project 3905 e maxx

hi all. thanks for all the help with my lipo questions guys. i finally ended up with 1 evolight 5s and 2 evo 25 3s to power me maxx and an e station 902 to charge them. project is going well so far. first thing to do was take out and throw away usless nylon cogs in the gearbox and make sum sexy ally ones from 6082-t6 like this the nylon ones lasted around 0.05 seconds also notice the roll pins has been repleced with solid pins on the input shaft. next job was 2 front and 1 extended centre rear drive shafts from 316 stainless like so.... i also needed some 17mm hexes so back on the mill... then to design and fabricate 2 chassis rails 40mm longer like this base plate is just ns4 3mm to test for now, it will be replaced by a carbon fibre custom one off , thanks for looking hope this inspires others to try a bit of custom parts for your truck. more pics soon bye all...

[suicideneil]

Nice work, did you machine the gears yourself or have a shop do them for you? RC4WD.com used to sell complete sets of alloy geaqrs, but they sdeem to have vanished now ( I got lucky ), and there used to be the olod UltraMaxxed gears too, but they have long since vanished aswell- always something people are willing to spend a bit of money on, worth thinking about 'tis that..

[medusa'd maxx]

nice work I would be keen on some of those gears if you wanted to run a few sets off
CVD's look good too

[Urgeoner]

thats awesome, I wanna learn to use a milling machine too

hi all...thanks, yes all parts so far i have made at home as i found the idler gear in steel (bit heavy tho is steel), but could not find the lower gears in anything but nylon, so they made from 6082 t6 alloy to keep things light.
so far they have around 10 runs on them and all is well, and the problem now is the palstic g/box casing is flexing when i use 6s allowing the idler gears to run at an angle to the other gears, so ally g/box is on the todo list but i will buy this as its hard to machine without cnc.
i will be making some more gears if anyone is in need but have no interest in mass production, i ran off both lower cogs (31/36 tooth) as i wanted to keep the 2 speed, pm me if you want cogs and we will talk.
thanks all byee...
urgeoner do it, learn to use a mill its not as hard as it seems...but you need to use the lathe to make cogs too, make it to size on the lathe then cut teeth on the mill.

[Urgeoner]

ya my school has a fatass machine shop with lathes milling machines etc might get a start!

hi all...sorry made a typo on the title of this thread, my e-maxx is a 3906 the very first version without the wide arms. so cogs are 3984 and 3985 36 and 31 teeth, is the newer 3905 have the same cogs in the g/box? can someone who has this version let me know please. thanks.
good luck in the workshop urgeoner

[suicideneil]

The tranny gears inside the new emaxx are slightly different looking, and there are two options of wide and close ratio gear sets, so I dont think they will swap over as such.

hi all... i have been well busy in the workshop making stainless steel spool holders for a fishing line company so my project has been on the shelve too long, anyway my last post was alloy gear cogs for the box on my 3906 e maxx. well alloy is not the way to go...

as you can see the power of the mm combo has just pushed the alloy away and failed (shame tho as the acceleration was insane). so after a conversation with an old school engineer who had dealings with gear cogs suggested i use ertalon 30gf (has 30% glassfibre and has better strength and heat figures than nylon 6),

oh dear, they lasted a few seconds about twice as long as original cogs.
so now after days in the workshop making cogs that where useless now i have made some that are usefull ....


these cogs are made from a hard grade steel and i finnished them today so now going to put my e maxx back together and sqeeze that trigger
i will post and let yall know how it went...
sorry about naff phone pics but my digital camera is not allowed in the workshop

[redshift]

That is superb work.

Big points for follow thru and making it work, looks like that trans will take unlimited power with the alloy case!

I strongly recommend STP Oil Treatment for your all metal setup, have a look at this- http://www.rc-monster.com/forum/showthread.php?t=17532

Any brand oil treatment or 'viscosity improver' will be magnitudes better than grease, great protection for your investment

And why haven't one of the mods fixed the title?

[Rivermaxx]

Yea as some others have found out steel on aluminum and aluminum on aluminum dont work for long. To be honest I have used the stock plastic gear on multiple high speed passes in an a heavy all aluminum truck a with no failures. I think the biggest issue is the slipper needs to be adjusted properly to prevent failure a strobe slipper helps also. Those steel gears are awesome but I wonder if the power loss from the additional rotational mass probably works out to be the same as a slightly slipping slipper. Is that a still a 2 speed tranny ?

[suicideneil]

Awesome work there dude, be sure to give those new gears a thorough test to see how they hold up- I imagine the stock upper most gear will be the one that fails/ wears out first though. In that case, a hardend steel mod1 pinion could be used as a substitute..

hi all...thanks guys, i had a quick test of the truck yesterday, on 5s it seemed to take longer to reach top speed but seeing as we have had lots of rain down here it was impossible to get the power down, wheelies on the dry tarmac and it just spun on the damp.
6s was as usuall virtually uncontrollable, but fun.
yes as these cogs weigh more it will take longer to spool up.
hello redshift, i found the link to be an interesting read and i agree grease is useless above 10 meters per second as it will be flung off so i have been using oil, well i use cam lube which is really thick and sticky, its allways still there when i strip down so i assume its doing its job, i have tryed engine oil but it leaks out through the bearings and any other gap/crack. i think a sealent smeared alloy case will hold oil though.
yes could someone please fix the title??? thanks.
hi rivermaxx, yes its the original 2 speed as i like to climb and go fast,
get the best of both worlds with 2 speed.
alloy and nylon cogs are no good for brushless..too much power for them to take. do you run a mm combo then?
hi neil, haha ye i think you may be right and if so they will be fabricated.
thanks again all...

[redshift]

Well I actually just rebuilt my 3906 trans. I wasted 2nd gear by shifting under too much power... I made it over a year without doing that. I am still using the nylon gears, but I have UE idlers. I only run a 9XL/4S so if I'm not stupid the trans holds up very well. I did also use a small amount of silicone to seal the case halves. As long as the fluid level is below the output shaft it should stay put.

You say cam lube, are you referring to engine assembly lube?

[Rivermaxx]

Originally Posted by chrismechanic

alloy and nylon cogs are no good for brushless..too much power for them to take. do you run a mm combo then?

I have MMM esc with a real neu 2700 kv on 6s and have also used a 2200 kv castle neu on 6s. I have multiple 80+ mph passes on my g1 single speed tranny with a UE gear and stock nylon gear in a 11+ pound truck. I also have a few 69 mph doulble wheelys with the same set up.


The current version brushless erevo and new brushless maxx also has steel on nylon gears and has no problems on 6s. I know you are not making more power than me on 6s either. Its probably the shifting under power causing the failure. Single speeds are probably more reliable. Not to mention turning the punch control down to atleast 50 %. It will still do standing back flips with a blip of the throttle at that setting. Check out these gears they are made of titanium really light weight too.