chevelle splined sway bar rates - Lateral-g Forums

The WidowMaker · #1 11-03-2008, 10:44 AM

im looking for some rates to compliment my setup.

front 550 springs, ats spindles, spc uppers, alston shocks
rear 150 alston coilovers straight up, parallel 4 link, watts set at 12"

any info would be greatly appreciated. i need to pull the trigger on a rear bar this week.

thanks, Tim

68protouring454 · #2 11-03-2008, 11:37 AM

it all depends where you will mount the bar and how long your arms end up being.

The WidowMaker · #3 11-03-2008, 01:04 PM

thanks for the reply. im not actually looking for the size of bar or length of arms. i just need the approximate rate and then i can tailor the arms to meet that rate with my bar widths. the arms will have multiple adjustment holes to dial it in, but i need somewhere to start.

right now im thinking about 500 for the front and about 300 for the rear. mark thought that the RRCH was a little low and would require too much rate with my 150 springs. therefore ill probably move it up an inch or two.

thanks again,
Tim

68protouring454 · #4 11-03-2008, 01:16 PM

yes, i would go for 450-600 front and 250-350 for the rear

The WidowMaker · #5 11-03-2008, 07:02 PM

sounds good, ill start there.

anyone know what the stock ones were? 1.25" front and 1" rear.

they are a solid bar with "x" length arms, but those figures come out pretty high. different steel?

thanks, Tim

Blown353 · #6 11-03-2008, 07:42 PM

Stock bar diameter depended on suspension package... most stock sway bars for 68-72 Chevelles were 3/4" to 1" in front and 7/8" was the only rear bar offered.

Keep in mind the way the rear bar is mounted by the factory really reduces the effectiveness.

The WidowMaker · #7 11-03-2008, 09:18 PM

yeah, the stock configuration for the rear is pretty bad. this will be a true frame mounted bar though, so it should be a huge improvement.

right now ive got a 1.25" front and 1" rear bar. could i just take the width of these along with the arm lengths and figure out the rate, or is the steel a major factor with the splined bars? i really dont need to do this, but im just interested to see what i had before.

i havent had any issues finding a rear bar around 300, but the front is a little more tough. since it needs to be 39" long and has 14" arms, even the solid bars are around 400, not 500. looks like ill need a bigger bar thats turned down to 1.25 at the ends. most of those are only 37.5 though, so it looks like i may have to pay some more for a custom length.

Tim

Blown353 · #8 11-03-2008, 09:49 PM

You can get a pretty good approximation of the effective rate of the factory bars using the diameter and arm length.

A 1.25" front bar is overkill if you're running springs of a more "modern" spring rate and will probably lead to poor turn-in and understeer.

With 550# front springs I'd probably start with around a 1.125" bar and go from there, my guess is that turn in will be best with a 1" to 1.125" front bar with those 550# front springs, but it depends on tire & driving preference too.

I'm running a 15/16" front bar with my 750# springs. Started with my old 1.25" front bar and the turn in was slow and had lots of understeer, 1.125" was better, and 15/16" was the best.

I do want one of Mark's adjustable A-body frame-link rear bars when they come out so I can fine-tune things...

Tom.A · #9 11-03-2008, 11:58 PM

Troy, Is your 15/16 front bar OEM or ?

Thanks,

MarkM66 · #10 11-04-2008, 05:32 AM

Quote:

Originally Posted by The WidowMaker

yeah, the stock configuration for the rear is pretty bad. this will be a true frame mounted bar though, so it should be a huge improvement.

right now ive got a 1.25" front and 1" rear bar. could i just take the width of these along with the arm lengths and figure out the rate, or is the steel a major factor with the splined bars? i really dont need to do this, but im just interested to see what i had before.

i havent had any issues finding a rear bar around 300, but the front is a little more tough. since it needs to be 39" long and has 14" arms, even the solid bars are around 400, not 500. looks like ill need a bigger bar thats turned down to 1.25 at the ends. most of those are only 37.5 though, so it looks like i may have to pay some more for a custom length.

Tim

How wide is your frame in the front? Mine's 35.5", so a 2" longer bar @ 37.5" will work. I want the arms as close as possible to the frame, as they do get in the way of the tire at full lock.

The locating collars don't need to be on the outside of the frame, unless your pillow blocks are all the way to the outside. Mine are in the stock location, so my collars go inside the frame.