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

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!

The factory transmission mount is particularly prone to breakage when power is added. Once it breaks, the trans clunks against the mount and beats the chassis to death. While our stock unit had not yet split in half, it probably would've after adding more power. The Energy Suspension mount is quite a bit stronger. The photo shows the new mount prior to attaching the trans crossmember.	At first blush, replacing the motor mounts looks like it would be easy. Just unbolt the mounts and lift the engine up. Roger and Aaron tried just that, but after a half hour of wrestling with them, the K-member had to be unbolted and lowered. Since the control arms were off getting bead blasted and the struts and brakes had been taken off, this was pretty easy. The Energy Suspension urethane motor mounts couple the engine to the chassis far better than the stock rubber mounts and are stronger too. Our check-out ride however revealed that they were a bit too noisy for our tastes.	With the motor mounts, upper bearing plates and struts installed, Roger and Aaron installed the steering linkage assembly. The Moog tie rod ends, drag link and idler arm come as bare castings, but Strope Speed Shop painted them for corrosion resistance. The red Energy Suspension tie rod dust boots not only protect the steering parts but are attractive too. Note that the tie rod lengths were duplicated from the old assembly but a full alignment must be done later on to put the car back into spec.
We did find one glaring omission in the design of the Hotchkis adjustable panhard. Unlike our Kenny Brown unit on 4th-gen project car Thunderchicken, the Hotchkis needs to be unbolted on one side for any adjustment to take place. You must also readjust the bar once it's on the ground (or an alignment rack) since the bolt holes won't line up when the axle is unloaded. With the Kenny Brown unit, both ends are adjustable--you don't have to remove one end from the car to change the length, you only have to twist the center section like a big turnbuckle. Once the Hotchkis piece is adjusted however, it performs!	Installing the Hotchkis trailing arms is a straight forward affair, once you get the old stock arms off. Hotchkis provides packages of silicone lubricant to aid installation and to provide free movement once installed. Strope also recommends using anti-seize on the fasteners to protect the threads against corrosion. Note that all bushings are urethane and have serviceable grease fittings--a real nice touch.	Swapping the rear shocks is somewhat of a hassle, unless you've got a good tool! To access the rear shocks, pull the rear carpet up and remove the protective foam wedges which cover the shock bolts in the corners. Here Aaron Strope uses a Lisle part No. 20400 shock removal tool. It has multiple bits to fit different types of shocks; the tool holds the shock's shaft while the nut is loosened.
Our old shocks were so worn out that they hardly offered any resistance when compressed. The Bilsteins are valved for performance, offering more dampening force in conjunction with our stiffer Hotchkis springs. Hotchkis designed their suspension around the use of Bilstein shocks and struts; springs and dampers are normally tuned together as a package and mismatches can cause unanticipated handling quirks. Here Aaron Strope tightens the lower shock rear bolt with a 22mm socket.	We used the tubular spacers out of the Mustang front-end spacer kit (Energy Suspension part No. 4.6102RX). Even with our homemade spring spacers at the bottom of the springs we were still a little short compared to the front. The tubular spacers thread over the pigtail and keep the spring coils separated once compressed. Currently, no part numbers are made specifically for F-bodies so a little creativity with the catalog goes a long way!	Here Roger Creech installs our Moog Problem Solver ball joint with a ball joint installer tool (OTC tool part No. 7249). Ball joints can be installed with an ordinary press, but this tool allows the user to install the ball joint on the car without removing the control arm--a big advantage if the springs are still in the car.
In this photo, the left-side control arm has already been re-installed. The stock control arms were bead blasted, painted and the Energy Suspension bushings and Moog ball joints have been pressed in. The Moog Problem Solver ball joint has an improved design over the stock ball joint; instead of a polymer bearing which distorts under load, Moog uses a steel gusher bearing which eliminates deformation and looseness. Alignment is easier to accomplish and life expectancy is improved.	It helps to have a pole jack handy when installing springs! There's a lot of spring pressure so take extra care that the spring is seated properly before compressing the control arm. From here it's just a matter of bolting on the spindle and reattaching the brakes and steering linkage. Before installing, Roger had cut roughly 1/3 coil off of both front Hotchkis springs to lower the ride height another 3/8-inch up front.	Before installing the new Energy Suspension front swaybar bushings, Strope cleaned and repainted our swaybars and brackets. It's a nice touch that goes nicely with the red bushings and powdercoated Hotchkis components. Make sure to thoroughly lubricate the swaybar bushings with the silicone grease (supplied by Energy Suspension) before bolting the swaybar into place. Next the Strope crew tightened the new Hotchkis endlinks. The process is pretty much the same for the rear swaybar.
We really like how Hotchkis makes all of their suspension joints greaseable.	There are four possible rear swaybars on 3rd gen F-bodies: 19mm, 21mm, 23mm and 24mm. Make sure you measure your swaybar before ordering bushings for either the front or the rear! Our 1988 WS6 rear swaybar bushing diameter was 24mm.	While we were at Strope Speed Shop, we also had our ROH ZS wheels and Yokohama A520 tires balanced on a Hunter GSP 9700. To call this machine a tire balancer doesn't do it justice; this machine measures road force, road force variation around the tire's circumference (in pounds!), and both lateral and radial runout. It tells the user precisely where to place the weights on the rim (both circumferentially and laterally) and it will even tell you if the tire needs to be broken down and turned on the rim for the ideal balance. This is the same machine used by the Indy Racing League to balance race tires.
	These two shots show the completed suspension with all the Hotchkis, Bilstein, Energy Suspension and Moog Problem Solver components. You'll note that Strope did not install the Hotchkis subframe connectors due to the custom dual-cat exhaust fabricated earlier for us by SLP. Being that this is a daily driver in a harsh northeastern climate, the Strope guys did some minor paint work (wire brush, prime and paint) to the floorpan. This will help protect us from the winter road salt.	Compare Magnum TPI's chassis before Strope Speed Shop performed our suspension work! Kinda makes us cringe!
Anytime you do major suspension work you need to do a complete four-wheel alignment. Don't forget to disconnect and readjust the panhard rod to center the rearend with the weight on all four tires. This should be done before the alignment is started. Roger aligned Magnum TPI right on the factory spec with ease!