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Get A Grip

You don’t need deep pockets to turn your 4th Gen F-Body into a world-class handling car.

Ricardo Topete - November 01, 2012 10:00 AM

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For Your Information:

 

GTR HIGH PERFORMANCE

(888) 447-6487

www.gtrhipo.com

 

BMR Suspension, Inc.

(813) 986-9302

www.bmrsuspension.com

 

KONI North America

(859) 586-4100

www.koni-na.com

 

TOYO Tires

(800) 442-8696

www.toyotires.com

 

SPEED VENTURES, Inc.,

www.speedventures.com

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1Our Camaro had a set of lowering springs of an unknown brand, which gave us a harsh ride quality and not much else. GTR tech Eddie Zapata removes the rear springs in minutes, and transfers over the stock rubber spring pad from the mystery springs over to BMR’s lowering springs.

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2BMR’s one-inch rear swaybar is only one pound heavier than the stock ¾-inch rear swaybar. Notice the polyurethane bushings and sturdy sway bar brackets and end-links included. Adjustments can be made by pre-loading the end-link bushings differently. Loosening the end-links will slightly reduce the effectiveness of the rear sway bar.

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3With the rear suspension buttoned up, GTR turned their attention to the front.

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4Don’t skimp on greasing the new polyurethane bushings or swaybar or you will have a squeaky front end. The more the better in this case.

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5Work begins on the front by removing the upper shock mounting bolts. The brake master cylinder must be unbolted from the brake booster for access to some of the shock bolts. The brake lines have enough flex to allow this.

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6The upper control arm must be disconnected from the spindle. The entire upper control arm/coil spring/shock assembly can now be removed from the car.

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7GTR President, Gonzalo Topete, lent a hand in assembling the new BMR springs and Koni front shocks. Be sure to orient the spring and “stack” the components properly.

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8The front shock adjustment “knob” is located at the base of the shock shaft, which is partially covered by the coil spring. Best to make your adjustment now.

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9Once the BMR 35mm front sway bar is mounted, the new end-link kit is tightened down. No need to go torque-crazy here; snug will suffice.

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10GTR’s Camaro is almost ready for battle thanks to BMR and Koni. Now only one piece of the puzzle remains.

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11These DOT approved, Toyo R888 ultra-high performance street tires and 17x9½-inch SS wheels allow you to drive to the track, race, and drive home. The Camaro’s stock 16-inch wheels/tires look wimpy in comparison.

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12The tremendous grip provided by the R888 tires were causing the Camaro’s stock Panhard bar, control arms, etc. to distort enough that the tire rubbed.

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13BMR’s Level 4 Koni Handling Performance Package (p/n HPP027) includes thicker front and rear sway bars, polyurethane bushings and end-links, 1¼-inch lowering springs, and Koni single-adjustable shocks. This simple yet highly effective kit transformed GTR’s Camaro into a top autocross participant.

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TAKING IT TO THE NEXT LEVEL

Below are just some viable options that will complement any fourth generation F-body that has suspension tweaks similar to our test vehicle:

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TOP: BMR’s adjustable length Panhard bar (p/n PHR002) is stronger and less prone to flexing than the stock non-adjustable unit. The adjustment feature is ideal for lowered vehicles, which require the rearend to be centered properly under the body of the car to promote more neutral handling. As was the case with our test Camaro, the stock Panhard bar was deflecting so much that our tires were rubbing under hard cornering.

 

LEFT: On some lowered F-body cars, wheel hop is introduced due to the altered rear suspension geometry. To remedy this, BMR offers their lower control arm relocation brackets (p/n CAB002). These change the lower control arm mounting angle to create positive anti-squat, which translates into more “bite” from the rear tires.

 

RIGHT: If max grip is what you are after, don’t forget to ditch the stock rear lower control arms. Their soft, rubber bushings distort easily under hard driving conditions. BMR’s solution is a set of tubular steel control arms with polyurethane bushings to keep traction robbing flex at bay.

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Images courtesy of the manufacturer

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The 1993-2002 Camaros and Firebirds (known as fourth generation F-body cars) have a strong following among GM enthusiasts.

The reasons for their popularity are many: affordable prices, versatile platforms and strong drivetrains. The most sought-after fourth generation cars are the ’98-’02 LS1 powered cars, mated to a six-speed manual transmission. Such equipped vehicles provide an excellent foundation to build a corner-burner.

Under normal driving, these F-bodies have decent road-holding capabilities. However, pick up the pace considerably around corners and the factory stock suspension shows its limits. Zooming around a corner will induce excess body roll, which distorts the chassis and quickly begins to transfer weight to the outside tires, which in turn, overloads the stock tires and causes them to slide. Ultimately, you end up with a Camaro/Firebird that is leaning and sliding around a corner.

Our friends at GTR High Performance applied some basic bolt-on magic to a near-stock 1999 Camaro Z28. The ’99 Z28 had over 155,000 original miles on its ticker and was upgraded with a Magnaflow catalytic Y-pipe, MAC cat-back exhaust system and a K&N replacement air filter. GTR verified the Camaro’s state of health by running it on their in-house Dynojet dyno, where it put down a strong 302hp at the tires. GTR’s plan was to build a dual-purpose Camaro that could serve as a daily driver and run with the big dawgs at autocross competitions.

