Serpent 966 - 1/8 Onroad brushless project

[othello]

After converting a 1/8 buggy, truggy, SC and stretching a truggy to 1/5 buggy i was looking for something different. I got attracted by 1/8 onroad cars as i always wanted to know the performance difference between those and a 1/8 buggy converted to onroad. After some research on the web i bought a used Serpent 966 roller off of ebay.

This was the basis of my project


I fitted a speed passion motor mount from their serpent 960 BL conversion kit which contains a motor mount and the necessary gear to convert a 2 speed into single speed.


I had a leftover Neu 1515/1y (1100kv) smooth can from previous conversions which i mounted after some dremel job to the motor mount (the motor mount is conceived for motors with 36mm diameter). I disassembled the 2 speed and converted it to single speed. A 18t pinion was one of the only pinions which meshed perfectly with the spur gear since i had not much room to change the motor position due to the bigger diameter of the Neu 1515 motor.

[othello]

Now on to the more challenging part of this conversion. How to fit a battery to this type of chassis? Since i'm using a 1100kv motor and as i want to reach around 45000rpm (Nitro onroad motors are close to this level too) i need to use 10s lipo cells using my trusted Kontronik Jazz 55-10-32 ESC. I mostly have red about 6s 1/8 on road conversions which used around 4000mAh. Well this corresponds to 10s 2500mAh in terms energy capacity.

I sourced 2 3s SLS 2200mAh lipos from a buddy and paired them with my leftover hyperion 3s 2200mAh which results in a 9s 2200mAh battery pack for testing puposes.

So this is what i came up with and how the car is setup right now using components i had in my parts bin. 2 3s Lipos (the green ones) are fitted under the top deck between the motor and the steering servo. And the 3rd one is laying on top of it. As i already mentioned this was for testing puposes only as i wanted to see how this car handles.


To offset the weight of the 2 lipos under the top deck which stick out more on the right side i placed the ESC on the left side of the top deck. This provides a perfectly balanced Chassis (r/l). A microsens BEC fitted directly in front of the third lipo provides power to the receiver and the steering servo directly from the 9s battery pack. This setup as seen here wheighs 2600gr (5.73lbs) without the body.


Chassis with protoform P909 body

[othello]

Although the outside temperature showed minus 10°C (14°F) i had to give the chassis some rollout.

This is the video of its first test run

With this kind of driving i used around 100mAh per minute. Battery setup will change as soon as i'm 100% sure which lipos to use. As of now i think i can perfectly fit 2 5s turnigy 2200mAh (10s in series) below the top deck with lifting it a few mm.

I already painted the body and it came out pretty much as i wanted it to be ...


Right now my place is covered with snow and it's still too cold outside to conduct more test runs. But i will update this thread as soon as i'm able to get more test runs.

[Jony Nitro]

Impressed with the 9s in there,and that you got it all in there, max mph?

[lutach]

That's a nice set up you got going on there.

[othello]

With 9s (around 37500rpm) and 18t pinion serpent's drive calculator puts it at 98,5km/h (61mph). With 10s top speed should be 110km/h (68mph).

I made a second test run yesterday and both the front and rear belt broke due to stones laying around everywhere. Lesson learned. I must protect the belts with lexan pieces.

[magman]

My mrx 3 conversion is similar to yours but different. I also chewed up belts due to stones on the pavement. It is amazing how fast these cars actually are and how well they handle. I run mine on a 6S setup with a 1518 motor and MMM esc.

Here is a pic of mine using 2 batts spread out on a homemade tray




If I were to do it over again, I would try a Tekin set up to run a sensored set up.

