'REBEL' STEALTH KART DESIGN CHANGES

As per usual, I decided to change things up at the last minute. The more I looked at the original plan, the more I disliked it. It's too goofy looking, for one. The new design is sleeker and more aggressive. 

ORIGINAL DESIGN

NEW DESIGN

The original is overcomplicated. The battery or specifically the battery box involves a lot of work, its position would make it a PITA to service later and raised the overall height and center of gravity, which increases roll potential, weight and the material needed to build it. The forced air TMS would also be an unnecessary feature that made me uncomfortable. Forced air cooling directly through the cells works fine in a controlled environment like a house or workshop, but with the constant humidity changes outside, I prefer to hermetically seal the battery. Given that it's dramatically oversized for the job, I highly doubt it will experience any heat build up issues when used. 

Instead of multiple modules being located below the seat, I split the battery into two modules with a 24P15S configuration on either side of the seat which will be connected in series to form 24P30S and have a single external BMS. This allowed me to lower the seat ~5" and subsequently the overall height of the kart without affecting the 11" of ground clearance below, which also lowers the CG and spreads more weight over a wider area to help with cornering stability.

The cabin was also narrowed and the TMS input in the blunt front end was removed and the front reshaped with a portion of the bottom angled up for better ground clearance and aerodynamics. I also added cowls over the front upper shock mounts and wheel fenders. These changes helped to lower the curb weight by ~100 lbs.

The last major change is in the drive train. The solid rear axle is being replaced with a 5" open differential from an '06 Honda CRV. An open diff isn't ideal, but I'll be installing an aftermarket limited slip kit as well to convert it to a LSD. This will eliminate any understeering that would have otherwise happened with the solid rear axle because the wheels need to travel at different speeds when cornering to compensate for following different radii. A solid rear axle works fine in the dirt where one of the tires can easily spin to keep up with the other, but it's harder to do on the pavement and will result in faster tire wear and/or a trip into the ditch. The LSD allows the wheels to spin freely of each other, but will lock up the axles as if they're one solid unit if one of the wheels begins to spin and lose traction. This will make it ideal for driving safely on pavement but also for tearing up the dirt in the trail = a win win. 

The LSD will be chain driven. The drawing shows the gear set with a sprocket in place of the large drive gear that would otherwise couple with a drive shaft. I omitted the housing in the drawing for the sake of seeing inside better, but the gears will need to be enclosed so they can be constantly lubricated without making a mess everywhere. I might change this configuration when the differential arrives and I can get better measurements to see what my options are and how I can modify the housing as needed.

I have to give a shout-out to Brian at XS Motorworks for figuring out this 'poor mans' LSD hack for DIY crosskarts and buggies. He's also building a crosskart atm, which is a little hybrid monster that he plans on racing against his friend. Check out his channel:
​https://www.youtube.com/channel/UCF6hn52lSuoXzIYnwLOUw9Q

That's it for now. The tubing was delayed at customs for a couple weeks but arrived the other day. Just waiting for the new rotary draw tube bender to be delivered tomorrow. I'll be starting the build for sure next Monday. Updates to follow.