 

The Parts

GTR knew that in order to accomplish their goal they would have to start with a solid foundation. They turned to BMR Fabrication, which recommended their Level 4 Koni Handling Performance Package (p/n HPP027). The Level 4 kit addresses the faults of a stock Camaro (undersprung and excess body roll). BMR’s 1¼-inch lowering springs offer a lower center of gravity and stiffer spring rates for less body roll during cornering and less nose-dive under hard braking. The stock 19mm rear sway bar is replaced by a 25mm hollow bar, while the stock 30mm front bar is upped to BMR’s 35mm hollow front bar. Combined, the larger bars only add an extra five pounds, which keeps unsprung weight to a minimum.

To dampen the extra spring energy, Koni’s single adjustable shocks are used as part of the Level 4 kit. Koni’s shocks are externally adjustable, which simultaneously adjusts rebound and compression to change the handling and ride-quality characteristics. At the track, we made several adjustments and found that our fastest laps were with all Koni shocks at their full “firm” setting. Naturally, different cars with different suspension, tire, and power combinations may require different settings to optimize handling. Therein lies the beauty of Koni’s adjustable shocks; they allow for easy tuning changes and can quickly be softened or tightened up for the street or track. Essentially, it’s like having multiple shocks in one.

Knowing full well that a car’s ability to hold the road is only as good as the grip offered by its tires, GTR outfitted the Camaro with a set of gumball-like Toyo R888 ultra-high performance tires. Toyo’s R888 tires are perfect for the weekend warrior, as they are street legal, so they can be driven to and from the racetrack. Complementing the chunky 275/40/17 Toyo R888 tires, GTR furnished a set of 17x9.5-inch Camaro SS replica wheels dressed in a matte black with machined lip which provide a race-ready look. Combined, the 17-inch wheel/tire swap only added 24 pounds; a fair trade-off considering the tremendous grip they offer. The price of admission for a killer street/track wheel and tire combo like this will set you back about $1,400 through GTR ($800 for the Toyos and $600 for the replica SS wheels).

 

The Test

When the wrenches stopped turning at GTR, it was time to hit the road and track. As a starting point, all the Koni shocks were set to full soft which gave us a very plush ride quality; almost too soft considering the hardware the Camaro was now sporting. On the street, the steering response felt better and sharper as a result of the thicker sway bars. Of course, the real test was still to come at the autocross course.

We hooked up with SpeedVentures Inc. and participated in an autocross event they were hosting at a local racetrack. SpeedVentures makes it possible for anybody, regardless of racing experience and vehicle, to try autocrossing in a controlled and affordable environment.

We began the day by running the car exactly how it drove to the track: Konis at full soft and 36 psi tire pressures front and rear. After a few warm up laps, the Camaro had settled into mid 43-second lap times. The Z28 felt good, but it felt a bit “lofty” at times; it was time to start tweaking.

For round two, the rear Konis were set to full stiff to induce a bit more oversteer to help the Camaro pitch around corners quicker. This small change made a huge difference in driving dynamics and the lap times plummeted to an average of 41.9 seconds with our fastest individual lap at 40.6 seconds. Our sleeper Camaro was now among the quickest cars at the event and oh-so close to the elusive 39-second club, which only a handful of cars had managed to break into.

With the rear Konis cranked up to full stiff, we created a bit too much oversteer and the car seemed tail happy, while the front end plowed or understeered in the really tight turns. To counter this, we maxed out the front Koni shocks to full stiff in hopes of creating a more neutral-handling car (which is the goal). After the first lap of round three, we knew we were onto something good as the Camaro blazed a 40.1 second lap. With the suspension tightened up, body roll was minimal and the Toyos were really able to bite down. Experimenting a bit with entry and exit angles into the turns rewarded us with our quickest time of the day of 39.1 seconds. Overall, our average lap was consistently low at 39.9 seconds.

 

The Bottom Line

In the end, we ran out of time as the course was closed as a result of a Corvette that spun and crashed (who says autocrossing is accident free?). However, we are confident that with more seat time we could have dipped into the 38 second range, which was a feat only accomplished by two other cars that day. In all, we were very pleased and surprised at how well the unassuming 155,000 mile Camaro had performed.

Throughout the day, many of our competitors, which included some exotics such as a supercharged 2011 ZR-1 Corvette and tricked-out Mustangs (including a new Boss 302) came over to inspect the Camaro. No doubt, expecting to see a supercharger under the hood or full race slicks, a roll cage or some other dead giveaway to a full race car. We were sorry to disappoint, yet happy to humble, all of our competitors that day, but the look of disbelief on people’s faces was priceless and certainly worth every cent of our transformation into a legitimate cone-crushing Camaro. Best of all, at the end of the day, we toned down the suspension and drove home in total comfort.

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