Fox Body Drag Racing Suspension - The Suspension Is Killing Me

With the factory K-member... 

   

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With the factory K-member out of the way, you can take a gander at what your Mustang looks like without anything under the engine. Check out those long-tubes. They were on the car when we bought it, so we weren't complaining, considering they're overkill on this 14-second ride. But, hey, free is better than cheap, right? By the way, now's a good time to fix a leaking oil pan gasket or bad motor mount.

For a complete, ready-to-go drag suspension package, it's hard to beat UPR's Pro Series 4130 chrome-moly tubular front suspension kit. It comes complete with billet-aluminum adjustable coilovers, QA1 springs, control arms, billet caster/camber plates, and offset rack bushings. Its Pro Street non-adjustable 4130 chrome-moly upper and lower rear control arm set was deemed a perfect compliment for our dual-purpose Pony. We elected to keep things streetable, so we chose street/strip coilover springs and a rear control arm set with poly, not solid, bushings. We had read about UPR's parts many times and have photographed plenty of race cars with its setup, so we figured we'd give it a shot.

We didn't want to tackle all this work ourselves because the use of a vehicle lift is highly recommended for a K-member swap. So, we enlisted the services of Automotive Effects in Westbury, New York, and its proprietor Russ Wetzler made himself available for the suspension upgrade. Because he was versed in this particular suspension conversion, he was able to give us some pointers and had us out in just a day. While there, he also recommended a set of HPM Performance Products' crossbar subframe connectors (HPM-5400-AU) and driveshaft safety loop (HPM-4000-AU) as he found them to be the best-fitting parts he's ever installed. Reverting back to a full exhaust with tailpipes was now necessary in order to clear the subframe connectors. The vehicle was fitted with a side-exit exhaust by the previous owner, which simply would not work and had to be removed. Russ steered us towards Bassani's BX-Series exhaust for its fit, sound, and construction. We agreed, and simply watched him pull the parts off the shelf, and took our pictures.

Weighing in at a rather hefty... 

   

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Weighing in at a rather hefty 73.2 pounds, the factory K-member and control arms are nothing much to look at. It should be noted that this test vehicle was originally a four-cylinder, so this crossmember is slightly lighter than what a V-8 car would have.

With the suspension installed, we were pleased to find a reduction in e.t., despite our return on a warmer day (it was about 80 degrees this day compared to the crisper 70-degree day we previously enjoyed). Our new times were 14.164 at 94.97 mph with a backup run of 14.165 at 94.99 mph. That's a peak drop of 0.143 second and a gain of 0.54 mph. No changes to the engine were made. Nada. Zip. More importantly, the car is pin-straight going down the track and no longer jerks to the side when we make an upshift. Street driving is also much better, thanks to the more responsive sensation from the driveline. This is largely due to the removal of eight rubber bushings in the rear-axle assembly and their replacement with "moy stiffo" urethane. Total weight savings was also impressive, with a total drop of 56.9 pounds, mostly in the all-important end of the car, the front.

Our little suspension experiment proves that unlocking e.t. isn't always found by bolting on more power. There's a lot left in everyone's suspension, should you choose to go down that route. Truthfully, we know that everyone likes to bolt on superchargers and add new camshafts, but in the end, getting the power to the ground in a consistent and safe manner is how it all happens. Let it happen to your Mustang. It deserves it.

The UPR Pro Series front-end...        read full caption The UPR Pro Series front-end kit includes a coilover conversion kit. Along with its billet aluminum adjuster sleeves, it includes a pair of QA1 springs that are powdercoated silver. Together, they weigh only 11.2 pounds for both sides. Comparing that to the factory coil springs, which weighed 21.0 pounds, we had a weight savings of 9.8 additional pounds.

With the UPR K-member in place,...        read full caption With the UPR K-member in place, we started with the rear bolts that go into the framerails. With everything cinched down, Russ centered it in the car and cranked down the bolts, setting it into final position.

The rear pads of the K-member...        read full caption The rear pads of the K-member have oblong holes to fit a variety of Fox and Fox-4 cars. Because of manufacturing variances at the Ford plant, this makes up for any odd fitment that you'd see from car to car. This Fox car lined up towards the front of the holes.