[Duncan]

I used to own a 100cc direct drive kart - it would hit 70 mph on the straights and corner like nothing else

I would suggest that you start by looking for something like that - with a blown motor - simple - no diff - just a brake on the rear axle

The kart supply place is where you get the wheels/tyres
And if you are 3 inches off the ground you are doing it wrong - aim for 1 inch

 

[428RC]

a good data point would be the hp number for the 100cc 2 stroke race engine, any idea what that might have been. I am thinking somewhere around 15-20HP? which would be 11-15 KW?

 

[Duncan]

a good data point would be the hp number for the 100cc 2 stroke race engine, any idea what that might have been. I am thinking somewhere around 15-20HP? which would be 11-15 KW?

Just over 20HP - 15 kW but that is peak power - you don't need that much if its an electric motor

I would definitely be thinking about small detachable battery packs - think Lithium Poly - like RC aircraft - but remember those batteries can go on fire and ensure they are charged outside on a metal plate

I found driving the kart to be incredibly tiring - five laps and I was knackerred - so you probably won't need a lot of endurance on a single pack

The motors that RC aircraft use may be usable as well - a quick look found a 4.4kW motor - start with one and add more later

 

[floydr]

I get what you're saying, it's not really for kids, it's for me to use(23) and a younger cousin who has been asking(18) for a smaller sporty looking car that we can play around with. There is this ginormous open unused lot near my house where we want to use it, it'll hardly ever get used on sidewalks.

How big is this lot? size would dictate how fast you can go. Paved or natural surfaces? condition of surfaces? This imo should dictate what you build for use on the unused lot. Sidewalks would mean it is in an urban area? Paved good condition asphalt Racing gocart. Poor condition asphalt gravel/dirt surfaces require more height suspension different tires.

later floyd

 

[Deane]

...& personally, I feel that a differential is a PITA (especially if used off road)
What the heck is a PITA? Never heard of it?

 

[Duncan]

...& personally, I feel that a differential is a PITA (especially if used off road)
What the heck is a PITA? Never heard of it?

PITA - Pain In The Arse

 

[gorfElectric]

What are you doing for a car body?

 

[remy_martian]

"Detuned" (inverter limited) Tesla front drive unit is the way to go on this one...

You get the open-PITA for free.

 

[KarlasPedron]

Building a mini electric car from scratch and designing the frame/chassis yourself is no small feat, but with your experience in 3D design, I'm sure you'll be able to create something really unique and fun. I'm not sure if you've already checked it out, but there's a car news portal that has a lot of helpful information on electric car components and DIY projects. It's not a sales site, just a place to get news and reviews on the latest developments in the world of electric cars. While most posts on here are about conversions, it's awesome that you're taking on the challenge of building something completely new.

 

[brian_]

I'm not an expert, but I've been told a differential is needed as well for times when you are turning. What do you think?

Yes, to turn properly on a high-traction surface (pavement) you need to allow different left and right tire speeds, which means either a differential or two separate motors... or just driving one tire (which is fundamentally horrible, but can work for a child's toy). Karts get away without a differential, but they are designed to essentially lift the inside rear tire in a turn, not off the ground but unloaded enough that it can slip enough to allow the turn. Anything that only drives in dirt can also get away without a differential, and in many cases that's preferable. Keep in mind that karts are intended to be driven with a much power to the drive tires as they can, making the forced-slip idea more viable than it would be for a normal vehicle.

 

[brian_]

I've built them both ways (live axle & differential)...

I don't think that "live axle" means what you think it does. It just means that the axle is powered, not that the two sides are solidly connected together.

 

[Functional Artist]

I don't think that "live axle" means what you think it does. It just means that the axle is powered, not that the two sides are solidly connected together.

Hey Brian,

Maybe in the automotive world
...but, in the go kart (not street legal) mini-car "world" there are usually (3) options:

A live axle, which is usually referred to as a solid rotating axle, that is mounted on bearings
...& is solidly attached to & "drives" both "drive" wheels

A dead axle, is usually referred to as an axle that is solidly attached to the vehicle
...with the bearings mounted in/on the wheel(s) themselves
...& the wheels rotating independently, of each other
...& "if" used as a "drive" axle, only (1) wheel is usually "driven" (AKA (1) "wheel peel")

A differential is usually (2) separate axles that "drive" the "driven" wheels via a differential unit

 

[brian_]

A live axle, which is usually referred to as a solid rotating axle, that is mounted on bearings
...& is solidly attached to & "drives" both "drive" wheels

Again, that's not what "live axle" means; "live" just means driven. "Solid" for both wheels on the same shaft, sure.
I listed that as an alternative.

A dead axle, is usually referred to as an axle that is solidly attached to the vehicle
...with the bearings mounted in/on the wheel(s) themselves
...& the wheels rotating independently, of each other
...& "if" used as a "drive" axle, only (1) wheel is usually "driven" (AKA (1) "wheel peel")

No, a dead axle isn't driven at all, and the term "dead" refers to the lack of drive, not anything to do with suspension.
I listed one driven wheel as an alternative.

