Noobie to Brushless, need little help/advice! - RC-Monster Forums

mudrunner4ever · **Noobie to Brushless, need little help/advice! -** 03.01.2007, 05:31 PM

hey guys,
i have a E-Maxx that has seen A TON of abuse and has some good mods to it. i just wasnt with the power i was getting with te stock motors so i turned to brushless. im over on rccrawler and savage-central a lot. i posted a thread on rccrawler and they got me started. they told me to go with the castle creations speed control(as i can see is very popular on here) and they told me to run a feiago motor. i started looking around and i noticed that there are a ton of feiago 540 size motors. so this is were i need you help. what motor do i go with?

i mainly race with my club(just short track J style or similar) and some bashing. when i get my motor i expect to do a lot more bashing. so basicaly a all around set up. and what is a rough estimate on gearing that i should run? thanks in advance!!!!!

Serum · 03.01.2007, 05:33 PM

Welcome to the forum Mudrunner!

Here is an interesting read, i think it will answer most of your questions.

http://www.rc-monster.com/forum/showthread.php?t=5115

If any question remains unanswered; Feel free to ask!

mudrunner4ever · 03.01.2007, 06:16 PM

o man, long read. ill get back to ya in a bit!

mudrunner4ever · 03.01.2007, 06:58 PM

Quote:

Originally Posted by Serum

Welcome to the forum Mudrunner!

Here is an interesting read, i think it will answer most of your questions.

http://www.rc-monster.com/forum/showthread.php?t=5115

If any question remains unanswered; Feel free to ask!

i read that. i didnt have very many questions to start with besides a sugested motor. i read through the whole page and then did the sugested motor chart thing. when i entered everything it didnt give me a certin motor. all it said was that my motor may over heat. so what motor should i go with?

BrianG · 03.01.2007, 07:10 PM

I assume you were using the "motor selector"? If it came up with the overheating warning, your required RPM based on the values you entered must have been over 40,000. And the reason why it came up with no motors is because there were no matches (kv wise) based on the weight of the vehicle and the required kv to reach your desired speed.

What values were you entering? (Hint: use the "Export Values" button on the webpage, highlight the data, and paste it here in a post).

mudrunner4ever · 03.01.2007, 08:51 PM

this is wat i came up with,
Vehicle Weight (approx): 15
Desired top speed in MPH: 50
Differential Ratio: 2.8461538461538463
Transmission Ratio: 2.769230769230769
Additional Ratio: 1
Spur Tooth Count: 64
Pinion Tooth Count: 20
Battery Voltage: 7.2
Tire Diameter (inches): 5.75
Total Ratio: 25.2213 : 1
Tire Circumference: 18.064 inches (458.83 mm)
Required Motor RPM: 73719.725 RPM
Required Motor KV: 10238.851 RPM/V
Good Motor Choices: No motors of this class fit the parameters you entered.
Better Motor Choices: No motors of this class fit the parameters you entered.
Best Motor Choices: No motors of this class fit the parameters you entered.

this is a rough guess. being that i dont now the weight of the vechile, top speed, what transmission gear(1st or 2nd), Spur and Pinion tooth and what tire size ill be running.

BrianG · 03.01.2007, 09:02 PM

I see a couple of problems there.
- Your voltage is too low at 7.2v. You should enter 14.4 for 2x6cells packs, or 16.8 for 2x7cell packs. Because the voltage is so low, the motor kv has to be extremely high to compensate.
- You want a 15lb truck to go 50mph! Wow. While possible, you're gonna need some serious power.
- It looks like you chose 1st gear as the tranny ratio. You're gonna be hard-pressed to get 50mph in first gear. Imagine what 2nd gear would do!

Most people lock their trannys in second gear - BL has so much power that first gear is useless unless you want to go very slow a lot.

I entered some more reasonable values and came up with this:

Vehicle Weight (approx): 15
Desired top speed in MPH: 45
Differential Ratio: 2.8461538461538462
Transmission Ratio: 1.7222222222222223
Additional Ratio: 1
Spur Tooth Count: 64
Pinion Tooth Count: 22
Battery Voltage: 16.8
Tire Diameter (inches): 5.75
Total Ratio: 14.25952 : 1
Tire Circumference: 18.064 inches (458.83 mm)
Required Motor RPM: 37511.425 RPM
Required Motor KV: 2232.823 RPM/V
Good Motor Choices: BK Wanderer 7 XL (kv=2145)
Better Motor Choices: No motors of this class fit the parameters you entered.
Best Motor Choices: Neu 1515 1y (kv=2200) LMT 1940/7 (kv=2239) LMT 1950/6 (kv=2178)

mudrunner4ever · 03.01.2007, 09:14 PM

ok, so that sounds better. i didnt think about have 2 packs. i only thought what one pack was, oppps!! i had no idea how much my truck weighs. its basically a bone stock e-maxx. i have pro-line power stroke shock, titanium turnbuckles, mip cvds on all four corners(not centers) and its got Maximizer diff in the rear(soon to be in front also). do you have a link to any of thoughs motors? preferably a site that takes paypal echeck or ebay? thanks for the help!!!

