anyone running 5s or 6s in a 3905 emaxx with stock diffs?

[blueb8llz]

is this possible or will the diffs have no chance? right now, i have a mmm/7xl gps at 47.8 mph with no probs.
but ever since i geared it so high, i lost my intial torque power. so now, i want more power, and a bit more speed as well. if i was to run 6s (with a new motor of course)geared for 55mph, and take it lightly on the take offs, will the stock diffs do fine?
what actaully causes the diffs to break anyways...wheelies or full throttle on stand stills? if i was already going like 20mph and then i wot, will that ruin the diffs too?

[JThiessen]

Originally Posted by blueb8llz

... so now, i want more power,...... and take it lightly on the take offs,

Now that right there is funny, I don't care who you are!!!!!

They will last until they blow. Everything else is speculation until it actually happens.

[lincpimp]

Stock diffs in the stock plastic cases are not the strongest in the world. I find that large/heavy wheels and tires usually kill the diff internals, and good traction with big power kill the ring and pinion.

[TexasSP]

My stock 3905 diffs held up fine to 6s for a year. This was with 40 series bowties/dish wheels and stock tires/wheels as well.

[blueb8llz]

one year huh. ill be happy with that. ill just buy another complete stock diff off ebay for 20 bucks shipped...unless someone has a complete 1/8 style direct bolt on diff for sale?

[TexasSP]

They have held up longer, it's just that I sold the maxx to sunnyhoutx. He runs BL through it as well, 6s I believe too.

[blueb8llz]

but did you guys have it geared for 55 mph+?
were you using 3s zippy lipos by any chance? because im having a heck of a time finding one that will fit the tray.

[TexasSP]

I was using Flightpower EvoLite 5350 mah packs in 3s config. I did not constantly gear for 55 but it ran fine when I did. I kept it geared for 43-45.

I ended up having to get the traxxas extended hold downs for the batteries to fit. It was still tight but worked.

http://www3.towerhobbies.com/cgi-bin...?&I=LXTKN7&P=7

[kulangflow]

My 3905 diffs were fine with 4-6s. I killed a couple of drive shafts, but never a diff.

[ZippyBasher]

I have busted 2 ring and pinions but that is from not having them properly shimmed.

Shim them from the start and you should be good to go.

6s Rhino 4900 Zippy's, medusa 70mm 1600kv.

[blueb8llz]

so those extended tie downs are just taller right? i was thinking of just using velcro. the thing about them drive shafts are....were you checking on that lil allen screw that connects the shafts together?
because after every run , most of the driveshafts need tightnening.
especially the ones underneath the truck..the centers plus that one on top of the chassis (underneath the tranny).
hey zippybasher, are you using one 6s lipo or two 3s lipos? if its two 3s lipos, can you give me a link to the ones you have.

[ZippyBasher]

http://www.hobbycity.com/hobbycity/s...idProduct=7298

These ^^ - 2 in series (of course)...

Just fit a 3905 battery tray if you remove where the black tie downs secure to the plastic grey chassis.

I got pics I can post later when im at home...

[blueb8llz]

sure please post pics when you get a chance. was it hard to remove that black tie down? and how did you do it?

[ZippyBasher]

Here ya go man! Always nice to help a fellow RCer.

Remove the Black tie downs from both ends of battery tray (I think it was screwed in from the bottom. )




and use a dremel tool to remove the grey "wall" in the back to make the tray longer.



cut a small slit in the chassis the allow velcro to slide through.

also a small cutout in the front for the wire to pass through.



PS Never had a problem after dremeling that part away, didnt seem to weaken it at all. because I snapped 2 chassis' after doing this and never was broken near that spot.
Now I have to take an updated shot of her because it looks nothing like that anymore. LOL

[ZippyBasher]

I guess this sums it up. Here is a tray from a 3905 I used as a battery tray for my FLM chassis. Perfect fit.

And no I dont run them on the bottom, I am in the process of making a lower AL plate.






There shots from this year...