1940/6 + MM Questions

[BP-Revo]

I know I'm just going to have a bunch of random questions so I figured I'd make a thread for it. First off, what gearing should I use? An approximate Pinion/Spur ratio would be nice.

Second, what kind of top speed will I be looking at?

What are you running this in?

[BP-Revo]

My G2R with a G1 Single Speed

[crazyjr]

the 6turn might be too much for the MM, the 7 turn is similar to the 7XLfegaio with awsome power. Thats what Mike has recomended to me

Yeah, that 6XL might be a tad much for the MM in a truck. The review that RC driver (I think) did had their Revo doing close to 50 with an 8L. I suppose that the 6XL is going to be close in terms of kv rating, but it will pull more amps. If you gotta run something that hot, maybe the MM isn't your best choice. If I were putting a Revo together, it would have either an 8XL or 9XL in it. For that matter, a 10XL and run more cells. I think you should take a good look at the Quark controller.

[BP-Revo]

I was actually probably going to wait until the MMM came out. Its supposed to come out in April, and I can't get my bent chassis fixed till mid March, so I'll just wait.

Also, even though its a 1940/6, its only being run on 4S. So watts will be similar to a higher turn motor on 5S.

[captain harlock]

BTW, who said the MMM is going to be out in April? this seems too good to be true.

April for the Monster Max? Can't wait!

[Serum]

Look at the KV values of these motors; this information can be found on www.bk-electronics.com; you can do the math, multiply the kv with the voltage of the 4S setup, and divide that number with the voltage of the 5S setup, and there is your KV for the same RPM on 5S.

Well, running that 1940/6 on 4S, may give you the same watts as running a lower turn motor on 5S, but the 1940/6 on 4S is going to draw a lot more current than the 5S setup, and current is where heat comes from.

[BP-Revo]

Well, I'll probably wait for the MMM. I would think it would be out by summer (which is the biggest deal for me).

Also, I have a question on the RPM's of a motor. I know I should aim for about 35-40k. But is this on 14.8v Nominal of the 4S Lipo? or 16.8 on a full charge? I'm guessing nominal voltage but I just wanted to be sure.

This sensorless bug is horrible...I'm now starting to debate whether I should get a 1950/5 Hi-Amp instead...Its KV is nearly the same but I know the 1950 will have a hell of a lot more torque.

I'm basically just aiming to get the right RPM on 4S...thats why I am wanting lower turn motors.

The problem is I know the 1950 will be way too much and I'm going to need a bunch of upgrades on my drivetrain lol...and my truck will become impossible to control...but its just so tempting...

[MetalMan]

When I calculate the motor to use on a certain voltage, I like to use values that are under load. For example, with Feigao motors, I use the kv values from BK that are under a load. For Lipo, I use 3.4-3.5v/cell, and for A123 cells I use 2.8-2.9v/cell. In 1/8 conversions, I shoot for 30,000-35,000 RPM loaded, since that RPM would pretty much be the worst case scenario (there's a good chance the RPM will be higher than that).

[BP-Revo]

Hmm...thats a good point there MetalMan.

Also, anyone know the difference between Hi-Amp and "normal" for Lehner motors?

Lastly, and this is really important. Do I have to grind my own flat spot onto the motor shaft? Someone PLEASE say no...I don't have the tools nor the heart to take a grinder to a brand new 300+ dollar motor lol...

[squeeforever]

The difference is that the Hi-Amp can't be reconfigured from wye to delta configuration as well as it just has wires coming out the back instead of plugs in the endbell. Oh, and sorry to say, but your gonna have to grind a flatspot on the shaft. A Dremel will suffice.

[BP-Revo]

CRAAAAAAAAAP... How will I go about it then? Clamp down on it with some pliers or possibly thin-nosed vise grips and grind away?

Also, will a compressor powered rotary tool suffice?