Racing brushless 1/8 scale
 

I just finished a brushless conversion on my Sportwerks Turmoil buggy. I went with a MM esc, a Feigao 7XL, and 3S and 4S Lipo.

I didn't have my 4S lipo in yet, so I ran the setup on 3S 4Ah lipo packs with a 14T pinion. I was getting 10-15 minutes of runtime. It was fairly cold last night and the battery was dead in my temp gun, so I didn't get any readings. I can say that my motor was hotter than the esc, so I'm going to assume that on 3S lipo, the 14T pinion left the motor a bit under geared.

Even still, I went out to the track to work on getting the kinks out of my setup. First thing I noticed was that the buggy had a tendency to nose dive when coming off of jumps. I was running the same suspension that I ran on the nitro rig. I figured that the back was just oversprung, so I switched to the stock springs and it got better. I think that I'm going to have to even lighter on the springs. I'm also running 40 weight shock oil. Perhaps a which to 30 weight will be in order for the colder weather we are having right now.

All in all is was a successful run. My lexan battery tray didn't survive and one of my packs got chewed by the spur. Thank goodness it didn't get all the way through the cell casing. I guess I'm going to have to go with my original plan for an aluminum battery tray. Other than that, I think that my setup is race worthy.

I'd also like to make some observations about the transition from nitro to electric. The first one was that I should have done this a LONG time ago. It was much smoother and controllable. Rather than having to blip the throttle to stay in the power band, it was more like using the gas pedal in a car. When I wanted the buggy to do something, I just issued the command. The torque is UNBELIEVABLE. There is one particular set of whoops that immediately follows a turn. It is a set of five and when the nitro guys usually run the track, they have to hit the turn just right to be able to clear the whoops. If you screw up sliding through the turn, you just have to suffer the whoops. With the brushless, all I had to do was take my time through the turn and just before the whoops, I hit the throttle and the buggy cleared them. We also have a jump that is about 3' high that is about 6 feet before a table top that is about 5' long right after an inclined 180 degree turn. Again it is critical for the nitro guys to drift the turn just right to have the momentum to make the jump to the table top. I was able to literally setup to right around 8' before the jump and hit it. Not only does it make the table top, but it clears it, landing on the opposite down slope.

that is really good to hear. as far as your batt tray, you can go CF. I think the website is graphiteelegance, they sell angled pieces that may work well for you!

Yeah, I wanted to go with cf, but it appears that there is a shortage or something. Prices are through the ceiling. I'm going to check that out right now though.

Thanks.

neweuser,

THANKS for the info. Great prices and just what I was looking for. Can anyone give me an idea of how thick I should get it for a battery tray for my lipos?

double post ha ha

Sounds good AA... kinda what I have seen too.

I suggest you go to 4s no matter what.... you can get the same speed and power with less amps pumping through system. A lower kv motor to match of course if the 7XL is overkill on 4s.

Heat of summer and a tall geared 3s setup may not work as well....

good job.... get a few guys converted and you won't have to be the lone ranger.

I have to do the fake pit stop too... about a 3-5 second stop and go. In our last trophy race I probably would have won had I not stopped. I finished 2nd, just a couple seconds back. I was a couple seconds behind the leader near the end of the race when I "pitted" and two turns later he wrecked and thought I was going to pass him.

I think it's the fair thing to do.

Thank Serum, he gave me the link when I was looking CF. They are about the best! Serum is the Pro on the thickness. I was going to go with CF and decided not to. I already have one and decided to go the other route. Although I did pick up some CF for the other chassis I have from here, but don't remember the thickness. You probably wouldn't need more than a 1.5mm though.

Sounds great. I love to read stories like that. I've got one word for for your batteries: velcro. I use velcro on the bottom and a Gorilla strap over the top and they do not move whatsoever. combine that with some angled CF and you will have a bulletproof setup.

Good point... I use a little velcro on the under the packs to. Good velcro under the packs and a velcro strap above... would take a horrendous wreck to lose them.

