Direct to Diff Redcat Updates

[lincpimp]

Spurred on by Sikeston's revo and Metalman's MT2, I decided to break out the redcat that I modified for a direct to diff drive and update it with a new motor. I purchased an Axi 2826/12 and modified the shaft so that I could drive from both ends of the motor. Modded my mount slightly to fit the longer motor and added some electronics. The truck runs much better, stil some startup issues with small throttle inputs. I ran it on 5s 2500 18c lipos and it seems to top out around 40mph, with plenty of power. Heres a few pics:




Heres a link to the old thread in the remp forum: http://www.rc-monster.com/tempforum/...read.php?t=845

[sikeston34m]

That looks good. How does this one do compared to the old motor? Are temps in range after a good run?

If you want some "stone cold" motor temps, check this out.

http://www3.towerhobbies.com/cgi-bin...?&I=LXPRB0&P=7 Tower is famous for typos. I know it says "Plastic Construction", but the cooler for the 41xx series are metal.

You could lose some weight with a UBEC.

How warm does your Lipo get if you run it hard? I'm just wondering if it can keep up with the demand.

How did you mod the cvd's? This motor looks longer than the old one.

Here's some suggested settings for the Quark that I have found to work best with the outrunner setups:

"Inrunner" setting
Starting Power set to "High"
Lipoly "Manual" setting with custom cutoff voltage

It looks really good though. I think the AXI motors are sharp.

[lincpimp]

Much better performance than the old motor. The stator is longer, but the shaft is the same overall length as the old motor's shaft. I like the fan idea, am I correct in thinking it bolts to the can with the fins pointing away from the motor?

I do need to wire up a ubec and make a battery tray, did not have any deans micro connectors for the ubec so I used the rec pack instead. The quark and the lipo barely got warm. The lipo did not have any issues, and I got about 20mins out of it with some left in the pack.

I had the settings as you describe, save for having the cutoff set at Lipoly High. I need to change that as I like a 3.2v cutoff.

I need to experiment more with this setup, I would like to go with larger tires and maybe drop down to 4s as the truck is plenty fast with the current setup and taller tires will just make it faster. The redcat seems to be holding together ok, only the servo saver spring is too weak and causes alot of slop. I may just make it solid at the the bell crank and use a heavy duty servo mounted saver.

[lincpimp]

Scratch that, I see that the fan blades point inward toward the motor. Does it draw air through the motor like a squirrel cauge (a/c) fan or does it blow air through?

[sikeston34m]

Originally Posted by lincpimp

Scratch that, I see that the fan blades point inward toward the motor. Does it draw air through the motor like a squirrel cauge (a/c) fan or does it blow air through?

It draws air through the motor, and blows out at the fan. The mounting end is where cool air enters, the fan end is where warm air exits.

The 41xx version moves a good amount of air. I'm sure this one will too.

[sikeston34m]

Woo Hoo! The Mail Lady came today bearing gifts!


Hey! There's something there on the left that you could use Linc. (Notice: The little smiley is looking right at it! LOL)

[MetalMan]

The Redcat looks pretty good! (or at least what you have done to it does)

That motor you're using, I'm using pretty much the same motor but the KMS version in my rock crawler.

I noticed our motors are both oriented with the mounting end of the motor toward the rear of the trucks. Interesting .

That chassis looks a lot wider than the MT2 chassis I'm trying to work with. And I'm sure it helps that your motor is also quite a bit smaller in diameter (for trying to fit everything on the chassis).

[lincpimp]

Originally Posted by sikeston34m

Hey! There's something there on the left that you could use Linc. (Notice: The little smiley is looking right at it! LOL)

Yeah, I have 2 of the ccbec brand new in the packs. I like to attach them to the esc wires by means of a short length of small gauge wire with a micro deans on it. That way I can remove the esc without having to remove the bec. For 20 bucks or so the ccbec is cheap enought to have one on each vehicle. I need some micro connectors so I just used the rec pack.

Metalman: so far the red cat seems to be well made in the diff and suspension department. I am having issues with the steering servo saver that is built into the bellcrank. I will try to find a stronger spring to tighten it up, it is a little sloppy at the moment. I am actually thinking of moving the steering servo and the motor mount so that I can fit an emaxx tray on the battery side of the chassis. Would lower my cg and look neater. I am sure that the off set motor would be ok, as the torque effect would be less pronounced. Moving the motor over would give the chassis more leverage in counteracting the torquing of the motor. I wil lift the steering side tires almost off the ground under hard acceration now!

