Newbie just bought a Kart with potential

[perceptionist]

Hey all,

My most recent purchase on Friday 7-11-08 happens to be what led me to these forums.

It is a homemade go kart with a 600cc motorcycle engine from a Kawasaki GPZ Ninja.

I have always wanted to build one of these. The engine runs fine but could use some TLC. I cleaned the carbs last night and now it idles without help. The guy I bought it from had it for 4 months and never changed the oil or filter, and never had a fuel filter on it which would explain all the junk in the carbs. I still need to synchronize them.

I am happy with the engine. I think I might be able to do better on the frame once I get myself a welder and learn to weld. I am undecided on whether I want to build a whole new frame around the engine or use the existing design and attempt some upgrades.

The only reason I can't drive it at the moment is the weld that held the brake caliper on the frame broke loose and the brake pads were lost. The caliper is not from the motorcycle the engine was from, so I don't know which pads to buy. I do have a neighbor who offered his old motorcycle to salvage parts from, it has good calipers and discs front & rear.

I am unhappy with the design of the rear axle. It does not seem to be designed for swapping out parts (sprocket, brake disc, U-joints etc...) as everything is welded together. I would like to look into some sort of axle kit or try my hand at fabricating one.

The suspension and steering in front also could use a face lift. (rack & pinion from a fiero?) :wai:

I have looked into the pros and cons of live axles and single wheel drive. I would like to design or find a 2 piece live axle that has two steel plates that meet and can be easily bolted or locked together when on the dirt or sand for power to both wheels and then I can disengage for driving on hard ground to facilitate easier turning. Has anyone seen a design that resembles this?

I am exploding with ideas on what I would like to do to this thing. I will definitely be frequenting these boards to pick some brains in my journey.

http://a234.ac-images.myspacecdn.com/images01/22/l_9d4316aa81487d8f96a8963603b25e71.jpg

http://a175.ac-images.myspacecdn.com/images01/91/l_c0e2966f87c70ed87940ffab05dac82e.jpg

http://a352.ac-images.myspacecdn.com/images01/127/l_1a0760af6e08938569c255c4350bb13f.jpg

http://a456.ac-images.myspacecdn.com/images01/68/l_adf718df3a4a7cfd2649375116cd3baf.jpg

http://a716.ac-images.myspacecdn.com/images01/47/l_c8c4ab1d2400ac97974e627179bc80eb.jpg

[Kenny_McCormic]

Nice, I hope he didnt run it without a filter.

[2or3wheels]

U want a limited slip diff rear axle

[oorgle]

do not go solid live axle you already have independent rear suspension. if your u-joints are welded to the axle i would just buy new u-joints and new axle shafts and then bolt them together.

if I were you i would not try to build a new rear end i would just swap out anything thats welded together for new parts. the new parts should be able to be bolted on as well. for offroading the rear setup you have is much better then a solid live axle.

you can use the dirtbike brakes but you may have trouble finding a hub to mount the disc to the axle. I'm actually in the same situation. they make go kart hubs but not hubs meant for bikes/quads AND karts.

your not going to find a 2 peice live axle that bolts together to give you live or single wheel drive. you can get a differential but they are expensive and not worth the money for an offroad kart. offroad you WANT both wheels spinning.



the frame looks fine other then it looks incredibly painful to try to get into lol.



your steering setup is not rack and pinion its just a standard hydrolic gearbox torn out of a car. you actually don't need that gearbox at all. it may make turning a little bit easier but i doubt it.




overall it looks like a great project and that 600cc will gives loads of power. you may want to invest in some meatier tires as that 600cc will burn the rubber off those ones in no time.

[sayre315]

thats is a big engine
its gonna have loads of torque at the same time have good speed

[modelengineer]

With that big of an engine dont worry about a differential, or one wheel drive, or any of that. You will EASILY be able to turn on any surface by spinning the rear tyres (unless you get some massively wide racing slicks or something)

I'm with oorgle, try to keep the independent rear suspension. It's good to have. Best bet would be to just replace the parts that are there with splined universal joints and axle so that you can dissassemble and reassembly easily.

