TorqueArm Tech

Quick Facts about Torque Arm Kits

• Increases rear traction (forward bite)
• Decreases stopping distance significantly
• Engineered to maximize ground clearance
• Can be used without other rear suspension modifications
• Presets pinion angle
• Longer U-joint life
• The most driver friendly way to hook up power.

When used with a Panhard Bar or Watts Link the TorqueArm will substantially improve overall controllability of the vehicle regardless of power output because it:

• Allows for the removal of the rear upper control arms and quad-shocks on cars so equipped.
• Decreases snap-oversteer
• Corrects rear roll center location
• Decreases rear bind
• Inspires driver confidence

The TorqueArm when coupled with a Panhard bar or Watts link is the best in terms consistency of control and improved braking due to is constant and consistent tire loading regardless of ride height changes as the car encounters surface irregularities, cresting hills, etc. Compared to 3 link, 4 link, 5 link or IRS designs, the improvement in car control under power offsets any arguable merits of the other systems in a high powered rear drive vehicle that is without aid of high down-force aerodynamic devices. For this reason the same basic geometry is used on most Sprint Cars, Supermodifieds, Late Model Stock Cars, and other professional race cars around the world where rules allow.  

TorqueArm geometry would be used in more forms of road racing were it not for rules restrictions in various organizations such as TransAm, and NASCAR, or where aerodynamic packaging is the priority of design as in Indy cars and Formula 1.   

Griggs Racing was the innovator of TorqueArm design application to the Mustang in 1979, and has produced many versions and improvements since its inception.  Currently there is one basic off the shelf versions of Griggs Racing TorqueArms; Severe Duty. The severe Duty TorqueArm is intended for most applications; from street use on cars with stock engines and transmissions to cars with over 500 RWHP and sticky tires that are drag raced, brutally road raced, autocrossed, or similarly abused. The structure of the severe duty TorqueArm consists of the appropriate appendages for the model and axle used, attached securely to the severe Duty arm.

These are not hard and fast rules and when in doubt you should contact us for specific recommendations for your application.  The Severe Duty TorqueArm is the most popular and Bruce Griggs races his AIX cars on the severe Duty TorqueArm and his cars exceed the power level described above and still win while being completely durable race after race. If absolute durability regardless of abuse is the priority, you should choose the Severe Duty unit which is the most popular or contact engineering@griggsracing.com for a specific recommendation for your application.

Griggs Dedication to Customer Service

There are literally thousands of suspension and performance related components that Griggs Racing offers to service our customers. This multitude of parts are necessary to accommodate so many different systems necessary to perfect our customers performance vehicles for any given purpose, however economies of scale are not in our favor.  That is why delivery of products can some times be delayed being that demand has been very hard to predict for the past few years. 

To provide the best possible service and quickest delivery we have added manpower and implemented the first elements of an improved inventory system which has already proven to decrease delivery time. Our ultimate goal is to ship all orders within 24 hours. Although we are not quite there yet, we are well on our way. However, with the popularity of some kits, its difficult, at best, to keep some items stocked and ready for immediate shipment. In events like these we will notify our customers via their local dealer or their sales representative and every effort will be made to fullfill the order in as timely a fashion as possible. Again our ultimate goal is to ship all orders within 24 hours and we have complete confidence that this goal will be achieved shortly. We appreciate the understanding of our customers and our readers in this regard. 


In the mean time call up your nearest Griggs Racing dealer and ask about our venerated TorqueArm for your S-197 Mustang. Trust us, you will love what it does for your corner carver.   

FAQ's

We have gone to great lengths to develop Mustang chassis components that meet or exceed the output of modified power plants. In the following post we will outline those components and give you a blueprint for turning your Mustang into a world class sports car.


The Mustang’s chassis was designed in the mid-1970’s, during an oil crisis, to be an inexpensive sedan or station wagon (Fairmont/Zephyr) and not a sports car. It had to be light, cheap and easy to build. The unibody chassis, suspended by McPherson struts (state-of-the-art at the time) and a solid axle, did a pretty good job as a family truckster (cheap!) When the oil crunch eased and Ford stated to think about sports cars again, the only platform they had was the Fox. The new body style Mustang, born in 1979, was built out of revised station wagon parts. The Mustang was soldiered on, to the present day, with the same simple underpinnings.


