1/5 Brushless 4wd Conversion

[Obeast44]

Hello guys, Ive been a member since 2008, just never posted before now. Ive been lurking for quite some time :D
Ive been a Largescale gasser guy for a few years coming from Nitro. With my work schedule and my kids I cant get away to my offroad bash sites during the week. This led me to purchase an Ofna JL10e 1/10 Onroad with a CC Mamba Maxx pro 5700KV combo on 3s, to drive during the week. After seeing the amazing power and runtimes I can get with brushless and the fact Redcat is introducing a new lighter 4wd 1/5th scale. It just seems like the perfect time to try a conversion. Here is a thread with a few pics: http://www.redcatrampageforum.com/showthread.php?t=3609

Its roughly 9kg RTR with the gas engine and all associated hardware. After getting rid of all that stuff the weight should drop down to about 6-7kg. Ive considered trying a direct to diff drive setup using a large super low KV outrunner on 12s. The buggy on 12s lipo, with the 130kv outrunner, 6.5inch tall tires, and a 3:1 differential ratio will have a top speed of 37mph@3.7volt per cell. The only thing that worries me is the rollout ratio, its 6.81. I know thats really high and it will probably cog like hell, but would the fact that itll be running at 44volts help? Bear in mind I am a complete brushless newb :)
Thanks again for any input you guys can give.

[lutach]

Great to see another member thinking about 1/5 scale electrics.

There have been a few 1/8 scale direct drive just like you mentioned and from what I can remember they ran great. One member here has a great idea for an outrunner direct drive. A 5th scale is much bigger than a 8th scale and you needing a large outrunner, I think a front and rear motor support will be ideal. I'll be following this to see how it goes.

[Obeast44]

Its going to be a fall/winter project as far as I can tell.Ive still got a Rampage I need to sell to help fund the project. The new Redcat buggy is at least 3 months away anyway. I will be buying 2, 1 to keep as a gasser and another for the conversion. Once the gas version is RTR then I will start on the electric.
Id like to use 4 of the 6s 5800mah lipos configured to achieve 12s 11600mah. It will be needed to complete those pesky 30min mains. I have a good idea of the ESC I will be using, its the Turnigy 200a Monster ESC from Hobbycity. The outrunner will be Turnigy as well, either the 13k0kv or the 180kv version. That is if the rollout wont be too high for a direct to diff drive conversion. If I cant use the outrunner because of the rollout I will have to use a setup similar to Ryu James's Rampage. Then I could essentially drop down to the cheaper 150amp HV esc from HC. The esc doesnt have a BEC so I probably will use a standard largescale 5000mah pack to power the the RX and steering servo, considering I have a few of those. A bec is something I can do at a later time if $$$ doesnt permit. Man I hope the Rollout ratio of 6.81 isnt too high.

[Ryu James]

OBeast,
just replied to your pm. very excited to see this build and must warn you that you will be hooked to doing conversions after this one. should be a lot of fun.

i am not familiar with outrunner motors and have never used one. are you wanting to use one cuz they are cheaper?

can you post pics of the buggy? the link you gave isnt working at the moment. i think the forums are down for maintenance.

is the chassis like the TT or more like an HPI baja "channel" type chassis?

anyway, in your pm you stated: "Its weight is approximately 9kg RTR with the gas motor and all associated hardware. My project has several goals that I am hoping I can achieve. Im looking to get 40min of runtime in race conditions, a top speed of 40mph, and cost less than a typical race motor ($600). Thats not counting batteries btw."

if it weighs 20lb with the gas motor RTR then you could get the weight down even more going brushless. and if you are wanting to do the conversion for less than $600 here is my recommendation:

at a weight of 20lb i think the new Castle 1717 1580kv motor would have enough power. plus going with this motor would allow you to run on 6s, also saving a lot of weight. the 1717 motor is 50mm in diameter and 3.3" long. thats a beefy motor and you can get it for $228 on ebay right now.

