I know we've discussed and done this over the years. I just can't remember how.
I think weve welded something to the bar center before to stiffen it.
I also know we have somehow stacked two factory sway bars together.
Anyway, how do we do this? How donwe stiffen a factory sway bar, or double one, for challenge purposes?
I've seen pictures of a straight center section of the bar with a piece of 90 degree angle iron welded to it.
You can also drill a new hole on the arms closer to the main section of the bar and make the arms shorter.
Could you find a thicker bar and modify it to fit? Ex: I put a 26mm bar from a Ford Ranger in my Miata a few years ago. I had to cut the ends off and replaced them with pieces of flat bar.
Some cars you can change the mounting points - the closer to the wheel the bar connects, the more effective it will be. Many Macstrut cars attach the bar to the middle of the control arm. Welding a tab to the strut housing with a long drop link to the bar makes the same bar dramatically more effective.
We modified the control arms on the Datsun so that it changes the leverage exerted on the sway bar.
Reason asking: i have the biggest factory rear bar installed, and biggest factory front. I also have a spare smallest factory rear, also in budget. I fugure adding it to the rear on addition will assist rotation.
Buzzboy: thats what i was looking for! Thanks!
Keep the ideas and tios coming yall!
In reply to Dusterbd13-michael :
What car are we talking about?
Angle iron options is the most efficient. Remember swaybar stiffness varies with diameter to the 4th power. Modifying mounting points is a small linear change. Doubling a bar works well, but double the weight also.
That said, it wouldn't surprise me if the angle iron created a stress hot spot. I would definitely chop the ends at the shallowest angle possible to make the load ramp up slowly.
In reply to DeadSkunk (Warren) :
Subaru baja
Prodarwin: id worry about it breaking at the welds as well. The weight won't be that much i don't think
ProDarwin said:Remember swaybar stiffness varies with diameter to the 4th power. Modifying mounting points is a small linear change.
I agree that adding diameter is the most efficient/effective, but isn't mounting point like the relationship between wheel rate and spring rate? That is, you have to square the motion ratio, because moving the wheel twice as far for a given spring displacement also halves the leverage the spring has on the wheel. Same for a sway bar, though the differences in mounting points tend to be small.
I'm not sure I follow the second part of your comment. Any motion ratio is going to have an impact on anything you do to the bar. My point was, shortening a 12" arm by 6" could double the bar rate (if you could even achieve that), however increasing diameter by 19% will double the rate also. Of course you can do some combination of the two as well.
ProDarwin said:Angle iron options is the most efficient. Remember swaybar stiffness varies with diameter to the 4th power.
This is only if you neglect the stiffness of the arms. Try to get too much stiffness out of the main, center section of the bar, and all of your flex will come from the arms. The stiffness of the whole bar is k = k_center * (k_arm^2) / (k_center + 2*k_arm), so the softest component will dominate. If that softest component is already the arms, then you get more than 1:1 because each arm is an individual spring.
It is easy to picture the two extremes whether either the arms or the center are made of hot butter. There will be zero stiffness in the assembly even if you double the stiffness of the part that is not butter.
Correct. At some point your arms will limit progress.
In reply to ProDarwin :
I think halving the arm length quadruples the rate.
If the arms are half as long they'll twist the bar about twice as much for a given displacement AND that doubled twisting force will be doubled by the shorter arms.
As you suggest, that's a hard thing to achieve from a practical standpoint. The math of it just occurred to me a couple of weeks ago.
gearheadE30 said:Some cars you can change the mounting points - the closer to the wheel the bar connects, the more effective it will be. Many Macstrut cars attach the bar to the middle of the control arm. Welding a tab to the strut housing with a long drop link to the bar makes the same bar dramatically more effective.
Popular mod in the small-chassis Audi world. The front bar is really thick and mounts halfway along some thin stamped control arms. Running the links up to the strut housing is fairly simple and extremely aggressive in comparison.
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