Brushless setups. HELP!
 

Hey all!

I'm new to RCM but have trolled for a few days and found that theres a whole wide world outside of the foolish Traxxas forums and that this site has a TON of info to offer. Not to mention, allow a sense of humor. =) Not to sound like I followed Suicide Niels bandwagon...but I did.

Anyhow... I'm looking for some help in the area of my first project! I just picked up a slightly used 8T with a few sets of tires and bodies for cheap off of ebay and want to get this truggy haulin. I am really looking for a solid yet fast setup <'round 55ish> due to my large and open track.

I was looking at the Tekno kit and liked the idea of an electri clutch.. any opinions?
Also with that kit I'd like to use mechanical brakes so I'd need a 3ch radio with servo mixing correct, as well as a servo for it..duh.

Radio: Spektrum DX3R
Brake servo: Hitec 985MG Strong enough to do the trick?

And now comes the hard part.... Brushless stuff... I haven't been into R/Cs for very long but I have done an insane amount of reading. For ESCs the MMM seems the be the feature filled top of the line speedo with the ability for 6s and amazing programability.<-- is that a word? Anyone here have faith in the v3? I wouldn't mind waiting if so.

ESC: MMM MGM
Motors: Neu?

For motors I was looking at the 1515 1Y and the 2.5D. I'd rather not run 6s through the MMM purely because its using the ESC to its maximum abilities and with 4s I'm not sure I could gear the 1515 1Y for the 55ish range safely. The 2.5D on the other hand is a amp hog and I'm not sure what that involves.

I'm as good with custom work and soldering as a monkey is. Yea.. that bad,
so working with receivers and BECs and all that garbage is out of the question for me. Its bad enough I'm gonna let my LHS rape me for soldering taps for my
balancers//chargers//batts//motors and ESC.

Other items I was looking at.
Charger: Hyperion Duo
Steering: Hitec 7955TG
Wheels//Tires: LPR blacks with Crimefighters.
Batts: I'm completely open here.

For batteries I was looking for an Enerland cell due to their great quality, other then that 4s,5s,6s. Whatever I can fit in the Tekno kit sounds great! I'm hoping for the most runtime possible...not sure what can be fit in that tray.

In closing <this post is prolly to long to even look at> any help, opinions, and knowledge is welcomed! Thanks for the help guys and look forward to getting my build underway! :yipi:

For mechanical brakes you can use a Y-harness and disable the brakes on the esc.
As far as your motor/batt combo, well thats tottaly up to you. I also have done a crap load of research (Converting a Revo, waiting on parts), and found that for me the best range is 30,000rpm (came to this conclussion watching my friends).
Bigger cell battery, lower kv motor is your best bet.
Medusa motors seem to be holding up pretty well and are gaining popularity. They are not overpriced and a few have claimed even ran cooler then Neu motors. Not trying to talk you out of the Neu, just giving you another option.
My buddies have been running their MMM v2 for a couple months and no issues. Most (not all) people whos esc's have been "failing" is user error.
And if it does happen to fail, Castle is really good if it comes down to it.

1515 1Y is 2200kv, I would imagine 40,000 rpm in a truggy will be more then enough (unless you are bashing and just want to be nutso fast).
So a 5c lipo would be your best bet, 18.5 x 2200 = 40700rpm. You will be surprised who fast you will be.

Hyperion is a very good charger. The duo will require a 12v power supply, but if you plan on charging your batts at the track with your car battery it wouldnt matter, but i like to go to the tracks with charged batts.
If you dont need to charge 2 batts at once the Hyperion EOS0606i is AC/DC.

Steering servo, excellent choice.
LPR's all the way.

I hope I answered your questions, i dont know much about the gearing you should run, but maybe someone else will chime in.

Thanks for the feedback! Your quite informative.

Yea gearing and battery size are what I'm unsure of I guess. Does anyone have the specs on that battery tray? Whats the biggest 5s I could fit in there without trouble? I believe the Tekno kits clutch bell is a 13t...

So 13/48 - 1515 1Y - 5S = Roughly:

Differential Ratio: 3.3076923076923075
Transmission Ratio: 1
Spur Tooth Count: 48
Pinion Tooth Count: 13
Total Voltage: 18.5
Motor KV: 2200
Tire Diameter (inches): 5.8
Tire Ballooning (inches): 0
Motor coil Ω: 0.006
Spur/Pinion Ratio: 3.69 : 1
Total Ratio: 12.21302 : 1
Total Motor Speed: 40700 RPM
Vehicle Speed: 57.5 mph (92.37 km/h)
Estimated Adjusted Speed: 53 mph (85 km/h) - 8% loss
Effective KV Value: 2200
KT constant: 0.61 oz-in/A

Is 13/48 an acceptable ratio for the motor? :oh:

Your diff ratio is wrong. The 8t has 10/43 ratio. So 4.3 diff ratio.

