how heavy can my frame be??

[Jaxonfox120]

ok my name is jaxon and im building a go kart, a guy at a fabricating place is gonna do a custom frame for me with a roll cage but i was just wandering if my predator 6.5hp (212cc) will be able to carry it all and still let me go fast i weigh 125 pound

 

[Jrgunn5150]

I weigh 260, and my Predator 212 could push my offroad go kart, that weighed an easy 300 lbs up to 35 mph in a reasonable amount of time.

 

[Hellion]

Don't go all crazy now, with excessive structural tubing and crossbraces. Lighter is always better for speed, maneuverability and similar concerns. Think race car...

. . .

 

[Damian Laffrey]

Your frame needs to be strong enough for your requirement. But, the lighter the better. Theres a way you can make a strong frame light enough to be lifted by a single arm.
You can take regular tubing woth a smaller gauge and reinforce it after welding .
We reinforce fiberglass with metal right....why not metal with fiberglass???...
After welding..we can use scrap bits of fiberglass fabric...nd blend in proper resin...cut a hole in your tubes enough to help u fill it, then using a rod or something...stuff in the fiberglass like how u do the turkey on thanksgiving.
Pack it tight...nd patch the hole back by welding.
Its a painstaking process..but trust me...the better the product wen u r ready to get your hands dirty. Reinforce all the tubes eith fiberglass or waste carbon fiber, then u get a light but solid strong chassis .

 

[Poboy kartman]

Your frame needs to be strong enough for your requirement. But, the lighter the better. Theres a way you can make a strong frame light enough to be lifted by a single arm.
You can take regular tubing woth a smaller gauge and reinforce it after welding .
We reinforce fiberglass with metal right....why not metal with fiberglass???...
After welding..we can use scrap bits of fiberglass fabric...nd blend in proper resin...cut a hole in your tubes enough to help u fill it, then using a rod or something...stuff in the fiberglass like how u do the turkey on thanksgiving.
Pack it tight...nd patch the hole back by welding.
Its a painstaking process..but trust me...the better the product wen u r ready to get your hands dirty. Reinforce all the tubes eith fiberglass or waste carbon fiber, then u get a light but solid strong chassis .

No...just NO!!!! Nothing about this makes any sense whatsoever....the strength of fiberglass or carbon fiber comes from the fibers being locked in by polyresins...what you're talking about is a total waste of time...

 

[Jrgunn5150]

I have to agree... Shoving tubes full of fiberglass wouldn't accomplish much. Just use the appropriate wall thickness to begin

 

[bob58o]

If done correctly, the whole frame can be a muffler?

 

[Damian Laffrey]

Fibreglass or carbon fiber with resin bro...resin is the sticky thing which hardens right....and stuff it in such a way that theres no room...increase the internal density as much . You should try a sample and check its linear strength....and shear strength.

 

[Poboy kartman]

Fibreglass or carbon fiber with resin bro...resin is the sticky thing which hardens right....and stuff it in such a way that theres no room...increase the internal density as much .

And the weight...without ANY benefit to stability over the proper sized steel. Not to mention...the cost is ridiculous!

Strength is determined by the amount of elasticity in the outer surface.

Now...wrapping steel with carbon fiber....???? NO if there was ANY merit to it WHATSOEVER you would see it on the drag strip....

 

[Damian Laffrey]

Composites are much lighter, much flexible, much much stronger than our conventional materials.
Integrating a hollow tube with a composite doesnt seem like a disaster to me. Im not telling to take a weak tube,...but the tube can be of a much smaller gauge than of regular . Fiberglass is one of the strongest composites ever made. And you can manage to get carbon fiber waste from any place, you have a composite 6 times stronger than steel.
You should mechanically test a tube internally reinforced with fiberglass.
Its stronger, much flexible,and reliable than a regular tube.

 

[Poboy kartman]

You don't have to explain composites to me....I painted F-16's....

But...it still doesn't make your advice practical or applicable...

If you gold plate it....it'll never rust!

 

[Damian Laffrey]

You don't have to explain composites to me....I painted F-16's....

But...it still doesn't make your advice practical or applicable...

If you gold plate it....it'll never rust!

