1/8 Electric Taken to the Text Level!
 

My patience waiting for companies to design an electric buggy from the ground up and done correctly had run out. Therefore it was time for me to go to the drawing board and attempt to do it myself. The compatibility a single brick pack or dual battery packs, a centerline driveline, centerline weight distribution and low CG all seemed simultaneously possible and favorable, yet did not seem to exist. So here is what I came up with, and it is a few steps ahead of both the Caster Fusion and Hyper 9e in terms of chassis layout.

It began with a Losi 8ight chassis, and me being a mechanical engineering student with access to the machine shop at school. I know the offset rear driveshaft makes it all that much more difficult to make completely centerline, but I’ve owned my 8ight as an electric for almost three years. I trust it, I know it inside and out – I could make it work. In short, after A LOT of thought, taking countless measurements with calipers, making a series of CAD models, drawings, and hours track mill time, here it finally is! (See attachments)

The first thing that had to happen was to put the front diff housing in the rear. This was not easy. The pivot braces that hold the a-arms are optimized for front suspension geometry and a front shock tower, which forced me to integrate the diff housing into the rear of the chassis… a few extra parts and some custom fitting, whatever… done.

As you can see, the center diff is moved as far forward as possible – the front outdrive nearly touches front diff housing. Keeping the wheelbase the same as stock, this leaves 214mm of space in the chassis for everything else. Dual battery packs of ROAR spec take up no more than 140mm, leaving enough room for a Tekin or Castle buggy motor on one side of the driveline and the rest of the electronics on the other side – even the big Mamba monster will fit with the receiver pushed off to the side. If one brick pack is used, everything else goes behind the motor. In the pictures are dual 40C 3000mAh 3s packs and a Tekno-Neu 1509 2.5Y/Mamba Max Pro esc.

Additional Design Features

Chassis: Made out of 3/16 inch thick 7075-T6 aluminum, countersunk .1100 inches to lower batteries by nearly a half inch, and then some due to the dual pack layout vs. a tall single pack. Right now, packs are just Velcro-ed to the chassis (works really well for slim packs weighing less than 12 ounces), but I will eventually make brackets that hold battery straps.

Motor plate: easy slide in allowing the motor screws to only need partial adjusting upon changing motors and pinion gears. Since the chassis is 3/16” thick, the Kyosho 46 tooth spur fits with ease. The motor plate also doubles as a servo holder and the servo mounts to it the same way the servo mounts in the Losi xxx-4 or in many other 1/10 scale vehicles.

Center drive shaft: Just an oversized aluminum rod poorly turned down on the lathe with holes to fit the CVD coupling and a press-fit pin for the dog bone end. It works.
Shock towers: Similar hole positions, but half inch lower shock mounts in the rear, and will be a quarter inch lower in the front (haven’t made the front shock tower to match the rear yet). I found that lowering the shock towers by this amount works just fine for all off road conditions through experience with using modded L8ight Model shock towers on the 8ight beforehand.

The end result?

A setup is approximately 6.6lb, and drops to 6.1lb with dual 40c 1800 mAh 3s packs – more than enough juice for 10 minute mains. I’ve only done one race night (I guess I can say I won) and some bashing in the street, but after this, the buggy’s handling is so much more precise with a lot more grip and no more lifting wheels in corners.

I am hoping after this, and the word is spread, companies will start catching on to finally do 1/8 electric the way it should be done. If by chance, you are an interested representative of a company, a PM would be highly appreciated.

I will add updates as this project continues.

I'm speechless. That never happens to me. Kudos!!!!!!!!!

Very Nice!

Well done! Terrific work!

Damn!

I would suckle on your titties if you were to put that into production!

Awesome!

How's side to side balance?

No chassis braces?

Looks interesting, nice job - A couple of points I would like to see though...

- Your servo arm angle / position looks off
- No chassis brace in the rear is going to cause a lot of stress / flex
- I see you pocketed the chassis but would still like battery trays

I second those 3 points as well.

However, it looks great!! I love the center and straight driveline! Not bad at all!!!!

I think you're definitely on to something :)

Nice work, looks similar in design to what Caster has, except they never learned to use better quality aluminum. Hyper 9e has a similar driveshaft as well, but yours is a lot larger diameter which may be a plus for the length.

What is the "text level"... chassis have writing on it? :lol:

Impressive doesn't begin to describe !

great work you got your liter than mine

Thanks for the replies.

I knew I was going to get the question concerning the lack of a chassis brace and the angled servo arm. I will be working on a chassis brace soon. The holes to mount it are already there. As for the servo horn, as long as it stays parallel with the steering arm, there shouldn't be any issues other than slightly more binding turning left vs. right. I could rotate the servo 180 degrees and move it out more, but then I would have to raise the servo link so it deosnt hit the servo.

As for why I chose to integrate the battery slots into the chassis instead of battery trays - lower CG, less weight and more freedom for different sized packs. I am going to build brackets that will sit flush with all sides of the batteries and hold battery straps.

awesome job!!!

