Hex axle vs round axle

[Greasyxb9]

I'm building a manco quicksilver 2 seater with a predator 420. It has the original hex rear axle and all the hex parts to go with it including the 7" wheels for the 16x8-7 tires. I like the way it looks as it sits but I'm extremely tempted to set it up like both my manco dingo's. They have the 1" round axle and 18x9.50-8 tires.

Now my question is are the hex axles as strong as the round? In the manuals I've found the quicksilver carts with 18" tires are round axle. Plus the power I'll be pushing through it worries me.

I race with a bunch of buddies on a small track in our back yard. It's not perfectly flat but pretty good. My dingo karts run fairly well but tend to bog down and I'm hoping to fix that with this 420 with out trying to tuck it in the dingo.

So what is everyone's thoughts on the hex vs 1" round or maybe even a 1 1/4" axle?

 

[Greasyxb9]

Here is a picture of the kart.

 

[Greasyxb9]

And how I bought it

 

[anickode]

A 7/8" hex axle is not as strong as a 1" round axle of the same alloy.

The advantage of a hex axle is the lack of a need for keyways and keys, and the mechanical engagement area between the shaft and component is much higher, which means it will (in theory) handle far more torque than a square key in a round shaft.

Think socket on a bolt vs a flat head screw.

 

[Greasyxb9]

True I didn't think about that. But is that advantage really worth it over the strength of the axle itself?

I raced go karts about 15 years ago and ran a open gx390. Some guys in my class ran 125 250 and even 500 cc 2 strokes and none of us ever had problems sharing a axle key but then again that is a 1 1/4" axle too.

 

[anickode]

A 1/4" key will sustain a whole lot more torque than a go kart will ever put on it, as long as the fitment is nice and tight.

Honestly I wouldn't worry about it. If you bend it, then replace it, but for the time being, save the money and enjoy your already functional go kart.

 

[Greasyxb9]

Ah it's not functional. I'm doing a full build and it needs rear tires are they are extremely dry rotted and need replaced. So before I buy new tires and then bend something, and then have to replace it again and buy new tires again for 8" wheels. That's why I'm looking about the hex vs round.

 

[Whitetrashrocker]

Round is easier to get parts for....

Otherwise run what you brung!

 

[dashi]

Basically, hex shafts (and round shafts with keyways) are both forms of live axles. With live axles, your bearings are held in pillow blocks to allow the shaft to rotate. This way, for example, a sprocket doesn't have to be physically connected to a wheel to transmit power. This can yield some advantages in maintenance if you design correctly, and live axles can be cantilevered, where a bearing is not the outermost element on a shaft.

 

[anickode]

Basically, hex shafts (and round shafts with keyways) are both forms of live axles. With live axles, your bearings are held in pillow blocks to allow the shaft to rotate. This way, for example, a sprocket doesn't have to be physically connected to a wheel to transmit power. This can yield some advantages in maintenance if you design correctly, and live axles can be cantilevered, where a bearing is not the outermost element on a shaft.

You don't say?

The question here was comparing the strength of a 7/8" hex axle to a 1" round axle.

 

[KartFab]

i ran a two seat larger dingo with a hex axle with a gx390 and jumped it with myself and wife in it no suspension and it didnt bend the hex axle.

Also have a hex axle on a manco 706b and its fine. ran amodified gx390 on it as well.

With this smaller kart i see no issue with a 7/8" axle. Chances are, if you get a different axle, whatever axle you get will probably be inferior quality to the original manco parts.

 

[Joe-405]

Golf cart + gs500e street bike engine + 1” axle with key way = no issues on some very hard wheelie 1/8 mile launches !!!! So I’d say you’d be good to go. Hahaha. It is finally starting to twist the key way a little bit tho but still running strong for about 6 months now.

https://www.youtube.com/watch?v=5BFs8VSp5Yo&feature=share

 

[Greasyxb9]

I went with the original 7/8" hex axle. If it breaks I'll be out a new set of tires and that's it. All the parts should be hereTuesday. I already pressure washed the frame and I'm waiting for the predator engine to show up and engine mount so I can start mocking up the jackshaft and mount. Thanks everyone!

 

[go-kart-game]

Hi guys,
I am new to this forum (can't even find the right button to start a new thread).
I am building a 3 wheels kart for my 8yrs old boy, something simple and scrappy.
I bought a 1/2 inch rod for the rear axle, but the hole in the sprocket is about 5 inch in diameter. Regardless of if I decide to take a more robust axle or not - How do you match the sprocket gear hole and fix it to your axle ?
Thanks!