What is a watts link and why do champions use them?

S197 Quiet Watts Linkage

Watt's linkage (also known as "parallel linkage") is a type of mechanical linkage invented by James Watt (19 January 1736 – 25 August 1819) in which the central moving point of the linkage is constrained to travel to a straight line within a certain travel length. Its applications in automobile suspensions are that of allowing the axle of a vehicle to travel vertically while preventing sideways motion. This type of locating device, however, does so much more than that for a race or track prepared vehicle. 

SN 97 Watts Linkage installed

Watt's linkage is used in the rear axle of some car suspensions as an improvement over the Panhard bar or rod, which was designed in the early twentieth century by a French car company of the same name. Both methods intend to prevent relative sideways motion between the axle and body of the car. Watt’s linkage approximates axle movement in a vertical straight line motion more closely, and does so while locating at the center of the axle rather than toward one side of the vehicle, as more commonly used when fitting a long Panhard rod. By locating the center of the axle the roll center of the vehicle can be clearly defined and thus be predictable and, in the case with Griggs Racing Watts links, completely tuneable. In fact we have found that our tuneable watts linkage lends itself to consistently Quicker lap times than a Panhard Bar. The reason for this is because, unlike a Panhard Bar, both right and left cornering characteristics are identical. This is due to the fixed roll center relative to ground of the GR40 Watts link, which is not so with Watts links from other companies.  

Not only are the linkages fully adjustable laterally for accurate real axle alignment, but also the Pivot which locates the roll center is vertically adjustable allowing quick easy and tuning of chassis balance with accurate and predictable results simply by unbolting it and moving it up for reducing understeer, and down for reducing oversteer. This Increases controllability and driver confidence under power and in cornering because the driver can predict easily what the vehicle will do. By having this adjustable rear roll center drivers have found maximum corner exit traction achievable while optimizing corner balance for faster lat times, and therefore optimizing their driving experience.  

SN 95 Watts Linkage/ TorqueArm  assembly  

 When used with a TorqueArm lateral tire loads are made independent of changes in engine & brake torque loads, vastly improving handling and power, applied performance, and braking making this rear suspension geometry THE best choice for competition vehicles, drag, autocross, road racing, and serious open tracking. However if a TorqueArm cannot be used due to race class rules or various other reasons the Griggs racing watts link can be installed independently of  our TorqueArm on any 9 " rear axle in any vehicle.  On Cars equipped with 8.8 rear ends, the addition of a TorqueArm Delete Bracket is required.

Watts Linkage for Ford 8.8" with TorqueArm Delete 

You can also trust that the Griggs Racing Watts link kit is going to be light adding minimal sprung and unsprung weight when compared to all other lateral linkages on the market. Not just light but also very strong; No bends in the main brackets affords zero flex and zero chance for failure of a well set up system. large tire guys need not fear either since the Griggs racing Watts linkage kit positively locates the rear axle laterally  use of maximum tire sizes is allowed with the least chance of rub.  

A further feature is the progressive failure design.  This feature has been proven real world testing. Lateral impact, such as impacting a curbing, can result in serious damage in competitor's systems, but in the GR40 Watts link each part is designed to fail in progression. If the standard Watts link with Aluminum Arms is installed, in an impact, the arms bend first, then the bell crank fails, then the main plate.  This usually saves the Aluminum rear end cover and the chassis bracket, so a quick repair can often be made so the car can continue to race.  This is not possible with copy cat designs that delete the Main plate. 

Therefore the very best choice in a lateral axle locator available regardless of ride height movement is The GR40 Watts Link.


Want one for your ride? Contact us at Sales@Griggsracing.com to get yours.

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 Suspension System

Why the stock Mustang suspension doesn't work and how Griggs Racing fixes it

In the beginning Fox bodied and SN-95 Mustangs feel so good. There's the easy V-8 power, the light steering and quick handling. Compared to other street cars the Mustang is ready and nimble, a joy to drive.
But for the ever-learning enthusiast there comes a day when that magic Mustang sunshine dims. Often it's because another, modified Mustang showed you its taillights, or perhaps you took your Mustang to the drag strip or slalom. You begin to notice things, like how the rear end seems so inconsistent. At the strip the car never seems to launch the same, and when you get what feels like that rare perfect launch, the tires blow off just as soon as the car gets rolling. Your front tires grind off their outer front edges long before the rest of the tread shows any real wear. Start whipping around freeway ramps faster and your Mustang begins to feel unsure; you find yourself waiting for the rear end to snap out unexpectedly. Ultimately, your Mustang feels more over-powered and less capable than simply fast.

All products are abused on the track prior to making it to the street.

Those first moments of insecurity about your Mustang's white-knuckled handling at the limit, or its fickle appetite for traction at the strip are not your imagination hitting the rev limiter. Those are the first realizations the Mustang chassis is far from delivering the confident handling its high-output powertrain deserves.

