Hollow sway bar?....

[musclecarmatt]

Hey guys...any company make a hollow 1 1/4 front bar?...i got a solid 1 1/4 bar on there at the moment i was wondering would be worth the weight savings to switch over?

Matt

[exwestracer]

IF you want a 3pc bar, Coleman Racing Products (among others). IDK about a bent 1 piece anymore, they were more popular 20 years ago...

The rate will change even though the bars are the same diameter (I know everyone says diameter is what matters, but there will be a difference)/

[astroracer]

Like Ray said, the rate will change with a hollow bar, which, if you want to keep the rate you will probably have to upgrade to a bigger bar. As an example. Your current solid 1 1/4" bar (at 6 ft long) weighs in at about 25lbs. A hollow 1 1/4 x .25wall x 6' DOM tube weighs 16lbs. To gain back your rate lets say you have to go to a 1 1/2 x 1/4 wall DOM tube. That weighs in at 20 lbs... 5 lbs less then your solid bar.
This is just an example but I don't think 5 lbs is worth the effort.
Mark

[musclecarmatt]

oh ok...thanks guys.....just an idea probably end up staying where i am at the moment!

[dontlifttoshift]

Hotchkis and DSE both do hollow 1 3/8" bars.

[nine lives johnny]

it's always worth the weight savings. you got to make all your parts add up to less. i recently went from a scatter shield to a stock bell housing to save 10 lbs. next year i'm looking to get down to 2300 lbs

[musclecarmatt]

yes...i want to loose as much weight as possible....currently running solid 1 1/4 bar with adjustable 7/8 rear bar....i thought about going with DSE 1 3/8 hollow bar but just wondering will that mess with the handling too much over the 1 1/4 bar?

Matt

[nine lives johnny]

when you start getting into shedding weight every where you can loose an ounce is worth it. 5 lbs to me is allot. hell if sell your old one you might break even.

[dontlifttoshift]

Matt, most of these manufacturers know what the rate on the bar is. if you know what rate you have you can compare to the advertised rate of the new bar and decide from there.

[UMI Tech]

Here's a good, simple calculator for rough comparison of bars. Keep in mind it's basic and simple.

http://www.circletrack.com/car_racing_calculators/torsion_bar_rate_calculator/index.html

ramey

[exwestracer]

Here's a good, simple calculator for rough comparison of bars. Keep in mind it's basic and simple.

http://www.circletrack.com/car_racing_calculators/torsion_bar_rate_calculator/index.html

ramey

According to that, a 1.375 bar with 1" hole (.188 wall) has the slightly more resistance than your 1.25 bar 642lb/in vs. 609 for the solid.

Didn't know any other parameters, so I just left what they had...32" long and 12" arms.

[musclecarmatt]

alright guys talked with mary P....and going to end up ordering the hollow bar...it save weight and will work well with my setup...thanks for help guys....

[UMI Tech]

I'm kind of interested hearing about your C-10 Driver/Project Truck... :drive:

[musclecarmatt]

I'm kind of interested hearing about your C-10 Driver/Project Truck... :drive:

ahh....she's just a driver at the moment....still got stock suspension on it lol

[UMI Tech]

Oh, not from a UMI standpoint to sell suspension (this time at least, ha ha). My dad had one and it brought back memories. He sold it and replaced with a '69 which I learned to drive with. Three on the tree!

[musclecarmatt]

it was my first vehicle to drive to high school...she never left me anywhere....so simple just keeps going and going!

[Hotchkis]

Hotchkis and DSE both do hollow 1 3/8" bars.

Every little bit of weight counts, if you want to be competitive or not. That’s why our hollow bars are so popular. The difference in weight between a solid bar and a hollow bar is significant, especially if your car has front and rear bars. :)

[Johnny Blaze]

Ramey, gald to see you here, talked with you on thirdgen about your crossmember. Im building a 69 c10 here as well, used to be a 3 on the tree.

Sorry, to get off topic. I have a hollow bar on my IROC!

[UMI Tech]

Hey JB. Nice to see you on here as well. I'm becoming a Pro-Touring.com addict...

[Norm Peterson]

According to that, a 1.375 bar with 1" hole (.188 wall) has the slightly more resistance than your 1.25 bar 642lb/in vs. 609 for the solid.

Didn't know any other parameters, so I just left what they had...32" long and 12" arms.
I know I'm kind of late tuning in here, but the quick and dirty formula for comparing the stiffnesses of two bars bent to the same shape simplifies down to the ratio that considers only their inside and outside diameters.

{[OD(bar2)]^4 - [ID(bar2)]^4 } / {[OD(bar1)]^4 - [ID(bar1)]^4 }

As in Mr. Bolles' calculator, ID = 0 for a solid bar.


Computing closer to the "actual" stiffness itself involves one or several additional formulas. Fred Puhn's goes a little further and adds a term for the bending of the arms (and basically assumes that the bar is all one piece).

500000*(OD^4-ID^4)/{0.4244*[ArmSideViewLength]^2*[TorsionLength]+0.2264*[ArmPlanViewLength]^3}

It still tends to predict a rate that's 5% or so high.


Norm