You need to upgrade the suspension and chassis to harness and fully utilize the power of an LS engine, While the Camaro’s unibody frame and suspension were modern manufacturing technology for the 1960s, these are antiquated now. The stock stamped-steel suspension arms and multileaf rear springs cannot offer a modern level of performance for an LS engine developing 400 hp or more. You need to define your application, budget, and driving style. Then you need to select the chassis and suspension systems to fit those needs. Your LS engine is part of an entire system and therefore the suspension and chassis needs to be integrated into your car.
This Tech Tip is From the Full Book, SWAP LS ENGINES INTO CAMAROS & FIREBIRDS: 1967-1981. For a comprehensive guide on this entire subject you can visit this link:
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Removing the Subframe
This procedure may seem a bit daunting at times, because much of the car must be removed to complete the task. Yet, this can be done in your garage with several sets of jack stands and a little patience.
Four giant bolts hold the factory subframe to the chassis, so removing those bolts is all that’s required. Sounds simple right? Well, it truly can be simple with some detailed planning and careful consideration for safety. The front subframe is awkwardly balanced, so I recommend making sure that everything is removed from the frame to make the process easier. I recommend making a check list of all the things that are still currently attached to the subframe and double-check that list to make sure they have been safely removed. These include fuel lines, brake lines, emergency brake cable, steering components, wiring, and any other modifications that have been made to connect the frame to the body of the car.
You need to isolate the body from the frame. To do this, you must raise the car high enough to support the body and let the frame hang free. I use two jack stands with blocks of wood to distribute the load better on the inside of the existing frame. Then I raise the jack to put a small amount of tension on the frame so it doesn’t come crashing down on me because of something silly and unforeseen. The four massive bolts are removed and the jack is slowly let down, allowing the body to rest on the jack stands. At this point the frame should be free and ready to be pulled away and chucked in the dumpster.
This is a great time to replace your old and worn-out body mounts with something a bit more sturdy. It might also be worth cleaning up the underside and adding some fresh paint to prevent rust. You may have to cut out the old body mounts, as they tend to rot from age. Pulling them out is straightforward and they typically fall apart if they are old and cracked. This is a good time to check for rust under the body and apply a coat of rust-resistant paint. Installing a new subframe is just as easy with some careful planning. You need to determine whether to remove the sheet metal, all the hoses, wiring harness connections (bellhousing to transmission), and all the other odds and ends. Make sure four jack stands are supporting the body. I place two jack stands on the frame rails behind the firewall and two jack stands under the rear axle. If you have access to a car lift, it makes this procedure much easier.
If the subframe is completely assembled and wheels and tires are attached to the hubs, you can simply roll the new subframe into position and easily align it with the body mounts. It’s much easier to install the engine and transmission on the subframe when it’s not attached to the body. Then with the wheels on the frame, you can move the subframe into place under the car. The wheels take all of the weight while you maneuver the frame under the car. Then, using a jack or your lift, lower the car onto the subframe, which is supported by jacks.
I chose to keep the wheels on the new subframe to make it easier to maneuver under and around the body. I also did this with the engine and transmission installed but in retrospect it would have been easier to do without the engine and tranny combo. Weight in this instance isn’t a factor as the front suspension holds the weight of the engine and transmission. I was able to move the front subframe and drivetrain combination by lifting it from the transmission mount. With all the weight on the front wheels, anyone with a modicum of strength can lift the rear drivetrain.
Lining up the new frame is a bit tricky and once the four bolts are snugly in place with new body bushings you can consider this part of the job complete. Four large bolts fasten the front subframe to the unibody. When you purchase new body mounts, they typically come with new Grade-8 bolts. If yours doesn’t, make sure to replace your old rusty bolts with high-quality new ones. After all, you’ve invested a tremendous amount of time and money so don’t cut corners at this stage.
Lining up the four bolts takes some time to get it correct. To properly align the subframe, you often need to move it back and forth and carefully line it up below the car body. Once you find a good location for the frame below the body, the shell can be lowered onto the frame. Be extra careful as the body may be a bit precariously balanced. (I was able to tip the body down at a sharp angle and lift the frame using a jack to mate the frame to the body.) The frame and body come predrilled with alignment holes. Use a long dowel to line up the holes to make sure the frame is square.
After I took the car to the alignment shop, my method was within .1 degree. It is laser aligned, so I know it’s accurate.
Buying the suspension as a system certainly has its advantages. When you buy a complete system you are also buying the engineering that went into it. It’s all designed to work together in perfect harmony. A system uses parts that are engineered to effectively function together and enhance performance. The upside to using a system is that you know the parts are meant to go together. This means the headers, engine mounts, and transmission mounts are all aligned properly and any interferences are minimized.
I’ve seen a few instances where headers don’t quite fit well with the engine mounts and hit the steering box or even the frame. The Speed Tech front subframe has been designed to work together with all the other components and this leaves me with less hassle in the long run. Not to mention the powder-coated gunmetal gray. That’s my favorite color!
A final word on aftermarket subframes. Regardless of manufacturer or subframe model, whether it’s Detroit Speed, Heidts, ChassisWorks, Speed Tech, it’s beneficial to buy the entire system. Most aftermarket suppliers, including Holley, ATS, and others, have their own version of the LS swap engine mounts and transmission crossmember. Each manufacturer has spent a considerable amount of time researching and engineering its own specific setups. Some companies even make their own version of headers, which is also designed to work with their subframes and accessories. I highly recommend that regardless of the aftermarket subframe you select, you should buy or stick with one company’s entire system. This prevents having to solve compatibility issues among systems and parts. Have confidence in the fact that the system you are working with is well designed and made to work right without interference in major components.
