"Direct Drive to Diff" MT2 18SS

[lincpimp]

Nice looking conversion Metalman! You were right, the MT2 chassis is quite a bit narrower than the old redcat that I am using. You still managed to get everything in there, and I really like your mech brake setup, quite innovative!

I am suprised that the esc is having problems, what kinds of adjustment does it offer? If it has some sort of startup power or torque adjustment, set it to high, or full. Since you are using mechanical brakes and high voltage you could try a phoenix 45 hv esc. The castle startup should be better.

[ilpufxit]

It was only after I sold my MT2 and paid 3 times as much for a CRT.5 that I realized just how similar they are. It seems like the CRT would be better if it was a little longer and guess what, the MT2 is. I bought the MT2 because I had blown up the diffs on several 1/10 cars with BL. I thought the MT2 diffs probably would hold up. I moved on to my E-Maxx without doing the conversion. The CRT is more refined and the center diff makes it much more driveable. So now I wonder how I could incorporate a center diff into a direct drive build. It might also provide the key to reducing driveline shock?

[MetalMan]

Originally Posted by BlackedOutREVO

Yeah, I have no clue what I would do direct to diff in... but that will be cool when the cogging is gone, or close to gone

Darn rain!

It's not raining anymore, but the rear diff is still toast, and I have finals this week so my RC time is going to be reduced. Hopefully I can still pull something off.

Originally Posted by lincpimp

Nice looking conversion Metalman! You were right, the MT2 chassis is quite a bit narrower than the old redcat that I am using. You still managed to get everything in there, and I really like your mech brake setup, quite innovative!

I am suprised that the esc is having problems, what kinds of adjustment does it offer? If it has some sort of startup power or torque adjustment, set it to high, or full. Since you are using mechanical brakes and high voltage you could try a phoenix 45 hv esc. The castle startup should be better.

Thanks! This ESC offers adjustments for LVC, LVC type, startup (super soft, soft, and normal), and timing. I currently am running it with essentially no LVC (not that it matters), normal startup, and high timing.

The HV-45 would be nice, and would definitely start better (my HV-110 starts the KB45 in my Savage very nicely), but it's still $35 more than this OEM RC ESC.

Originally Posted by ilpufxit

It was only after I sold my MT2 and paid 3 times as much for a CRT.5 that I realized just how similar they are. It seems like the CRT would be better if it was a little longer and guess what, the MT2 is. I bought the MT2 because I had blown up the diffs on several 1/10 cars with BL. I thought the MT2 diffs probably would hold up. I moved on to my E-Maxx without doing the conversion. The CRT is more refined and the center diff makes it much more driveable. So now I wonder how I could incorporate a center diff into a direct drive build. It might also provide the key to reducing driveline shock?

It's too bad the MT2 diffs can't hold up to that much power, even with aluminum diff housings and all hardened gears. The CRT.5's diffs are much better.

It would be interesting to incorporate a center diff into an outrunner motor. Based on how we are currently doing this "direct drive to diff" stuff, there doesn't seem to be a way. However, a oneway on the front driveshaft would be helpful, as it would allow us to have rear-only braking, which can put the trucks sideways into turns.

There has also been another way to reduce stress on the driveline that we have only briefly discussed - adding two slipper clutch setups, with each one between the outrunner motor and the diffs. I've put some thought into it, but am very far from actually making anything of that type.

[sikeston34m]

Originally Posted by ilpufxit

It was only after I sold my MT2 and paid 3 times as much for a CRT.5 that I realized just how similar they are. It seems like the CRT would be better if it was a little longer and guess what, the MT2 is. I bought the MT2 because I had blown up the diffs on several 1/10 cars with BL. I thought the MT2 diffs probably would hold up. I moved on to my E-Maxx without doing the conversion. The CRT is more refined and the center diff makes it much more driveable. So now I wonder how I could incorporate a center diff into a direct drive build. It might also provide the key to reducing driveline shock?

The E maxx setup behaves different than the Direct Drive to Diff Revo. With the E maxx, you have gear options. It will cog occasionally when you take off in 2nd gear. But will explode out of the hole in 1st every time even if you "grab" WOT from a stand still. That's the difference gears can make.
Be thinking ahead of time about upgrading your diffs. The rear one won't last long.

[GO-RIDE.com]

MetalMan, that is a really cool project. Thanks for sharing the build. Is there a smaller outrunner motor that would work good with a MambaMax and fit in a CRT.5? I really like my CRT.5, but I wish it was lighter and had more room on the chassis for batts. Does removing the center diff make driving on a track a lot harder? Is the direct drive system more for bashing?

Thanks again!

[MetalMan]

Originally Posted by GO-RIDE.com

MetalMan, that is a really cool project. Thanks for sharing the build. Is there a smaller outrunner motor that would work good with a MambaMax and fit in a CRT.5? I really like my CRT.5, but I wish it was lighter and had more room on the chassis for batts. Does removing the center diff make driving on a track a lot harder? Is the direct drive system more for bashing?

Thanks again!

I'm sure there is a smaller outrunner that would work just fine. In his Redcat 1/10 4wd truck lincpimp is using a 2826, which is a bit smaller than mine. You'll want a motor with a kv of ~900 if you use 4s Lipo and 3.5" tire to achieve 40mph. The Mamba Max might have difficulty starting the outrunner with its current software, but the future software release (if it ever comes out) should fix that.

I honestly couldn't say if this setup is good for bashing. Bashing can put a lot of strain on drivetrain parts as it is, and if you remove the center diff and not have a slipper clutch with an outrunner setup, you'll put even more strain on the drivetrain components.

As for driving with this setup on a track compared to a center diff, I have absolutely no idea. We can make guesses, but no one has tried a "direct drive to diff" outrunner setup on the track so far, and certainly no one has compared it to an inrunner/center diff setup.


Well, I have good news. I took apart the MT2 diffs and found no metal shavings in either the diff housing or the diff cup. There was, however, a wheel nut that loosened while driving last night, which caused one of the wheel to get stripped at the hex (the MT2 has metal drive hexes). That was the problem that I thought was the rear diff.

[sikeston34m]

I'm glad you found it wasn't any worse than that.

[lincpimp]

I really think that the direct to diff outrunner setup could do with some sort of slipper arrangement. I was thinking to use a revo slipper on each end of the motor. Where the spur is normally mounted, a plate with standoffs and some sort of adapter to mount a drive cup could be substituted. This would require shorted center driveshafts. Not sure if this would be feasible, but it is all I can come up with.

Here is an idea that will really annoy the electric diehards!!!

Why not make the center shaft of the outrunner capable of mounting a nitro clutch on either end? That would create a mechanical disconnet, and cure the startup cogging problem. Mechanical brakes would also have to be employed though, raising the complexity a notch.

Plus I have no idea how big the diameter the nose of a nito engine crank is. It would have to be smaller than 5mm to allow the shaft to plass thru the bearing, etc, in the outrunner. Bigger outrunners use the 6mm shaft, so maybe it would work.

I only throw this idea out cause the cluch adapter on my revo really makes the motor work smoothly. I have no idea if the nitro cluch would be strong enough to handle the power and torque of the outrunner.