Third-Gen F-Body - Suspension Upgrade - Better Than New!

That's How Our Third-Gen F-Body Handles After Suspension Upgrades From Hotchkis, Energy Suspension, Bilstein and Moog.

Johnny Hunkins Jul 1, 2001 0 Comment(s)

Step By Step

We ordered a full complement of third-gen suspension components from Hotchkis for our 1988 Firebird Formula 350 project car. (We had already installed the Hotchkis springs and strut tower brace.) This system consists of adjustable panhard, rear trailing arms, subframe connectors, dampers, and torque arm bushing and goes a long way towards improve handling, responsive turn-in, and fewer rattles. The performance struts and shocks are from Bilstein are valved specifically for the Hotchkis springs and Energy Suspension bushings.

We opted to install a full complement of polyurethane Energy Suspension components. One of the big advantages of polyurethane over rubber is that it doesn't deteriorate when exposed to ozone, oil, road salt or other chemicals. Rubber is widely used in OEM bushings and mounts due to its compressibility and compliance; this translates into reduced or delayed driver feedback and binding within the suspension. Energy Suspension's polyurethane construction is designed for the enthusiast who wants improved performance and longevity.

Technicians Roger Creech and Aaron Strope removed the steering linkage assembly from the car as a unit since all parts were being replaced. You'll note that the stock tie rod sleeves are prone to severe corrosion due to their open design. The Hotchkis sleeves are a sealed tubular design and they're machined flat for ease of adjustment. Strope also used Moog Problem Solver tie rods and drag link which have a greater bearing surface area and better lubrication properties than the stock parts. The new parts are being assembled with anti-seize compound to make future alignment adjustments easier.

While the Roger finishes the steering linkage assembly, Aaron Strope checks the front swaybar diameter with the measuring tape provided by Energy Suspension on the back of their catalog. (Make sure to cut it out instead of photocopying it.) Our WS6-equipped Formula had the 32mm swaybar. (There are four different 3rd gen front swaybars, so it's imperative to get the size right before you order.) The urethane Energy Suspension bushing is firmer than the rubber stock bushing. The urethane pieces not only last longer, but react faster to steering input.

Half the weight of the car rides on the upper bearing plates, and when the steering is turned, the strut assemblies rotate in these bearings. Many people replace all the suspension pieces and use the original bearing plates, which in many cases are worn out and binding. In our original 13-year-old plate (right), the bearing was binding, so we replaced them on both sides.

You want to install the Bilstein struts using a torque wrench set to 52 ft.-lbs. Use a 7mm Allen key for the center of the strut and a 22mm box wrench to hold the outer nut in place. You want the bearing in the bearing plate sandwiched between the bottom of the strut shaft and the retaining washer on top. This ensures that the bearing turns with the strut.

The problem with building up a 13-year-old project car is that, simply put, everything on the car is 13 years old! Even though we made a conscious effort to purchase a car in pristine condition (it had less than 60,000 miles on it when we handed over $4900 greenbacks in November 1999), there was much that needed attention--especially in the suspension department.

The ride, handling and steering of a brand new third-gen F-body isn't what we would call horrible, in fact it was quite good in its day. Nevertheless, years of wear and exposure have caused most of the rubber bushings and joints on our 1988 Firebird Formula 350 to deteriorate into slop. Magnum TPI might've looked good from the outside, but this hoop-dee was handling and riding about as well as a Conestoga wagon.

Low-buck project or not, we cried uncle and decided to spend some cash to make things right. (Check out the total cost involved in our sidebar. Note that all costs are suggested list, which means you'll likely find the stuff for less.) The plan of attack was laid with the help of Bill Strope at Strope Speed Shop in Washington, Pa. You may remember that Strope's was responsible for curing our clutch woes last issue in fourth-gen project car Thunderchicken using a SPEC clutch package. Bill reminded us that a large part of our 3rd-gen's problem was created by the steering linkage, ball joints and control arm bushings. Bill recommended we totally rebuild the front suspension and steering with new parts. "It will feel like a new car when we're done. You won't believe the difference!" Mindful of our recent success with Thunderchicken, we put much faith in Bill's suggestion, so we took it to heart.

A few of the parts which Bill suggested, such as the drag link and idler arm, were stock replacements from Moog, but whenever possible we opted for upgrades such as the Energy Suspension control arm bushings (front) and Moog Problem Solver tie rod ends and ball joints. But the big question on many minds is "what about serious performance upgrades?"

