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Project Build - Hellfire Brushless Conversion

orcusomega

Well-Known Member
Messages
653
Location
Royersford, PA
Since I have a Hellfire roller sitting on the shelf, I decided to put it to use and convert it over to brushless. I am trying to get my son (Alex, who is 9) more into racing, and I need a platform he can learn on that won't make him (or me) too nuts when it comes to reliability, tuning, etc.



So, that said, I started with a bone stock Hellfire, and removed everything from the chassis and removed the upper plate for modification. When it was removed, I cut it down to keep as much material as possible to maintain the structural rigidity by tying the front bulkhead, steering servo assembly, and middle diff together.



This will be the main support "spine" with supplemental supports added further in the process.

With the main body of the chassis opened, I needed to find a place to mount batteries. I want to use 3S and they tend to be fairly big. I needed to find a way to mount them securely to the chassis - and I didn't want to have to make mounts. After pouring through some options, I settled on a set of Vorza battery boxes that I picked up from eBay for $15 or so. In looking at the chassis when stripped down, the center diff is slightly offset to the right side, so I decided to mount the battery trays to the chassis on the left. The nice thing about the Vorza battery boxes is that they are slightly raised, allowing for the use of fasteners from the bottom of the chassis up without the fasteners hitting the battery. I put them CLOSE to the driveline, since I was trying to keep the weight centered as much as possible. In the future, I may end up mounting the battery on its edge, which will move it inboard even more, but we will see how well the balance is as is.



With the battery boxes mounted, and being able to leverage the stock steering layout, now its time to address the motor. I picked up a brushless Savage at the World Finals, and in it came a Feigao 2080KV brushless motor and a Castle Phoenix-80 ESC. These are not exactly true racing components, but they are MORE than enough to help my son learn how to race, etc.

In order to mount the motor to the chassis, I used a motor mount I picked up from eBay that was intended for electric model airplanes (I think). It is nice and beefy, light, and leaves a lot of material to be able to create adjustable mounts to the chassis for different pinion sizes. I decided to start with a 12T Mod1 pinion, pretty much because it is what I had on hand. One thing to remember with the Feigao motors is that they do not have any flat surfaces to line up the pinion set screw with so you will need to make one (I used my handy-dandy Dremel). I lined up the pinion and spur, and drilled the necessary holes to mount the motor to the chassis. I drilled the holes in the chassis just a tad larger than necessary to allow for a little adjustment - I will be adding slide holes to the mount later once I see how well this solution works.



So, this is has far as I have gotten so far, more progress to come in the next few days.

Comments and suggestions always welcome!

Bob
 

frddyj

Well-Known Member
Messages
6,822
Location
boston
waitin to see how this all pans...

my son has a hellfire with a F that doesnt have a whole lot of life left in her.

+rep bob.
 

orcusomega

Well-Known Member
Messages
653
Location
Royersford, PA
Just a quick update from over the weekend.

I got everything mocked into place, and learned that the Phoenix 80 can also be programmed with Castle Link - so I did :) One thing to remember with the Phoenix-80 is that it is meant for airplanes, and NOT surface vehicles, so programming it is a pain in the tail to get it to behave like a normal surface ESC. The most notable difference is the lack of braking - kinda important on a surface vehicle :) When they come with the Kershaw Designs kit, they work perfectly, since you also use the throttle servo as a dedicated braking servo, but since I moved so much around on the chassis of the Hellfire, I don't have easy access to the OEM braking setup. If I can shoe-horn one in there I will, but I don't think I am going to be able to pull it off. So I am looking to see about picking up a Mamba Max ESC (again, this is for my son) at some point, but I will be trying the brushed (gasp!) combo from his SC truck when I get home. It has a Super Rooster ESC, I just need to figure out which motor to put in - I have a 14T Traxxas motor, but I wonder if it is strong enough to move that much weight - but worth the shot, since I already have it lying around and I know it works :)

Bob
 
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frddyj

Well-Known Member
Messages
6,822
Location
boston
One thing to remember with the Phoenix-80 is that it is meant for airplanes, and NOT surface vehicles, so programming it is a pain in the tail to get it to behave like a normal surface ESC.
bob watch your temps on that esc also, if i remember correctly it doesnt have a fan incorporated as it takes advantage of a plane or heli's airflow to cool it. :dunno:
 

orcusomega

Well-Known Member
Messages
653
Location
Royersford, PA
Quick update:

I was able to pick up a Mamba Max Pro ESC for a good price, and dropped it in the Hellfire. I also was able to get my hands on a Hacker Feigao cooling fin set - it wraps around the motor to help keep it cool - and it works like a charm! I just need to find a good way to mount the ESC and brace the rear bulkhead to the center diff, and it's playtime :)

More info soon!

Bob
 

orcusomega

Well-Known Member
Messages
653
Location
Royersford, PA
Well, I decided last night that enough was enough - I was gonna finish this sucker :) Unfortunately, the blade in my band saw was no good, so I ended up doing this last part by hand :(

So the big issue so far has been that I needed a way to support the rear bulkhead to the center diff to keep the chassis from flexing. I started with a piece of 1/8" aluminum plate and using the upper deck from the Hellfire I attached it to the real bulkhead. I added a few bends, and drilled it do that it attaches to the center diff, and wala - all done :)

Unfortunately, I didnt take pics during the making of the part, since my battery was dead, but here are the final results:









Once I get the motor polarity right, I will heat-shrink the connectors to cover up the exposed area - I don't want that shorting out to the chassis!

Hope to be able to shake it down later today - but I love the way this came together!

Bob
 
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orcusomega

Well-Known Member
Messages
653
Location
Royersford, PA
Thanks! I don't like the battery boxes are offset, but that's not a functionality issue. Once I shake it down, I will definitely straighten them out.

Only other thing I am thinking about is the pinion size - I have a new motor mount system in the works, but won't be done for a while (no time) but the new one will allow me to use different pinion sizes using a pivot type system. I finished them in CAD, just need to transfer that to the aluminum angle stock I have and go to town.

If I could get it cheap enough, LONG angle would be even better, then I could utilize existing holes in the chassis... but we'll see how all this goes yet. I need someone to donate a Flux 2200 motor to the cause - then I could use the Vorza motor mount too :)

Bob
 

jays13

Member
Messages
12
hi i know my battery tray isnt a looker, but with the power of brushless it came out pretty nice to have the lipos mounted all the way front.

but i guess that might be a problem for an well balanced track truggy, but served me well for bashing.

 

jays13

Member
Messages
12
lol when this pic was taken, i was constantly swapping the brushless setup between the hellfire and my xl. and therefore i didn't do a permanent installation on either rc.

zip ties ftw lol
 
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