Various subframes are installed using the same method, but some of the details may be a little different. To make sure yours works properly, it’s important to consult the manufacturer. They ask you important questions, such as which engine you are using and what transmission you plan to run. These questions, along with suspension style and brake considerations, are all part of planning a solid build.
Many complete subframe assemblies are available on the market today, and most bolt up to the stock mounting holes, so a great amount of fabrication isn’t necessary. Popular high-performance or pro-touring subframes, from companies such as Speed Tech, Heidts, Chassis Works, and Detroit Speed and Engineering, conveniently and easily bolt up to the stock chassis.
Art Morrison Enterprises
Art Morrison is a long-time builder of high-performance suspension and chassis systems. It has been offering a variety of suspension and chassis parts for some time. This premium-quality subframe bolts to the unibody Camaro like other leading units. Using designed finite element analysis the GT Sport front clip provides excellent strength and rigidity while tipping the scales at a paltry 105 pounds.
The subframe itself features mandrel-formed 2 x 4-inch frame members, coil-over shocks, power rack-and-pinion steering at a 20:1 ratio, adjustable transmission crossmember, and anti-roll bar. The subframe carries specially modified C6 spindle and front suspension parts, including forged-aluminum control arms. The power rack-and-pinion steering is positioned 2 inches lower in the frame for increased handling agility.
In fact, the subframe readily accepts all LS engines and the transmission crossmember is compatible with popular highperformance transmissions, such as the Tremec T56, TH350 and 400, 700-R4 and 4L60E, Muncie 4-speeds, and Richmond 5/6-speeds. It can be fitted with stock C6 brakes or Wilwood brakes with 13- or 14-inch rotors. Other optional equipment includes custom headers and an adapter for the stock steering column. However, Morrison recommends an aftermarket column.
Detroit Speed and Engineering
Detroit Speed and Engineering (DSE) front subframes have proven themselves in competition throughout the country. Most notably Mark Stielow’s Mayhem won the 2012 Optima Ultimate Street Car Challenge using the DSE front subframe. This direct bolt-in subframe features premium tubular upper and lower A-arms, coil-over shocks and tuned springs, power rack-and pinion steering at 12:1 ratio, splined anti-roll bar, steering knuckles with late-model sealed bearings, and C6 Corvette steering knuckles with hubs.
The frame tubes are constructed using hydroforming technology in which a hydraulic press forces water through the frame rails. It creates a piece with uniform wall thickness for greater strength and rigidity. This process doesn’t require welding so the strength of the frame rails is retained. The assembly comes with stamped-steel main and secondary crossmembers that provide greater strength and stability.
The LS engine fits cleanly on the subframe. DSE’s front subframe can accommodate a 10-inch-wide wheel with 335-series profile, but before you buy wheels, you must measure your particular F-Body to be sure it can accept that wheel size. Both main and secondary crossmembers are stamped for structural rigidity. Most LS engines are direct bolt in on DSE subframes. The DSE subframe comes as bare metal but it can be powder coated for an extra charge.
Optional equipment for the subframe is a Z-bar mounting bracket, stock parking brake cables, Baer brake packages, stock or half-height body mounts, custom rack-and pinion hose kits, steering input coupler shafts, and stock-style transmission crossmembers.
Total Cost Involved Engineering
TCI’s front subframe unit is billed as the only front subframe on the market that has dual camber curves so it can be effectively set up and performs well in a variety of competition situations. The subframe is a double-rail mandrel-bent design for exceptional strength and vastly improved performance over stock. Most mounts and necessary brackets are installed. Those include body mounts, engine mounts, suspension brackets, and core support.
Subframe equipment includes urethane-bushed tubular A-arms; coil-over spindles have TCI’s custom 2-inch drop spindle or stock height spindle; billet rebound adjustable coil-overs with powder-coated springs; 1 x .156-inch-wide DOM steel upper tubular A-arms and 11 ⁄8 x .156-inch-wide DOM steel lower tubular A-arms; Moog upper and lower ball joints; manual rack-andpinion steering; 11-inch drilled, slotted, and zinc-plated rotors and big-bore calipers; 1-inch anti-roll bar; multi-position transmission crossmember; and mount.
Chris Alston’s Chassisworks
While Chris Alston established a solid reputation for chassis parts in drag racing, he has produced high-quality subframes and suspension pieces for pro-touring F-Bodies. Chassisworks first started offering pro-touring subframes in 2001 and has kept pace with the sport since then.
The latest G-Machine bolt-on subframe kit features stainless-steel A-arms, coil-over shocks, 11.75-inch Wilwood rotors with four-piston calipers, and Chassisworks hubs, anti-roll bar, manual rack-and-pinion steering, and transmission crossmember. The frame tubes are laser cut and welded from 7-gauge steel. The subframe allows the use of 17 x 8-inch front wheels. All of the other suspension parts are installed on the factorywelded subframe and dropped crossmember. Presently, LS-series engine mounts are in development.
The optional equipment for this subframe include billet engine mounts, power rack-and-pinion steering, A-arms in polished, stainless, or powder-coated finish, inner fender splash guards, urethane or aluminum body bushings, 13-inch Wilwood rotors with four-piston calipers or 14-inch Wilwood rotors and six-piston calipers.