Mine took me awhile to get the esc settings just right to minimize wheels spin, right amount of drag brake, etc. But since I did, WOW it flies and is so quick if I do not completely focus on the car, bad things will happen

[magman]

Actually, where did you get the yellow wheels for yours....I am looking for black ones for mine and having little luck finding some

[myndseye]

I'll share a W-Boyz tip with you. You still may have some gearing options, if other spurs can be fitted. We have "the magic number", for our conversions where the motor can't move. After you lock your motor down, find that perfect pinion that meshes with your spur correctly. Add together the number of teeth in the spur and pinion, and once you have the total, thats your "magic number" for that rc. Any spur and pinion combo that adds up to that number will go on, without you having to move a thing.

[Overdriven]

Originally Posted by magman

Actually, where did you get the yellow wheels for yours....I am looking for black ones for mine and having little luck finding some

Amainhobbies has 1/8 tires, and with black or white rims. They kinda look like the yellow ones he has.

Cool conversions guys. I've watched vids of these cars nitro and electric. I'd love to drive one, but wow they are fast. I guess you get used to it, but I don't think I could relax and enjoy it, lots of concentration to not turn it into a million worthless pieces!

[Brow]

Nice looking conversion. Do you have any pics of the motor mount after mod to suit the 1515?
I am interested in the mount for a project using a 1521 but don't want to do too much grinding.
Any updates on the 10s config?

[magman]

Originally Posted by Overdriven

Amainhobbies has 1/8 tires, and with black or white rims. They kinda look like the yellow ones he has.

Cool conversions guys. I've watched vids of these cars nitro and electric. I'd love to drive one, but wow they are fast. I guess you get used to it, but I don't think I could relax and enjoy it, lots of concentration to not turn it into a million worthless pieces!

Thanks for the tire advice.

Yes these are very fast and a handful. The speed is extreme but for me the sheer quickness is astonishing and what gets people in trouble real fast. You blink and you are doing 50+ mph. Concentration is soooo key to running these successfully and even then you need some luck to bring it home in one piece. I only plot race with friends and their nitro mrx-3's and it is quite the scene when 4 of us are running in a small space...someone usually goes home with a broken car. As fast as my friends nitro cars are with the 2 speed, mine with a one speed and electric is still quicker and easier to control

[othello]

@Magman
I initially also planned to use a 6s setup with a 1518 motor but came to the conclusion that it would be easier to convert this car with a Neu 1515/1y smooth can motor. Nice setup you got there. What motor mount did you use? You obviously had to remove the carbon brace to fit your motor and motor mount. I atually never tried it but had the impression that the 1518 would be slightly to long when used in conjunction with the speed passion motor mount which sits right behind the carbon brace (leaving less space for a longer motor can).

I got the yellow wheels on a sale of an rc wholesaler at my place which a buddy of mine has good contacts with. If i remember it right those are Jaco 30 shore tires and wheels. But as they are offset 1 wheels i had to dremel the front and rear wheels to fit them"properly". So i can't recommend them for a serpent 966. I have now fitted ATS tires with 35 shore with proper offset 2 wheels (and the wheels are white which does look better with the way i painted the body).

@Bow
I actually did not make any pictures of the mount after i had finished my dremel job. But you basicaly only have to widen the motor mounting holes somewhat since the motor will sit a few mm or inches higher then a 36mm wide motor. That is all i have done to fit the wider Neu 1515 smoothcan. This will take you a few minutes.

No update yet concerning the planned 10s setup. I have to protect the belts at first. Then i will make a few test runs with 9s again. And only then i will move to a 10s setup.

@myndseye
I will keep this in mind if top speed is not satisfying with 10s.

@Overdriven
It really depends on where you drive those cars. As seen in my video i posted i want to use this car only on this wide open space. I do not intend to drive to race track ... unfortunately no time for that at all. If you have enough space you really will feel comfortable after a few runs with the speed of those cars. They handle like a train on rails. Very stable and predictable at high speed. But i do agree that driving this car on a tight race track must be very challenging and concentration is key.

[magman]

I used a Revo motor mount actually. A PITA to install as there was very little room for the screws as they came up into the mount to add ny-lock nuts as the motor is so wide. My car is a hand full but fun!!