E-Revo M-Twin (Lots of Pictures)
 

Since I'm new to this site I figured I should post my E-Revo set up here. Those on (or formally on) the Traxxas forums have likely already seen it.

This is from when I got it to more or less how it sits now, though I do intend to replace the Dual Mamba setup with a Mamba Monster/Neu combo soon.

Hop-Ups:

Dual Mamba Max ESCs
Dual Mamba 5700KV Motors
RPM A-Arms (Front)
RPM Tru-Track Rear
Spektrum DX3R Transmitter/Receiver
Orange/Gold Springs on Progressive-2 Rockers
Traxxas Sway Bar Kit
HPI Phaltline Wheels/Tires (For On-Road)
Proline Racing Crime Fighter Wheels/Tires (For Dirt Track Racing)

Unboxing
http://btallack.com/Pictures/E-Revo/...%20of%209).jpg

Still in the plastic
http://btallack.com/Pictures/E-Revo/...%20of%209).jpg

Switching out the Receiver for a DX3R
http://btallack.com/Pictures/E-Revo/...%20of%209).jpg
Receiver Size Comparison
http://btallack.com/Pictures/E-Revo/...%20of%209).jpg

Installing the Receiver
http://btallack.com/Pictures/E-Revo/...%20of%209).jpg

Installed and back together (Before I fried the stock Titans)
http://btallack.com/Pictures/E-Revo/...%20of%209).jpg

So at this point I fried my Titans after running them through water and getting debris in them. I was intending to simply replace them with another set of Titans until the Castle/Neu Combo was released, but I couldn’t even get a set of Titans anywhere soon as my LHS’s suppliers were all out.

That’s where going with the Mamba Max twin idea come in. I already had a spare Mamba Max 5700 combo from another vehicle that I wasn’t using, and my LHS had one in stock. Two hours later and three of us working on the RC at the LHS, we had a working M-Twin. I can’t say it was the first however, because that morning the Hobby Shop owner had already put a pair of Sidewinder 4600 Combos in his E-Revo. (He likewise fried his motors on the third run)


Mamba Maxes Installed
http://btallack.com/Pictures/E-Revo/...%20of%209).jpg

Three Quarter View with Mambas
http://btallack.com/Pictures/E-Revo/...%20of%209).jpg

Sway Bars
http://btallack.com/Pictures/E-Revo/...%20of%209).jpg


I must say this thing flies. It’s easily as fast as a Nitro Revo now. (Which is exactly what I was going for) I’m using 12T pinions and I have the timing on the ESCs set to normal. I intend to experiment until I find a good Speed:Temp ratio.

I’m using a Castle BEC and a variant of the “Unslow Harness” I’ve connected the ESCs power directly together and I use a parallel Y-Harness to power both ESCs. It’s being powered by a pair of Venom 5000mah 2-Cell LiPos, though I have MaxAmps 4700 7-Cell NiMHs as well. I also have a series adapter for speed runs but it gets really hot very quickly so I have to limit that to about 5 minute runs.

Looks nice but you won't find many fans of that setup. General view is 1 biggest / better motor is the way to go.

Given you have a MM and 4s lipo I would seriously look at a medusa 60-2000 - This will go very well with your setup.

Or you could look at the MMM 1515 1Y - It runs very well on a truggy/revo sized vehicle on 4s.

Well...that was a nice "good to meet you" :lol: . How has you m twin standing up for you so far? I think I have finally decided on the 2200kv Monster combo whenever it becomes available. How's the weather there...did you guys get snow (I heard Calgary got some)???

although most dont go for that type of setup it looks very very nice.

as long as it runs clean and does not overheat then its all good.

great job man!

No snow here yet. It is a whopping 0 degrees celcius here though which means it can't be far behind.

I've actually got a Mamba Monster at the LHS waiting for a Neu motor to come in for it so I can replace the dual Mamba Max set up. This set up does work fine, but I'd prefer the simplicity of a single ESC/Motor setup.

My boss has setup his own hoddy shop (helis and planes for now) so he can get me darn near anything I want for cost :party: . It's kinda nice to have an inside track this stuff. What Neu did you get?

1512 1Y. It should fly on 4S.

I like the green scheme.

Haha, yeah. That wasn't intentional though I do have a tendency to paint my bodies green. Maybe I'll get a ProGraphix body and paint it green to match.

What gearing (for bashing on grass and dirt) would you recommend on an MM 4S lipo setup w/ the medusa 60-2000? Also, what temps should i expect on it?

Nice. Why didn't you get a 1515 1y?

I intend to stick with 4S Li-Pos which is about ideal on a 1512. Were I planning to go with 6S I would have definitely gotten the 1515.

I plan to run 22/58 gearing which should give me a top speed of around 50mph. Plenty fast enough for me.

Good spot I read it as 1515...

I have a 2 x 1512 and a 1515 1y I run the 1512 on a buggy and the 1515 on the truggy - I think you will need to watch the gearing 50MPH on a revo on that motor is too much IMO.

I gear my GTP2 for 50 with the 1512 but that is too fast for it in a revo with MT wheels etc... I think you will be dissapointed.

http://www.scriptasylum.com/rc_speed/_top_speed.html

Aim for 35-40mph at most.

Temps:

motor = 130*F, 180*F maximum
Esc = same pretty much
Batts = 100-110*F average, 130*F maximum (lipos).

Hot motor + cool esc = undergeared
Cool motor + hot esc = overgeared
Hot everything = way overgeared
Warm everything = happy electronics.

You think so? Hmmm, maybe I should see if I can get a 1515 1Y instead.

