Building a custom sway bar...

[zeroescape]

So i thought about building a custom sway bar after coming across Speedway Engineering's website.

I was wondering has anyone tested a stock sway bar to get an idea of where i need to start in terms of spring rate.

Speedways rates are in lbs. force @ 5 degrees of twist.

http://www.1speedway.com/swaybar35.htm

Thanks in advance.

 

[Vorshlag-Fair]

Is there a specific reason you want to build a custom rear swaybar?

There are so many Off The Shelf options I couldn't see a range of bar stiffness that you couldn't find with an OTS solution. Custom swaybars usually entail a good bit of custom fabrication and other "not bolt-in" type work - it is a lot more than just ordering some parts out of the Speedway catalog. There are calculations, for sure, but you will spend a lot more time doing work.

What type of racing do you do... this is in corner carvers section so I assume not drag racing. What organization/class/competitiveness level?

And its fine to say "I just want to do a custom bar because its cool", or "to potentially save 3 pounds". Just curious.

 

[zeroescape]

Hello,

I was kinda hoping you would respond, I remember reading about you thinking of going to a splined sway bar.

Iam not racing in any organization at the moment. I do plan on getting on to the road course in about a years time. Right now iam building my 12' GT the way i want it and will find the best organization that it fits in. I like the sound of nasa TT so far.

My objectives right now are brakes and a tuneable suspension.

Im 95% sure ill go with a off the shelf sway bar, but your right in the fact that there are so many options. The bars range from 33mm to 38mm, tubular to solid, and stiffness explained in relative terms.

I thought it would be easier to keep a standard bushing diameter and switch the bar out if needed. Also Speedway Eng. gives good data on each bar and i thought i would try to be a little more technical then just soften/stiffen by going to the next hole.

 

[Vorshlag-Fair]

Jason M who works here at Vorshlag has built several of these splined custom bars (aka: "Circle Track style") for various race cars and we installed a similar kit on the back of on a drag racer's 4th gen F-body recently.



After trying a few brands, settling on the Whiteline bars, then doing a dedicated/timed autocross set-up test day - with full sweeps of bars, shocks, camber, tire pressures and more - we found that the full range of adjustment on the big Whiteline bars was adequate for us.



I tend to gravitate towards bigger, stiffer swaybars that have a large adjustment range, no matter what the car is. That gives us the largest range of stiffness, usually softer than stock to considerably stiffer. With 4 holes per side the WL front S197 bar (above) has lots of adjustments and a massive range.


Eibach vs WL front bar. As your an see, there's not a lot of weight to be found in the swaybars (relative to a 3600 pound car)

And while I wouldn't mind losing some weight, we suspect there is only about 8-10 pounds to be lost in swaybars at each end; that's just not a lot of weight to be chasing for the amount of work involved. Hence why we haven't gotten to it just yet. But we will, someday...


Weight with driver and 1/2 tank of fuel... too heavy

Right now our car is a heavy boat (we took that 3815 pound weight about 3 minutes ago), and even with a 3770 pound minimum weight (w/ driver), we're over weight by 45 pounds. This full weight, full content street car w/ emissions is just killing the scales right now. Knocking 10-15 pounds out with custom swaybars isn't going to make a dent for me. I need to find 100-200+ pounds, then add ballast to the back (its about 54%F/46%R now). Ugh. Bound "pounds are made by ounces..."

Anyway... not trying to discourage you, but there are a lot of things involved in making custom swaybars, and losing a little weight is only a small factor. Jason (and Brandon) is driving to Pikes Peak supporting a friend's Unlimited Class EVO at the PPIHC for the next week, but when Jason gets back (July 2nd) I'll have him chime in with some more info.

Gotta load the car on the trailer and head to another NASA race weekend. All new spring rates, ride heights, front track, and wider front wheels. This throws our old set-up out the window! I will likely be making swaybar adjustments to get the balance right, of course...

Cheers,