homemade swaybar?
I know what a sway bar is and does. wondering if i could make one myself. could i just use a 25 to 30 mm bar and bend it to connect the two sides of my suspension, then flatten the ends and drill some holes to put some rod ends in it? is there some kind of special process used for bending the tube so the structure stays the same or would it be fine to do it with room temp metal?
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Re: homemade swaybar?
i thought of this idea myself. its possible to make your own with the right metal and precision
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Re: homemade swaybar?
lol they are tempered after they are made, kinda like a spring steel.
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Re: homemade swaybar?
easy to do i am making one right now for a full size truck i will post a how to after its done this weekend.
Its really simple and has an adujatable mouting sytem so that you can adjust the torson of it. |
Re: homemade swaybar?
why not just simplify the design and just use a straight bar? with the arms at right angle? would be better then the stock design since you get all the force going to torsion in the bar, rather then losing some in bending moments.
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Re: homemade swaybar?
I dont think you can go straight-thru w/ right angles it'd probly bump into something when the suspension traveled, might be possible though...i'll check out my car and see
so i would need to have the metal tempered after bending? what exactly is tempered metal thanks |
Re: homemade swaybar?
if you use a straight bar/pipe you wont have to temper anything.
and with CRX's 4g civics you dont have to worry about subframe tearout since our sway bars arent attached to there. but lemme see if i can a pic of straight bar setup... this is a holy hardcore 32mm swaybar setup made by a-spec racing. http://www.we-todd-did-racing.com/we...MXk1NDE%3D.jpg would be simple to duplicate. this is on a EG though. 4g civic and crx would attach to the frame rails like the stock sway. |
Re: homemade swaybar?
not sure how well a tube sway bar would work way to rigid.
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Re: homemade swaybar?
like i said thats a hardcore bar, i wouldnt recommend anyone running something that size unless its for a track car.
but tube or solid bar, makes no difference. with a tube, you can generally get the same amount if affectiveness as a solid bar with less weight. since a thin walled larger tube will be lighter then a smaller solid bar. |
Re: homemade swaybar?
lol that thing is HUUUUGEEE :o
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Re: homemade swaybar?
That is awesome! I'm gonna have to search around and see if they make one that is more suited for street use...if not i guess i'll just make my own.
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Re: homemade swaybar?
yeah it should work fine for the rear doing a strait through design, but on the front I want to upgrade to a larger sway bar and that would definitely have to be bent. so anyone know what the tempering process does
thanks |
Re: homemade swaybar?
Originally Posted by gsrcrxsi
and with CRX's 4g civics you dont have to worry about subframe tearout since our sway bars arent attached to there.
Originally Posted by gsrcrxsi
but tube or solid bar, makes no difference. with a tube, you can generally get the same amount if affectiveness as a solid bar with less weight. since a thin walled larger tube will be lighter then a smaller solid bar.
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Re: homemade swaybar?
yup, most of the torsional rigidity (thats the word i was looking for, been a year since my mechanics class lol) is on the very outermost part of the bar anyway.
^just in case anyone wondered why a thin walled tube can be the same rigidity but with less weight |
Re: homemade swaybar?
Really Honda Bars are hollow. Didn't know that.
But ya, Statics and Dynamics 101, In a Torsional Shear Stress application such as a sway bar, Tube wall thickness is not an issue. Example of Torsional Shear Stress. The length of the Verticle line Represent the magnitude of the Tortion Shear Stess. Notice how the further you are from the center, the bigger they are. http://www2.propichosting.com/Images/500802/23.JPG |
Re: homemade swaybar?
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Re: homemade swaybar?
Na, Lazy and using Auto Trim in AutoCAD. Thanks
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Re: homemade swaybar?
Originally Posted by bumblezc
Really Honda Bars are hollow. Didn't know that.