Updates: (2 entries, one from last week, and one today posted into one)

Sorry it has been a while. Been busy lately.

Peformance:

Overall, the buggy is much more responsive with a little bit more steering - something that my original 8ight has been dying for. ...And no more traction rolling . Weight bias with the 3000 mAh packs is 48.5F/51.5R, verses the original 8ight E's 47F/53R.

So far I have completed a few indoor races and a few outoor races with some pretty outstanding results! For one, no DNF's and all finishes in the top third of the pack except when my esc unplugged from my reciever on one occasion. (It wasn't plugged in all the way).

The outdoor races were the real test as I had to run 30 minute mains in a field of mainly nitro on a very large dirt track of 40 second laps. Still I was able to complete all three mains with 2nd, 5th, and 2nd, out of 7, 15, and 7 respective fields that included sponsored drivers, adding a lap to my total each race. Next time i will be trying a brand new set of AKA enduros, instead of year old city blocks with the outer pins gone.

I timed a battery change with my velcro solution (entering pit lane to exiting) and it took 27 seconds - still slower than nitro's three 7 second pit stops, but I think I can chop off 5 or so more seconds with better communication with the pitman and neater wiring.

The total mAh that my 3000 mAh 6s sets took was 4000 mAh each time, with a single set lasting over 21 minutes during practice, but at race pace. Last year on the original 8ight chassis, my Tekin 1900 on 4s 5,000 lasted 19 minutes on the same track, so quite an improvement.

The Tekno Neu 1509 2.5Y (1450kv) motor was topping out at 160F geared 12/46 which matches the top speed (maybe slightly faster than) of nitro. The light motor was a good concept, but it is causing more problems than it is worth. The motor leads extend over th batteries, making battery changes more difficult (unfortunately it is not a good idea to bend or cut those types of wires). It's also way more powerful than I thought it was going to be. I was looking for something with less punch than my Tekin 1900 on 4s, but it ended up having considerably more. For fun i put 17 tooth on for running in the street, and it could still pull wheelies with ludicrous top speeds.

So far, the velcro has been working well in terms of holding the batteries down. I still have not made a chassis brace yet, but I have gotten away without one sor far. My first priority is to remake the chassis with better jigging in the machine. The pockets ended up being to deep in some places because the aluminum sheet bowwed upward during cutting. Some places are paper thin and have caused me to worry. There are also some slight changes that I want to impliment that will relieve stress at the hole locations where I can see some cracks initiating.

This saturday is another outdoor raceday. Next week I will build the chassis. I will have more pics once I get a hold of a decent camera.

Saturday Race results:

2nd out of 13 this time in the 30 minute A-main. The aka enduros were great. Better grip overall so very consistant, but less peak grip than the worn city blocks. I should start machining the new chassis on wednesday.

great update, pm me and let me know if you could have another one of your chassis made, i would like to buy one and try it out

Brilliant work, I'd love to see manufacturers adopt that chassis layout in the same way they've adopted Mike's motor mount designs ( albeit with some interesting variations ) :lol: :yes:

Here are some pics of the new chassis. Still need to add the finishing touches & bends, but otherwise everything went as planned. I used a 1/8" aluminum plate as a back brace to keep the chassis from flexing so much while I was machining. So... I ended up with two new chassis! One 3/16" thick with pockets, the other 1/8" plain. Clever huh?

I will be trying both. They both weight about the same, but the 1/8" has a lower polar moment forward and back. It also flexes more so I may bend up the sides. The 3/16" has everything sunken in, so everything sits about 2-3mm lower.

I also made a new motor/servo mount as seen in the second pic. The third pic is just of the front shock tower I made next to the stock one.

Semi, I am just going to say it here. I can't sell any of my work. I am just a student not a machinist. It takes a lot of time for me just to make one part, let alone replicas. You'd need all 8 parts to make it work anyway. Not only that, but it is against the rules of the shop to be distributing my stuff.

Now if I end up working with a company to design a 1/8 buggy, I can assure you that it will be far better than this!

Great work!

I like this, very forward thinking here. I could see a really nice cam type battery hold down and some permanently mounted power cables. That would eliminate your battery changing issue and hold the packs in at the same time. I will attempt to illustrate my ideas on that and post here. Keep up the good work!

Thanks! Got to race it at the indoor track yesterday and took the win and tq in a field of eight or nine. First win for me at that track with more than three other people in the race :lol:. I am experimenting with battery straps instead of the velcro holding the pack. I think I can make it so I can change batteries in a reasonable amount of time. Two straps that go across the entire chassis.

Yes... please show me your thoughts! One thing that you have to click release the batteries would be nice - like a seatbelt or bicycle helmet.

nice BL buggy bud.
does it run good?

Nice idea and execution. Your layout and powertrain are very similar to mine, I just didn't make a new chassis.
I would definitely recommend some sort of battery holder, which keeps them from moving when nose landing from jumps etc.