Tech Tips
This information is provided to help you decide which type of suspension or chassis is best for your needs.
Ladder Bars vs 4-link Wheelie Bars, do I need them?
Leaf Springs vs Coil Springs Subframe vs Chassis Kit
Rear Suspension Locaters Roll Bar vs Roll Cage
LADDER BARS vs 4-LINK
A 4-link is like anything else that’s infinitely adjustable: If you’re not going to spend the time it takes to get it adjusted correctly, you’re better off with a part that doesn’t adjust. If you want to buy something that’s inexpensive; that doesn’t take a lot of real care and extra energy to install; and that basically works right out of the box, then ladder bars are for you. If you want your car to go as fast as possible, and you’re willing to invest whatever energy it takes, choose a 4-link.
Neither type of suspension is perfectly suited to all-around highway operation. To be 100-percent streetable, a rear suspension must allow the rearend to “roll” independent of the body. This movement is necessary to smoothly transverse potholes, speed bumps, curbs and other irregularities in the road. Chassisworks now offers ladder bars and 4-links with large, urethane-bushed rod ends which greatly increase the amount of rearend roll available — a real plus for Pro Street applications. Additionally, these urethane bushings will absorb some of the road vibrations.
The importance of rearend roll is greatly diminished on smooth surfaces, of course. Typically, a 4-link allows the rearend to roll a few degrees more than ladder bars. Our new Pro Street 4-link offers an unprecedented amount of suspension travel and, consequently, an incredibly smooth ride. Incidentally, this is the first race-type 4-link ever designed specifically for high-powered street cars and trucks. Beware of old-style “4-bar” designs. These are borrowed from the street-rod industry, and will not hold up to high horsepower.
One more thing: All of your chassis and suspension components should be purchased from a single source. If you buy a Chassisworks 4-link or ladder bars and another company’s subframe, you’re compromising whatever science was designed into each system — assuming you can even get the parts to fit! Frame design has a tremendous amount to do with the bracket design. A knowledgeable chassis builder actually designs the suspension first, and then designs a frame that will hold it.
LADDER BARS
Unlike “slapper bars” and other bolt-on devices, welded ladder bars give you a strong suspension with some basic adjustability. Any ladder bar that uses an adjustable front mount can be adjusted for three things. First is what we’ll call the suspension’s “intersect point” in the chassis. When you raise or lower a ladder bar in its front mount, you’re actually adjusting the intersect point of how the drive loads are applied in the chassis. Secondly, you can adjust pinion angle by rotating the two rod ends at the rear of the ladder bar. Finally, you can adjust the preload in the car by setting one side differently from the other, effectively shifting weight from one rear tire to another. Adjusting pinion angle or preload in a standard-type ladder bar requires removing the bar, then screwing or unscrewing the ends.
What’s known as a “double-adjustable” ladder bar allows you to adjust pinion angle and preload in the front intersect point without removing the bar from the car. A double-adjustable style is just easier to use. It has right and left threads, so it works like a turnbuckle: You can loosen and rotate the adjuster without taking off the bar. There are two real advantages to having the adjuster in the bottom bar, instead of the upper bar: (1) It’s easier to get to with a wrench, which solves a real problem in many cars; (2) the rod angle goes straight back and straight forward, so you can move it a lot further before the spread between the two tubes gets so great that you can’t put the bar back on the car.