to do. You can probably guess where I live once you see it.

http://home.earthlink.net/~aywang67/...Blue%20Red.JPG

I'm thinking Houston Texas

If I were you I would try to find a aluminum chassis. Maybe a ue thunder chassis(about 100 on eBay) it is a direct fit for the 3906 trans. It will be as long as the new emaxx. You can use the newer emaxx driveshafts also. You will also have to buy some rcm battery trays.

The 3906 chassis is very weak where the bulk heads meet the chassis.

That's a very good suggestion -- I hadn't thought of that option for a longer chassis. I think for now I'll continue with the 3906 ugprade with the stock chassis, and then if/when it fails, I'll look at stretching it.

I've spent loads upgrading my 3906 and could never part with it. Here's a few things you'll need to do; bin the old diffs in favour of 3905/3908 diffs, any Maxx or Revo CVD will do, but you'll need the newer carriers to fit them due to bearing sizes, the gearbox you've covered and so should be ok. I wouldn't go with the Tekin system, apparently weak in terms of bashing, look at HK and Hobbywing.


You've listed a lot of other good upgrades already, how's the build going? Is it running yet? Have you looked into lipos yet?