In our last installment with Larry Dixon and his 1966 Chevy Nova, he walked us through the adventure he endured that we all know as Drag Week. That was just the lastest in a series of articles that started with this series allowing us to show what Larry was planning to do with his Nova, and then how he rebuilt the suspension with the help of Classic Industries, installed the Chevrolet Performance LT4, and had a Strange driveshaft and C&R Racing cooling system built. Now that Drag Week is over, Larry still had some things that he wanted to improve about the car, and this time, the update revolves around a Church Boys Racing rack-and-pinion steering system.
Since Larry plans to drive his Nova frequently and make eventual 9-second passes down the track, the rack-and-pinion system will give the car a much more controlled feel.
Upgrading a classic to incoporate rack-and-pinion steering is a guaranteed way to improve the handling and driving characteristics of any musclecar. While most hot rodders jump head first into installing big engines and even suspension upgrades, often times, many will stop there and not update the steering so they can’t realize the full performance potential their car can achieve.
The CBR rack-and-pinion conversion not only improves the car’s handling, but is fully adjustable.
Let’s face it, our classic Chevys were built with ‘60s and ‘70s technology, and although high tech at the time, it can make a classic car feel like you’re driving a shopping cart on ice. Climb out of a stock ’60s musclecar and into a late-model vehicle, and you will definitely notice a difference in the steering characteristics. The reason for that is because new cars have tight and very responsive steering, while most classic cars had slow steering boxes that were anything but reactive. Many times, the power steering in classics were often even over-boosted, and had a tendency to eliminate any semblance of road feel.
Do a quick online search, and you’ll find more than a few steering conversions. But not many people actually understand how difficult it can be to design a proper, upgraded steering system.
Why Reinvent The Wheel
According to Chuck Jr., there are things you should consider when contemplating a rack-and-pinion upgrade:
- Cheap is not always better, you get what you pay for! Ask questions about the completeness of the kit you are looking to purchase.
- How does the steering connect? What items do you need to buy on top of said kit to make it connect?
- What headers or exhaust is required to fit?
- What oil pan is required?
- Can an LS engine be installed?
- What power steering rack and pump is required? This is a big issue when manufacturers use a Ford-based rack-and-pinion, and the customer is using a Chevy power plant. The Chevy pump and Ford rack do not play well together. The Chevy pump puts out too much pressure for the Ford rack, and the car becomes extremely sensitive at freeway speeds.
- Where is everything made? Overseas/USA?
A quick overview of the steering system makes it look like a simple-functioning part of the car. You turn the steering wheel, and since the two front wheels are connected – to the steering box and each other, the car turns. But the real trick to designing a steering system focuses around geometry. See, your teacher was correct, you will need this stuff in the real world.
Anyway, in order to create a steering system that delivers any feeling of control, means getting all of the angles and ratios present in the individual parts of the system to collaborate and work together. But what are these guiding principles that must be understood when designing upgrades to improve the steering function of a car? Figuring that out requires advanced geometry and physics, as well as deciphering complicated equations. Luckily, we don’t all have to be an engineer or chassis designer. We can leave that task to guys like Chuck Church, Jr.
Why create a rack-and-pinion system for classic Chevy cars? The stock system has been adequate for years. Chuck Church, Jr. told us, “In 2006, my ‘67 Nova was running low 10’s in the quarter-mile with stock steering. This set up was in desperate need of an upgrade, as it was a back and forth affair with the steering wheel to keep the car between the guard rails.
“I developed this system to allow me the confidence to eventually run mid 9s at over 140 mph. Other kits on the market at the time did not allow me to alleviate any of the known Nova issues (i.e: steering linkage under the oil pan, use of a front sump oil pan, excessive negative camber, and quickly-wearing front tires).”
Church Boys Racing has put together a rack-and-pinion kit that includes a paintable steel steering column, floor support bracket, proper wire harness adapter, two Borgeson steering U-joints, a section of double D shaft, the power-assited rack-and-pinion, outer tie-rod ends, new steering arms, and a tubular crossmember.
A Phase II upgrade is available, and includes tubular lower control arms and a 1-1/8-inch sway bar. According to Chuck Jr., “As far as a weight savings, it is a wash. The stock steering box is heavier than the rack, but my tubular arms are much sturdier and weigh more. My kit does, however, deliver a more balanced weight distribution compared to the stock system that carries the heavy box on the driver’s side. Also, the factory crossmember that runs under the harmonic balancer is light and flimsy, and we replace that with a 1-5/8-inch .120-inch DOM tubing crossmember.”
The CBR kit is a complete bolt-in system.
We all know that the OEs put a lot of science into developing a reliable, properly working steering system, but if an aftermarket kit is not properly designed, your ride could become nothing more than unsafe-to-drive lawn art. One of the most frequently discussed concerns is that some aftermarket systems can induce bumpsteer. We asked Chuck Jr. about this, and he had this to say, “The stock system has the drag link routed under the oil pan, thus limiting where the pivot points can be located for proper pivot point setup and bumpsteer reduction.
To keep bumpsteer at a minimum, the suspension and steering need proper geometry. If you visualize a line extending through the center of the ball joint’s pivot point and inner mounts of each arm, they should intersect at Instant Center (IC). In order to have near zero bumpsteer, we also need the tie rods on each side to point toward the IC. This is one of two criteria for minimal bumpsteer. The other thing needed is for the tie rod to be a specific length.
“Because of this, GM had to compromise suspension design and its effectiveness. We have redesigned the pivot points with our tubular upper control arms to eliminate the static bumpsteer that is present in the factory set up. Case in point: the stock upper control arm creates too much negative camber (wheels lean in at the top) when the suspension lifts. When this happens, the steering arms are moved out as well. This movement causes static bumpsteer because the tie rods cannot grow longer and then shorter, so they turn the wheels.”