Similar to others on the market, this complete subframe simply bolts in place of the stock subframe assembly. The Heidts unit lowers the ride height by 3 to 4 inches and has a track width of 581 ⁄2 inches. The Pro-G subframe features tubular A-arms in painted or polished finish, 2-inch dropped spindles, 11-inch Wilwood brake rotors and calipers, rack-andpinion steering, and 10-position rebound-adjustable coil-over shocks. With this subframe, you can install brake rotors as large as 13 inches with six-piston calipers, choice of two different Heidts anti-sway bars, a kit for installing a stock steering column, reversible transmission crossmember, and the transmission mount.
After reviewing all the relevant market offerings, I installed a Performance Pro Touring subframe. If you’re building an F-Body car for ultimate handling, you need to select a leading high-performance subframe. When doing so, you are making an investment in your F-Body and expect to pay $5,000 on up for one. In the case of the project car for this book, I opted for the Track Time package of the Performance Pro Touring subframe, which simply bolts up to the factory mounts on the frame and firewall.
This fully adjustable suspension tips the scales at only 125 pounds, so it takes a lot of unsprung weight off the front end of the car. It has a rear-steer rack-and-pinion system. It also includes tubular upper and lower control arms; a tubular, heattreated, powder-coated, and chromemoly sway bar; solid aluminum body mounts; and AFX spindles. It comes with adjustable coil-overs, but it can also be ordered with an Air Ride Shock Wave 3.0. It also carries high-clearance control arms that accommodate up to a 10-inch 295 wheel/tire with a 7-inch backspace. The crossmember is fully adjustable so it fits a variety of GM transmissions, including the Tremec T56 and 4L60E automatic transmission. This subframe readily accepts LSLSx engines.
With the Speed Tech subframe and others like it, it’s simple and easy to install and I didn’t have to cut, weld, grind, or fabricate the existing frame to install it. After all, it was a bolt-up procedure and that makes installing a subframe, such as this one, a less daunting affair. The subframe is designed to work with the rest of their suspension parts, engine mounts, and headers. It comes as a kit and is designed to work as one unit. I opted to have the subframe powder coated gunmetal gray and cleared over for a killer finish and professional feel.
A front spring rate of 500 pounds for the coil-over shocks was suggested to me. If you choose to keep the stock springs, the small-block front springs typically suffice. If you plan on having a more performance front spring, you have to check with your favorite suspension manufacturer for a custom spring rate.
You need a stiffness, damping control and the correct geometry for maximum road holding if your LS engine is going to effectively and efficiently transmit the torque and horsepower to the ground. Many aftermarket rear suspension systems are available today. These offer different approaches but all these suspensions are quantum leap beyond the stock rear suspension. These suspensions minimize if not eliminate all the those old handling traits of wheel hop, extreme body roll, and tire spin.
As I looked at the original plan for this build, which was a performance car with enough balance to run on the streets, I decided to go with the Speed Tech rear torquearm set up. When I purchased Speed Tech’s Track Time package, the other half of this equation was their rear suspension kit. It differs from other three- and four-link aftermarket rear suspensions by being a rear torquearm kit. It delivers exceptional road holding and vertical stability. The torque-arm setup has been around for years and the experience with the American Iron series in the NASA racing series has proven to me that the torque-arm setup is not only viable but established as a great performance suspension arrangement.
The spring rate in the back is set at 250 pounds for aggressive applications. The stock leaf springs do just fine, but again remember that if you want to step up the suspension, you have to check with your trusted suspension company to determine the correct rate for your application. I do recommend that if you have a stock mono-leaf setup, you want to look at upgrading them to something a bit stouter. Chances are that the engine you put in your car makes more power than whatever you just replaced. That said, the mono-leaves are notorious for wheel hop. If your plan is to only do parade laps, you should be fine, but I still recommend upgrading to multi-leaves or even a coil-over setup if the budget allows.
The kit includes the torque arm, a panhard bar, panhard mounting bar, coil-over shocks from QA1, the front mount for the torque-arm, lower Articulink lower arms, and all the hardware, which include the tabs that must be welded onto the rearend if you choose to use your own rear end. The kit requires minimal welding compared to other similar rear suspension systems.
I purchased a 9-inch rear end with the mounting plates and tabs already welded into place from Bears Performance Products. They built me a custom length 9-inch housing to fit the wheel and tire package. They completed the rear-end package with a Strange center section and 3.89 gears.
The rear suspension setup is designed to work with the front subframe and ties into it using the rearward-most body mount with a special crossmember to hold the torque arm in place with a Delrin bushing. I chose the Speed Tech rear suspension because I wanted a balanced and integrated suspension system for the car. However, other creditable rear suspension options are on the market.
The g-Link rear suspension package features VariShock coil-overs or air springs and tubular upper and rear control arms, control arm braces and spherical bushings, and an antisway bar. This full bolt-on system does not require a lot of fabrication for installation. The G-Bar air spring rear suspension comes with canted poly-bushing upper and lower control arms, suspension cradle and brackets, and VariShock adjustablevalve air spring shocks.
Art Morrison Enterprises
Art Morrison Enterprises offers two different rear suspension systems for the first-generation F-Body: three- and four-link. Both have 2 x 4-inch mandrel-formed frame rails that provide exceptional rigidity and maintain suspension geometry. Both suspensions are compatible with the stock gas tank. The frame rails and components offer a design that provides optimum ground clearance. These rear suspensions are built around the venerable Strange Engineering 9-inch differential, featuring Strange adjustable coil-over shocks and a special sway bar.
