1G for 2GS: GMS Suspension Upgrade!

The Fox Body Mustang was designed with a unibody construction, so with frame rails integrated into the body and a front subframe, body flex and poor suspension geometry just sort of came with it. Thankfully, the aftermarket has been kind to this platform and you can pretty much build the entire car with parts from your favorite speed shop. Granatelli Motorsports’ 1G suspension is the perfect example. They redesigned the pony car’s sloppy stamped steel suspension, and crafted a system capable of handling the punishment associated with different forms of racing. We decided to take a closer look at it, so we took a stock suspension ’85 coupe up to Oxnard, CA and handed the keys over to the GMS boys to see what they could do.

In this article we are going to show you what components are needed to transform a twitchy, non-stable pony into a road hugging corner carving stallion by way of the 1G suspension upgrade offered by Granatelli Motorsports.

There are a lot more photos to see. You can find them in the photo gallery here!

1G Suspension Upgrade Kit for 1979-1993 Fox Body Mustangs

I have some pretty lofty goals for this not-so glam coupe. Road racing and Autocross are my passions. For me, there is nothing more satisfying than finding that “perfect line” around a corner to overtake your opponent. Before the upgrade, the car was a mess. It felt as though the floorpan was no more than heavy duty foil twisting at the notion of RPM’s. The rear end was sloshing around during hard cornering, and the front springs and shocks were absolutely worthless, giving me superb body-roll! Joe Granatelli, the owner of Granatelli Motorsports and known around the shop as J.R., explains: “The reason for this is that in Ford’s efforts to make a more street compliant car, they sacrificed some of the performance improving components.”

Now, don’t get me wrong. This car was totally awesome in 1985. However, substantial improvements in suspension technology have been made since then, and the coupe was in dire need of a upgrade.

The Kit includes:

  • 1979-1993 Mustang Caster / Camber Plates
  • 1979-1993 Subframe Connectors
  • 1979-1993 Tubular A-Arms
  • 1979-1995 Mustang K-Member
  • 1979-2004 Mustang Front Coilover Kit (Eibach Springs 350lb.)
  • Tokico D-Spec 24-way Adjustable Shocks
  • 1979-2004 Mustang Rear Lower Control Arms (with weight jacker)
  • 1979-2004 Mustang Rear Upper Adjustable Control Arms

The Car

This coupe began life in 1985 as a 4-cylinder, and more likely than not, it was probably a middle-aged mom’s daily driver. When I picked this baby up for a steal last October, the 4-banger was long gone. It was sporting a 302 with GT40P heads and intake.

The first order of business when I received the car was to convert it to 5-lug and get the stock wheels off. As the car sits, I am running 28 spline axles, 5-lug rotors, and 2000 Mustang wheels. I was also able to pick up a Sparco Monza seat for a cool 80 bucks!

Future Upgrades include:

  • 8:8 Rear End with disc brakes.
  • More Power – 185 HP barely rocks the socks off a 4-cyl, so we are thinking a nice 369 Dart SHP SBF should make around 500 HP.
  • More Stability – Full cage with supports.
  • Paint, Paint and More Paint!

The Install

I realized the daunting task that was before us when I arrived and saw a mound of shiny black glossy parts that screamed PERFORMANCE. When GMS says this is a complete kit, they mean it. In fact, there isn’t a single OE part or bolt that is reused.

I remained reluctantly optimistic that our one day allotment for install was achievable. J.R. assured me that once we pulled those ugly overweight stamped steel parts off the car, the install would be quick and painless – excluding a few knuckle busters here and there.

Laying The Ground Work

We took no time at all ripping my coupe to shreds. Off came the A-arms, K-member, and all of the front suspension components.

While we slaved away near the front of the car, Bob Fox took the luxury of welding some Granatelli Subfame Connectors to my tired subframe. As J.R. explained, “The connectors will center the car and act as splints to keep the subframe from twisting and turning under heavy load and hard launches.” Now, when we put the power to her, all of the power will be transferred to the wheels rather than heaving the car to one side.

Here you can see the incredible difference between the new Granatelli K-Member and the stock K. Thirty pounds lighter than the stock part, the Granatelli piece is more rigid and will eliminate some weight from the nose of the car, improving handling considerably. As you can see, the spring pocket is completely eliminated on the Granatelli piece, allowing for improved camber curve and roll center height.

We are adding a GMS coil-over front suspension to the car, so the stock spring and shock combination is outta here!

GMS A-Arms

Next we moved on to the Tubular A-Arms, Part Number: GM-TA7993. When we placed the stock arm next to the Granatelli piece, the structural differences were obvious. Granatelli informed me that his piece “will move the wheels forward 3/4 of an inch, which improves ackerman suspension geometry and will allow the ‘Stang to have a smoother ride altogether.”

The stock A-arms from Ford are stamped steel components with loads of “extras” that did nothing but cause flex and add weight to the vehicle. With Granatelli’s A-arms and their tubular construction, the Mustang will gain TONS of rigidity and eliminate weight towards the front of the car – something that’s been a major issue for the Fox platform.