With the notable exception of dangerously unpredictable handling at the limit (fish-tailing), the current chassis works fairly well. After continual tweaking by Ford, the Mustang feels pretty racy to the average driver. But you wouldn't be reading this if you were the average driver. You may have discovered that Mustang cannot be driven near the limit. If you follow the steps laid out in this catalog, you can plan on owning a car that will pull over 1.0 G on a skid pad and outrun ZR-1s or Vipers in the Slalom without giving you white knuckles. By focusing on geometry and load management, we have developed a blueprint for building the perfect Mustang.


If you think this sounds an awful lot like Math and Physics, bear with us. Making a car perform well is an exercise in managing physical forces. The better you understand these forces, the easier it will be to build your pony-car without wasted time and money. Throughout this catalog, you'll see constant references to geometry and physics and information about roll centers, camber curves, anti-dive and anti-squat. Detailed explanations of all these terms are beyond the scope of this catalog, but where necessary, we have included engineering drawings to help illustrate why our changes are so effective. If you have more detailed questions about geometry changes for your application, please contact us. Our knowledgeable staff is always willing to explain the finer points to a valued customer. To save you the phone call for simpler stuff, we have answered some of the most common questions here.




What should I do first?


If you haven’t made any of the popular modifications to the suspension of your car you are actually ahead of the game. Lots of our competitors sell a set of shocks and stiff springs and sends a guy down the road, even though this can actually hurt performance. The first thing you should really do is to decide what your priorities are for the car: handling, drag strip launches or spirited street driving. Then, before you buy anything, read and understand the technical info in this blog. We have provided a lot of detail because if you understand the flaws of the stock Mustang, you'll probably wind up a customer. If you are careful about defining your goals, you can be sure that your project goes smoothly without wasted dollars on components that require replacement later on. If you can afford to build your entire chassis in one step, you should. You will save money on labor and have the best handling Mustang possible.


Your stuff sounds pretty racy. I just want my car to work better on the street do I really need all this stuff?


90% of our customers are streetcar owners. Our World Challenge and Drag Race customers are a small minority of our total sales. They buy our parts because we engineer our parts to do the best possible job of increasing grip within the confines of the production body and frame.
 
Since we are so focused on fixing geometry, our cars can be run with soft springs, shocks and sway bars for better performance on rough surfaces with more comfort.


How does the GR-40 Kit affect ride quality? One of my friends already bought springs and shocks and his car rides like a tractor.


Believe it or not, GR-40 cars ride about like a production Mustang. Our focus on high quality shocks, geometric perfection and suspension travel help us deliver ride-quality as good as stock. Our suspensions do, however, reduce the amount of insulation and compliance in the car, to improve its responsiveness. Your car will be a bit noisier over broken pavement or really bumpy surfaces, but in the words of Muscle Mustangs Technical Editor, John Hunkins, (who drove one of our cars from Texas to New Jersey during an east coast tropical storm), “The Griggs Racing approach is to restructure the basic geometry of the suspension from the ground up. By doing so ride harshness, jounce and dartiness at speed are practically eliminated....the GR-40 Mustang feels essentially stock in its ride quality....Other suspension systems have had us begging for mercy but the GR-40 provided a compliant comfortable ride.” (MM&FF, February 1996) We couldn't have said it better.


What about exhaust clearance? How do you guys get all that stuff to fit?


Exhaust clearance actually depends a lot on the car. Ford has very broad production tolerances for things like exhaust hangers and crossover tube location so some cars are easy to fit even with big tailpipes, other cars cause some problems. The problems, however, are really quite simple to resolve and each of our installers has the capacity to make the necessary changes.


I have heard TorqueArms create vibrations. Is this really a problem? If so, can you guys fix it?


TorqueArms do not create vibrations, but they may transmit existing vibrations. 98% of the vibration problem we encounter are the result of poor balance factors within with the original drive shaft. The installation of a high quality lightweight unit (which we offer) will usually sort things out.
 
The remaining problems are generally the result of a well-meaning installer trying to shim the TorqueArm to create a high-performance pinion angle. There is no such thing! The TorqueArm installation sets the pinion angle, and prevents it from changing under load. If the TorqueArm is installed, as delivered without modification, a car in good condition should not vibrate. However, variations between individual cars may require adjustment to driveline angles–which is a simple procedure.