The three-link suspension uses a special Watt’s linkage in which two links are connected to a shorter adjoining link for lateral stability; it’s well suited for pro-touring applications. It has a lot of adjustability for particular operating conditions. This geometry provides excellent rear end articulation without any binding. It has an adjustable Watt’s linkage track locator and it includes all the suspension links and rod ends, sway bar, adjustable shocks, and a 9-inch housing designed for your particular application. With this suspension, you retain the stock gas tank but sometimes it can encroach on the rear seat area and you need to make a floorpan modification. This suspension geometry is often preferred for a competition car.
The compact triangulated fourbar four-link rear GT Sport suspension is a popular choice for pro-touring applications. The fourlink design with coil-over aluminum shocks capably handles forces placed on it and it fits below the stock F-Body floorpan. “Johnny Joints,” are integrated into the suspension, which uses special spherical bushings that use a Delrin cushion inside the joint for a compliant ride with accurate linkage actuation for superior performance.
Detroit Speed and Engineering
Many consider the Quadra-Link the finest aftermarket solid-axle rear suspension on the market, and it certainly is a leader in the market and delivers impressive road holding and traction. Like several of the other rear suspensions, this offers a quantum leap in road holding, traction, and ride quality but the installation requires substantial cutting, fitting, and welding. This fabrication includes cutting and modifying the rear frame rails, which is not a job a novice installer can often tackle. If you’re not skilled or comfortable using a pneumatic cutting tool, welding, and metal working, I recommend having a professional shop install this suspension for you.
The Quadra-Link features the Swivel-Link so the suspension is enabled to articulate. That allows it to adjust to suspension loads and road conditions. Keep this in mind: You may have to install wheel-well tubs so you can run large 12-inchwide wheels with this rear suspension installed. Similar to installing the suspension, integrating wheel tubs into the body requires extensive, cutting, welding, and fabrication. A well-positioned adjustable panhard rod effectively controls roll center, ride height, suspension loads during aggressive cornering, and enhances handling and traction. This suspension uses high-durometer rubber bushings to control suspension movement. The extended upper arms provide an ideal pinion angle from the driveshaft to the differential for long life and effective transmission of torque. It also uses DSE/JRi aluminum body coil-over shocks that are specifically valved for it.
The Pro-G complete bolt-in independent rear suspension (IRS) provides incredible performance and tremendous road holding, so it does not require extensive fabrication work to install it. It has a track width of 581 ⁄2 inches, uses top-quality tubular upper and lower A-arms, 9-inch aluminum coil-over shocks, front pinion support, 10-inch Wilwood brake rotors and calipers, billet single-adjustable coil-over shocks, and steel outer uprights.
According to Heidts, the upper link has a -.5 degree of camber curve and delivers 3/4 inch of total travel during aggressive cornering. The subframe connectors attach to the forward struts and anchor the rear suspension during heavy acceleration.
This is an actual IRS complete with half-shafts, rather than an engineered and tuned solid-axle suspension. In a turn, the outside wheel in an IRS suspension is able to squat and transfer its torque load better to the pavement while the inside rear wheel remains in contact with the pavement and does not lift. With a solid-axle rear suspension, the outside wheel stays planted during hard cornering, but the inside wheel is placed under a reduced load and often lifts. When hitting road bumps, potholes, and so forth, the force or jolt is absorbed by that particular side of the suspension and does not upset the balance of the car as in a solid-axle setup.
Wheels are your direct connection to the road, and as such, you need high-quality wheels to transfer the torque to the pavement. You also need strong, well-built wheels because you cannot compromise safety. When installing an LS engine into an F-Body car, the horsepower increase over the stock engine is significant and in many cases tremendous. A stock LS engine often produces more than 100 hp over a stock Gen I Chevy small-block from the 1960s and 1970s.
If you’re installing a highperformance LS engine, you can easily double or triple stock horsepower levels. If that is the case, you need a much larger contact patch than the stock 14- and 15-inch wheels offer to harness that power and effectively apply it to the ground. Otherwise, it’s simply wasted and your engine’s horsepower goes up in tire smoke when you get on the throttle.
Therefore you need to carefully consider whether your rear suspension and wheel package is adequate (or preferably, ideally suited), for your particular setup. Wheels are only one aspect of the complete highperformance transformation. Suspension, brakes, and wheels should be purchased as a complementary package because the operation of these components is interdependent. Therefore, you have to consider all the aspects involved in the total package, such as suspension, drivetrain, brakes, and wheels. Your wheels need to have the ideal combination of strength, light weight, and the correct size and backspacing.
You need strong wheels because you can’t afford a wheel to collapse at high speed on an autocross track, road course, or on the street. The results will be disastrous. While cast and billet aluminum wheels are available, most pro-touring drivers select forged wheels for strength, lightweight, and affordability. My goal is maximum handling and minimal unsprung weight.
Two-piece forged wheels are now available but they are offered in limited varieties. The three-piece design is still the most prevalent forged wheel type. The center sections can be cast or forged, but I recommend forged because the molecular structure of the forged center delivers higher strength. The 18-inch or larger wheels that carry low-profile tires are subjected to substantial loads during high-performance use and bumps and pothole jolts can be transferred to the wheels. Weak offbrand wheels or cheaper cast wheels can easily bend.