But ya, Statics and Dynamics 101, In a Torsional Shear Stress application such as a sway bar, Tube wall thickness is not an issue. Example of Torsional Shear Stress. The length of the Verticle line Represent the magnitude of the Tortion Shear Stess. Notice how the further you are from the center, the bigger they are. http://www2.propichosting.com/Images/500802/23.JPG inertia( J=pi/2(r)4 ) and calculate to torsion formula (Jmax = Tc/J ). Tau max units are given in force/size; i.e. lb.ft. Tubular torsion uses the same torsion formula, but J will = pi/2(ro4 - ri4), which gives you the cross sectional area of the tubing wall. The tubing used doesn’t need to be tempered. Without getting too involved use same dynamic equations to figure out how much force the bodyroll will have in a given turn on at a given speed minus the pressure of the force of the spring(stiffer springs will lessen the force on the swaybars). You’re trying to find how much force is lifting up on the car’s inside(side on the inside of the corner) suspension. Take that force(sigma or n) and times it by the distance from the point the swaybar and control arm link to the point where the sway is parallel with the firewall(heading to the other side) (d ). Measure 90° back. This will give you your bending moment and torsion back at where the swaybar heads to the other side. Calculated sigma max of your tubes bending moment and cross check that the tension and compression are this in the elastic region of the material you are using (modules tables for specific materials can be found on the web or in the back of your statics and mechanics books). Next, cross check that the torsion does not exceed the elastic zone. If you forces are so great that they enter the yielding or even the strain hardening zone then the stress on the bar is too much and the swaybar will permanently deform. Bigger, thicker, stronger(material used) will give you a higher moment of inertia and handle more torque(from bodyroll forces). Just like everything you have to do you homework to do it right. Homemade swaybars are definitely possible and would probably work well, but expensive namebrand bars are expensive for a reason. They give you functional performance in a perfect balance. If you don’t want to do all the math I would try and copy the specs of a namebrand bar and find a material that has the same or as close to the same elastic region on the stress-strain diagram. |
Re: homemade swaybar?
wow, nice reply. I didn't know all of this. Can't wait to start taking these Mech Eng classes over at Georgia tech in a couple years, chem and calc are pretty boring, can't wait for physics and higher level. I'm a dork :-\
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Re: homemade swaybar?
i know im a noob, but here is my two cents, i used a 4340 steel bar for mine, just machined it first then i bended it and slaped it in, im runing slalom ties as close as some racecars in a tercel 4wd weighing 3400 punds
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Re: homemade swaybar?
Originally Posted by mugenblacky16
First of all, it's not dynamics because swaybars are fighting a bending moment and torsion and the sum of all those forces is zero. Second, what do you mean, "wall thickness is not an issue"? Of course it's an issue. Your graph is just a picture of the shear load distribution. It doesn't mean ----! Torsion applied to a tube is calculated different to factor that the tube has much less cross sectional area, not to mention that tau average is way out at the mean radius. A solid bar with a torsion applied has a bigger cross section. For example, to find the max shear stress(tau) in a solid shaft you would simple find the polar moment of
inertia( J=pi/2(r)4 ) and calculate to torsion formula (Jmax = Tc/J ). Tau max units are given in force/size; i.e. lb.ft. Tubular torsion uses the same torsion formula, but J will = pi/2(ro4 - ri4), which gives you the cross sectional area of the tubing wall. The tubing used doesn’t need to be tempered. Without getting too involved use same dynamic equations to figure out how much force the bodyroll will have in a given turn on at a given speed minus the pressure of the force of the spring(stiffer springs will lessen the force on the swaybars). You’re trying to find how much force is lifting up on the car’s inside(side on the inside of the corner) suspension. Take that force(sigma or n) and times it by the distance from the point the swaybar and control arm link to the point where the sway is parallel with the firewall(heading to the other side) (d ). Measure 90° back. This will give you your bending moment and torsion back at where the swaybar heads to the other side. Calculated sigma max of your tubes bending moment and cross check that the tension and compression are this in the elastic region of the material you are using (modules tables for specific materials can be found on the web or in the back of your statics and mechanics books). Next, cross check that the torsion does not exceed the elastic zone. If you forces are so great that they enter the yielding or even the strain hardening zone then the stress on the bar is too much and the swaybar will permanently deform. Bigger, thicker, stronger(material used) will give you a higher moment of inertia and handle more torque(from bodyroll forces). Just like everything you have to do you homework to do it right. Homemade swaybars are definitely possible and would probably work well, but expensive namebrand bars are expensive for a reason. They give you functional performance in a perfect balance. If you don’t want to do all the math I would try and copy the specs of a namebrand bar and find a material that has the same or as close to the same elastic region on the stress-strain diagram. |
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