I still like to have a little side skirt of some kind as extra insurance too.

glassdoctor,

I am definitely going with 4S. I've already ordered the batts. :) I was just really impressed with the performance on 3S. Oh why did I wait so long to do this? My 7075 is coming in today, so I'll get on making the final version of my mount. Doing all of this mill work on my drill press is less than ideal though. Boy, do I miss my mill. What I really want to do is mill me a mount that incorporates the rear center diff mount. That, however, is beyond me capabilities right now. I can't get that accurate with my drill press.

As far as the motor goes, I'm starting to think that I should have taken your advise in the first place and gone with the 2000kv motor. If/when I get the Neu motor, it's going to be the 2000kv. I just can't see going wrong with that on the track.

neweuser,

I was going to make my battery tray out of architectural aluminum channel, in fact I ordered it and it's coming today. My apprehension is with the tensil strenth of the aluminum that the channel is made from. It isn't even 6061, so I don't know how hard it is. Gotta protect those lipos. If the aluminum it too heavy, I'm going with the cf. No choice there.

Cartwheels,

Now that's an idea. Velcro on the packs too. That should make them easy enough to get out, but should do away with the lateral movement. I ordered some gorilla straps last night.

CF is light and durable. I think it was Serum who made a box for his batt tray out of CF, he said he was really pleased with it if I remember correctly. Try the aluminum, see how it goes.....if you don't like it, then you know where to go for the CF :)

Oh... about the velcro on the lipo packs:

Never stick velcro on the bare cells. Don't ask how I know this ... :013:
It will mess up the cell when you peel it off. :035:

It's fine if the pack has shrink on it... but not without shrink. :007:

Well, talk about a dead give away! LOL:005:

OK, so velcro on bare cells = a bad thing. Got it.

Haa haa yeah I used some sticky velcro too... the cells still work ok, but it stretched and wrinkled the skin of the lipo.

I think it didn't do any real damage but I was a bit concerned... definitely not happy. And I didn't do it again. ;)

Glass - "here liath the lesson"!!!!!

Knowledge is power!

made my tray from some carbon fiber cloth scraps I had laying around ,depron foam and some good finishing epoxy...4 layers of 3.7 oz 80/20 cloth seems plenty thick .I made the bottom thicker with depron foam between the 2nd and 3rd layers so I could notch the bottom out for the mud guard nuts on my Cen MAtrix chassis. There are a couple pics here http://www.rc-monster.com/forum/showthread.php?t=4994

pinolelst

Very nice... where do you get the cf cloth and foam... I didn't know what depron foam was : )

That turned out pretty good. You made the CF yourself?

pinolelst,

Nice job on the tray. I'm starting to get burnt on working on this thing. I'll likely take an easier route for now.

I was also hoping to get a package from RC Monster today. I placed the order Thursday night, and with all I've read about the quick shipping, I kind of expected it today, but it was a no show. Oh well....

I would expect it tomorrow at the latest depending on your location. I would say it went friday morning.....2-3 day...

I use carbon fiber and glass fabrics to vacuum bag glider wings so I have a supply at hand usually .The depron foam is relatively high density stuff that has been used to form rc airplanes out of besides whatever commercial use it started out as and can be had in most craft stores I think in various thicknesses from 1- 6 mm or so.I just used some white EPS foam for the form and wrapped cling wrap around it before laying up the carbon fiber fabric .Then after the 4 layers and the depron bottom layer were all wetted out over the block I wrapped the whole mess tightly in cling wrap again trying to avoid any wrinkles that might show up and let it cure a couple hours before I trimmed it to basic size.

Really took me less than an hour to do and cost very little since I had scraps laying around and epoxy is still relatively cheap
hope this helps

pinolelst

I think we could use like a "how to" do it your self CF sticky with some pics and product names or something since many of us customize our own stuff. that would be really cool!

neweuser,

I don't know. The email that I got when I placed the order said that they'd be in contact, which I took to mean an email, but I haven't heard anything.

I'm usually a compulsive person with a need for immediate gratification. I think that God has been testing me with this project. I've had to WAIT for everything.

It went the same way with mine! Seems that way doesn't it! you'll get it, no worries! If it's coming from Mike, then it'll be for sure. I do know however, the contact email does not always come for some reason. I think it's a system thing.
you could try calling Mike though, that may help and ease some wondering....

