Brushless MGT - pics and details (long)
 

Hey all -

I took a pretty lengthy layoff from the hobby, I was lurking around the boards still, just keeping up to date on new parts, mods, and just waiting until I got the bug back.
One thing I had always wanted to do was an electric MGT. Like most people probably have done, I started on electric years ago, got some nitro trucks, then pretty much just ran nitro (except for the RC18T I had). Then I took the layoff and sold everything off, even my built from the ground up MGT that was awesome.

So, the bug bit me a couple months ago and I started planning for an electric MGT conversion. Why? Honestly I don't like nitro. For someone that lives in a city, it is just too messy, a pain to get fuel, draws attention from people that end up not letting me just play with my truck in peace, etc. Also, fuel prices are going up. I also think that electric technology has way more room to advance. LiPo batteries are almost to the point that everyone knows about them (they aren't quite the standard yet though, due to safety issues and people just not doing their homework), motors are brushless and super effecient, lighter weight for all of those parts, and it's honestly easier.

Plus, I have always loved the torque of an electric setup, especially in a truck where power rules.

Anyway, back to the truck rather than my personal theories.

The hardest thing for me was figuring out the mount for the motor. It has to be an "L" shape, and I initially thought that aluminum would be great, but it's hard for me to work with since I am an apartment guy without huge equipment to mill down parts. I tried it with some 2" x 2" stock I picked up at Lowes, but wasn't happy with it.

I then decided to try something out of Lexan (polycarbonate), and loved it. It was easier to work with, and I think stronger, which is key for holding up that big electric motor. I made up a few designs in Visio and cut out templates from paper, and after 2 tries I got one that was good. All I used was a jig saw and a cordless drill, so I had a hard time lining up holes and getting things perfect.

http://ride247.googlepages.com/mgtmotormount.jpg

Next thing I had to tackle was figuring out how to brake. I can either do it with the motor/esc, like a normal electric vehicle, or I can use the mechanical disk on the truck in stock form. Well, stopping a 13 pound truck over and over is rough on an ESC, even one rated to 300 amp surges, so to keep heat down and stress on the expensive electronics, I am using the stock disk. What this also does is let me use the stock tranny (I did install a FOC like most do), so I still have a 2-speed. Otherwise, if you choose to use the electronics to brake, you need to lock your tranny somehow so it is singlespeed, and turns the wheels both forward, and reverse, so the motor can stop the truck (otherwise, if you try to stop, the spur gear will just spin backwards, and you'll coast, but not brake). Some have done it by using an E-Maxx tranny, and some have made center diffs, like on a buggy, but I wanted to keep the MGT close to stock, with electric power.

http://ride247.googlepages.com/mgtlayout.jpg

You'll notice if you look closely that under my motor, I have a brace. This lets me rest the motor right on there, so it is fully supported, and bolted to the "L" I made, so for landing, hopefully I won't have any issues. I may put a Velcro strap around the whole thing just to be extra safe, but it is super stiff how it is now.

http://ride247.googlepages.com/mgtmotorbrace.jpg

I adjust gear mesh by moving the whole mount on the chassis and bolting it tight. That's a little bit of a pain to do, I have to remove the spur, then the motor, then move the mount, then reinstall and hope the mesh is right, but I'm pretty good at getting it right. I honestly don't move it though, I have a 16 tooth pinion with the stock 52t spur and it is fine.
I also had to do some Dremel work on the bracket to let me get the gears close, the MGT tranny has some pieces that stick out, and rather than ruin the tranny, I ruined the mount (always ruin the cheapest/easiest to fix). Also had to Dremel the base of the mount to allow for room for the center driveshaft to spin. No biggie.

http://ride247.googlepages.com/mgtneu15151y.jpg

So, that's it in a nutshell. The only other thing someone may notice is that I'm using a Quark 125 Air Master controller, rather than the 125 Monster Pro that is designed for trucks (so they say). However, if you look at the specs of each, they are identical. I called Quark to ask and they confirmed that they are indeed pretty much the same, differences being with software obviously since the Air Master is for helis/planes. They said they would support me trying it out and help me out if it fails, and I've been in contacts with them a few times to let them know status. So far so good. Why not use the Monster Pro? It's considerably more expensive for some reason.