If you want to buy parts such as disc brakes and hubs and such, I would look here: www.edge.au.com
No affiliation, just a happy customer. The stuff they have is REALLY heavy duty, designed to work with even their Hayabusa powered buggies.
I'm sure there are other places to get this stuff in the US if you don't fancy the shipping.

[GoAlterBridge]

^^^ I agree ^^^

[Dang]

Man that thing look sweet, you might wanna get bigger tires for it. How much did you paided for?

[perceptionist]

Saw it on Craigs List for $400, went to check it out and took it for $350. Although the front and rear suspension/steering assemblies could use some improving, oh and the wheel bearings were shot, I think the motor alone was worth it.

I just changed the oil & filter yesterday. Old oil was pretty thin & dirty. Definitely needs new plug wires and plugs. The tires on it now are all cracked and ready to burst so I will be looking around for some. This kart has definitely seen better days, but it is a great starting point for something cool. :wai:

[Dang]

dude thats an awesome deal, that kart will haulass once you get it up and running.

[perceptionist]

Little update. I got the new plugs & wires. Also bought new straight boots for the plugs. Now it idles great and revs ok. I plan to synchronize the carbs tomorrow in hopes that it will smooth out the revving.

Still no brakes, but I am really itching to take this thing for a little spin :auto: :drool5:

[redcali]

you can use the dirtbike brakes but you may have trouble finding a hub to mount the disc to the axle. I'm actually in the same situation. they make go kart hubs but not hubs meant for bikes/quads AND karts.

he doesnt need to find a mounting kit as he has a disc already mounted.

just take the caliper into a bike shop and ask them for new pads for it. and if they dont know what it is take it to an auto parts store.

more then likely though, it is a motorcycle caliper of some kind.


i would work on a new front end of some kind. it looks like anything you hit and causes damage that isnt a foot in height will be taken up by your steering setup.

[redcali]

and if they cannot work it out, worst case scenario.
you measure the diametre of the hole where the hose attatches to the caliper. which will most likely be 10mm
and buy a new caliper with a 10mm screw and you are done.

[I like karts]

:drool5: look at those beautiful carburetors.

For an axle though, for a kart with that much power, I would just go to the nearest junkyard and take the rear axle from a small car (/w diff)

[perceptionist]

How would I make the chain drive motor compatible with the shaft driven diff? I would like to eliminate the chain/sprocket assy altogether if I could find a shaft drive unit to bolt to the motor.

[AutoMX]

well you just answered your question, you get a shaft drive unit and dump the back half (90 degree > shaft > another 90 degree that you dont need) and just somehow secure the shaft to the car driveshaft.
weight would be a concern, the car diff, regardless of how tiny the car seems, is gonna be like 1/4 the weight of the engine/tranny you have. way overkill in my opinion, and diff = good on street, bad offroad. if you're gonna have a diff offroad, you pretty much need a locked diff which again defeats the point of doing all the work. you would have a 150lb rear axle which would slow down the kart by who knows how much and every bump would compromise the frame from all the weight flying up and down.

look at the setups on http://www.minibuggy.net/forum/
they build exactly what you have

[redcali]

can someone point out the need for two sets of shocks on the rear?
the drive setup you have at the moment is the best for basically all applications of this kart. enjoy it, dont make it more work for yourself!

[perceptionist]

I don't know what the idea behind that design was, but the ones w/o the springs are air adjustable if that makes any sense. Perhaps the double shock setup was an attempt to make up for a poor suspension design or old worn shocks.

[AutoMX]

bike shocks, when used on [light] cars, are usually doubled up to make up for the weight.

[perceptionist]

Well I just got the pads for the brake caliper today and finished welding the bracket nice & sturdy to the frame. I took it for a ride around the block. Absolutely no complaints on the engine/clutch/throttle setup, however it handles like absolute crap. As I mentioned before the steering setup is horrible and the live axle seems to greatly mess up the handling. When I try to turn, it just pushes on straight forward. In order to do a u turn on my street, I had to get out and push it back & forth in like a 10 point turn. Need to solve this somehow, this cant happen with all live axle assemblies does it?

