Marc Christ
Brand Manager, Modified Mustangs & Fords
December 5, 2011
Photos By: Justin Cesler

If you've been reading MM&FF since 2010, then you've seen project Street Smart Windsor make the transformation from a ragged-out, bone-stock '89 GT to a slick street machine. The budget 359ci Windsor from Latemodel Restoration Supply, coupled with heads from RHS and a Trick Flow Specialties intake, pumped out 312 rwph and 365 lb-ft of torque through the stock T-5. On track, it went 13.06 at 106 mphùall with a stock-sounding, mild camshaft.

The purpose of the build was to maintain stock idle and driveability, while making 350-400 hp (at the crankshaft). We accomplished this with the engine swap, but for this to be the best daily driver it could be, we had to add more than just horsepower.

Since the engine swap and subsequent track test (July '10), SSW sat for about a year. We had most of the suspension components in hand but were waiting to install the brakes from Baer. A couple of issues ago, we installed the Baer brakes, along with a new clutch from Ram, a diff, 3.73 gears, and axles to complete the five-lug conversion. We also added the flashy Billet Specialties wheels and Firestone rubber from TireRack.com.

On the road course at Gainesville Raceway, it unpredictably crawled around the track to a best lap of 1:12.86, but averaged 1:13.53 over nine laps. With completely stock suspension, though, we couldn't complain. The power of the Windsor, grip of the oversized tires, and unyielding dependability of the Baer brakes made it perform leagues better than a stock Fox. But it wasn't to our liking. It was wobbly going into turns, and inconsistent coming out under acceleration.

Our next step was to install the new suspension components that have been waiting patiently, the centerpiece of which is a Watt's link from Fay's2. Owned and operated by Jim Fay, this innovative suspension company specializes in bolt-in Watt's links, and offers them for classic Mustangs as well as '79-present.

What is a Watt's link?

James Watt, one of the fathers of the Industrial Revolution, was a Scottish inventor and mechanical engineer. He discovered how to convert reciprocal engine motion to rotary motion, revolutionized the steam engine, and coined the term horsepower.

In the late 1700s, Watt invented a four-bar mechanical linkage that allows an object to be moved up and down on a relatively perpendicular axis to the outer mounting points by pivoting from the center "propeller." This design has been used in racing suspensions and street applications throughout the 20th century into today, but has never appeared on a production Mustang.

The point of the link is to locate the rearend (to prevent side-to-side motion) in relation to the chassis and maintain that position throughout the full operating range of the suspension (up and down), regardless of weight transfer caused by acceleration, braking, or turning. Other mechanisms, like a Panhard bar (which pivots from one side), are designed for the same purpose, but the Watt's is more effective. Some argue that the arc created by a Panhard bar is negligible, but the jury is still out on that one.

Why is it important?

Under extreme driving conditions, the triangulated four-link suspension on Fox-body and SN-95/New Edge Mustangs will move side to side. This is caused by deflection in the control arm bushings. Spherical ends help but significantly increase noise and ride harshness, and still don't eliminate lateral movement.

The Watt's link keeps the axle stationary (laterally), allowing the car to be more predictable both during the unloading of the rear suspension (braking/turning) and during the loading of the suspension (acceleration/turning). This gives the driver a more connected and confident feel.

Mount Up

Jim Fay takes pride in his product as a bolt-in option for racers and serious street drivers alike. Unlike most options, the Fay's2 bolts to the subframe without any welding or cutting. A few holes must be drilled, but the rest is just bolts, washers, and nuts.

To install ours, we headed to Bayside Autoworks in Spring Hill, Florida. There, owner and lead wrench Greg Fenton helped us with the install. Though not necessary, we started by removing the after-cat exhaust system. The entire install of the link took about two hours total, including adjusting it. It was quite an easy install.

Other Concerns

When installing a piece such as a Watt's link, it's recommended to complement it with other quality components. At minimum you should replace the shocks and struts, so that's what we did. We turned to Koni for a set of its Sport (Koni yellow) shocks and struts. These single- adjustable pieces are perfect for street and mild track use.

Up front, we found badly worn inner tie-rods. We called National Parts Depot (NPD) for a set of its replacement rods, as well as Steeda's caster/camber plates and bumpsteer kit. Other than those components, (and the struts) we left the front alone. Fay also recommends aftermarket sway bars and/or lowering springs, but we wanted to try it first with stock springs and sway bars.

Another problem we ran into during our baseline testing on the road course was engine cooling. Since we increased displacement significantly, as well as the engine's workload, the single-core, stock-style radiator wasn't doing the job anymore. We turned to PWR Performance Products for one of its '79-'93 aluminum radiators. PWR manufactures components for NASCAR, off-road vehicles, ATVs, and motorcycles, as well as performance street cars.

On Track

Back at Gainesville Raceway, we anxiously began our first session and were pleasantly surprised with the results. Under hard braking going into turns, the car was much more straight and balanced, allowing harder braking. Coming out of the turns under hard acceleration, it was even more noticeably predictable and controllable. More than anything else, though, it improved driver feel and confidence.

So what did that translate to on the track? Well, from an erratic 1:13 average in our before testing, we improved by a full three seconds to an average of 1:10.30, and it hustled to a best lap of 1:09.83 exactly two seconds slower than the 50-plus-rwhp-better '11 GT with the Brembo upgrade (July '10).

Our SSW would undoubtedly outdo the stock GT, as we noticed brake fade in that test, and our Baers in this test didn't miss a beat, even after grueling hot laps. Mind you, this is a 1.1-mile course, so a couple of seconds are huge. Add a set of R-compound tires and springs, and this car would be into the 1:07 territory.

With all that we've done to this car, absolutely nothing has been sacrificed for street use. In fact, this would be an amazing daily driver for anyone with a Fox-body fetish.

Check back next month as we install a set of springs from H&R, and take SSW to Gainesville Raceway for a final track test on the road course and dragstrip.

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