OK, I spent all afternoon working on my buggy, trying to get it race ready. We beat the heck out of it last night, trying to break something, and we did manage to break the lexan battery tray and the esc mount. What I wound up doing is making an integral mount for the battery and esc. It all comes out as one unit. I made use of all existing holes. I didn't have to drill a single hole in the chassis. Now, when it's time for a new chassis, there won't be anything to do but to swap parts.

Here are some pics. There are some rough areas, but it's a work in progress.

http://www.fototime.com/%7B9875E7C1-...7D/picture.JPG

http://www.fototime.com/%7BED38F8CE-...7D/picture.JPG

http://www.fototime.com/%7B5D0E2A89-...7D/picture.JPG

http://www.fototime.com/%7B208836F5-...7D/picture.JPG

I have to make a couple of comments about the conversion. I did make use of delrin round stock to make the stand offs for the battery tray and esc mount. I've gotta say, delrin is some amazing stuff. It's strong, it drills and works easily, it taps easily, it weighs next to nothing, and CA will bond it like concrete. Of course, I drilled and tapped for a good mechnical "bond" for this project.

I did get my 7075 stock in today. I've gotten started on making a new mount. I have a couple changes in mind and I've started implementing them. Nothing functional really, just cosmetic changes.

If you have any constructive critism, let it fly.

Looks good! Lots of fun! Is that a metal spur? You may have to find a way to get a plastic spur gear on there. I haven't heard of too many pinions holding up to a metal spur gears even the hardened ones get eaten up. It crazy but a plastic spur seems to work a lot easier on the pinion with brushless. The exception being if you have some kind of slipper or clutch setup.

Looking very good. Good luck racing. It looks to me like a champ. :027:

Cartwheels,

That is indeed a metal spur. I don't know if you can see it, but the pinion has about had it. That's after about 5 packs of 3S. I'd hate to think of what it's going to be like on 4S. When I was at my LHS, I bought a Kyosho plastic spur gear. It wasn't what I needed, but the holes did line up with those in my diff cups; so, I took a chance and ordered two of the ones that RC Monster has. They look right in the pics. I hope they are what I need. I'd hate to have to go through $25 in pinions everytime I take this thing out to the track. At that point, it will no longer be cheaper than nitro. I have my fingers crossed.

why are the esc, and srvo wires going over the drive shaft??? seems like something bad there.. other then that, SWEET!!!! r u going to get any vids?

What do you need 7075 for? A new chassis?

Delrin is pretty good stuff, but you can get the sam performance with cheaper plastics, most of them work pretty easily...ABS, Nylon, etc..

I still haven't settled on the wire routing yet. I had them zip tied to the center diff top plate. I want to get them out of the way, but keep everything accessible, just in case I have to do repairs between races. The same reason that I don't have my steering servo laid down. Four fewer screws to deal with.

I'll try to shoot some video the next time I'm out clowning around at the track. Things are too hectic on race days to worry about it. I have a video camera that shoots straight to compactflash in mpeg format, so it'll be pretty easy to post something. You guys are going to have to go easy on my driving though.

I'm using 7075 for the new motor mount I'm making. I've found that it's a lot stronger than 6061 and isn't that much harder to work. I don't want the mount flexing at all, especially when my buggy is doing cartwheels down the track.

I like the delrin, and it isn't that expensive. Although I may be mistaken, my personal experience is that delrin taps well and really holds the threads.

ohhh ok

and lol i dont think i could do much better on the track lol

Looks good... a solid conversion.

Did you say it was nosing on the jumps? It looks like the cg should be back farther than a nitro to me. That layout is similar to my 8ight but I have the battery forward more and it flies pretty level, seems balanced. I wonder if the rear was slapping the jumps?

Only thing I would change is just based on personal preference... where to stick the esc and rx. I like to put the rx over next to the servo and esc either right in front or right behind the battery, down on the chassis. Putting in the front is the best spot but does require a little more wire to reach the motor plugs. With it up front theres' plenty of room for a ubec and a big fan. The battery would have to slide forward to fit it behind. Not a big deal...