At Griggs Racing we've dissected the Mustang chassis and suspension to identify its shortcomings and engineer cures. Our fix for the Fox and SN95 chassis Mustang is no quick medicine; it's a fundamental change in the suspension geometry that yields a fundamental handling improvement. Our suspension is also adaptable to a huge range of Mustang performance. From the street, to the strip, road course or slalom circuit, our re-engineered GR-40 suspension system provides the stable, consistent, responsive platform you need. It's only shortcoming is it has to be experienced to be believed.

So what are the issues working against you in the Fox and SN95 chassis Mustang? For starters, the unibody structure is lightly built, with insufficient rigidity. High torque and cornering loads deform the structure, causing the suspension to lose precision, doubly so with convertibles. Welding in reinforcing structure is the cure.

Knowing where to reinforce the structure is important, as indiscriminately adding braces wastes money and adds weight without gaining meaningful increases in rigidity. By twisting a Mustang unibody on a frame table, we learned the main problem is in the middle of the car. Ford counts heavily on the rocker panels as the primary structure between the firewall and rear wheelhouses, especially with the '79-'04 cars. This lets the front and rear axle forces to twist the car far too easily.

Naturally, a full roll cage will cure this, but that solution is cumbersome and expensive on street cars. More practically, a dual-plane brace to provide triangulation of the floor pan is required; we do this with our Full Frame Kit.

The mid-car twist also explains why we don't offer g-load and strut tower braces. By strengthening one end of the car they actually increase the mid-car twist.

An even larger concern is found in the rear suspension. Ford uses a 4-link design, but with the upper two control arms angled heavily outward. This means the lower and upper rear control arms are not parallel, so as the suspension moves the upper arms are twisted in their bushings. During performance driving this quickly leads to a near total binding of the rear suspension, called roll bind. With the axle bound, it acts like a giant anti-sway bar, causing the rear roll stiffness to skyrocket and the overloaded rear tires to loose traction and spin. This is why the rear end snaps into uncontrollable fishtailing when cornering, and it is also why the rear tires break loose at the drag strip once the body starts rising from the initial power hit.

2005+ Griggs Racing TorqueArm and Panhard Bar

Ford addresses the roll bind by fitting the upper arms with very soft bushings, a sloppy fix, to say the least. Our cure is to fit a torque arm and either a Panhard bar or Watts link to provide the necessary axle location, then remove the stock upper arms. Roll bind is then impossible, and the tires freely follow the pavement.

You may have noticed we use two locating devices, the Torque-Arm, and either a Panhard Bar or Watts link, to do the job Ford uses just the upper control arms for. This is to separate control of the fore-and-aft engine and braking loads from the lateral suspension loads. More precise suspension control is then possible.

GR40 Watts Link

Additionally, the rear roll center is now defined by the Panhard bar or Watts link instead of the upper control arm angle as Ford had it. Stock the Mustang's rear roll center is far too high, which overloads the outside rear tire and causes oversteer. By lowering the rear roll center with the Panhard bar or Watts link we get the rear tires to carry more of the load so the rear end will stick longer.
More compromised geometry is found in the front suspension, a point made abundantly clear when driving a car with the rear suspension fixed and the front suspension stock. Ford built the Mustang with generous steering axis (king pin) inclination, which requires equal amounts of caster to keep the tires flat to the ground when turned. Unfortunately, Ford gave the Mustang only minimal caster, a condition we reverse with caster plates and redesigned K-member.

GR40 SLA System

Also at the front, Ford's tall ride height comes into play. Lowering the entire car benefits the center of gravity, but causes the front suspension geometry to lower the front roll center well below ground level. Combined with the tall rear roll center, this results in a roll couple (the relationship between the front and rear roll stiffness, of which roll centers play a part), to heavily load the front tires. Imagine trying to drive your Mustang around a corner with the front end squashed below ground level and the rear end raised a yard or so in the air; obviously the car would be trying to turn using just its front tires. That's about what the stock suspension tries to do. Lowering the rear roll center with the Panhard bar or Watts link helps this condition, of course, but we also raise the front roll center, accomplished by relocating the points where the front suspension attaches to the chassis. Moving the suspension pickup points is done by redesigning the K-member, which is the crossmember the front suspension attaches to. Redesigning the K-member also allows us to add more anti-dive to the front suspension help correct the lack of caster.

Ackermann is also a concern on stock Mustangs. Ackermann is the steering geometry that steers the inside front tire more than the outside tire, a necessary condition as the inside tire follows a smaller diameter turn radius. With the Mustang, Ford actually ended up providing reverse Ackermann, meaning the front tires toe-in slightly when turned. We also cure this with our K-member.
So, did Ford really goof terribly on the Mustang? Well, not by accident. By selling a relatively high-powered, inexpensive car into the youth market, Ford wanted a car that signed off in the handling department so soon that only the fool-hardy would get in high-speed trouble with it. In short, Ford designed the Mustang for inexpert drivers.

