Along with the Big Bar and Soft Spring revolution comes a need for amore reliable and adjustable sway bar.
Most stock car drivers use a one-piece sway bar and find it more thanadequate for normal setups on average racetracks. There can be somedisadvantages to the one-piece bar, and there is an alternative. Acurrent trend among asphalt teams is to run setups that use a biggerdiameter sway bar in combination with softer springs. It has beendiscovered, along with this development, that certain components andsettings on the cars need to evolve along with the radical change in thesetup.
BBSS Necessitates Rethinking our Designs Racers have learned that theyneed to address issues such as front geometry moment center design,camber change issues, associated clearance problems that arise fromusing very soft springs that create increased dive, and certaincomponent modification when it comes to suspension parts like the swaybar assembly in order to gain full benefit of the BBSS setups.
A NASCAR, or splined, three-piece style sway bar is a much-improvedcomponent to use to reduce chassis roll. When properly installed, it canreduce friction and binding in the suspension and provide moreadjustment and choices of bar stiffness.
"Big Bar" can mean the installation of anything from a 1 3/8-inchdiameter sway bar to upwards of a 2-inch bar. If we were to install whatwe call a "NASCAR style" or splined sway bar, our option on diameterselection would become much greater.
Many teams have already opted to convert their car from aone-piece-style sway bar to the splined style. We talked with a team whodid a nice job of converting their Super Late Model car over and learneda few tips in the process that we will pass along.
Why Switch to a Splined Sway Bar?
A properly-installed three-piece swaybar will offer the team a smoother operating bar devoid of much of thebinding associated with the one-piece bar along with plenty ofadjustability. Because the three-piece unit uses bushings or bearings atthe end of the sway bar, the movement in both twist and dive of thechassis is much smoother. The sway bar arms are ridged with the splinestyle as compared to the one-piece bar, which has arms that can flexquite a bit. This causes a reduction in the bar rate of the wholeassembly.
The Heim connector must be exactly perpendicular to the lower controlarm as well as the sway bar arm to avoid binding. Check the alignmentfrom a front and side view before finalizing the layout. This setupallows bolting the upper Heim to the shock mount bolt to avoid having toweld a bracket onto the lower control arm. The sway bar arm will need tobe bent and fitted to this location.
Binding can be a major source of problems when we are sorting out ourhandling balance. We need to make sure that all of our pivot points arefree of bind and that the whole suspension operates freely, even thesway bar.
The splined sway bars are usually enclosed inside a tube. For largerdiameter bars, the tube will need to be large enough to accommodate upto 2-inch diameter bars. The roller bearing bushings used for these barsare 1 1/4 inch inside diameter, and that matches the splined end diameterof the larger sway bars. A bushing spacer is installed in the end of thetube to match the bearing/bushing to the tubing.
Clearance Matters
Clearance is an issue when installing the sway bar. Ifthe crossmember is 4 inches off the ground, then the sway bar componentswill need to clear 4 inches, too. The end of the arms at the control armcan be lower because the control arm will hold it off the ground whenthe car dives.
Our example car had a piece of square tubing welded to the front chassisrail directly under the spot where the old one-piece bar adjuster wasfixed. The length of this tubing for your application will depend onclearance for chassis dive as well as clearance between the sway bar armand the tie rod. An offset, dropped arm will most likely have to be usedhere.
Make sure the sway bar arm clears the tie rod through all of the travelthe car will experience. It is a good idea to mock up the assemblybefore getting too far along so that issues such as this are addressedearly on.
Right-Side Connection
The best connection at the control arm end of thesway bar arm on the right side is the double Heim (left- and righthandthreads) joined with a threaded length of rod and two lock nuts.Remember that the Heim connector must be vertical and perpendicular toboth the sway bar arm and the lower control arm. If this connection isnot made at 90 degrees, a severe bind will take place and affect thesetup.
The end connections should be placed as close to the lower ball joint aspractical. This increases the rate of resistance of the bar assembly tothe roll tendency of the suspension. There is a motion ratio thatapplies here, just the same as the spring to lower control arm mountinghas a motion ratio. The farther the spring or sway bar is from the balljoint, the less effect the spring or sway bar will have.
A square piece of tubing is welded from the very front of the frame tothe sway bar housing tube. The length of this connector tube willdetermine the arm angle relative to the lower control arm as well as theground clearance of the assembly.
Left-Side Connection
The connection at the left side consists of a flatsway bar bumper that rests on a plate welded to the lower control arm.This bumper should be lightly lubricated, as it will slide aroundslightly as the car goes through dive and roll.
An added touch is this unique adjuster that attaches to the end of thesway bar and the sway bar arm. This unit allows easy adjustment of theheight of the end of the arm so you can precisely align the sway barwhen setting up the weight distribution of the car at the shop. It alsoeliminates the need for a dropped arm. This team used a straight armthat was made lower in the car by the adjuster.
At the left side of the car, the sway bar arm is attached to a sway barbumper, or "slapper," which rests on a plate welded to the lower controlarm. Note that it is placed as close to the lower ball joint as possibleto give the sway bar the most effect.
Preload Not Necessary
Large sway bars do not need preload. If you wereto apply preload to a 1 1/2-inch or larger bar, the weight distributionwould change dramatically as well as the overall attitude of the car. Ihave watched teams preload the larger bars and have the ride heightschange over 1/4 inch.
The fact is, the car will get on the bar immediately when the driverturns into the corner and stay there all throughout the turn. Preloadwould only serve to ruin our carefully planned weight distribution andlegal ride heights.
The choice of material for the sway bar arms is important, too. Forlarger high-roll resistance bars, a more ridged arm is needed. The steelarms are really the only ones that will do the job without bending. Theydo weigh more, but this weight is very low in the car and can be asubstitute for other ballast.
The addition of a free-moving splined sway bar is an improvement to anystock car that uses a sway bar. You don't necessarily need to run theBBSS setups to benefit from this suspension component. Sway bar sizechanges and adjustments are quick and easy. Most dealers now stock, orcan get, the parts needed to build the splined sway bar attachments.Once completed, you'll wonder why you didn't make the switch earlier.