Polyurethane vs Rubber = NO MATCH

Check out the beating that these 23-year-old bushings took during the life of this car. They needed replacement – ten years ago! Which means the slop I was experiencing in the front of the car wasn’t the shocks and springs. As J.R. told us, “Polyurethane bushings are the best of both worlds. You get high performance with extreme durability.”

Energy Suspension hooked us up with some just short of indestructible bushings to attach to the newly installed K-member. According to Energy, here are the facts on polyurethane:

  • Polyurethane wears better (outlasts traditional rubber 50 to 1).
  • Offers higher load bearing capacity.
  • Weighs less
  • Noise abatement
  • Oil, gasoline, grease, and solvent resistant.
  • Tear resistant (Tear Strength 500-1000 lbs/linear inch)
  • Weather resistant. Resists oxidation, sunlight, ozone, and extreme hot/cold climates.

After the Tubuar K-member and A-arms were in place, we moved on to the Tokico D-Spec shocks and Granatelli coilover kit installation.

Tokico’s D-Spec Series 24-way adjustable shock has an extremely advanced piston and valve design compared to the stock shocks. It utilizes a unique variable-aperture bypass that’s controlled by a slide valve on the shock itself. D-Spec (damping specific) adjustments change both rebound and compression damping simultaneously. Between soft and hard settings, the D-Spec has a wide range of adjustability. J.R. explained that in a lowered vehicle with the Coilover/A-arm combination, the A-arms “work in concert, and allow the A-arms to remain flat in relation to the ground, thus eliminating excessive oversteer and understeer.”

Bob went ahead and raised the newly built Granatelli/Tokico coilover set into position.

As the threads breached the engine bay, it was time to add the fully adjustable Granatelli Caster Camber plates in order to attach the coilover.

Once the caster camber plates were bolted to the engine bay, we attached the top nut to the coilover with a 1/2-inch impact wrench – something that comes in very handy with an installation such as this.

When lowering the car, Granatelli informed us that, “Caster/camber plates are essential. This allows the strut to be adjusted in the top plate for proper suspension alignment. That way, the wheel base can be lengthened (via the front lower control arms) without sacrificing handling and performance.”

Keeping The Power Planted In The Rear

With the front of the car wrapped up, we moved to the rear to install the Granatelli Weight Jacker Lower Control Arms and Upper Adjustable Control Arms.

Taking a look at the Weight Jacker, it is immediately apparent that these are no ordinary control arms. With a 23-degree bend and an adjustment screw, these beefy control arms mean business. The “dog” leg curvature, JR explained, “allows the weight jacker to accept any size spring, whether it be aftermarket or stock, thus giving you more dynamic range of spring travel.” Plus it allows us to adjust our ride height.

The weight jacker’s unique design offers height adjustment without having to remove them from the car. I found it handy that the adjustment screw used is an ordinary 1/2-inch socket, since I already keep a 1/2-inch in my car “just in case.” It’s a convenient way to make last minute adjustments at the track or in the driveway.

The install of these bad boys was easy. After yanking off the cruddy stamped steel lowers that literally crumbled in my hands, we slid the Granatelli pieces into place in the stock location on the 7.5 rear end.

The poly rod end combination of the lowers will offer stability, traction, and eliminate wheel hop with minimal noise, vibration, and harmonics.

After attaching the Weight Jackers, Bob went ahead and moved on to the fully adjustable upper control arms. These control arms are HD tubular steel with precision welds, as opposed to the stock stamped arms – plus they look a whole lot better! The adjustable control arms allow for a wide range of pinion angle adjustment. According to J.R., they also have “a range of up to five degrees of adjustment that allows you to dial in traction and decrease wheel hop / body-to-rear end flex.”

Granatelli’s rear adjustable upper control arms are a direct OEM replacement that provide full adjustability of the pinion angle, eliminating wheel hop and greatly improving traction.

With all the essential components of the 1G suspension installed, we attached the wheels and tires to see how the ride height and stance had been improved. Looks sweet huh?

When J.R. and the guys began the build, they told me how much of an improvement this suspension would be. But when they said that this would be a completely different car when it was done, I was a little unsure. However, once I stepped foot into my coupe, I immediately realized just how right they were.

While the stance was the first thing I noticed when the car came off the lift, it was only after I turned the key over and gave the cammed 302 a little gas that I fully understood the advantages of what Granatelli had done to my car.

It is actually FUN now! I can hit corners at speed without constantly worrying that the rear end will wash out. Launches are no longer sloppy burnouts with frame twisting lurches. When I say go, the car goes forward – not to the side. Even the chatter of the tires has disappeared. Problems that I had believed to be normal, unavoidable inconveniences have been transformed and handling has greatly improved.

The guys at Granatelli were right! Hopefully I can get my coupe onto an autocross course and drag strip in the near future and really put the coupe through its paces.

Stay tuned!

About the author

Andrew Wolf

Andrew has been involved in motorsports from a very young age. Over the years, he has photographed several major auto racing events, sports, news journalism, portraiture, and everything in between. After working with the Power Automedia staff for some time on a freelance basis, Andrew joined the team in 2010.
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