running the 1717 would allow to use the MMM which you can get for about $140 and also have esc braking so you wouldnt have to worry about any mods to keep mechanical brakes.

for a battery tray i would use the RCM tray that is made for the RC8t conversion kit. its on the drop down list of battery tray in the RCM store.

then i would pick up a 6s lipo that is at least a 30c rating and over 5000mah for extended run times. i doubt you will be able to get 40min of racing run times period but if you went with a 8000mah+ pack you could get close. also, running 6s at 1580kv motor gives you a 35000rpm which is right where you want to be and will yield cool temps.

the mounting holes on the 1717 are same as standard 1/8 motors so i would just take you center diff mount to a machinist, along with an example center diff motor mount, and have them make a custom one. or send your diff mount in to Mike here at RCM and he could do one very easily. i have a 40t spur gear to take the place of the stock beveled spur if interested.

with this conversion i bet you would be right at 20lb RTR, get 25min+ of race time and 40min of bash time, have esc braking, and spend less than $600 before buying the battery. even with the battery you wouldnt be much over $600.

i really do think this could work and i think you would be very happy. plus it would be an easy conversion.....depending on the layout of the buggy. need to see pics of the chassis and layout. the only thing i would do first is check what the output of the 1717 is. i couldnt find the specs anywhere online but i am gonna say it puts out 2000 watts constant and up to 4000 burst. that is perfect for a 20lb buggy. my buggy weighed in at 27lb and the 2215 motor i ran was capable of 2500 to 5000 watts and i had cool temps and lots of power.

if you have more money and time to spend then you could do things entirely different and go the 12s route, with large outrunner or inrunner, and an HV esc. but all that will put you over $600 for sure.

idk, what do you think forum members? weigh in on this idea. do you guys think it would work? what are some other options that OBeast has?

hit me back on the pm i sent you and will chat more. btw, you said you saw my conversion on the rampage forum. i actually posted my complete build thread here. i am not sure if you saw it but here is a link. http://www.rc-monster.com/forum/showthread.php?t=21657

and here is a vid: http://www.youtube.com/watch?v=Zgx-ySspOhk

be sure to post all your questions in the forum. without the RCM forum members i would have never been able to build mine.

here is the spur gear options you could use. these need to be machined just slightly and then hardened. (or you can use my 40t that this has already been done). https://sdp-si.com/eStore/Direct.asp?GroupID=591


1717 motor:

http://cgi.ebay.com/Castle-Creations...item35a70c24c8

I have been using Neu 1900's to replace the zenoahs they are great value, light cheap and go very hard on the standard gearing. Most important on 10-12s coincides with the max efficiency point under full throttle loads. Unlike outrunners they can handle high power and run much more efficiently across the amp range from 0-140 amps. The performance bonus is huge.

[Obeast44]

The main reasons I want to use an outrunner are the price, the torque, and it will free up lots of room for batteries. Allowing me to have increased runtimes which is always a plus. The chassis is VERY similar to the Rampage, it uses different diffs and suspension but the center driveline is almost identical.
@ Ryu James If the outrunner direct to diff is a no go, I would definitely like to use the setup you used on yours.

Here is a few pics of the buggy to help show what I want to do.






I have more pics that I have found online, but these show exactly what ya need to see. Its almost identical to the rampage in the center. See what I mean when I said youve been down this road before :)

[Ryu James]

is this buggy out yet? when do you get yours? where can they be purchased? i like that. i love how it looks just like a 1/8 buggy even more so than the rampage tt. it looks very agile. looks like a great conversion candidate.

i am sure you could do the outrunner direct pinion to spur setup. you just need to swap the bevel spur gear with a standard mod 1.5 spur gear. the last post i included a link to site to order gears that lutach had given me when i did my conversion.....assuming the part is the same as on the rampage.

when will you be getting this buggy?

