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-   -   sway bars: solid vs hollow (http://chevelleforum.net/showthread.php?t=279)

Bungy L-76 01-05-2010 03:17 PM

sway bars: solid vs hollow
 
I'm looking at getting sway bars for my car. My biggest question is, Are solid bars "stiffer" then hollow given the same diameter? If they are, what's the comparison. Would a 1 3/8" hollow bar be the same as 1 1/8" or 1 1/4" or ???
Any other ideas and/or suggestions/thoughts on sway bars welcome.

rak1 01-05-2010 04:09 PM

Regarding hollow bars they use stronger steel to make up the difference in strength, but don't go cheap or it will cost you in the long run. In theory if all else was equal the solid bar would be stiffer then the hollow one but that's why hollow bars are made up of stronger steel and you get weight savings too using hollow’s. Just be sure to go with a good manufacture and don’t go to aggressive or you’ll have problems. Remember everything has to work together so go with a proven system such as a complete kit or go on the conservative side to be safe. As to your question it depends on the materials they are made from so we would need more infomation to answer your question. Are you looking at a certain maker?

Derek69SS 01-05-2010 04:30 PM

Solid bars are stiffer if the diameter is the same. I know the 1-5/16" "thin-wall" Helwig bar is comparable to a 1-1/8" solid... The rate of it would depend on the wall thickness, which of course would depend on the manufacturer.

The big advantage to hollow bars is that they are are much lighter weight, given the same rate. As the metal gets farther from the centerline, it takes less metal to do the same amount of work. The metal near the center of a solid bar does very little to add rate, but adds just as much weight as if it were placed elsewhere.

A secondary advantage is that they look really big, without actually having so much rate that they take too much compliance out of the suspension. This pleases the "if some is good, more is better" crowd. ;) I actually prefer a smaller solid bar for this reason... the whole "how the heck is he doing that with a stock sway-bar?" is worth a few pounds to me. :D

The best thing to do before ordering would be just to ask the manufacturer what rate it compares to in a solid bar, but if you want to play around with the math, rate increases by diameter^4.

Solid 1" bar: 1x1x1x1 = 1
Solid 1.125 bar: 1.125x1.125x1.125x1.125 = 1.60 times stiffer than a 1" bar
Solid 1.25 bar: 1.25x1.25x1.25x1.25 = 2.44 times stiffer than a 1" bar

A 1.25 hollow bar with 0.125" wall thickness would be 1.44 times stiffer than a 1" solid, using only 56% as much material (weight) of what a 1" solid does. :cool:

Crap, I think I just convinced myself I need to spend money on a new hollow bar. :eek:

Andy69 01-05-2010 04:33 PM

Quote:

Originally Posted by Derek69SS (Post 2633)
"how the heck is he doing that with a stock sway-bar?"

you mean this??:

http://www.youtube.com/watch?v=uttIBqX5Rf0

wah ah ahaahaaha!! :D

Derek69SS 01-05-2010 04:36 PM

Can't blame the car on that one. :o

Andy69 01-05-2010 04:38 PM

so, what bar ARE you running on that?

Derek69SS 01-05-2010 04:58 PM

Currently, the stock 15/16" front, and no rear bar... I should have the new Helwig "Pro-Touring" link-mounted adjustable-rate rear bar showing up on my doorstep any day now, and will swap in a 1-1/8" front bar that I've had sitting around also.

I didn't have anywhere near enough roll rate and couldn't put a stock type bar in the rear with my Wolfe rear arms, so I was band-aiding it with too stiff of rear springs, and still couldn't get enough rear rate to be able to go bigger on the front.

Bungy L-76 01-05-2010 07:42 PM

I don't really have any particular manufacturer at this point. I was looking at a Hotchkis 1 3/8 hollow bar and a Hellwig 1 5/16" solid bar (fronts) and was just wondering about the comparison between the two.

Derek, looked at the videos you posted. The in-car video is great. That course reminded me of the L.E. training I did at St Cloud, but those whale body Caprices didn't sound anywear near as cool.

498 SS 01-05-2010 11:44 PM

It was explained to me like this just last week. A solid bar flexes more than a hollow bar, because the hollow bar has two sides working against the flex. This came from a guy at Summit. It made me think of a comparison.... A one inch branch, and a one inch piece of bamboo of equal lengths.

Bungy L-76 01-06-2010 05:15 PM

Now you're confusing me. (which isn't hard to do) :confused:


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