Since the ideal scenario was to have an above-average handling daily driver, we did some research on third-gen suspension upgrades and came up with two more key names: Hotchkis and Bilstein. These two companies know third-gen F-bodies and have proven it time after time in sanctioned road racing and autocrossing. We ordered the rear suspension package (trailing arms and adjustable panhard bar) and tie rod sleeves from Hotchkis, and a full compliment of shocks and struts from Bilstein.

Since we had already installed the Hotchkis spring package and strut tower brace previously (see, "Magnum Makeover," Sept. 2000), we kept everything in the family. We say this because it's important to remember that dampers are tuned to work with specific spring rates and bushing compliance parameters. If they aren't compatible--such as when a lightly dampened shock absorber is teamed with a stiff spring--poor handling, instability and possibly suspension damage can result. In this case, Hotchkis and Bilstein have worked together to formulate products that compliment each other. In fact, Hotchkis stocks and sells all applicable Bilstein dampers (as well as key Energy Suspension components) so that customers are assured of receiving a properly tuned suspension.

Energy Suspension is another company known for its no-nonsense performance heritage, primarily through their extensive use of polyurethane. The superior performance of polyurethane in bushings has been long documented, but rarely taken advantage of in production vehicles due to its minimal compliance and elevated NVH characteristics relative to rubber. A rubber bushing is a compromise between handling and comfort, and the OEMs clearly err on the side of comfort, even in high-performance vehicles. Energy Suspension clearly has a different priority: if a solution lowers lap times, other factors are secondary. That said, polyurethane doesn't sacrifice terribly much in terms of ride comfort once the considerable performance gain is taken into account.

As work proceeded at Strope Speed Shop under the guiding hands of technicians Aaron Strope and Roger Creech, we took the opportunity to rectify several smaller matters. The brake hardware (sliders and pins) was dry from insufficient maintenance in the past, so these components were lubricated and the wheel bearings were repacked. The upper bearing plates were also replaced with new units from Monroe. These are mounted on the front strut towers and serve as load-bearing pivot points for the struts. Typically when the strut bearings wear out they produce a loud creak or screech when the steering is turned near full lock (such as in a parking lot).

Prior to a four-wheel thrust alignment on Strope's Hunter alignment rack, all of our wheels and tires were precision balanced on a Hunter GSP 9700. This machine goes way beyond normal balancing; it measures every parameter of the tire's performance, from runout and roadforce, to actually placing the weight on the tire automatically. When you've had your tires properly balanced on a GSP-9700, you can really tell the difference!

Some folks will note that we elected to forego the Hotchkis subframe connectors and Energy Suspension torque arm bushing. In both cases these pieces did not fit; in the case of the bushing we had been shipped one of three possible designs and it was the wrong one, and the subframe connectors were not compatible with our custom dual-catalytic exhaust system. We'll address these items in a later tech story as both have the potential to improve performance substantially. Please note that before placing an order for a third-gen torque arm bushing, it's best to remove and inspect the old one to see which design you have!

We don't plan on doing any road racing or autocrossing with this car, at least not yet. The goal is simply to improve the handling and steering response in a daily-driven car. The poor winter weather prevented any type of A/B comparison test on the skidpad or slalom, but it's doubtful that such testing would've picked up on such subjective criteria as steering response or road feel. What counts most to us with this particular project car is how well it drives us to work (i.e., how fun it is!).

That was affirmed almost immediately with a quick spin on the highway followed by an impromptu slalom in an empty parking lot. Most noticeable was how precise and responsive the steering was. All the slop was out of the system thanks to a completely rebuilt steering linkage, fresh ball joints, struts, bearing plates and control arm bushings. The adjustable Hotchkis panhard in the rear finally allowed us to properly center the rear axle with our lowering springs so the track was a bit better too.

The rear control arms made a difference; these typically come into play when severe cornering is encountered. One aspect of the control arms that was immediately noticed was the improved bite in the rear of the car. This was a result of the polyurethane control arm bushings which are far less prone to compression and bind like the OEM rubber units.

On the minus side, we were not happy with the significant increase in engine noise and vibration that was transmitted into the cockpit with the new Energy Suspension motor mounts. If your car is for racing only, you won't mind it, but for a daily driver you will have a hard time listening to your stereo. We'll probably pull these out as soon as the opportunity arises.

One final noteworthy item is that we were able to rectify the slight "ass dragging" stance that Magnum TPI has had since the Hotchkis springs were originally installed. We ordered from Energy Suspension a rear spring spacer kit for late-model Mustangs which helped raise the rear. Strope also used a carbide cut-off wheel to remove 1/3 coil out of both front springs to lower the front. Now the stance and handling are just right!

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