Also keep in mind, large wheels and tires are necessary to transfer more horsepower to the pavement, and are heavier and therefore have greater rotating mass. As a result, you need larger than stock brakes to provide adequate, if not excellent, stopping power. Therefore, if you’re running 17-inch or larger wheels, you should use 11- to 14-inch highperformance aftermarket brakes.
Let’s take a little trip back in time. In the 1960s, many muscle and passenger cars were fitted with 14-inch wheels from the factory, and special high-performance cars, such as the Z28, were fitted with 15-inch wheels with 60-series tires. In stock form many of the V-8 F-Bodies of the late 1960s and early 1970s cranked out 200 to 400 hp. Flash forward and today’s popular LS engines often produce at least 400 hp. The LS3, which is one of the most popular engines for LS swaps, cranks out 436 hp in stock trim. To utilize the output of a modern LS engine, you need large wheels that give the tires a large contact patch on the pavement.
It’s a balancing act to optimize handling and traction and therefore the selection of wheels is critical. Some of the suspension manufacturer may have recommendations for your setup. Commonly, for a pro-touring setup, the 17- and 18-inch wheels offer the best balance of traction and handling. Pro-touring owners avoid 19-inch or larger wheels because there is not enough clearance between the axle and steering components and stock sheet metal. Often large wheels require large fender flares and a custom body. That’s added expense and on the aesthetic side, 20-inch or larger wheels are sizable and many owners feel they are proportionally too large for the F-Body. Most of the front subframes accept 8-inch-wide wheels up front and some accept as much as 9-inch-wide wheel.
You also need to take backspacing (see below) and fender clearance into account, and you should have a 1/2-inch clearance between the bodywork and tires. In addition, you need to take your brake system rotor and caliper size into account and make sure there is enough clearance between the wheel’s edge. The stock front subframe accepts up to 18-inch-size wheel with back spacing of 4.5-inches, while the rear suspension accepts 18-inch-size wheel with backspacing of 4.75 inches.
Many top-quality forged wheels are available on the market and new ones are entering the market all the time. I would not buy more inexpensive aluminum cast or heavy steel wheels. These do not have the desired strength for high-performance use. HKE, Weld, M/T, Boze, iForged, Fikse, and many other top brands make premium forged two- and three-piece wheels. When it comes to buying wheels, buy the wheel with the correct dimensions and rely on a reputable brand. I could fill an entire book with all the different wheel constructions, types, and designs. I selected Forgeline, which is one of the most popular manufacturers of wheels on the market. My wheels measure in at 18 x 9 inches with 6.5 inches of backspacing up front and 18 x 12 inches with 7.5 inches of backspacing in the rear. The fronts and rears have the standard GM 5 x 4.75-inch bolt pattern. I opted for the titanium-color centers with a brushed outer lip. The center sections are left matte, and the lip has been clearcoated. These wheels bring an updated stylish look to the project car. Now, these wheels aren’t by any means cheap. The old phrase “you get what you pay for” certainly rings true with wheels as well. These ultra-light wheels are as attractive as they are durable.
Fender Clearance and Backspacing
With any wheels, you need to get the backspacing correct for your particular suspension and brake setup. If the backspacing is excessive and there’s negative offset, the suspension arms, tie rods, and other components may interfere with the wheel. If there’s minimal or little backspacing and a positive offset, the wheel may extend too far and contact the fender or wheel-well lip.
To best allow for the correct fender clearance, measure the width of the wheel-well housing. Be sure to take into account that some lowered cars with a shallow wheel-well housing many limit the size of tire you can mount on the rear axle. Once the measurement has been taken, subtract 1 inch so you can have the necessary suspension clearance of 1/2 inch. Up front you may need more clearance so you may need to subtract 11 ⁄2 inches.
You also need to determine the amount of wheel backspacing. Place a straight edge across the brake rotor. Then use a tape measure to determine the distance to the inner wheel well. You should factor in 1/2 inch of wheel-well clearance and then you have your backspacing measurement. Following these procedures helps you to determine maximum wheel/tire size for your particular car.
At this stage, you know the application of your F-Body, and that dictates the choice of tires. Highperformance street, street/strip, drag race, autocross/road race, and protouring all operate under different demands and conditions. For example, road-racing tires operate at sustained high speeds, under high loads, and therefore the tire is subjected to a lot of friction and heat. On the other hand, a high-performance street tire typically operates at low to moderate speeds and may be placed under high loads and high speeds for short amounts of time.
Tires need to be at their operating temperature to provide maximum performance. If your tires are over or under the ideal operating temperature, you’ll be slipping and spinning. As a rule, you can have a soft tire that provides exceptional grip and short life. Or you can opt for a hard tire and long life, but then it delivers reduced grip. Tires do not exist that provide ultimate grip and long life, so you have can’t have it all when it comes to tires.
This means that selecting tires is a compromise and it takes some research and careful consideration to find the ideal tires for your car. The following are examples of leading high-performance tires. It isn’t possible or practical to provide information on every single relevant tire model for a high-performance F-Body car. Therefore, I provide guidelines to help you select the ideal tires.
Let’s assume you’re building a high-performance or pro-touring F-Body car and are looking for highspeed, aggressive handling, and sticky tires. Most of these tires fall into ultra high-performance summer tire category and are suitable for a high-performance street car. These tires often have a relatively high tread wear rating of 300, traction grade is the highest at AA, temperature is the highest grade of A, and a speed rating of W, Y, or ZR. If you’re going to use your F-Body car for road racing or autocrossing, it needs to have a tread wear rating of 200 or lower.