The cross shafts on the CBR upper control arms move the wheels back 1/2-inch to increase caster. They also lower the pivot point to aid with bumpsteer reduction. The tubular lower control arms are a Phase II upgrade.
Chuck Jr. continued by saying, “Our upper control arms allow the wheels to stay perpendicular to the road surface, keeping the static bumpsteer in check. Another benefit is less tire scrub, less tire wear, and faster mph and e.t.’s at the track. On the street, this translates into better steering response because more of the tire makes contact with the road surface as the suspension cycles up and down.”
Larry confirmed that by stating, “As for the way the car felt before the upgrade, the Nova’s steering was very free feeling – like trying to balance a stick on end in the palm of your hand. I was constantly chasing it to keep it straight. Afterwards, the car has a very solid feel and doesn’t wander at all. I don’t have power steering, and with the additional positive caster built into the new system, it does take more effort to turn the wheel.” Chuck Jr. told us that the extra effort that Larry feels can be decreased with an alignment adjustment.
But, is a rack-and-pinion upgrade really an upgrade? According to Chuck Jr., “Yes. For starters, it is a front-steer set up that allows room for a standard small-block or F-body LS style oil pan. The CBR rack requires only three turns of the steering wheel to achieve lock-to-lock, as compared to the sloppy 4-1/2 turns of the factory steering box.” That is only the beginning, as Chuck Jr. continued, “With the CBR rack-and-pinion, driving your Nova will feel more like a modern-day car without the back and forth of the steering wheel movement to keep the car in its lane.”
Overall, the CBR kit does not shave a lot of weight from the car, but the stock components do not deliver the strength and adjustability of the CBR kit.
Since the OEs and guys like Chuck Church, Jr., do what they can to make a great working steering system, you don’t need to concern yourself with things like Ackermann angles and how to eliminate things like bumpsteer, but you should at least have an understanding of these terms that need to be considered when it comes to the steering system in your car.
This condition occurs as the front suspension moves up (compresses) and down (extends). While this action is happening, the lower control arm moves in an arc around its pivot point on the frame. The tie rod is connected to the moving control arm through the steering, so it also moves in an arc. But if these two arcs are different, the wheel will turn in either direction as the suspension moves through its travel. This can cause the car to suddenly want to dart one way or another without any driver input.
…before the upgrade, the Nova’s steering was very free feeling – like trying to balance a stick on end in the palm of your hand. Afterwards, the car has a very solid feeling and doesn’t wander at all. – Larry Dixon
As Chuck Jr. alluded to earlier, the two main things that affect bumpsteer are the angles and the lengths of the tie-rod ends and lower control arms. Ideally, they should be the same length and also parallel to each other. Factory steering and suspensions are sound in regards to alleviating most bumpsteer, but because an aftermarket rack-and-pinion swap can obviously change the location and length of the tie rods, this presents the opportunity to induce bumpsteer, especially if the vehicle is lowered.
Since CBR has taken care of instilling a proper Ackermann angle and virtually eliminated bumpsteer, you don’t need to concern yourself with those aspects.
In early steering systems (think horse and buggy), many of the parts involved worked in a symmetrical fashion. In other words, both front wheels turned an equal amount during a turn. This is fine when turning at a relatively slow speed, but it causes serious problems as speed increases.
Ackermann means that the inside tire turns slightly more than the outside tire when cornering.
Basically, the Ackermann concept means that all four wheels rotate around a common point during a turn. Proper Ackermann means that while initiating a turn, the inside tire has less distance to cover since it is further within the circle. A steering system without any Ackermann arrangement causes the wheels to fight against each another since the inside wheel wants to follow the same line as the outside.
A correct Ackermann arrangement means the inside wheel turns a tighter radius to create a condition where each tire can cover the correct amount of ground. All cars on the road today incorporate some variation of the Ackermann principle in the design of their steering system.
While an Ackermann angle has little affect on a drag car that always drives in a straight line, we’re talking about a street car that sees occasional drag strip usage, so it stands to reason that Ackermann be considered.
When it comes to a proper front end alignment, most people understand caster and camber. These are two principles most commonly addressed in a typical front-end alignment. To visualize caster, visualize a straight line from the top ball joint through the bottom ball joint. If the upper and lower ball joints are perfectly vertical, you have zero caster. This is great for creating less rolling resistance, but negates any stability or control of the car.
Positive caster is achieved when the line you visualize lands forward of the tire’s contact patch. Positive caster wants to straighten the wheel when the vehicle is traveling forward. This why your steering wheel returns to straight if you let go of it after cornering. Positive caster enhances straight-line stability. A car with negative caster will typically be easier to steer, but will lack directional stability.
Now that you understand that caster is the forward or rearward “lean” of the strut/shock from vertical, we can discuss camber. This term describes the amount “lean” the top of the tire is tilted inward (negative) or outward (positive) from vertical.
Although the average enthusiast knows a certain amount of camber is required in a car’s steering, they might not realize that there are actually two camber angles to consider. One is the camber angle relative to the road, and the other is the camber angle relative to the chassis. In a perfect world, the tire should always operate with a slightly-negative camber relative to the road. Maintaining a proper camber can be challenging since suspension travel, body roll, and suspension dive must all be considered.
Now that you understand why an upgrade to rack-and-pinion steering is something you should check into, and you know about Ackermann, caster, and camber, isn’t it time you let Church Boys Racing help make your Nova a super Nova?