One last detail I try to do is get the rear of the motor secured. It's not always easy but it makes the motor really solid. If you are using the motor heatsink that bolts on, you could use the rear bracket to tie onto.. with a simple piece of L angle, bolted to the chassis. Something like this only bolted to the heatsink:

Notice in this pic I have the esc in the same place you do :)

glassdoctor,

I put the esc where I did because, as luck would have it, there are no aftermarket manufacturers of bodies for my buggy. All of the Sportwerks bodies have the holes pre-cut for the engine and fuel tank. I figured that I'd take advantage of that and put the esc where it could get a good source of cool air. As for the Rx, I put it there for accessibility. Although I usually run a Spektrum, you never know what's going to happen on race day. I actually had one occassion where I had to run a borrowed am radio system. With the Rx there, I could do a quick switch with any system and be assured that interference from all of the current flying around would be at a minimum. I really put a lot of thought into the accessibility issue on this buggy. You can get to just about everything without having to mess with something unrelated. I also didn't have to drill any non stock holes, so all I have to do is keep a spare chassis in my box and I can do a swap in about 30 minutes, if need be. I just can't emphasize how bad a driver I am. I do like racing, but do it for the thrill rather than to win. I like hitting the jumps hard, just to see my buggy fly, when everyone else is taking it easy to hit that turn at just the right angle. What can I say, I'm careless.

As for the nose diving, I don't think that the weight is too far forward. When I went to light springs in back, the buggy's behavior improved. I was thinking that the back was way over sprung and it was pushing the nose down when I left the jump. I don't think it's slapping, although I'll have to check for that.

Is the rear support for the motor really necessary? On that note, does anyone know exactly how deep the threads are in the mounting holes? I want to get screws that will utilize as much of the threading as possible without danger of screwing anything up.

I'm still patiently awaiting my orders from RC Monster, Maxamps, and a few other places. At least Mike emailed me to tell me that my order shipped yesterday. Of all the people that I ordered from, Mike seems to be the only one on the stick. Maxamps says that my batteries are shipping today or tomorrow. That means that I won't get it until Monday. No racing this weekend.

Thanks for all of the input.

Nice conversion, One of this days i will convert a buggy to brushless also....

Anyway, I think the idea of the rear motor mount is to lessen the motor movement, lessen the flex on the motor mount. This way you'll have a solid setup that doesnt move, good for you pinion i bet :)..

Mike will always be mike he so fast....look af the testimonial page...though he might have some issue (we dont usually know) he will find a way to make it work best for his customers

I haven't seen many others doing a rear brace... but I really like to have it, if I can find a way to get it done. I have run without it also without anything bad happening except maybe the motor sliipping a bit, but no doubt a brace at the rear makes it stronger.

As you have said, 1/8 buggies can see some wild action on the track. It's just a little something extra to keep the motor locked down tight.

I have heard talk about bracing the rear of these big motors, but I don't know if anyone else actually does it but me.

I hear you on the layout... a million ways to do things. It's looking good. I like how it's a bolt-on conversion and that you didn't just stick the battery on the side guards, but made a really good strong mount for it. I don't think you will see your $$ lipos come flying out or get smashed during a wreck...

When you get the ubec it may be tempting to put it up by the rx.... but some say they can cause glitching so watch for that if it's near the rx.

Hey, good things come to those who wait right? :035:

I think a rear brace is a good idea.Particularly with the xl can motors.Think of how heavy they can me and all that mass supported sometimes solely by screws in a press fit endbell and how it's going to react when you cartwheel down the track or even just bottom out on landing after a jump...
just my $.000000000000000000000000000000000000000000002 worth

pinolelst

Would the use of one of RC Monster's heat sinks help? I'm just thinking that a rear brace could make quick pinion changes a PITA. I'll see what I can come up with.

I just finished version two of my motor mount. I used a piece of 3/16 aluminum. I was going to go 1/4", but felt that it would be overkill. I'm at the point that I'm watching the weight. It's plenty rigid. Attempts to "jiggle" the motor results in the whole center diff mount shimmying (is that a word?). It's what I want. I want the motor to move with the center diff. I got in some aluminum diff mounts too. With the aluminum diff mounts and the new mount I was able to attach the mount to the diff mount at five points. Two through the top and three from the side. It think I'm going to be sticking with this mount. Now I just have to figure out the suspension.