[Obeast44]

They are still about 90 days out, unfortunately. Thats why its going to be a winter project for me. If the outrunner wont work with the direct to diff drive, I will just use a big inrunner using the direct drive with the pinion/spur, just like your conversion was.
They cant be purchased just yet, they are still working on the preproduction samples from HSP. I PMed Rob on RRF about possibly doing a conversion on one when they get released, and he said he would see if he could get them to build a brushless sample, after they finalize the gas version. Granted itd probably use the Hobbywing 150a ESC on 6s though, like most of the other chinese conversions. I cant imagine it being terribly fast on 6s, at least not much faster than a gas motor.
I know outrunners dont like dirt and run hot. But at $100 each they are cheap enough to run for a while and throw away when they go bad. Also the low price will allow me to use the 130kv and 180kv version as a kind of gearing option. I know the neu motors are powerhouses and are very reliable, BUT they are more expensive than what I am looking to spend on the entire conversion.
Its all depepnding on how the motor and ESC will handle a rollout of 6.81( possibly less with the FG style tires). If it wont cog so bad that it stalls I can move forward and start designing some things on emachineshop.

[Ryu James]

hey beast,
do you know if this new buggy is longer than the rampage and more like the length of a baja 5b? i know the new MCD v4's are longer than the predecessor to be similar in length to the baja 5b and more true to 1/5 scale instead of 1/6. i am wondering if redcat did the same thing to answer to MCDs new release.

[Obeast44]

Judging from the pics its appears to be about the same wheelbase as the Rampage. I cant really say for sure but it does appear to be wider.

This car is more track oriented, with swaybars ,captured hinge pins, and a significantly reduced weight than its predecessor. So maybe they did set their sights on MCD.

Im really hoping to get to see one in person this weekend at LargescaleRC's Powerjam. I will have a tape measure and a micrometer onhand just in case :)
Dont hold you breath though :)

[JAILBIRD]

Regardless of what powers it, that is a damn nice looking buggy! Being brushless will be the icing on the cake.

-JB

[Obeast44]

I have more pics since everyone seems to like it :)
Heres a few:





and the best for last :D

[Ryu James]

Obeast,
just read through the thread on rrf. so i guess redcat makes an improved version over this one which is available through engage rc? engage's site shows they have 1 roller in stock for $419. have you checked to see if that is really available or just for pre-order? or are you just holding out for the redcat so that you know it has been beefed up?

btw, where are the swaybars you keep mentioning? havent seen them in any pics yet. am i not looking hard enough?

i hate you and love you for showing me this. oh the pain of spending all my money on rc!

[Chadworkz]

Me wants!

[Obeast44]

Originally Posted by Ryu James

Obeast,
just read through the thread on rrf. so i guess redcat makes an improved version over this one which is available through engage rc? engage's site shows they have 1 roller in stock for $419. have you checked to see if that is really available or just for pre-order? or are you just holding out for the redcat so that you know it has been beefed up?

btw, where are the swaybars you keep mentioning? havent seen them in any pics yet. am i not looking hard enough?

i hate you and love you for showing me this. oh the pain of spending all my money on rc!

Hahah glad I could help :)
I will try and explain this to you the best I can. HSP manufactures the buggies in China, Redcat purchases large quantities with their decals and options required. They order enough they can dictate design changes and improvements. Engage RC gets their buggies from Riverhobby who in turn gets small quantities from HSP. The Riverhobby owner is personal friends with HSP's owner. The reason the pics I have of the buggy dont show swaybars is because they are taken from EngageRCs website. They get the baseline models and sell them.
Redcat has a few pre-production samples they are testing, and after the needed improvements are made they will be importing them. The sample they have has the swaybars, and you can also see them on the truck on RRF
Heres a pic of the MT version with the swaybars, look closely :):


And trust me, I hate and love you for showing me the brushless conversion Rampage! Hehehe So I guess we are even :D