As for the steering I found the front end for sale from a yerf dog spiderbox with rack & pinion steering, couldn't hurt to try it out...

http://i22.ebayimg.com/02/i/000/d6/56/11a4_1.JPG

[5trucks]

Sweet engine. Scary frame. Not trying to bash your purchase. I love a good deal but that thing looks like it's gonna fall apart. I Would start over if you want something you can SAFELY have fun in. That is an *** load of engine for a rusty poorly designed frame. Sweet score on the motor. I am sure you can find a great frame and just re-use all the existing parts.

[AutoMX]

i have to agree, the frame looks like it was built with heavy tubing but theres absolutely no triangulation. it's prolly a good thing the suspension design is bad since it prevented the previous owner from going too wild with the thing, and i'm pretty sure the frame would have just bent over in a big bump. notice how the shape lends itself perfectly to just being skewed over to any side and breaking the welds to the floor.

[5trucks]

Rear shock mounts are what really got me to look at the entire thing closely. Again, i am not bashing your score. I would love to have that power plant at that price. Take a good long look at the frame, that is the exact opposite of what you want to have that kinda power in. Square tubing is great if you want to build the lower frame out of it. But round tubing is way cleaner looking. I'll be that thing weight 600lbs +

[perceptionist]

It is VERY heavy, I would like to weigh it and find out exactly how heavy. On my test run last night, it was clear that the weight was not an issue with regard to the motor pushing it. Straight forward driving was cool, turning made it no fun at all. I just bought a MIG welder and have been practicing. I would like to eventually build a frame or at least make some major adjustments to this one so it's drivable until I get something more ideal.

[5trucks]

Good man! What kind of mig? Flux core? If so, be careful welding thin metal (.095 and smaller) It loves to burn right through that stuff. If gas mix then you are set. You should be able to make a sweet suspension buggy weighing in around 350-400lbs dry that will be super safe with that power. The rolling chassis i build weigh around 225-250lbs and they are plenty strong for that power. All round tubing though. Good luck man. Nothing more satisfying than burning metal and putting power behind it.

[Aryukei]

When I try to turn, it just pushes on straight forward. In order to do a u turn on my street, I had to get out and push it back & forth in like a 10 point turn. Need to solve this somehow, this cant happen with all live axle assemblies does it?

]

Of course it is. Your using a live axle. They're for offroad terrain. You just said your on the road. (concrete) You'll always be turning bad. A live axle spins both wheels at the same speed which makes it hard to turn. Unlike a differential, which is single-wheeled drive, Only 1 wheel spis which makes it alot easier to turn and is for on-roading. If you want a on-road kart get a differential axle. You wont be able to drive off-road because single-wheel drive karts will spin out.

[AutoMX]

regarding the type of tube (round vs square) it doesn't really matter unless you plan to bend the tubing. sure it's possible to bend square tubing, but it takes one very expensive bender to do it even half decently, so sticking to round is pretty necessary when making a frame from as few pieces as possible, such as a rollcage.
in this case though, theres no bends and using round tubing in this exact frame would be kind of a nightmare to get the tubes to interlock. and round is often times 50% more expensive to buy. square is fine to use, it's just a question of how the design is.

[5trucks]

The problem with square is you end up a$$ welding everything together. Round tubing can be bent and coped to fit very clean. That kind of power with an a$$ welded frame spells disaster if it does a roll or two. Do it once and do it right. Safety isn't something that should be overlooked just to take a few shortcuts. It's safe when you can comfortably place your kids in there and know that if it rolls, flips, endos or comes to a sudden dead stop, they will be protected. Nothing is for certain but there is no such thing as an accident.

[Kenny_McCormic]

Square is easy to bend, notch, bend, and weld.