My street car is supercharged, develops 500 ft./lbs. of torque and traction is terrible. Will the TorqueArm really fix it?
If anybody tells you they can prevent a street tire from spinning on a car with that kind of power, look elsewhere for the truth. It just isn't possible. We can give you the best possible improvement in forward bite that does not compromise the street ability of the car. Mark Ray Motorsport of Charlotte, NC, has a street strip car, which makes 495 ft./lbs. from its Vortech-boosted engine, has run 1.53 60 ft. times on its 8 inch slicks. This kind of time is typical from cars with larger 10 inch slicks! 
Moreover, the car launches and runs perfectly straight and is totally consistent. Our testing with radial street tires show consistent reductions of .2 to .3 seconds over any other rear suspension system.
 
You'll still have some wheel spin, but your car will be predictable and easy to drive.


I have heard all about the GR-40 system. I think I understand it but I have heard you have to do the whole system at once if you want to avoid understeer problems. I can’t afford to spend that kind of money in one chunk. Can the system be done in stages?


Modifications can be done one at a time or in stages. Please call us if you wish to discuss a customized kit. Each additional stage will increase your car’s performance even more than the last, and the total combination gives an unbelievable level of grip and balance. 

Call for details on our three-stage method. Either way, with a little planning you can get exactly what you want, save money and keep your car fun to drive at every step of the way.

The GR40 Mustang Experience

Although the S197 Mustangs are a huge improvement over their predecessors, their limitations remain, designed to keep average drivers cocooned. Understeer is, if not grinding, excessive to the enthusiast. Precision is leagues better but hardly ideal, the rear axle hops when driven hard and the whole thing is too heavy. Furthermore, as power is significantly increased with superchargers and such, the compromises in the stock suspension are made more apparent. So, while the S197 Mustangs do well making the meek feel sporty, they still need significant help before they are sporting.

As we investigated the new Mustang, we were thrilled to find a highly rigid—if heavy—chassis, and disappointed to encounter weaknesses in the spindle, ball joint and K-member. They dashed any hope of lightly modifying the car up to Griggs standards, resulting in a new set of highly developed A-arm front suspension parts that are lighter, stronger, more durable and far more precise. In the rear Ford’s 3-link suspension needs corrective measures when lowered, and is best replaced by our proven torque arm system for the ultimate in axle control and traction. The bright spot is the unibody; thanks to Ford’s stiff chassis there is no need for supplemental reinforcements such as subframe connectors, saving money, time and weight.
Transformed with a full Griggs suspension, the result is simply stunning. The GR40 suspended S197 Mustang graduates into a real sports car; a delightful, precise companion in the curves. Building on Ford’s new found chassis rigidity, the Griggs SLA front and torque arm rear GR40 suspension puts feel in the steering and delivers front end grip that has to driven to be believed. The car points into the corner with enthusiasm and carves right down to the apex with a light, precise, linear feel to the steering. This authority is even more appreciated in mid-corner, the place where the stock steering goes vague and responds slowly and unevenly. Here the GR40 front suspension, its tires flatly planted to the asphalt, answers with immediate, precise corrections. It’s a revelation to anyone experiencing the joy of piloting a precise, spirited chassis for the first time, or to the old hand who didn’t expect such excellence from a heavy powerhouse such as the Mustang.

Squeeze on the power and the GR40 answers with torque-arm traction, the bite that handles both huge torque and yet remains precise to the throttle. And bumps? They soak into the rear suspension and stay there while the tires remain on the ground. This is one confidence inspiring suspension; you can stand on the gas and the rear tires will claw the car forward while the supple front end takes care of directional duties without fuss.

Also unexpected is the incredibly civil ride from the GR40 suspension. It feels as plush as the stock suspension, and in the bumps when trying hard, even more so. The combination of stiff chassis and accurate, correct GR40 suspension geometry means we can let the wheels move up and down, which in turn delivers a ride that’ll please the fussiest daily commuter.
If the GR40 system has a fault on the S197 it’s that it works so well you’ll want more from the tires. The car tracks so honestly right up to the limit, and has such gentle manners as the tires sign off that you’ll be ready for more grip. It’s that good.

I must also mention the 4on4 brakes. Besides reducing unsprung weight, these brakes offer a new level of precision in the brake pedal. This is especially true in the brake release, an area where stock brakes are absolute dullards. The 4on4 brakes let go of the discs with the same sensitivity they apply them; on open track day that means slowly coming off the brake in perfect confidence while the tail end –so expertly controlled by the GR40 gear—rotates magnificently outward as much or as little as you wish. The transition from threshold braking to the throttle while holding the car at the limit has never been so rewarding.

So yes, the S197 Mustang is a huge step forward by Ford, and the GR40 suspension delivers the full promise of this greatest of all Mustangs