Here's the calculations based on the 1512 1Y:

Differential Ratio: 2.8461538461538462
Transmission Ratio: 1.8333333333333332
Other Ratio: 1
Spur Tooth Count: 58
Pinion Tooth Count: 22
Total Voltage: 14.8
Motor KV: 2750
Tire Diameter (inches): 5.65
Tire Ballooning (inches): 0
Motor Current Draw: 0
Motor coil Ω: 0.0035
Spur/Pinion Ratio: 2.64 : 1
Total Ratio: 13.75641 : 1
Tire Circumference (inches): 17.75 inches (450.85 mm)
Total Motor Speed: 40700 RPM
Vehicle Speed: 49.73 mph (79.88 km/h)
Estimated Adjusted Speed: 46 mph (75 km/h) - 7% loss
Effective KV Value: 2750
KT constant: 0.49 oz-in/A


So the adjusted speed is about 46mph. Plenty fast enough for my needs. Based on those numbers do you figure it'll run too hot?

The 1515 will be a better choice for the Revo...IMO

Don't suppose anyone has some temp comparisons between the two?

Very nice build on the M-Twin. Looks clean and glad it runs great.

Thanks Neil. I'll keep this in mind. Currently, with my single 700HO, i'm getting the same temp readings below. Good to know. Now the long wait till the 70-2000 Medusa gets delivered.

50mph may be a bit much to shoot for with the 1512, and I prefer a system that doesnt quite run at that rpm, but that said... I run my revo on a 1512/2.5d and 5s and it has no problem geared for 42mph and run on a track. In race conditions it comes off the track after 15 minutes solid run at a cool 140F. I have run a 1515/2.5d in the same setup and it came off around the same temps, but I had it geared a few mph faster. With the setup I have I think there is still some headroom to go up in gearing, I just dont need it for the track, but you should be able to squeeze a bit more from the motor than I am now.

I think you can make that motor work, just start on the conservative side (around 35-40 as others have said) and see how the temps do. if they are fine add a tooth or 2 untill you find the point where you start to run into the motor limit. I dont think you will be too disapointed. Those 1512s can put out some power.

I got my 1512/1Y today and installed it and that motor is crazy powerful. I geared it 58/20 and got the following temps after 15 minutes of hard bashing and speed runs:

ESC: 95'F
Motor: 135'F
Batteries: 70'F

I'm almost thinking I should kick it up to a 22T pinion if Neil's "Hot motor + cool esc = undergeared" is accurate. (And from what I've seen, Neil is usually very accurate) And it would put me up to about 46mph (adjusted) according to the calculator. Not that I have any objections with the 43mph I'm getting now.

It would be cheaper to get a 56 or 54T spur and have a similar effect. :neutral:

unless of course you already have the pinion.

Hmmm, you are definitely right about that but I'm not sure the 54T spur would reach the 20T pinion gear. The 56T Spur might work but it wouldn't be much of a difference.

Is this in a e-revo? or converted?

Because if its in an e-revo, I made a chart that might help;
(short answer is yes, if you mount the motor in the low-cg spot)
http://i87.photobucket.com/albums/k1...sam/pinion.jpg

This is used in an e-revo with a tekno neu and RCM pinion gears...
unfortunatly, I dont have a 22t, but I got the 20t pinion to mesh with a spur as small as 53T...using the low-cg mounting holes;
http://i87.photobucket.com/albums/k1...motormount.jpg

It's an E-Revo but I'm using the single motor plate and cover so it's not mounted in that bracket. The single motor plate places the motor in the center but higher CoG battery position towards the front of the truck.

I'll post some pictures shortly.

weird. all the pics I have seen of the single plate, still use the same mount;
http://i87.photobucket.com/albums/k1...am/intro13.jpg

I just looked it up and holy crap, you're right. My LHS sold me the kit for the E-Maxx.

It does work, but that would work better. Guess I'll have to get the right kit.

I actually feel kinda dumb for not realizing that it wasn't right.

ah! that makes sense then.

Well at least if I ever decide to upgrade my E-Maxx to brushless I don't need to buy a motor plate. ;)

Well I got the proper motor plate and installed it. My LHS had to order me the correct cover though.

Unfortunately I foolishly used too much loctite when installed the pinion gear so I can't get the set screw out. I was able to get the Pinion off by heating it up and prying it off so I just need to go get a new pinion gear. I'll be doing that Tuesday so hopefully I'll have my E-Revo up and running then and will report back here.

So far though, no complaints about going with the 1512 over the 1515. It is a Killer motor and very well made. (I was amazed to see that the build date on the motor was less than two weeks before I received it.) No heat issues either.

Blue threadloc (tamiya stuff) is what I use to keep the pinion setscrew in place, rather than normal loctite. With the pinion off the motor now, you may be able to keep screwing the setscrew into it, and that will break the glue seal (if you havent stripped out the hex that is).

I really should have used blue loctire instead of red stuff. I even have some Tamiya stuff from building my M03.

That said, I did manage to get the pinion gear back on, despite the fact that I did utterly destroy the hex head on the set screw when I tried to get it out. I just had to pretty much hammer the pinion back on and use a small dab of loctite to keep it in place. I let it set for about an hour then took it for a rip.

HoovHartid, you were right on about the 54t Spur gear. The temps on the motor dropped about 10 degrees, and the ESC is sitting at a comfortable 105 degrees after a 15 minute bash. (Mixed terrain, grass, ashphalt, dirt) Top speed and acceleration are awesome. I can honestly say I wouldn't want it any faster. The Top Speed calculator gives me an adjusted top speed of 45MPH. That's about the perfect speed for my liking.

I imagine on a longer run, temps would get a bit higher, but I still have comfortable headroom so I'm not very worried about it.