Please give me some time bro..I l try my best to prove it to you. I tried reinforcing steel with fiberglass once bro...but not on a larger scale. I will work on this. Thanks for correcting me.

 

[itsid]

Jaxon..
try playing with the calculator here:
app.kartcalc.net (solely for mobile devices as of now)

click quick calc and punch in some numbers (estimated weight estimated wheels yadda yadda)
until you find something that comes close to your liking and doesn't give you an error.

Yes.. one could make this easier.. but I haven't yet.

'sid

PS change weight from kgs to lbs in settings

 

[Poboy kartman]

Wouldn't his kart go faster if he didn't change his weight from Kilograms to Pounds?

What if he converted Pounds to USD?

He could FLY then....OK...that's my mischievous posting for the day....

 

[Denny]

Filling the tube will increase the strength of the tube BUT do nothing for the welded areas. So now the weak spots will be where the too thin tubing is welded. THAT IS A STUPID IDEA! Use the proper sized tubing and you won't have to worry about getting impaled by a rigid tube that the welds failed on when the kart broke apart.


Denny

 

[itsid]

.. but I think what Damian was trying to say was..
to fill the tube AFTER it's been welded together (which opens up a whole new can of worms)
but in fact could support a welded section just enough perhaps (when necessary).

since fiberglass reinforced resin isn't exactly a low viscosity fluid it'd be nearly impossible to NOT trap any airbubbles inside (which is WORSE than unfilled tube since the bubble would concentrate all abuse on the unsupported section)
and we're back on the "stupid idea" track

Also: the weight of a resin filled thinwall tube can be (and will be) higher than the weight of regular tube that's up for the task from the beginning.

So yeah it is a stupid idea to just fill the tube with resin.. reinforced or not.

BUT if you'd be able to properly carbonfibre the tube from the inside(and that means laying strands of fiberglass, in crosshatching layers, properly resinsoaked), it'd indeed be perfect..
but that's not possible I'm afraid, especially not in DIY mode
(kart sized autoclave oven anyone?)

It'd be even easier to buy carbon tubes and make a true carbon chassis..
it's very likely even cheaper (just 30-40 times more expensive than a steel chassis)

Ah well... but it's a mind full of ideas, too bad it doesn't have a pricing table installed.

'sid

 

[chancer]

It'd be even easier to buy carbon tubes and make a true carbon chassis..
it's very likely even cheaper (just 30-40 times more expensive than a steel chassis)

If you could buy, "carbon tubes" how do you make the joints?

 

[itsid]

joints are easy Eric, just notch as usual then wrap with carbon bandage and resin
or precut patches of carbon cloth
resin cures over time and isn't as good (rigid per layer) as properly baked carbon.. but an additional layer or two and it'll be fine.

it's the bends that make it difficult .. although I've seen that be done as well.
basically the opposite of what Damian suggested.. a very thin wall aluminium or even plastic tube.. prebent used as a core for a hand-wrapped carbon tube
(there're even presoaked bandage for just that but IIRC that's heat curing so back to the autoclave )
not ideal but not impossible at least to do the same with resin and bandages

If a plastic tube was used, it's likely some PET with a low glass transition temp, that way it can be removed from the finished carbon tube to again reduce weight.

'sid

 

[chancer]

Maybe I am old school. But i would not trust that joint connection for a go kart frame.
If it is as strong as a typical welded steel joint I am very impressed.

 

[itsid]

well.. it's as strong as you make it of course...
but if you trust the carbon tube, you basically should trust that connection
if done correctly it's properly fused afterwards (just like the single layers of the original tubing);
sanded and clean tube assumed.
but true. you cannot hotsnot your way to a good joint..
I think on a kart frame we talk about 3 inches overlap or something..

But frankly, I cannot remember too much of the details.. it's been well over a decade since I saw that video (IIRC it's been even pre-youtube)
I remember the guy made a bicycle..
and used maybe an inch of overlap on the seat tubing joints.
looking a little something like this:


And maybe two inches on the head tube or so.

'sid

PS yes.. it looks flimsy.. carbon always does somehow..
especially when you see/feel how light it actually is...
until you try to break it amazing stuff!
unfortunately as expensive as it is rigid.