"Direct Drive to Diff" MT2 18SS

[MetalMan]

Prompted by sikeston34m's "Direct Drive to Diff E-Revo Build" thread I have started work on turning my speed demon, inrunner-powered MT2 18SS into an insane outrunner setup.

Here's what I currently have in my possession:
-HPI MT2 18SS with aluminum diff housings
-KMS 4120/6 outrunner motor
-OEMRC 100amp 12s airplane ESC with programming card
-PiStix adapter
-10 fresh A123 cells from a Dewalt 36v pack (will be run 6s normally, 10s for speed runs)
-CCBEC for running with 6s A123
-Airtronics 357 for steering, and I'll try to work with my Hitec 5245mg for braking

Need:
-turn motor shaft from 6mm to 5mm, and modify it to work for the intended setup
-Servo mounts (steering and brake)
-motor mount, looking into making one out of polycarbonate for decent shock absorbtion and low weight
-gotta make the battery packs (6s shotgun and 4s shotgun)
-work on dogbone lengths

Like the AXI sikeston34m is using, this motor uses 3 bearings, and appears to be of good overall quality. And it helps that I got it at a good discount. Also, it looks like the stator is keyed to the bearing holder/front endbell (I can take a pic of this if you guys want to see what I am referring to).

This build will be better documented than my other projects. Usually I tend to outline a project, get initial pics, finish it, and then post finished pics. But that's no fun for anybody besides myself.

[sikeston34m]

Hey!

I hope you don't mind if I drop in on this thread from time to time.

I love that ESC! I wanted to use it, but I haven't figured out how to put the mechanical brakes and the servo back into mine. When the transmission was tossed out of the setup, my brake bracket went with it. I have thought about designing a bracket that bolts to the frame, since the 4120 is shorter and allows room for the brake rotor.

That's a good looking motor. Yes would you please show me the keyed stator? Sounds like a possible candidate for a custom wind project if I can make it removeable. To wind, test, take apart and rewind, test again.

Can you lead me to some pictures of the HPI MT2 18SS with the body removed? I wanna check this out. TowerHobbies shows spec but not many pictures.

4" tires.....hmmmmm. What diff ratio are we looking at?

Weight: 4.96 pounds!

It does look like a good one to convert. I'll help you if I can.

[sikeston34m]

Ok, I see it now. Diff Ratio: 2.92:1

I've been looking at the LSP and considering a Direct Drive setup for it. It already comes with the 4.3:1 Diff ratio's. I also like how the frame is setup. It comes with cvd's and alot of tough stuff. I also like how low the center of gravity is.

[sleebus.jones]

Originally Posted by sikeston34m

I love that ESC! I wanted to use it, but I haven't figured out how to put the mechanical brakes and the servo back into mine.

Same here, but I'd rather stay away from mechanical brakes if I can. I just wish this ESC could handle the braking chores of cars, but I don't think it's up to it.

[sikeston34m]

Originally Posted by sleebus.jones

Same here, but I'd rather stay away from mechanical brakes if I can. I just wish this ESC could handle the braking chores of cars, but I don't think it's up to it.

No it doesn't have conventional car/truck brakes. It probably has some sort of drag brake, but that won't work.

Some good power handling ability though.

I think MGM has got it all figured out though, except for that price tag.

[sleebus.jones]

Originally Posted by sikeston34m

I think MGM has got it all figured out though, except for that price tag.

I agree with you 100%. I would LOVE to run the 9032, but that price tag...

[johnrobholmes]

This will be cool to watch come together. I will have to post my build up now, Im doing a solid axle direct drive conversion.

[MetalMan]

Here's the stator:


I was modifying the motor shaft, and got both ends turned down to 5mm, and the groove for the snap ring cut, using a combination of my drill press, Dremel with reinforced cutoff wheel, and file. However, I wasn't able to drill the holes the pins will go through. One hole is now about 1mm deep, but then my drill bit broke... This steel is very tough. Time to order a new drill but, and hope for better luck next time.

[sikeston34m]

Originally Posted by MetalMan

Here's the stator:


I was modifying the motor shaft, and got both ends turned down to 5mm, and the groove for the snap ring cut, using a combination of my drill press, Dremel with reinforced cutoff wheel, and file. However, I wasn't able to drill the holes the pins will go through. One hole is now about 1mm deep, but then my drill bit broke... This steel is very tough. Time to order a new drill but, and hope for better luck next time.

Better order more than just one drill bit if you plan on drilling that. Get Cobalt! That's some really hard stuff!

The AXI I used on the Revo had the snap ring too. I didn't use it. The magnetic force keeps everything in line as long as you don't have a prop out there pulling on the endbell.

That looks like one tough stator. You don't have to worry about that one spinning on the bearing holder being key like that. Thanks for the picture.

[MetalMan]

I ordered three drill bits, all having different coatings, and two of them are short-length:
-short length high-speed steel
-regular length heavy duty cobalt steel
-titanium nitride coated short length
All are about 2.5mm which is the diameter of the screw pin that holds on the dogbone cups.

[starscream]

Does the OEMRC 100amp 12s airplane ESC have Lipo cutoffs?

Never mind, I found the online manual and see it has the LVC built-in

[MetalMan]

Unfortunately I can't take advantage of the Lipo cutoff settings, since this truck will be running A123s. It's set to NiMh Low, so I will have to make sure I stop driving when I lose power.

[sikeston34m]

Originally Posted by MetalMan

Unfortunately I can't take advantage of the Lipo cutoff settings, since this truck will be running A123s. It's set to NiMh Low, so I will have to make sure I stop driving when I lose power.

What is the lowest Lipo cutoff per cell on this ESC?

I have been setting the Quark Lipo cutoff to 2.4v, I think it was, and it works great with the A123's.

By the time they get that low, they are pretty much done anyway.

[Arct1k]

MM Can do custom as well...

[MetalMan]

MM, as in my user name or Mamba Max? LOL
If you're referring to the Mamba Max, that's true, but it doesn't pertain to this discussion. If you're referring to me, then I'm just confused .

The OEMRC 12s 100amp ESC can be set to cut off at 2.6v, 2.85v, or 3.1v. 2.6v is a bit high for A123 IMO, which is why I have chosen to run the truck until it dumps.