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1/8 Electric Taken to the Text Level!
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SpEEdyBL
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1/8 Electric Taken to the Text Level! - 06.02.2010, 05:35 AM

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.
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Check out my custom converted 8ight:
Sub 7lb, lowest CG of any 1/8 buggy

http://www.rc-monster.com/forum/show...894#post367894

Area 52 Ranch Raceway
T.R.C.R.
   
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_paralyzed_
working on a brushless for my wheelchair.....
 
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06.02.2010, 06:51 AM

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


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It's "Dr. _paralyzed_" actually. Not like with a PhD, but Doctor like in Dr. Pepper.
   
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brushlessboy16
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06.02.2010, 07:37 AM

Very Nice!


Benjamin White
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magman
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06.02.2010, 07:39 AM

Well done! Terrific work!


1. MBX-6 T8 1900KV, RX8 ON 4S
2. MBX-5T 1520, MMM ON 5S
3. MBX-5 ONROAD CONVERSION 1515, MMM ON 5S
4. MRX-3 ON ROAD CONVERSION 1512, MMM ON 6S
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MikeW
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06.02.2010, 08:32 AM

Damn!

I would suckle on your titties if you were to put that into production!
   
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sabongi
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06.02.2010, 09:30 AM

Awesome!

How's side to side balance?

No chassis braces?
   
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Arct1k
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06.02.2010, 09:54 AM

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
   
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nitrostarter
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06.02.2010, 10:05 AM

Quote:
Originally Posted by Arct1k View Post
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!!!!


N. Rustler conversion
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pinkpanda3310
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06.02.2010, 10:27 AM

I think you're definitely on to something :)
   
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reno911
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06.02.2010, 10:40 AM

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.
   
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bdebde
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06.02.2010, 03:17 PM

What is the "text level"... chassis have writing on it?
   
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Bondonutz
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06.02.2010, 04:33 PM

Impressive doesn't begin to describe !


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Semi Pro
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06.02.2010, 05:19 PM

great work you got your liter than mine


Quote:
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......maybe they want to be more like novak
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I'm telling Patrick you said that!
   
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SpEEdyBL
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06.03.2010, 03:11 AM

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.


Check out my custom converted 8ight:
Sub 7lb, lowest CG of any 1/8 buggy

http://www.rc-monster.com/forum/show...894#post367894

Area 52 Ranch Raceway
T.R.C.R.
   
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motorman17c
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06.05.2010, 09:32 PM

awesome job!!!
   
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