Durability of aluminum and hollow axles

[GreyhoundOfYerfDogs]

Hello,
I'm building a kart for off roading that I will probably eventually power with a Briggs V-twin. Also the kart gets heavy off-road use. I'm considering a hollow chrome-moly axle, but I was also looking at the tubular (or maybe solid) aluminum axle.

My questions are these. How do aluminum axle keyways hold up to very high torque? Are they suitable for heavy, high-power karts or best for racing applications only? I'm wondering if aluminum deformation tends to occur at the key. I've read of side-loading force against the key reaching hundreds of pounds.

Next question, how do hollow axles hold up under heavy off-road use, be they steel or aluminum? Are they only fit for pavement use?

Obviously, I could "just" use a solid axle, but weights tend to add up quickly. I wanted to know of any real-world experience with these axles before I buy.

Thanks,

 

[redsox985]

For the added durability, a solid axle is probably worth it. And if you slap in a V-twin, there will be no noticeable difference because of its power.

 

[brendonv]

Get a solid steel axle. The difference in weight wont be enough to make a difference. An aluminium shaft vs a steel will be about 2kg difference. Not enough to notice.

 

[porsche930dude]

i agree. the axle is the last place you should be going to reduce weight

 

[tundrazach]

Aluminum is not durable. Yes it can be strong depending on its alloy and heat treatment, but it does not fatigue well. Say you hit a nice rock at speed, a solid steel axle with most likely take the hit, and spring back. Aluminum starts to crack as under stress.

 

[GreyhoundOfYerfDogs]

Okay, well I decided to go with the tubular chrome-moly axle, rather than the aluminum or plain tubular steel. I'll let you know how it holds up.
It will be at least a month before the kart is riding.

I figure if it bends, I'll buy the solid steel one for under $35, and say live and learn. Considering that he rest of the axle components (including complete hydraulic brakes) came to almost $500, a potential replacement axle is peanuts.

Thanks for the input, and I'm still curious to hear from anyone who has run aluminum axles, especially with high horsepower.

If you're wondering why I didn't just get the solid steel, my plan is now to make a hydrostatic drive system, which has a LOT of heavy parts that really add up. The weight difference of a hollow axle may seem like mousemilking in many applications, but in this case I find it a blessing to get a part that's half the weight. Chrome-moly is a good alloy, too.

 

[sideways]

I've seen a bent solid 1" 4140 chromoly that was on a sidewinder that rolled pretty bad, that stuff is about as strong as you can get.

I've also seen a kart with an aluminium axle, it had a GC160 (4.5hp) and was just an on road kart, the axle seemed fine, it was still quite a heavy kart (they weighed it at 190kg with driver I think).

Good luck with yours.

Thanks

Hayden