[Aryukei]

Said bend twice o.o

[5trucks]

I'm speaking from a safety stand point. I have built square tube chassis before. They just don't look nice and feel unsafe to me. Cut a notch and bend in a jig and you can get it to look ok but it's not that safe. Look at it this way, what do race cars use? Round tubing .120 wall hrew minimum. That's 1 3/4" diameter x 1/8"thick. There has to be a reason for this. I say do what you can with what you have but that is a $hit load of power you are gonna bolt to it. Even motorcycle chassis are round.

[5trucks]

This is the style i build for my kids. Would easily handle that kinda power. If you look at the rear end you will see it was designed to be altered for a larger power plant when they learn how to shift. Frame costs about $150 in steel including the custom spindles,a arms and swing arm. If you dont have a bender then get one. You can get a manual bender and die for 400-500 bucks. Then all your buddies will want to build carts. You will make your money back fast.

[AutoMX]

it really depends on the use. auto manufacturers almost never use round tubing and their designs work fine. i'd be more worried that the tubes dont match up perfect and that welds are used to fill the gaps which is no good.
i'm not sure what you mean by a$$ welding but if you mean bad welding, then it doesnt matter what kind of tube you use, it's just badly done. i have quite a few kit car builder firends and they [commercially] build chassis out of 1" 16gauge square tubing and they work really well, and the weight is about the same as a simpler round tube chassis with thicker tubing, but the square tube one is way more complex. the logic is if some welds fail, there's 2x to 3x the number of welds holding it all together. the strength is really down to the design, not the tubing.

all i'm saying is either choice is good, as long as you get the right kind of tubing (thick square = heavy and overkill, thin round = flexible and unsafe).
alot of offroad or racing chassis use round around the passenger cell because in the case of an accident, people wont bash their arms or heads on 90 degree corners.
i'm using square for the chassis but round around my head and body for that reason.

[perceptionist]

This is the welder I got:

http://content.lincolnelectric.com/pdfs/products/literature/e738.pdf

In case the link doesn't work, it is a Lincoln Weld-Pak 125HD bought from Home Depot. Uses Flux Core wire or gas. I am currently practicing with the included Flux Core wire, then I am sure down the road I will experiment with the gas option to compare.

To be honest, I am not too concerned with looks on my kart. I am mostly concerned that it will take a beating and not bum us all out with downtime having to make repairs after every ride. I actually like the looks of it as it is now although that bar across the knees definitely needs to move as it makes it feel cramped, leg room lengthwise is fine though.

As for the live axle, I have been drawing up some ideas on how to design an axle that would provide the best of both worlds, check it out...

http://perceptionist.fileave.com/AxleConcept.bmp

I have searched for a design that would do this but came up empty. Feedback would be appreciated on this rough draft of my concept.

I am still looking into a way to engage/disengage the live axle by way of a lever or some sort of control while driving or at least while parked and seated, otherwise I think it wouldn't be that hard to just get out and bolt the axles together for off road use, then stop and unbolt them for hard ground.

Criticism welcomed, remember I am totally new at this but that doesn't mean I am without imagination :D

[5trucks]

By a$$ welding i meant butt welds. End to end joints to create the illusion of a bend.

it really depends on the use. auto manufacturers almost never use round tubing and their designs work fine. i'd be more worried that the tubes dont match up perfect and that welds are used to fill the gaps which is no good.
i'm not sure what you mean by a$$ welding but if you mean bad welding, then it doesnt matter what kind of tube you use, it's just badly done. i have quite a few kit car builder firends and they [commercially] build chassis out of 1" 16gauge square tubing and they work really well, and the weight is about the same as a simpler round tube chassis with thicker tubing, but the square tube one is way more complex. the logic is if some welds fail, there's 2x to 3x the number of welds holding it all together. the strength is really down to the design, not the tubing.

all i'm saying is either choice is good, as long as you get the right kind of tubing (thick square = heavy and overkill, thin round = flexible and unsafe).
alot of offroad or racing chassis use round around the passenger cell because in the case of an accident, people wont bash their arms or heads on 90 degree corners.
i'm using square for the chassis but round around my head and body for that reason.