I'm using a Neu 1515 1/y brushless motor with 2200 k/v rating, the Quark Air Master ESC, an external BEC rather than a hump pack to save weight (it is in the hump pack compartment of the truck), Airtronics 94358 for the steering, and the stock steering was moved to the braking duties. Other upgrades are a FT steering kit, FT shock caps with gold/red springs (50wt in the gold, 40wt in the red), FOC in the tranny, and I think that was it. I am going to order some Maximizer beadlocks with some Losi Zombie Maxx tires to drop some weight on the wheels, and then some aluminum diff housings just for kicks, and then the truck is just going to be run until something breaks. I shimmed the stock diffs when I had the truck all apart, but I'm waiting to embezzle another 100 bucks from my monthly budget to get the diff housings.

I have run the truck on junk 9.6v packs for testing, and it wheelies when the pack is fresh, then drops off. I can't get it to shift with those packs though, but I did run the truck a few times with 2 9.6v packs in series, and it shifted fine and is super quick. Also has so much torque it'll flip right onto it's lid with a blip. I have a 4s2p LiPo pack coming, but it was backordered so I have to wait until 6/15 (hopefully) for it to get built up. I'm peeved about that, because it was not noted on the site and having a 2 week wait as a "gotcha" isn't making me happy. But, with a 9.6v pack, it was quick enough for backyard fun by far. So, having a 4s setup, I should be MORE than happy.

I will get a video after the LiPo gets here and I have that all figured out. I need a better mounting option for the battery, and wanted to wait until I had the actual battery I was going to use before I cut away some of the chassis guards for another Velcro strap.
I really want the layout different, but am not sure where to move the electronics. If I could move the ESC to the rear of the truck, and the BEC/Receiver to the right side, I'd be happier. I just want a cleaner setup. I'll have to set it on my table and have a good look at it for a while, and see what comes to me.

I'll end my post here. After I get the battery and have it mounted, I'll get a follow-up picture for final layout, but you can see where it goes (left side of the chassis). Any questions post back here, I will try to check regularly.

10k

the lexan is a neat way .. have you ran the truck yet?.. have it melted anything so far?....

very interesting using the lexan - i may have to start with that when i build the motor mount for my jato. how thick is it? looks like maybe 1/4"?

It is 1/4" that is used to mount the motor, and the base is 1/2". The 1/4" is really stiff, especially when it is only 2.5" of it, but the problem was mounting it to a base that was thick enough to screw into, so 1/2" fit the bill.

Rather than getting huge sheets of it too, I found an online resource, www.estreetplastics.com. They sell smaller pieces, 6" x 12" if you only need a little bit of it. I still have some leftover. Took about 2 days to ship, then it came in the mail, easy transaction.

I prefer Lexan over aluminum after this. Key to Lexan/Polycarb, DO NOT USE LOCTITE. The Loctite will eat right into the Lexan and ruin it. So if you screw into it, make sure it gets a good bite, and if you can, use a nut on the other side to hold it, rather than rely on the threads. Lots of bracing to avoid bolts pulling out.

Also, for people that don't know, Plexiglass is different than Lexan/Polycarb, much more brittle and not really tough for what you'd want in an RC application. While it is cheaper to buy, don't be fooled.

Great work. How do you like the airmaster?

So far so good. I don't see a reason to get the Monster Pro when the Air Master is exactly the same thing, and much less money. I was informed by Sky and Technology that I was the first to attempt it that they had heard of, but they gave me their blessings.

"cordless drill & jigsaw" - Now there's a man after my own heart, though I use a hacksaw- my arm is the motor!
Q. A stupid question probably, but I'll ask it anyway. Does the esc have reverse, since it is intended for aircraft, and can you update the software to give it more setting options?

