[Kartbuilding] Greetings kart builder!

[Stephen Burke]

Hi Jared,

The diameter of solid rear axles depends a lot on the purpose of the kart. 
The weight of the rear axle goes up significantly with an increased 
diameter.
1" (25mm) diameter rear axle sounds a little small.
I would recommend 1.25 or 1.5" (32 or 38mm) diameter rear axle. The exact 
size depends on the availability of the pillow bearings, brake and 
sprocket carriers. It would be much easier if you could get an exact size 
of rear axle to suit the pillow bearings, brake and sprocket carriers.

Depending on the distance between the wheels and the rear bearings, you 
may need a larger diameter rear axle. If the distance between the rear 
wheel and the pillow bearing is large, then you will need a larger axle. 
If the distance between the wheel and the bearing is small, then it would 
be possible to get away with a smaller 1.25" (32mm) rear axle.

As for mounting the rear wheels. Depending on your hubs, what material 
they are made from etc. the methods of mounting them will vary. If the 
hubs are made frm mild steel, a simple weld would suffice (which can be 
gound off later with an angle-grinder).
If they are aluminium, then you probably will have to use a "keyway" and 
key as is outlined on:
http://www.kartbuilding.net/racingkart/Free_Racing_Kart_Plans_PDF/Main_Kart_Complete_06_Rear_Axle_Complete.pdf

The ends of rear axles are not threaded. Instead hubs, sprocket and brake 
carriers have "grub screw" holes, which will accept a bolt to tighten the 
carrier/hub to the rear axle. See:
http://www.kartbuilding.net/gallery/v/Kart_Clearance_and_Memories/DSC01056.JPG.html

I hope this information helps.
Best of Luck,
-steve

On Mon, 7 May 2007, Jared Rattray wrote:
> Hi Stephen,
>
> I have done a lot of research and got most of my basic plans coming along
> fine.  I have a MaxTorque clutch coming and a Mig welder also.  The only
> thing im a bit stumped on now is the axle.  I want a live axle, and will
> have it mounted with pillow block bearings, but I dont know what diametre to
> use. Is 1" a good size? Really I just want to be able to get sprocket
> holders, brake disk holders and bearings that will all be the same size and
> buy a steel rod according to them.  As for the rear wheels should the end of
> the shaft be tapped with a thread and the wheels bolted on? I realise you
> can get proper hubs but my budget doesnt allow for a lot of fancy bits.
>
> Cheers!
> Jared