Selecting a Rear Suspension – Chris Alston’s Chassisworks

Product Tech<strong>Selecting</strong> a<strong>Rear</strong><strong>Suspension</strong><strong>Chris</strong> Alston ExplainsDrag Racing <strong>Suspension</strong>sOur popular Battle Cruiser line offers two affordable, fully adjustablestyles of rear suspension. The “double-adjustable” ladder bar isideal for e.t. brackets and street-strip applications. The 4-link isnow available with a choice of front-mount designsthat fit aftermarket rear frames (as shown)or a boxed crossmember.LADDER BARSUnlike “slapper bars” and other bolt-on devices,welded ladder bars give you a strong suspensionwith some basic adjustability. Any ladderbar that uses an adjustable front mount can beadjusted for three things. First is what we’ll callthe suspension’s “intersect point” in the chassis.When you raise or lower a ladder bar in itsfront mount, you’re actually adjusting the intersectpoint of how the drive loads are appliedin the chassis. Secondly, you can adjust pinionangle by rotating the two rod ends at the rearof the ladder bar. Finally, you can adjust thepreload in the car by setting one side differentlyfrom the other, effectively shifting weight fromone rear tire to another. Adjusting pinion angleor preload in a standard-typeladder bar requires removing the bar, thenscrewing or unscrewing the ends.What’s known as a “double-adjustable”ladder bar allows you to adjust pinion angleand preload in the front intersect point withoutremoving the bar from the car. A double-adjustablestyle is just easier to use. It has right andleft threads, so it works like a turnbuckle: Youcan loosen and rotate the adjuster withouttaking off the bar. There are two real advantagesto having the adjuster in the bottom bar,instead of the upper bar: (1) It’s easier to getto with a wrench, which solves a real problemin many cars; (2) the rod angle goes straightback and straight forward, so you can move it alot further before the spread between the twotubes gets so great that you can’t put the barback on the car.LADDER-BAR LENGTHAnyone who tells you that short-wheelbase carsneed 30-inch ladder bars, intermediatecars use 32 inches and long-wheelbase carsuse 36 inches is just showing you he doesn’tunderstand the big picture. What makes aladder bar work is dependent on where thefront mount is in relation to the car’s center ofgravity. A 32-inch ladder bar can be adjustedto have the same intersect point as a 36-inchbar in relation to the car’s center of gravity.The reason everyone uses 32-inch ladder barsis a space consideration. Bars shorter than32 inches tend to rotate the pinion angleexcessively, plus they require a front mountthat is very close to the ground.On a long-wheelbase vehicle (like a truck),the 36-inch ladder bar may be the best choice.When under-body clearance is not a factor, thelonger bar can transfer weight more easily.<strong>Chassisworks</strong>’ exclusive frontcrossmember features a tighterbend, more adjustment holes andstronger, 360-degree brackets.4-LINKSA 4-link is definitely superior to ladder bars.However, a 4-link is only superior in applicationif you are willing to invest the time it takesto sort it out. A ladder bar has two or threeadjustment holes that actually work; a 4-linkmight have 50! Actually, the 4-link doesn’thave 50 places that are better; it has perhapsthree that are better, a couple that are thesame, and a whole bunch that are worse. Youjust have a lot more possible intersect points.A tremendous amount of engineering goes intoa properly designed 4-link. There are 4-linkson the market that won’t gain you anything,because the spread on the holes and/or thebrackets themselves are improperly located.Consequently, there are lots of adjustmentsthat you can’t even get to. Email: sales@cachassisworks.com Web: cachassisworks.com <strong>Chris</strong> Alston’s <strong>Chassisworks</strong> Inc., 8661 Younger Creek Drive, Sacramento, CA 95828