Can you open it and shoot some pics!? :)

the only difference IMO is software.. it would be quite lame if this is true..

Not true- the name/logo on the front is different too.:027:

Yupp, cordless drill and jigsaw for me, and I did use my hacksaw a few times for the test aluminum I was messing with. I actually used it again last night for my heatsink for the unit.

Yes, the Air Master does have reverse/brakes, and you can even say how strong you want the brakes. Mine are set to 0, but they go from 0 to 100 in some increments. Check manuals here - http://www.sky-technology.net/home.htm. That's what I did to confirm I could do what I wanted with the air controller.

No popping that thing open either, at least let me get some runs on it with LiPos before I ruin it!!

Yea... If the only difference is the software I'm gonna be really annoyed that they have been extorting the extra $100 from us all this time. If the only difference is the number of competitors in the marketplace for the markets they are trying to sell into thats just weak. I now feel ripped off.

I'm gonna boycot Quark.

No Quark!!! No Quark!!! No Quark!!!



Oh yeah... Nice MGT. I can wait to see a vid once you get your Lipos. And please keep us informed of how the 125 AirMaster does. You will probably need a heatsink on the back like the 125 monster pro does if they are indeed the same hardware inside.

That is pretty nice. Are you running the 2 speed or 3 speed trans?
I see you converted to FOC to.

I made a heatsink last night just for kicks, cooler is better with electronics anyway. Since I have so much time to kill before the LiPo cells get back in stock.

MGT only has a 2-speed, Savages have 3-speeds. I did the FOC just to get some rotational mass out of the tranny, to lighten the load on the motor. I did it with my 3 previous MGT's too, which were nitro. More pep without all of that stuff spinning around......

2 speed, there aren't any 3 speed bolt on options for the MGT as far as I'm aware of.

10k, thats SWEET! im not a bg fan of the mgt, but i LOVE the motor mount!!

how heavy is this thing? loaded, unloaded?

and how do u like the air esc? i think id buy quark if that esc is 100 bucks cheaper!

and do u have any cogging?

Nice job on the MGT. I love mine, although I ultimately went with a center diff setup.

Truck was 10.6 pounds without motor, mount, ESC, BEC, and battery. So, you can probably get close with a guess. I'd say 13.5 pounds. It's heavy but not ridiculous, I felt a few all aluminum trucks and they are tanks. The MGT is big though, not like an E-Maxx or even a Revo, which are more track oriented designs.

I stopped weighing parts when I got the real meat and potatoes, if I have stuff off sometime I can weigh it.

Haven't noticed any cogging so far, but let's wait until I get the LiPo until I give a true rating on the Air Master. Like I said though, so far, no issues.

so the same wieght really as a muggy then, cool thats what i wanted to know, all the stuff on it wieght =) thx!

and i know, i dont want al on this guy, far to big for that lol... rpm stuff tho for shure!

and cool! i cant wait to hear how it does on lipos! r u runing a ubec? and hows the temps?

Actually, I don't know that I'd spend the money on the rpm stuff. The stock arms have been fine. The only problems I've had is with the rear tie rods bending and occassionally snapping. Just stock up on rod ends and devise something to stop the tie rod from popping off.

u can get those parrts in rpm.... id do that then lol

Very nice truck, I got an E-MGT in the planning stage, but will be a little different

Nice conversion. I am really liking the motor mount. Clever idea. Hope it runs well for you.

RPM for MGT - save your dough
 

It isn't bad in any way, it does what it says, but the stock ones do the same and cost less. Also, there are issues with suspension travel limits with the RPM arms, you need to grind them, or Dremel the tabs off the skid plates to allow full droop.

Not sure if that has been fixed, but I switched to the stock ones with an older truck and was happy with them.

Lunsford and dubro make great replacement products.

Great convo man!

I thought the new 4.6 had the 3peeds on them. I could be wrong.