[Kenny_McCormic]

That frame will be fine if you crossbrace it in a few places, maybe double up some of it.

[perceptionist]

I was able to remove the set screws and axle key from the right wheel & u joint effectively defeating the "Live Axle" allowing me to turn on hard ground. I also had to quick weld a bar to keep the u joint from sliding off the axle temporarily for the test drive. This thing is friggin tough and really has potential, I ripped down the dirt alley behind my house. turns WAY to wide still, but much better with the rear wheels spinning independently.

http://perceptionist.fileave.com/mod.JPG

Don't get me wrong, I do not plan to leave it that way, but after having the thing sit in my garage since I bought it, I just HAD to find SOME way to drive it just once before I went crazy!!

Now I have some ideas of what needs to be done, I need to learn some things first to see if my ideas can be applied though.

In my axle concept drawing above, I am wondering what could be used to keep the axle from sliding back & forth through the bearings, I considered using collars with set screws, but wouldn't these scrape against the bearing housing?

Hit me back with some ideas on making my drawing a reality, I really dig the idea of a split axle capable of going live if needed.

[AutoMX]

what about the fact you only have brakes on 1 side? its fine if its only for slowly 'crossing' short segments of street but i wouldn't drive at any rate of speed knowing one wheel will lock up when braking and the other will potentially still be spinning with the motor. great for ripping tires apart in a J turn but really dangerous if someone or something appears in front of you. i'd just get dual brakes and solve that issue.

[fluxcored]

I'm speaking from a safety stand point. I have built square tube chassis before. They just don't look nice and feel unsafe to me. Cut a notch and bend in a jig and you can get it to look ok but it's not that safe. Look at it this way, what do race cars use? Round tubing .120 wall hrew minimum. That's 1 3/4" diameter x 1/8"thick. There has to be a reason for this. I say do what you can with what you have but that is a $hit load of power you are gonna bolt to it. Even motorcycle chassis are round.

Perceptionist, 3 points:
a. You've got a lot of power.
b. You've got a minimalist chassis
c. You plan to do offroading

The risk of roll over is high coz of (c)(a) and with (a) it's gonna be nasty and thus must ensure that (b) is as strong as can be.

Thus 5trucks has got a solid argument - mandrel bent round tubing cannot be beaten and should be considered in this application

Anybody who's got a proper bender please put your hands up - I can't afford one so I'm compromising and planning my build around low speed + on road only.

[AutoMX]

i completely forgot to mention but it's really important to go with DOM tubing and not just ERW, as ERW can and will split at the seams.

[5trucks]

i completely forgot to mention but it's really important to go with DOM tubing and not just ERW, as ERW can and will split at the seams.


Oh sweet Jesus! Not the seam thing. DOM does not have a physical seam after production. It starts life as cold rolled welded seam tubing and is cold worked after welding by drawing it over a mandrel to remove the weld flashing and further work harden the tube. Sometimes you can still see the seam, but it should not compromise the concentricity of the tubing. Hrew or Erw is fine. DOM is overkill for this application. I have been building rockcrawlers for years and have yet to have a piece of hrew split. I know it has happened but triangulation and design are major factors in preventing this. DOM is far better as far as psi and strength but you are talking 3 times the cost of hrew. With Hrew always bend with the seam on the inside of the die. Most splits occur at the bender not on the trail. This is due to placing the seam on the outside face of the die and that is the part that stretches the most.

[fluxcored]

Look at it this way, what do race cars use? Round tubing .120 wall hrew minimum. That's 1 3/4" diameter x 1/8"thick. There has to be a reason for this.

5trucks - been thinking about this for the whole day and night: Why, why, why, why!!

Could it be that round tube deflects impact stress across a wide area while with square it concentrates in a smaller area (the corners.). I mean do you want to be hit in the face with a square or a round tube?

That's the best I can come up with without doing a Googly. Anyways. my brain's starting to hurt.