This helps your suggested setup, I think it will be fine with the kit gearing...

Differential Ratio: 4.3
Transmission Ratio: 1
Other Ratio: 1
Spur Tooth Count: 48
Pinion Tooth Count: 13
Total Voltage: 18.5
Motor KV: 2200
Tire Diameter (inches): 5.8
Tire Ballooning (inches): 0
Motor Current Draw: 0
Motor coil Ω: 0.006
Spur/Pinion Ratio: 3.69 : 1
Total Ratio: 15.87692 : 1
Tire Circumference (inches): 18.22 inches (462.82 mm)
Total Motor Speed: 40700 RPM
Vehicle Speed: 44.23 mph (71.05 km/h)
Estimated Adjusted Speed: 42 mph (67 km/h) - 6% loss
Effective KV Value: 2200

I just built and tested a 8T brushless conversion for high speed. I dropped in the following:

18/44
Mega 22/30/1 3500kv
5S FP Evo25 5000mah
OFNA Foam Tires = 4" diameter
LOSI E8 Conversion Kit

The car ran max at 57mph. The ESC and battery ran cool. The motor got to 172 after about 5 minutes. This motor is physically to small so you definately want to go at least 1515 if you are thinking Neu.

Whoops
 

Oops, didn't know that. Thanks for the correction. That chops my speed down a bit there.. anyone have a suggestion on gearing or otherwise to get me back between 50-55?

EDIT:
Differential Ratio: 4.3
Transmission Ratio: 1
Other Ratio: 1
Spur Tooth Count: 48
Pinion Tooth Count: 16
Total Voltage: 18.5
Motor KV: 2200
Tire Diameter (inches): 5.8
Tire Ballooning (inches): 0
Motor coil Ω: 0.006
Spur/Pinion Ratio: 3 : 1
Total Ratio: 12.9 : 1
Total Motor Speed: 40700 RPM
Vehicle Speed: 54.44 mph (87.45 km/h)
Estimated Adjusted Speed: 50 mph (81 km/h) - 7% loss
Effective KV Value: 2200
KT constant: 0.61 oz-in/A

Is that pinion a little to steep? I think I can get the electri-clutch in a 16 also.

If you are racing 45mph is enough imho. You only go fast on the straights. And running an electric gives you that advantage of getting up to speed quicker. It takes a nitro engine more time to get up to speed, where electric BAM!! Now im talking about racing, if you're bashing then I understand, but im pretty sure you said you were racing and had an open/fast track.
Oh yea, the traxxas site is yag!

If you really want max speed, Id go the 1Y on 5S or the 2.5D on 6S (its fine on the MMM, really)

45 is more than plenty for the track, so a 1Y on 4S, a 2.5D on 5S or a 3D on 6S are all good choices. The 3D would be the coolest, but a 2.5D is really good two. Can't go wrong either way.

Also, take the time to learn to solder. Its really quite easy and really needed if you will be using elecs. Its like not knowing how to clean an air filter and running nitro.

Everybody wants to go fast. High voltage and a lower kv motor that is geared up will perform better for longer at higher speed. Temps will be better that way. 55mph will be a handful, that is for sure.

Just make sure you get resin solder.

Wow, first thread I've ever started and first posts ever and I am getting replys!

As for the electri-clutch... whats it do? Prolly tames the torque a bit huh?
with the clutch what are my gearing options? A LOT of people swear by the 1Y and with its great KV I am curious what I can work with on gearing. By shooting for 50-55 am I gonna lose a lot of punch?

You won't really lose any punch but you will stress the motor a little more causing some heat. If your going to be running in mains, you need to keep the temps down as much as possible. 45mph is very fast on a track and at 55 you would need to start braking much sooner. This could cause some control issues entering the turns and probably equate to slower lap times. You best bet is going to be gear for 45 and drive the track a few times. If you feel you need more speed, gear up a little until you find the perfect set-up for your driving style. Everyone runs different lines so your times will vary from others running the same gearing. Just find what suites you and win some races.