Have some LMT questions...

[jhautz]

Originally Posted by jordan...

Patrick: I'm from Perth as well

so would the 1940/7 be able to handle 6s pretty easily?

I run the 1940/7 on 5s and it is very happy. This is in a big Savage as well. I think that motor on 6s would be a bit much. If I had the choice from the list you made below I would go for the 1950/7 on the 6s in a monster truk or truggy. It sounds like you will be running this in a truck of some sort. The slightly bigger 1950 will be happier in the heavier vehicle. For a buggy the 1940 would be a perfect choice but on 6s I would go for something more like a 1940/9. You really dont need to push these motors that hard to get them to make power. Another thing to keep in mind is that the Lehners give loaded kv values while almost all other manufactureres are giving unloaded kv values. so I tend to add +15 or 20% to the kv that Lehner lists when comparing the kv to other brand motors. And I also use the kv rating from http://www.lehner-motoren.com/ms19.php?la=en rather than from the speed calulator. I know there used to be some discrepancy in the kv on the calculator, I'm not sure if thats fixed or not.

Like Patrick says, you can use the rcm heatsink, but you cant put the bar across the back so it doesnt act as a clamp, and in reality it doesnt neeed the heatsink. The lehners run cool enough without it.

[jordan...]

sorry, i never mentioned i will be running it in my UE-Gmaxx (build thread in the Gmaxx section). I'm not going to be racing it, so i'm definately wanting it to be a bit overpowered

Looks like the 1950/7 is the go as my truck is full Alu/Carbon. So, am i right in saying that in a larger vehicle, the 1950 will run cooler and not be pushed to the limit, but be a tiny bit slower than the 1940 would be on 6s?

i really appreciate all the help, thanks guys
jordan

[jhautz]

Yes it should run cooler than the 1940. No it shouldnt be slower. With the bigger motor you can pull taller gearing to make up for the lower RPM.

[jordan...]

ok, so i've been crunching numbers in the calculator. I've been using 51/20 as a benchmark gearing (have no idea what pinions to consider with this one):

Enter Front/Rear Differential Gear Ratio (?): UE 1/8 scale
Enter Transmission Gear Ratio: E-maxx 2nd gear
Enter Spur Gear tooth count (?): 51
Enter Pinion Gear tooth count: 20
Enter total battery voltage: 22.2v
Enter kv rating of brushless motor 1867 (Lehner 1950/7)
Enter tire diameter in inches: 5.8

Total Motor Speed (?):41447.4 RPM
Theoretical Vehicle Speed (?): 49.23 mph (79.09 km/h)

not too shabby!! but then i tried with 51/25 gearing:

Enter Front/Rear Differential Gear Ratio (?): UE 1/8 scale
Enter Transmission Gear Ratio: E-maxx 2nd gear
Enter Spur Gear tooth count (?): 51
Enter Pinion Gear tooth count: 25
Enter total battery voltage: 22.2v
Enter kv rating of brushless motor 1867 (Lehner 1950/7)
Enter tire diameter in inches: 5.8

Total Motor Speed (?):41447.4 RPM
Theoretical Vehicle Speed (?): 61.54 mph (98.86 km/h)

thats more like it with tyre ballooning it pushes the 'theoretical' speed way over 60

Is it weird that the motor rpm did not change with the change of the gearing? Would it be alright to run that gearing, no warnings came up on the calculator, but would it be harmful to the motor or ESC? (probably going to run a MMM). I'm guessing some cooling issues might be experienced, and maybe a total lack of bottom end

thanks alot
jordan