BP-Revo · 03.01.2007, 09:24 PM

If your run 5S lipo, it will be much easier to acheive the 50mph.

mudrunner4ever · 03.01.2007, 10:06 PM

i cant run lipos. 1. i dont have the charger for them and 2. the club leader said we cant run them, hes seen wat they can do.

jhautz · 10:49 PM

Quote:

Originally Posted by mudrunner4ever

ok, so that sounds better. i didnt think about have 2 packs. i only thought what one pack was, oppps!! i had no idea how much my truck weighs. its basically a bone stock e-maxx. i have pro-line power stroke shock, titanium turnbuckles, mip cvds on all four corners(not centers) and its got Maximizer diff in the rear(soon to be in front also). do you have a link to any of thoughs motors? preferably a site that takes paypal echeck or ebay? thanks for the help!!!

Hmmm.... How about this site!:018:

http://www.rc-monster.com/proddetail...540C_XL&cat=20

Quote:

Originally Posted by mudrunner4ever

i cant run lipos. 1. i dont have the charger for them and 2. the club leader said we cant run them, hes seen wat they can do.

People are paranoid about lipos cuz of the old horror stories. I agree they should be treated with respect, but as long as you pay attention to what your doing and use common sense you wont have nay issues.

IMO most of the lipo scare stories came from a couple years back when people had no clue what they were doing. CHargers are better now and so is the knowledge of lipo.

If Lipo is still out, check into the A123 Li-Ion cells. Safe and high power.

Remember... A brushless setup is only as good as the power you supply it.

mudrunner4ever · 03.01.2007, 11:04 PM

Quote:

Originally Posted by jhautz

Hmmm.... How about this site!:018:

http://www.rc-monster.com/proddetail...540C_XL&cat=20

People are paranoid about lipos cuz of the old horror stories. I agree they should be treated with respect, but as long as you pay attention to what your doing and use common sense you wont have nay issues.

IMO most of the lipo scare stories came from a couple years back when people had no clue what they were doing. CHargers are better now and so is the knowledge of lipo.

If Lipo is still out, check into the A123 Li-Ion cells. Safe and high power.

Remember... A brushless setup is only as good as the power you supply it.

to start off with, whats the difference between the 7XL, 8XL and the 9XL?

and our club has sent out trucks 60ft in the air, YES 60ft! on average they see about 20-30 so the shock of the landings my cause a big boom:004:

BrianG · 03.01.2007, 11:11 PM

I agree with jhautz about the lipo thing somewhat. I have some now and am still paranoid about them, but I do think that the technology and understanding has advanced quite a bit since the horror stories. Some people have even tried to blow some by deliberate mischarging/running them over (yes, you CHC :)) and they puffed, but that's it. But, no matter what, the owner of the track sets the rules so that's that.

I would shoot for a 40mph top speed at the most, especially for track use. Consider a stock emaxx goes about 25mph IIRC, doubling the speed to 50 would just be insane, especially in a monster truck. And I don't even want to think about the damage from a crash at that speed! :) Anyway, 35-40mph would be much more attainable using regular cells, and you'll get better runtime since you won't need such a powerful system.

And the motors in the "motor selector" are all available here. :)

BrianG · 11:14 PM

The number is the number of turns of wire in the motor. More turns means the motor spins less rpms per volt. Less turns means a faster motor. The XL part refers to the length of the motor. And you do want an XL for a larger truck like a Maxx. You pick the motor turns by the amount of battery voltage you plan to use while keeping the max total RPMs to about 35k.

jhautz · 03.01.2007, 11:37 PM

OK... I wouldnt send my lipos 60 ft in the air either. That falls in the ''use common sense'' clause.:005: A123 cells are still very viable for you though. Just as durable and safe as the old NiMH cells, but capable of putting out much more current.

As an addition to brians last post:

Generally a motor with more winds will generate more torque with less rpm on the same voltage. Also with the same load (ie. gearing) it will draw less current which translates into a cooler running system and longer run times but lower top speeds.