Muscle Mustangs & Fast FordsHow To Chassis Suspension
Fox Body Drag Racing Suspension - The Suspension Is Killing Me
Upgrading a Fox Mustang's underpinnings for lowered E.T. and increased safety.
Fox Mustangs are light, cheap, and best of all, easy to get parts for. Oh yeah, they're also simple to tinker with, and they really stand out in today's world as a respected performance car in all arenas. We could go on forever, but those are just a few of the many reasons we love them so much. With street values at rock-bottom prices, getting an early Fox of your own requires little financial obligation.
Unfortunately, time and flimsy unibody design have caught up to our favorite little Pony, causing most examples to be inconsistent to race, and in severe instances, ill-handling on the street.
The truth of the matter is, any Fox Mustang you come across will be from 12 to 27 years of age. Parts go bad, chassis flex, and rust always shows up. Although clean, good-running cars are still out there, you can no longer treat them like they're new-more work is required before you can get an older Pony galloping at full speed.
The '90 LX 5.0 coupe you see here was picked up with over 120,000 miles on the clock, but it drove more like it had 300,000 on it. It bounced, bucked, and rode like an old lawn tractor because it spent the last 16 years of its life negotiating the war zone of a highway system that threads the city of New York. It had a couple of things already done to it (namely a K&N panel filter, a 14-degree timing bump, and a full exhaust), and seemed to run decently. But things got real ugly when we decided to do some baseline drag testing.
Taking it on its inaugural pass down Old Bridge Township's 1,320 was more of a game of chance as the years of use and abuse reared their ugly heads. Wheelhop was apparent, the car wallowed like a greased pig in a mud pit, and it jerked from side to side faster then George Michael could scream "Wham!"
With our adrenal glands flowing at maximum capacity, we catapulted our hooptie down the quarter-mile and were rewarded with a rather ho-hum 14.305 at 94.56 mph. By no means was this car quick (especially since it was on slicks), but it was sure an adventurous, borderline white-knuckle, ride. For the sake of this story, we jumped back into this bucket and posted a 14.308 at 94.45 as a backup. All launches were made at 5,000 rpm, and powershifts were thrown down at 5,500. Aside from the starting-line shenanigans, the car was quite squirrelly on the big end. Typical of most 5.0s with mileage on them, the stock rubber bushings that locate the rear axlehousing were completely shot and made the car steer to the left at each upshift-not safe by any means, especially if you want to go faster than low 14s. So, before we test any go-fast parts on this car, we want to get the suspension sorted and readied for future battle. Thanks to the aftermarket, it's now cheap and easy to update the suspension with genuine, hard-core parts.
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.
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.
|Weights and Figures|
|Item||Factory Weight||UPR Replacement Parts||Weight Savings|
|K-member w/Control Arms||73.2||28.0||45.2|
|Springs (w/Sleeves for UPR)||21.0||11.6||9.4|
|Rear Upper Control Arms||5.6||4.8||0.8|
|Rear Lower Control Arms||5.8||5.1||0.7|