Many ultra-high-performance summer and extreme-performance summer tires are available, and new tires are introduced in rapid succession while established tires are often discontinued. In the lower R-rated performance category, many tires are suitable for high-performance street use.
The Bridgestone Potenza S-04 Pole Position offers excellent traction and road-holding characteristics in a variety of conditions. The tire’s asymmetric tread design features interlocking tread blocks and a large outboard shoulder. A central rib promotes exceptional steering response and road holding. The intermediate ribs have high-angle tread blocks, which help prevent tread squirm for improved braking performance. The tire’s carcass uses two steel belts supported by and spirally wrapped with aramid/nylon cord reinforcement for high-speed driving and longevity. These R-rated tires have a 280-tread wear rating, AA traction rating, and A temperature rating. The 17- and 18-inch wheels weigh between 23 and 31 pounds.
Another R-rated offering is the Yokohama S Drive, which provides solid and predictable performance in most conditions and applications. These tires feature a nanotechnologybased micro-flexible tread compound,which produces a silica-based compound for excellent grip and response. This high-tech compound is molded into a directional tread pattern that also has independent shoulder blocks, notched intermediate ribs, and a continuous center rib. The tire’s carcass features jointless nylon cap plies that reinforce twin steel belts and belt-edge strips for increased longevity.
These R-rated tires have a 300- tread wear rating, AA traction rating, and A temperature rating. The 17- and 18-inch tires range from 20 to 28 pounds.
The Nitto NT555 285/30–20 tire is another ultra high-performance summer street tire. It features Nitto’s Extreme ZR compound that delivers exceptional grip and precise handling. An excellent choice for street applications, the tread pattern provides high-speed stability and superb cornering performance. The relatively stiff high-tread block maintains consistent road contact in a variety of conditions and offers a sizable contact patch. The high-traction tire also provides respectable tread life. Both the tread pattern and the compound were designed to deliver exceptional dry performance. This particular tire has a W speed rating, tread wear of 300, traction of A, and temperature of A.
Michelin recently released its top-line Super Sport that has been tested and developed into a leading ultra high-performance road tire. Michelin’s Bi-Compound tread is in an asymmetric design that has an inboard wet design and an outside dry design. In other words, the outside shoulder is a very grippy compound for high-speed street and track duty while the notched center ribs and inboard shoulder feature a compound designed for superior performance at very high speeds and in wet conditions.
The tire’s carcass contains two steel belts and a spirally wound Twaron cord. The high-density Twaron fiber in the carcass delivers structural reinforcement so the tire maintains its shape at all speeds. The tires deliver enormous grip at midcorner allowing the driver to hold the chosen line even when the tire is under great strain. In road tests, you can actually turn in more when the tires start to push and it holds its lines.
The tires are offered in sizes from 18 to 22 inches in widths ranging from 225 to 345 and aspect ratios from 25 to 45. These ZR rated tires have a tread wear rating of 300, traction rating of AA, and temperature grade of A. The tire weight for 17- to 18-inch wheels ranges from 20 and 26 pounds.
Street and Track Tires
I chose the BFGoodrich KDW2 street tire for many reasons. The car will see some street time, which may include wet weather driving. These are well rated for grip in dry and wet weather. This tire has a speed rating of ZR, a tread wear rating of 200, a traction rating of AA, and a temperature rating of A. This tire fits another one of the categories for road racing regulations. Autocrosses and road races in which street-going cars compete are now mandating tires with a tread wear rating of 200. Thankfully these tires came in my size.
The events I plan on running are local autocrosses and big-time protouring events, such as the Optima Challenge in which I recently participated with a respectable showing for a brand-new car. The tires for my car measure 275/35/18 on the front and 335/30/18 on the back. The bigger contact patch should help plant the power I make from the upgraded LS3. You want to take this into consideration when planning your build. Often times, the theme of the build dictates what wheels and tires are used and what sizes are required.
BFGoodrich has recently released another extreme-performance tire: the g-Force Rival. It’s one of the leading tires for pro-touring and trackday cars. The g-Force Rival combines the best qualities of the R1 street tire and g-Force Comp2 tire. In skid pad tests and on road courses, this tire has proven to have extraordinary grip for rear-wheel-drive cars. It supplies copious amounts of grip and provides road holding that’s difficult to match. This tire has a ZR speed rating, 200 tread wear rating, AA traction rating, and A temperature rating.
Yokohama ADVAN Neova AD07 is another tire that is designed for the demands of racing and autocrossing. It features micro silica tread compound for excellent grip. The directional tread pattern has sizable tread blocks and rounded edges for precise steering. Five large circumferential and multiple directionally aligned lateral grooves resist hydroplaning and enhance wet traction. The AD07 has a 180 tread wear rating, traction rating of AA, and temperature rating of A.
The Dunlop Direzza Sport Z1 Star Spec is its Extreme Performance Summer tire and it has performed very well in independent tires tests. This particular tire is suitable for F-Body pro-touring, autocrossing, and road racing. The Direzza Sport Z1 Star Spec comes up to temperature quickly and delivers phenomenal grip. The tread compound features continuous shoulder ribs and big shoulder blocks. The carcass has two wide steel belts reinforced by JointLess Band (JLB) Technology. The structure of the tire also contains steel cord reinforced two-ply polyester sidewalls, and spiral-wound polyamide to maintain uniform roundness. This tire has a 200 tread wear rating, A traction rating, and A temperature rating.
