Direct Drive to Diff E Revo Build

[DrKnow65]

servo mixing could be used to drive the front motor harder when turning as the front wheels spin more rpm in a turn. Assuming a 3 channel remote is used. ch1=steering, ch2= rear esc, ch3= front esc.

[sikeston34m]

I'm finding the limitations of the bearings in the truggy diffs.

With the spiral cut gears of the 4.3:1 ratio, the pinion not only side loads the bearing, but it also pushes or pulls against the bearings.

I've been using steel ball bearings and they aren't holding up to the increased torque levels of my setup.

I could hear the diff Pop occasionally in the rear under hard acceleration. I took the diff back apart, and found alot of slop in the bearing closest to the pinion. I swapped positions with the two bearings, reshimmed to take all the play out and it worked perfect.

Now about 4 runs later, it's doing it again. On 6S, it will do 60mph+ and top out very quickly. With NO slipper, the setup is able to transfer all the torque that the motor will make. Which is alot!

A needle bearing with thrust bearing type qualities would be ideal, but I can't find any in this size. 8x14x4mm.

Is Ceramic Nitride the toughest out there in a ball bearing? like this one:
http://www3.towerhobbies.com/cgi-bin...?&I=LXPVB1&P=7

I've heard they are.

@Lincpimp - You need to consider this on the setup you're looking at. Tough Diffs are a must.

[zeropointbug]

Wow, that is deadly looking! Use that with a speed record! I have mentioned the wheel motor idea a few times on this forum, but yeah it won't really work with these monster trucks. MAYBE, smaller on road cars... but they would need a very high power density to keep the weight down in the wheels, like someone said "unsprung weight" is a killer.

A few companies are doing wheel motor for full scale cars however, with GREAT results, works much better than motor/tranny/driveshafts.


About the diffs Sike.... I think all pinions have thrust on them when loaded, these spiral cut gears may just have more pressure is all. I don't really know what the best bearing are in these sizes? Sorry.

[sikeston34m]

Originally Posted by zeropointbug

Wow, that is deadly looking! Use that with a speed record! I have mentioned the wheel motor idea a few times on this forum, but yeah it won't really work with these monster trucks. MAYBE, smaller on road cars... but they would need a very high power density to keep the weight down in the wheels, like someone said "unsprung weight" is a killer.

A few companies are doing wheel motor for full scale cars however, with GREAT results, works much better than motor/tranny/driveshafts.


About the diffs Sike.... I think all pinions have thrust on them when loaded, these spiral cut gears may just have more pressure is all. I don't really know what the best bearing are in these sizes? Sorry.

What diffs are you running in your 7S1P A123 setup? Ever had problems?

I know that truck really runs!

[zeropointbug]

I recently got a Revo 3.3 (September), and am running 7s1p at the moment, with the emaxx tranny (GM single speed). I am using the stock diffs right now, as the truck is quite light (just over 10lbs) the diffs are holding up fine.

7s1p has pretty good power... 7s2p however, halls ass man!

[lincpimp]

Originally Posted by sikeston34m

@Lincpimp - You need to consider this on the setup you're looking at. Tough Diffs are a must.

Yes, I understand the need for a good diff! I have a feeling that your combo of larger (heavier) wheel/tire and higher (numerically) diff ratio put more strain on the pinion gear than my smaller (lighter) wheel/tire and lower (numerically) diff ratio. Your truggy pinion has fewer teeth than my buggy pinion (10 to 13) and that can cause mesh problems as well (not sure if it is?). Plus I will run on road which should offer less traction as my tires have much less contact patch than a mt tire.

The ceramic bearings are most likely a good idea, as they are built better and should last longer.