Nope, I own one and it's 2. :)

OH well. I could have swore read about a 3 peed for one.
Must be first sign of crazy. Dreaming up more speeds than is there. :)

no 2 speed, but they got steel gears, as an upgrade

i cant belive quark would sell the same thing with a different name for a significant amount less with a different name. thanks man good to know.

Updates....
 

I've been reading this thread off and on, but didn't really have anything serious to contribute. Still don't actually have anything to report on with the truck, but if you want to know why, read on....

Let me say too, that even though the Quark 125 Air Master is way cheaper than the Monster Pro, I hope that no one has flamed Quark directly for the price difference. Take it as a learning experience, so we can keep getting them for a good price. I've goofed a few times in my life and learned the hard way, so hopefully we can all do better in the future.

Now, on to the truck. I STILL DO NOT HAVE A BATTERY. I'm not holding back now and being vague with my e-tailer, it is maxamps.com. They are terrible with service and letting the customer know what is going on.

The story begins when I originally place my order on 5/31. Site says the 4s2p's are in stock, I order it up, start getting amped up, and a few days go by. Order still says "in process" on the site.

I finally email them to ask what is up, and I find out that the cells are backordered. Peeves me off that I was not told after the fact, or before the fact for that matter via a note on their site, email, SOMETHING.

I write back a well-crafted email, explaining how that could possibly not be the best idea for business, not having an up to date status, and secondly not communicating if there is an issue.

Few days go by, and I get a postcard (remember those?) in the mail, from Austin. Note on the back was a half-apology, half you were right, and half disturbing all at once.

Disturbing? Yes. After a sentence explaining that the reason they do not post backorder status is because they often do not have a "Definite" ETA, there is a sentence "We lose more business to the delays than if we say nothing."

Pretty much, if we let people know that we don't have things in stock, we'll lose more business than if we just let it go, and essentially LIE to the customers.

"People want their product now" was the next line in the postcard. Well duh, that's why I ordered from you in the first place. Their point was made, if it had said that it was out of stock, I honestly would have tried elsewhere. BUT, knowing that they have the cells that I want, for the application I have, I probably would have waited. I'm not one for buying something quick just to get it quick, I'll wait a while and get the one I want.

"I just wish there was a more beneficial solution" is how it was left. There is, let us know as customers what is going on BEFORE we order. If your cells are that good, then people will wait. At least they'll KNOW what is going on, and not find out that their beloved project is going to last x weeks longer because you want to lie to us just to make a buck.

And speaking of which, I paid via Paypal, and that money has been sitting in their account since 5/31, earning the paypal rate of 5.25% most likely. That money is just as good in my pocket earning interest, and if you couple that with all of the other people they are hosing, it adds up to free money.

If I don't have a real answer, as in "cells are in, pack is being assembled", I may cancel the order and find another solution. I was told the cells would be in 6/15, nope, pushed to Monday, I asked today, and haven't heard back yet.

This is borderline pathetic, and I can't believe people run a business like this. I'm going to wait patiently for an answer, and hopefully someone on this board will calm me down, but I honestly am not happy at all.

Back to the truck - I made a heatsink for the Quark, since I have so much time on my hands while I wait. It is a simple "L" cradle for the bottom and top-side of the unit, and I popped a graphics card heatsink on the top via some Arctic Silver Thermal Epoxy (thanks Brian, awesome tip). Have some aluminum diff housings coming, they'll be here in a couple of days and I can at least build something fun for the truck.

That's my update. Sorry it is lame, but hopefully others see the frustration in this.

-10k

It sucks. It sucks like a giant vacuum hoover. I had similar issues with rc4wd.com. I placed an order for various TXT-1 parts -newera skid & various other items- and then I waited. After a few weeks part of the order arrived, but not the NE skid. I checked my account and it said 'backordered', yet it was still for sale on the main site. So I waited again. Fast forward about 3-4 months and I finally get pissed off waiting and email them via my btinternet email account (hotmail doesnt seem to get through), and I get the response "we dont sell those items anymore". WTF?! I'd been waiting for months and they dont sell the NE stuff anymore, and they didnt bother to tell me either?! I replied back and used the store credit they gave me to get some other stuff I needed.