If you’re going to run 17-inch or larger wheels with 275 width or larger, they do not fit under the current bodywork, and as a result you need to install wheel tubs to fit the large tires required for maximum performance. Many wheel tub kits are available on the market for first- and second-generation F-Body cars. These include Chassisworks and DSE. These kits make completing these projects much easier than having to fabricate all the parts. However, you need to keep in mind that installing wheel tubs requires extensive cutting, fitting, welding, and often some fabrication.
Installing mini-tubs can be done over a period of weeks and roughly 40 to 60 hours, depending on your skill level. You’re widening the wheel wells and this is reducing interior space in the back, so you often have to shorten or eliminate the back seat. In addition, you often need to run shorter axles. While it isn’t the most difficult and complex project, it is not a project for beginners. Performing a mini-tub install requires a fair amount of welding and metal fitting skills as well as patience.
You need to be careful if your car has a fresh paint job because you don’t want to damage it. It’s also smart to take caution not to scratch your paint or get near it with heat, even if the paint is old. I needed to install mini-tubs so I could fit the 18 x 12-inch tires under the quarter panels. These wheels provide a huge contact patch that enables the engine to transmit its power to the ground.
Each kit contains extensive instructions, templates, and parts needed to complete the project. First, you need to strip the interior of the car: seats, carpet, plastic interior pieces, and all the other parts that cover the trunk wall and the wheel wells. In a nutshell, you need to remove the old inner tubs.
Drill out the spot welds, place the template over the wheel well, and mark the cut lines with a sharpie or scratch shawl. Then use a pneumatic rotary grinding tool with 3-inch cutoff wheel to cut out the old wheel tubs.
Some kits require notching the rear frame rails to fit the new and larger tubs. If this is the case, the frame needs to be reinforced. Fitting the new inner tubs requires a lot of trial fitment and minor cutting in the appropriate places. Most kits have some trim or reinforcement strips that require extra cutting of the rear wheel well and trimming, fitting, and welding. As each install is somewhat different, you need to make new plates out of a minimum of 1/8-inch plate steel.
After welding the plates into place you can put the new inner tubs in and weld them into place. This can be somewhat difficult as you weld two vastly different thicknesses of steel. I fill small holes with thin-gauge sheet metal and finish off the install with a thick layer of seam sealer all around inside and out of the new tubs.
Once the tubs have been installed, you need to paint them in the wheel well, the trunk, and the passenger compartment.
For the first two years of production, F-Body brake performance was lackluster to say the least with fourwheel drum brakes on many cars. Chevy offered a heavy-duty brake service package and JL8 brake system; a four-wheel disc brake system, was a rare option in 1969. The JL8 was not a great brake system and the brakes that followed on the secondgeneration cars weren’t great either.
To determine which brakes are best for your F-Body and application, you need to determine the relative size of the brake rotors and calipers because these parts must fit under the wheels. You need to consider styling price, overall production quality, and suitable strength for your application.
Brakes are your number-one safety feature so you need to invest in a top-quality brake system, such as from Wilwood, Baer, AP Lockheed, or another manufacturer. I strongly recommend against using off-brand brakes. You don’t want to use suspect or substandard brakes because a loss or failure in braking power puts your life and others’ lives at risk. Therefore, the braking power needs to be at least equal to if not greater than the power output of your car. The stock brakes on an F-Body car are not designed to handle the increased speed and performance of an LS engine. A stock LS engine produces about 400 hp, and most of the installs I’ve run across have well beyond that.
When upgrading the power, it’s also important to take safety into consideration. The brakes are your defense against plowing into the car in front of you and help you avoid hazardous conditions. Making sure you can stop in time is equally, if not more, important than getting your car up to speed. If you’re using your F-Body for street cruising and have only a few hard-braking situations, you could use the stock brakes, but I still wouldn’t recommend it. If you’re increasing the horsepower and torque significantly over stock, you need a brake system to match it. Brakes turn kinetic (motion) energy into thermal (heat) energy, and a high-performance F-Body needs large discs, calipers, pads, and the right brake fluid to handle all this energy and heat created by high-speed and aggressive braking. Achieving top brake performance is part of getting maximum performance from your car .
If you’re building a highperformance street car, street/strip car, autocross, road race, or pro-touring car (and that’s what this book is for), aftermarket high-performance brakes suited for these applications are an absolute must. I implore you to always upgrade to the best braking package you can afford so that you can enjoy your F-Body for a lot longer. After all, you can never have brakes that are too powerful or responsive.
You need to be sure your wheels are large enough to accept large aftermarket brake rotors and calipers. Wilwood, Baer, and other top manufacturers typically require the use of 15-inch or larger wheels for many of their top brake kits. If you’re building a genuine high-performance F-Body, you should be installing a 17-inch or larger wheel. Many owners are using 18-inch wheels so brake caliper clearance with the wheel is more than adequate.
The aftermarket offers a wondrous variety of brake system kits and brake parts for your F-Body car. While I can’t possibly cover every single combination for wheel sizes and popular suspension setups, here are some popular brake manufacturers.
A top manufacturer of highperformance brakes for several decades, Wilwood offers several brake systems that are designed for the F-Body. All the major aftermarket brake companies, including Wilwood, offer disc brake conversions as well as drum to disc brake conversion kits that contain all the brackets and hardware.