[sikeston34m]

How hard does it accelerate?

[BL_RV0]

let us know how that fan works.

[lincpimp]

Originally Posted by sikeston34m

How hard does it accelerate?

Very Hard!!!!

If you punch it from a standstill it takes off spinning the tires violently, and then usually torques the chassis and unloads both tires on one side and then spins out, sometimes flipping over. Once the tires warm up the grip much better and that helps. It is not slow at all, must be near 40mph, need to radar it when I charge the battery again.

[sikeston34m]

Originally Posted by lincpimp

Very Hard!!!!

If you punch it from a standstill it takes off spinning the tires violently, and then usually torques the chassis and unloads both tires on one side and then spins out, sometimes flipping over. Once the tires warm up the grip much better and that helps. It is not slow at all, must be near 40mph, need to radar it when I charge the battery again.

There has been some concern expressed in the past about "spool up" time when using outrunner motors. How would you describe the AXI's "spool up" time?

Can you get us a video sometime?

I thought you might be pleased with that motor.

[lincpimp]

Ahh "spool up time"

I will say that it does not spool up as fast as an inrunner with a transmission. Now I will also say that I do not have any experience with a direct to diff setup using an inrunner. I will say that my experiences running an align 600 l and xl thru a stock emaxx tranny on 5s was different than a similar inrunner setup. The align had tons of power, but it did accelerae more smoothly, and slightly slower. Still emough rpm to brake the tires loose and wheely, but not as violent as a similar kv inrunner with the same batts, gearing, etc.

The axi in the redcat can still light up the tires till 20mph or so and has enough rpm to flip it over if the tires get loose and it slides sideways. I may try a monster 125 and 4s 5000 20c batts with some taller tires and see how the startup is. The taller tires should make the motor work harder and the 125 and 5k batts should be able to provide the necessary current if the motor needs alot to get moving. Performance on 5s is great, but I would like to run a taller tire and if I stick with 5s it will be geared for almost 60mph, which is a bit much.

[sikeston34m]

Originally Posted by lincpimp

Ahh "spool up time"

I will say that it does not spool up as fast as an inrunner with a transmission. Now I will also say that I do not have any experience with a direct to diff setup using an inrunner. I will say that my experiences running an align 600 l and xl thru a stock emaxx tranny on 5s was different than a similar inrunner setup. The align had tons of power, but it did accelerae more smoothly, and slightly slower. Still emough rpm to brake the tires loose and wheely, but not as violent as a similar kv inrunner with the same batts, gearing, etc.

The axi in the redcat can still light up the tires till 20mph or so and has enough rpm to flip it over if the tires get loose and it slides sideways. I may try a monster 125 and 4s 5000 20c batts with some taller tires and see how the startup is. The taller tires should make the motor work harder and the 125 and 5k batts should be able to provide the necessary current if the motor needs alot to get moving. Performance on 5s is great, but I would like to run a taller tire and if I stick with 5s it will be geared for almost 60mph, which is a bit much.

The outrunner has plenty of torque to push it geared for 60mph. When you do tire/battery changes, let the starting behavior show you the limits.

With the Revo, I have noticed if I "blip" it to about 1/4 throttle just for an instant, then back off, it starts great.

It doesn't seem to like trying to start with that first small step on the trigger.

Aaah, Rain, Rain, go away. I wanna take my Revo outside and Play.

[lincpimp]

Originally Posted by sikeston34m

The outrunner has plenty of torque to push it geared for 60mph. When you do tire/battery changes, let the starting behavior show you the limits.

With the Revo, I have noticed if I "blip" it to about 1/4 throttle just for an instant, then back off, it starts great.

It doesn't seem to like trying to start with that first small step on the trigger.

Aaah, Rain, Rain, go away. I wanna take my Revo outside and Play.

I noticed the same thing with my outrunner setups, a quick blip gets it moving and as long as it is rolling small throttle inputs work fine. I wish the quark had an adjustable throttle curve like the mm. You could give the curve a sharp rise at the beginning and then level it out again. I think that would given the motor enough "kick" to get it moving. Just ordered a fan for the axi and when that comes in I will rearranege the chassis so that the battery can lay flat. I will also try larger tires before I do anything and see how that works.

I know what you mean about rain, it rained here yesterday and it is so nasty and humid outside now.