Thats what some smallish companies are like, they arent run like a proper business with different staff for the various areas, theres just a few people who do all the website stuff, manufacturing & despatching etc, which is highly inefficient- but it saves money. The web is fantastic, but theres nothing like walking into a shop, picking something up from a shelf, and paying for it there and then....

I considered maxamps.com small too, until I read around online for LiPo sources, and also just realizing an ad in RC Car Action magazine, one turn of the page before they review the new Traxxas VXL brushless series of vehicles.

A full page ad in a real magazine must cost something more than chump change.

And, over on the maxamps forum, on this site, there is a thread stating how they just hired 2 new employees, can get back to turning around orders in 48 hours or less, customer service this, customer support that.

In this day and age of databases, web sites, and programmers, somehow not everyone is using this technology. One of the reasons why I order from Towerhobbies ALL THE TIME is the up to date stock status. Even tells me when it is getting low. Even lets me know when it gets back in stock. Accurate too. I've had things on backorder before through them, ON PURPOSE, and had them come in on time and ship out pronto.

Still bitter. I'll sign off for a bit and chillax.

Have a cold one, and a snickers; does the trick for me!

any word on the truck and how its running with the quark air biscuit?

Yupp, small update. Battery pack was received on 6/25, so Monday of this week. 25 days total!

Balanced the pack and charged it up for the first time. No issues.

Had to modify the chassis slightly to fit the pack, it was bigger than I had planned. No big deal.

Changed the settings on the Quark to cutoff at 3v, set it to LiPo Normal, changed my torque back to the lowest setting, and outside I went into the 90/90 weather for a few tests in the street.

BLAZINGLY fast. The MGT is a big truck, and if I full-throttle the setup, the truck does a standing flip. You usually see this with the mini's, but the 1515 1/y with a 4s lipo flips the truck around like a toy. Full throttle can be attained by going smooth, letting it hit second gear, and then going SMOOTHER. At any point in the run, if you suddenly goose the throttle, the truck lifts up off the ground, and if you are really not careful, it flips over.

The Quark Air Master was about 122 where the leads come in from the motor, so I figured that was hot enough after the running in the hot weather. The motor itself was actually hotter than I thought it would be, 135 was the temps on the fins. Battery was barely warm.

No glitching, no cogging, nothing out of the Air Master but performance. As far as I can tell, without taking both units apart, the Monster Pro and the Air Master seem to perform the same, BUT, I have never owned a Monster Pro, I'm going off of what people say on the forums.

I will have a camera for the weekend, and then edit something together and have it uploaded somewhere early next week. It won't be long, I just need to show the torque.

While I was running, I had 1 person ride by on a bike and ask me if it was gas, and I chuckled and said no, they are too loud and slow. Guy said "yeah your truck is pretty fast for electric."

Someone else asked the same thing while walking by, and I said no again.

Then someone that lives across the street in some apartments came out to load their car, and they asked me the same question. He said that he has a gas car, which I have no idea how he could think mine was gas as it was not making any real noise or smoking, but whatever. I said jokingly, "can your gas car do this?", and I did a standing flip. His eyes lit up and said "not a chance".

I can't wait to get this video shot and edited for everyone, it's scary torque!

10k

I will say maxamps has been going through growing pains recently. I placed an order right after the holidays and they were swamped and looking to hire additional people.

I too received a hand written card apologizing for the delay and thanking me for my business. I also received a refund for the shipping costs. I thought both were good service recovery attempts.

Sorry to hear about your experience, hopefully it will cause things to change with how maxamps hold inventory or at least reports it on the site.

I'm going to assume those temps were fahrenheit.

So it sounds like the Quark Air is suitable for applications with a mechanical brake. Thats good to hear, it could be a $$ saver for some.