1940/6 + MM Questions
 

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?

My G2R with a G1 Single Speed

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.

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.

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!

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.

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...

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).

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...

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.

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?

Whats the difference between Wye and Delta configuration too?

It's not hard to dremel a flat spot on the shaft. Just make sure the bearing and screw holes are covered so metal dust doesn't get in there. I just held my Neu shft with two fingers and used a small sanding drum on the dremel. Took about 1 minute.

IIRC, If you re-wire the LMTs from D to Y, you reduce the kv by a factor of 1.73 (I think). This allows you to run higher voltage in Y, and lower voltage in D and keep the same rpm.

Oh...ok.

Well, do you guys think I should stick with a 1940/6 or try a 1950/5 Hi-Amp? They have very similar KV (difference of like 1), but the latter obviously has tons more torque (and current draw).

Do you think it would be too much? I just figure if I'm going to spend this much money, I want to make sure its what I really want so I wont feel like "I should have gotten a more powerful one." But on the other hand I don't want my truck way over powered.

This is just what i have experienced with 4s2p 8K lipos, 1950/7T geared 16/44 in my truggy.. It is TOO much speed. I mean, this thing has amazing acceleration, the top speed hasent even been completely reached yet, but at around 2/3 throttle you dont even want to go faster, i cant imagine a lower Turn motor. If you were to go with a 1950, imo a 6T is the lowest i would go.

What speeds are we looking at here? 50mph? 60mph?

A vid would be great if you have one.

I guess I'll either go 1950/6 or 1940/7 then. That way I will get the Hi-Amp version of which ever I choose...the delta and Y stuff is too confusing for me...3 wires are pushing it;)

If i had a cam i would get a vid of it, im looking at getting one very soon.

I cant really say its top speed, but at not much more past half throttle it is well over 35, i might just get a GPS on it, need one of those too, lol.

Wow...that would put top speed over 50mph at the very least. Thats very fast. I have the same batteries (2x 2S 8K lipos = 4S), so if I run a 1950/6 it should be even faster...which would just be insane...

I think you just made my choice Sylvester.

Does anyone know how well a G2R drive train holds up to this kind of power?

Also...are 1950's pressed endbells or what? Please don't say they are pressed...

If your running a single speed, center dogbones, normal revo shafts, i think it should be fine. I hope your running a metal idler in your tranny :)

Current drivetrain is:

Stock Revo Diffs
Stock Sliders on 4 Corners
G2R "Stock" Dogbones in the middle
G1 Single Speed with UE Idler - but I think I'll be taking my lightweight output shaft out and opting for the steel one again... :eek:

Now...the big question would be 32P or Mod1 Gears?

Mod 1 gears for sure.. a strobe with the ofna 51T gear would be ideal..

Your drivetrain will be tough as nails once the 1/8 diff conversion comes out for the revo.. the stockers should last for a bit if not abused too hard, but once mike releases those diffs, you will be golden:)

But that would suggest sinking more money in...hopefully the stock one work. If not, I can throw in some robinson gears and maybe an aluminum diff cup and even diff case and hopefully that will work.

After I put in the 1950 and whatever ESC I use, I was hoping to be able to just run this thing without spending any money (other than a repair here and there).

Sylvester, do you know the overall gear ratio of your truck (the one with the 1950)?

The stocker or robinson slipper will never hold, I ripped up a pair of robinson pads before i went strobe, that was with a 9XL

I was referring to diffs.

For a slipper, I think I'll be getting ProCharged5.0's HSR slipper setup. That way, I can use Revo spurs too. Because I think I'm going to need a 40T spur with a 20T pinion to get the gearing I'm gonna need...

I don't think you can get down to the 40 but Procharged is doing a spur gear custom.

I'm running 4+year old Emaxx diffs on a 7XL and up to 5s without problems (stock plastic-cupped) so you should be ok with the upgrades

Procharged's HSR uses a Revo slipper...which means I can just use Nitro Revo spurs, which are available in 36, 38, and 40T. I'm going to need these because according to Brian's calculator I need to gear like 16/40 to get just 40mph...

Edit...nevermind: BrianG's calculator can only be so accurate. Lehner's KV values must be underload values, and his estimator must be set to accomodate for unloaded values. Because I just put in the specs for Sylvester's LSP and it gave me like 44mph...and from what I understand its a hell of a lot faster...

OK, I was under the impression it was a custom

BP - Spur/pinion ratio - 2.75 : 1
Final - 11.825 : 1

Based on your gear ratio's, I think a 16T pinion with a 48T-50T spur will be a good start for me.

Hopefully Mike can make me a 17T pinion...do any mods know the answer to that?

He can not make odd number pinions above 15T He has never been able to find gear rod stock in those tooth counts. I asked a while back. Anything above 15T is only even tooth counts.

Aww...oh well. Thats fine I guess...I'll find the right gearing some how.

Does the 1950 (or and 19 series motor, for that matter) have pressed or screwed endbells? Please don't say pressed...

Pressed.


Ha ha, just kidding. I believe they are screwed and are quite solid.

NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! (in an epic star wars style moan) :020:

lol :005:

Ok good...when I run with MetalMan he has at least 1 problem each time with the pressed endbell, so I didn't want to deal with that lol...

Not each time... 7XL first time, and 9L third time :). This was of course after running many times with both motors prior to that :).

Front is screwed and is solid. Same goes for rear. The lehner isnt ever gonna come apart itself, thats for sure!