A differential is usually (2) separate axles that "drive" the "driven" wheels via a differential unit

That's two axle half-shafts, which are part of one axle assembly.

 

[Functional Artist]

Hey Brian,
You may want to do some more research (on this one)

For example:
Go Kart-Live Axle kit
6" Live Axle Kit

Go Kart-Dead Axle (Drive wheel with bearings & drive sprocket)
145x70-6 Drive Wheel Assembly Complete with 5/8" Bearings, Sprocket & Brake Drum

Go Kart (riding mower) Differential
Peerless 100-224 Differential 1" Axle | Peerless | Brands | www.surpluscenter.com

For example:
This kart (Excalibur) has a "live axle"
...& this video shows "it" pretty well

This kart (E-Lemon_Aid) has a "dead axle"
...& this video shows "it" pretty well

This kart (Double Trouble) has a differential
...& this video shows "it" pretty well

 

[remy_martian]

What kind of axle is it when the front wheels fall off from the impact loads due to popping wheelies? 😂

 

[Functional Artist]

What kind of axle is it when the front wheels fall off from the impact loads due to popping wheelies? 😂

That would be an axle that's NOT being "operated within its specified parameters"

For example,
The front & rear axles on my !ARRIBA! kart would both be considered to be "Dead Axles"
...because neither of the "axles" themselves, actually rotate

The front wheels have bearings in them & are mounted on spindles
&
The rear wheels also, have bearings in them (plus, the drive sprockets)
...but, are mounted on a "full length" axle
...& since that axle doesn't rotate, the "ends" are, or could be considered, the same as spindles

 

[Functional Artist]

Again, that's not what "live axle" means; "live" just means driven. "Solid" for both wheels on the same shaft, sure.
I listed that as an alternative.


No, a dead axle isn't driven at all, and the term "dead" refers to the lack of drive, not anything to do with suspension.
I listed one driven wheel as an alternative.


That's two axle half-shafts, which are part of one axle assembly.

Hey Brian,
After re-reading both of our responses, it looks like & I think we are kinda saying the same things

IMO you have a lot to add to this "field"
...but, continually correcting folks gets irritating

* Ya know how Remy gets (sometimes)

It's better when you (& Remy) actually "join" the conversation
...& help further the discussion

 

[brian_]

Hey Brian,
You may want to do some more research (on this one)

For example:
Go Kart-Live Axle kit
6" Live Axle Kit

Yes, as I said that's a live (driven) axle.

Go Kart-Dead Axle (Drive wheel with bearings & drive sprocket)
145x70-6 Drive Wheel Assembly Complete with 5/8" Bearings, Sprocket & Brake Drum

Despite your label that web page does not use the term "dead axle"

Go Kart (riding mower) Differential
Peerless 100-224 Differential 1" Axle | Peerless | Brands | www.surpluscenter.com

Yes, that axle assembly includes a differential. The seller does not label it as just a differential.

Hey Brian,
After re-reading both of our responses, it looks like & I think we are kinda saying the same things

IMO you have a lot to add to this "field"
...but, continually correcting folks gets irritating

You can spread misinformation if you want - I don't think that's constructive, and I do think that corrections are constructive, because they help people learn, as you apparently have in this discussion.

 

[Functional Artist]

The terminology is a bit different, because we're talking about (2) different "fields"

You're referring to full size cars
...& I'm (& the topic of this thread) referring to (not street legal) "electric mini-cars"

Mis-information?

I posted links to the (3) different types of mini-car/go kart axles (that I referred to)
...& I even posted (3) videos showing "real world" examples of all (3) types (in use)

To be clear

A Live axle refers to an axle that is "alive"
...meaning "it" rotates, with the wheels

A Dead axle refers to an axle that is "a dead"
...meaning "it" doesn't rotate with the wheels

A Differential, on an "axle assembly"
...or incorporated into a motor (case)
...or even as a totally separate unit is "basically" a box of gears
...that transmits the rotation from the motor (or engine) to the wheels via "live axles"

The rear axle, on most RWD cars would be considered a "live" axle (because the axles, rotate)
...with a differential (incorporated) to aid maneuverability
...& the front "axle" would be considered a "dead" axle (because it doesn't rotate)
* Technically, (2) totally separate spindles are not really "an axle" (as a component)
...but, that's another subject

The front axle(s) on most FWD cars (again, technically NOT "an axle") are considered "live" axles (because they rotate)
...& the rear axle (more axle like) would be considered "dead" (because "it" doesn't rotate with the wheels)

 

[Duncan]

I'm with Brian on this
A "Live axle" is a driven axle - like the old Escorts and Cortinas - an axle that is one piece - normally with a diff in the middle