[kibble]

I mean do you want to be hit in the face with a square or a round tube?

Hmmmm we'll have to test this out and get an honest opinion. Oscar! Come here boy! :toetap05:

I think I understand your theory and think it sounds ok. I guess it would be worth doing some sort of test with identical thickness pieces of square and round tubing and see how each one is affected by either impact or damage in certain places. :confused:

[AutoMX]

most of the commercial mass produced chassis use square tubing because they use large complex chassis jigs which allow them to easily and quickly put together a chassis and weld it together in hours not days. square tubing is cut in straight planes using standard saws, so it takes seconds, and then you pop it in and weld.

custom chassis makers (racing, offroad, etc) don't need to finish a chassis in less than 3 hours and each customer wants something different, so they can afford to use round tubing which can be bent in all directions and doesnt require as heavy duty of a bender as square. the chassis jigs used are usually much simpler and allow for modifications.

which is better isn't really a valid question, it comes down to opinion. formula 1 uses vacuum formed carbon fiber, and lotus uses glued together extruded aluminum for their chassis, both of which are extremely safe. ferrari and lamborghini use exclusively square tubing, lotus 7 type cars most often use round tube, and the saleen s7 i believe uses round tubing for the rear.
none of these are unsafe cars, they just appropriately used what they picked, and thats what needs to be done.

as for the DOM thing, i just heard it from a bunch of baja guys and i trust their judgment. i do agree that ERW is probably good enough for most cases, i know of a few people who used it out of desperation and never had issues (nor crashes) but my logic is safety first and thats what i suggest to others. my metal supplier actually doesnt even sell ERW so i'm stuck anyway.

[JerryAssburger]

Hey! A fellow Spokanite! Well I was up until 84....
Perceptionist .... that is a cool gokart! I think you're right about the "Got to be a better way"... but short of starting over with the kart and re-using the drivetrain... who knows? I think you're definitely going to be the Top-Speed Champ of the home-builts!:drool5:

[fluxcored]

Auto - I'm not qualified enough to argue your points but I believe that you're looking at safety as a function of design rather than whether a square or round tube is safer/stronger. My end goal is to build a Lotus 7 replica and most of them are square tubed, space frame chassis' - very light, safe and strong.

So, your points are more than valid but when it comes to roll cages, I'll rather bet my life on round than square.

GoKart Geeks Unite!!! Roy, you're not gonna comment?

Let's make love not war, eh!

Kibble, good luck with your experiment. Be scientific - verify the results at least 3 times!

Nice weekend dudes - I'm off!!

[oscaryu1]

Hmmmm we'll have to test this out and get an honest opinion. Oscar! Come here boy! :toetap05:

I think I understand your theory and think it sounds ok. I guess it would be worth doing some sort of test with identical thickness pieces of square and round tubing and see how each one is affected by either impact or damage in certain places. :confused:

Ya Kibs? :D

*goes back crying to mommy* :sifone:

[kibble]

whether a square or round tube is safer/stronger. My end goal is to build a Lotus 7 replica and most of them are square tubed, space frame chassis' - very light, safe and strong.

Let's make love not war, eh!

Kibble, good luck with your experiment. Be scientific - verify the results at least 3 times!

Whoa! I wanna see that when you're done.

Second comment, I'm not so sure about.... :arf:

I'll be sure to conduct multiple experiments with various sizes of tubing.

Ya Kibs? :D

*goes back crying to mommy* :sifone:

Get back here! That was just the 1/2" pipe, we're not done yet!:roflol:

[perceptionist]

Hey Jerry, Thanks for the kind words, yes this project has motivated me to buy a 60 Gal air compressor, a Welder, A 20 gal solvent wash tank, and a whole lotta other tools to give this baby what she needs. I am looking into getting the air/manual 12 ton bender from Harbor Freight today after work:

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=97433

Anyone ever see locking Manual Hubs used on an all terrain Kart? I am also researching Locking differentials but most I have found to be for heavy duty 4x4 truck use.