If you’re converting a disc-brake 1968–1969 Camaro, Wilwood offers the D52 calipers as one of the easiest brake upgrades for an F-Body because it’s a direct bolt on to the existing brackets.
If you’ve chosen to stick with smaller or stock-type 15-inch wheels, they are a suitable choice because they clear most wheels of this size. The dual-piston aluminum calipers replace the stock single-piston calipers but provide far superior braking performance. The dual-piston design applies pressure across a larger surface area of the backing plate so it provides greater braking power and more consistent pressure against the rotor.
The forged aluminum caliper body is far more rigid than the stock cast caliper body so it provides exceptional strength as well as cooling. The floating Wilwood caliper operates by sliding on two pins and pulling both pads into the rotor with about equal pressure. These substantially stronger calipers and the stainless-steel design provides improved performance over the long haul because the pistons don’t rust or pit like the cast OEM calipers. In addition, the pistons maintain their seals better.
For the rear axle, Wilwood offers the aluminum dual-piston D154 caliper but these are smaller than D52 front caliper for accurate brake bias with the front end.
The Dynapro brake system calipers and rotors are the next step up from the D52 parts and deliver a substantial increase in brake performance. The Dynapro Big Brake Front Brake Kit (PN 140-10510) supplies massive stopping power and features 12.18-inch rotors with fourpiston calipers. These brake kits are a cost-effective solution for highperformance street use and some track use.
For a significant step up in braking power from stock, you can opt for a Dynapro 6 Big Brake Front Brake Kit (PN 140-10738). This brake improvement kit features Dynapro six-piston calipers and 12.19-inch rotors in a standard or drilled-and-slotted style. Many owners building track cars and pro-touring cars choose the Dynapro 6 Big Brake Front Brake Kit (PN 140-104485) because it features the large 12.88-inch rotors in slotted or drilled-and-slotted style and forged Superlite 6R six-piston calipers. With the 13-inch rotors, the minimum wheel size is 17 inches.
Further up the product list is the Forged Billet Superlite brakes that feature 13-inch rotors in slotted or crossdrilled style with six-piston calipers. The billet brake calipers offer increased strength and improved cooling over the cast-aluminum calipers.
For F-Body rear axles, Wilwood offers rear brake kits, including the Forged Dynalite Rear Parking Brake Kit (PN 140-7149) featuring Forged Dynalite four-piston calipers. These calipers fit the 12.19-inch rotors in a standard or drilled-and-slotted style that works with the internal drum parking brake system. Additional kits are available to fi t your particular application.
During the 1970s, the steering spindle evolved and became larger, but the Wilwood brake kits are compatible with these spindle changes, including the larger 1979 spindle.
Baer is known for its killer brake components so it was an easy call to install top-shelf Baer brakes with a 14-inch rotor and six-piston caliper combination front and rear to complement my killer wheel and tire package. (I used Baer PN 4301352 for the front brakes and 4302351 for the rears.) These massive rotors and premium-quality calipers deliver top performance on a road course as well as the street.
When selecting Baer brakes for your car, you need to select the brake kit for a particular spindle whether it’s stock, ATS, or SS4-Plus Deep Stage. In this particular ProPlus kit you get a six-piston billet caliper with stainless steel pistons, abutments, noise suppression springs, and dual seals. The calipers hold 1997–2004 Corvette C5 and the 2005–2012 C6 pads for highperformance and easy replacement. High-performance 14-inch rotors are a one-piece design. A hat brake uses a drum for the rear brake system. If you have a C-clip axle, the kit includes Baer’s Verislide selfcentering brackets.
The Pro kit is the same basic system as the Pro-Plus kit but with a one-piece rotor instead of a twopiece. Don’t be told by competitors that a six-piston rear is too much brake. Due to the fact that Baer builds all its own calipers I can spec the rear piston sizes to function properly, but also allow the use of a standard two-port fi rewall mounted master. In C-clip applications Baer’s Verislide self-centering brackets provide the only proper engineering solution to mounting opposed piston calipers on C-clip bearings in housing-style axles. I also stagger the rear piston size (as with the front) to correctly minimize pad taper issues. Due to different wheel builds, templates are always recommended to verify fi tment of the brake. Templates can be found in the catalog section of the Baer site once you search by your make and model.
The Baer Claw Pro-Plus disc brake kit converts four-wheel drum F-Body cars to four-wheel disc brakes. These are built for rigorous use under competition use so they are also suitable for high-performance running. The Baer 6P compact six-piston calipers are machined from 2618 forgings so they provide minimal defl ection and excellent cooling under high operating temperatures. The brake rotors come with zinc-coated surfaces and a matched set of brake pads. The twopiece rotors have an aluminum hat for lighter weight and to accommodate rotor expansion. These kits provide exceptional performance but they are not cheap at more than $2,000.
Baer also has a kit that is a similar replacement to the factory disc brake kit. The kit contains 11-inch front discs and 10-inch rear discs, single-piston brake calipers, organic brake pads, caliper mounting brackets, stock-style spindles, gold cadmium-plated brake backing plates, single-piston brake calipers, and all related parts. The rear brakes can be installed on 10- or 12-bolt rear ends and with straight-across or staggered shock mounting locations. Baer offers 7-, 9-, or 11-inch brake boosters. These are dual-diaphragm units that are similar to the original AC Delco booster. The 7- and 9-inch brake boosters are compatible with most LS swaps while the 11-inch booster works with engines that have compact valve covers.
Written by Eric McClellan and Posted with Permission of CarTechBooks