[AutoMX]

regarding the bender, the manual one at half the price is probably a better choice, it takes only a few seconds to pump it up, but more importantly you can feel the work being done. the dies on that bender are fine, but the anchor points (the stupid rollers) are not the best thing and push/crinkle thinner tubing pretty easy, so i wouldnt turst the bender to do a good job every time, especially automated with air. badly bent tubing = costly mistakes.

and yes a practical test should help see how much of a difference there is. i'm quite confident both are strong enough.

[kibble]

:iagree: with AutoMX. I used the manual one to do all the work on my kart.

Yes it kinda sucks that the rollers make the metal bend in a bit where they make contact with the material. One other thing that sucks is that the thing doesn't retract automatically as it doesn't have the springs like that one you linked to.

It's not horrible though and gets the job done if you're careful enough.

[5trucks]

The HF bender is for pipe, not tube. Tube will kink or flatten if you don't modify the dies. I had said before that square tube for the bottom half of the frame would be fine. Square tube head hits SUCK!!!!!!! People this is all just my opinion here. Not trying to start an "i'm right you're wrong " war. Build what you can with what you have. just be mind full and ask for lots of design help. It may be the difference between life and death.

[perceptionist]

Ok maybe I am unclear on the difference between tube and Pipe, I will hold off on the bender till I am more educated. Help?

As for the square tubing head danger, is this not eliminated by enclosing all square cage tubing in that protective foam?

[5trucks]

Not really. Pipe is what you would use if you were a plumber. There is structural pipe and the crap stuff you buy at home depot. Structural stuff is strong. Pipe is generally heavier. Pipe is measured by inside diameter, tube is measured by outside diameter. Sch 40 pipe is .144wall where most people who use hrew/erw use .120wall (1/8") Strength tests usually come out the same but there is a huge difference in weight. Pipe will generally dent much easier also.

[5trucks]

5trucks - been thinking about this for the whole day and night: Why, why, why, why!!

Could it be that round tube deflects impact stress across a wide area while with square it concentrates in a smaller area (the corners.). I mean do you want to be hit in the face with a square or a round tube?

That's the best I can come up with without doing a Googly. Anyways. my brain's starting to hurt.


Square tube is designed to be used in structural applications, but because it doesn't have a completely uniform cross section (i.e. round) it isn't efficient. You will have to use heavier material to get the same overall strength if you go with square tube. The bends are considerably weaker than properly bent DOM or HREW round tube.

Round tube is stronger than pipe. Pipe is made of softer steel and has less cross sectional uniformity. Pipe is intended for carrying things inside of it under pressure. It tends to have thick sidewall, poor cross sectional uniformity, and is HEAVY.

[AutoMX]

i'm definitely sticking round around my head and elbows anyway, for safety reasons.
i also don't trust the strength of rippled bent tubing thus why i'm avoiding using it where structure is essential.

it's funny i saw a high end pro shop on TV using an HF bender on a rollcage for a SEMA show car :oops:

[jr dragster Tyler]

Well if it helps my Junior dragster uses seamless round chromoly tubing everywhere including around the roll cage. I do agree it's best to have round tubing around the roll cage because I have hit my own head on it from the holeshot power.

[5trucks]

Well if it helps my Junior dragster uses seamless round chromoly tubing everywhere including around the roll cage. I do agree it's best to have round tubing around the roll cage because I have hit my own head on it from the holeshot power.


Chromo opens up a whole new can. If you mig weld 4130 for example. Without post weld treatment of chromo you basically have the ability to say "I built it out of chromo" but aren't getting any real benefits out of it other than the bling.

People do it all the time and mig welded chromo is strong. Again, do what you can with what you have.

[AutoMX]

from what i read its actually weaker if untreated after welding. oh and its 3x the price of typical steel. no thanks heh.

[jr dragster Tyler]

I'm sure my junior dragster is built correct. It was built by halfscale dragsters in new jersy and NOT somone in there backyard with a mig welder. It was all profesionally TIG welded.