Unfortunately, dumbing-down the chassis is a common manufacturing tactic in the affordable performance car market. That is why it is so difficult to describe the incredible improvement a complete chassis re-engineering provides; few enthusiasts have experienced the huge thrill of piloting a powerful V-8 machine that starts, sticks and stops as well as it's engine goes. Once you've wheeled a GR40 car, however, you'll be one of the few.

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

Test Drive "Ol' Blue"

While we at Griggs racing have become quite familiar with the G-force monsters racing vehicles that inhabit our shop its often refreshing to get the viewpoint of others who are not so familiar with the view from inside. Here is an up close and personal interview of "Ol' Blue" by Tom Wilson of 5.0 Mustang & Super Fords.

Griggs Racing's Old Blue Road-Racing Mustang - Extreme Winner
Griggs Racing's Old Blue Is Arguably The Single-Most Victorious Road-Racing Mustang In History-We Drive It And Try To Keep Up


Griggs Road Racing Mustang Platform

Fox coupes make good race cars because they are the lightest modern Mustang platform. Old Blue is fairly bursting with engine and tires, and has the air filter sticking through the hood and the front fenders bulged away from the body to prove it. The wheels are 10.5-inch-wide AFS; the tires are 315/35-17 Hoosier SO4s all the way around.

Horse Sense:

Awesomely fast race cars make an adrenaline-fueled impression that's impossible to convey in print. Strap a saddle on a great white shark and ride it through an aquarium if you want to know what it was like to drive Old Blue on a track choked by schools of Miatas.

Griggs Road Racing Mustang Roof Stickers

Like a fighter pilot keeping score, Old Blue's rows of roof stickers each denote a race win. After driving this friendly handling car, it's clear to us Griggs has it dialed in to perfection. Race days are an easy matter of squirting into the lead, then simply guiding the car around to the finish.

Another sure-fire candidate on our short list of significant Mustangs is the car shown here, Bruce Griggs' Old Blue. While not necessarily well known on the East Coast, the 40 car, as it is also known, is an institution in West Coast road racing. It's a multiple NASA American Iron Extreme champion, a dominating performer that amassed 20 race wins in a row to claim an undefeated AIX season in 2003, and it has also been the spoiler in SCCA American Sedan and ITE contests. For more on Old Blue's impressive record, see the 40 History sidebar.

Long ago the victor in more races than many race cars are ever entered in, the 40 car is still going strong. An engineering testbed for Griggs Racing , Old Blue is still trying out new, typically radical, hardware and waving the Griggs banner at numerous events. The car has been cut and stretched, beat on, drilled full of holes, crimped and welded, crashed and rebuilt, and hammered and massaged. It's no beauty queen, but it's always fast and sports something new and trick each time we see it.

Griggs Road Racing Mustang Sla  Front end

Griggs' new SLA  front end is designed to work with its tubular K-member, coilover shocks, and familiar-looking lower control arms. We shot the 40 car with one tire on and one off so you could get a feel for just how huge a 315 front tire really is. Smaller than expected is the tiny bellhousing; it's more compact than the oil pan or Jerico gearbox.

When we visited Infineon Raceway in Sonoma, California, the latest trick part was represented by Griggs Racing's newest project, a Short/Long Arm (A-arm) front suspension. The SLA details are in The Short and the Long of It sidebar, but suffice it to say it completely eliminates the strut front end and provides unprecedented, incredibly powerful front-end grip.

Poking around the 40 car, you soon realize that the number of stock, unaltered Ford parts on the car can be counted on the fingers of one hand. The unibody is made nearly redundant by the Griggs rollcage and through-floor subframe connectors, while in back a Griggs 9-inch rear axle hangs off Griggs control arms, torque arm, and Watts link. Coilovers are used all-around, of course, as are huge Sierra disc brakes.

Griggs Road Racing Mustang Rear Suspension

Compared to the complexity at the front of Old Blue, the rear suspension is remarkably simple but powerfully effective. The cambered 9-inch axle is located by the two lower control arms and the Watts link, which mounts its bellcrank on the rear of the axle housing. The adjustable-length torque arm features a pivot bolt at the differential end, along with a safety chain at the forward end. Koni coilovers finish off the installation. Sort of crafty are the muffler attachments. Griggs runs the car with and without the mufflers depending on the track. To expedite the mufflers' installation, attach brackets are welded directly to the mufflers so they can be installed in about two minutes.

The 9-inch is an artifact of Old Blue's age. Today Bruce would fit one of Griggs more efficient and just-as-robust hybrid axles with an 8.8-inch center and 9-inch outer sections. Also interesting is the lack of a rear sway bar and Griggs' penchant for relatively soft spring rates. He attempts to extract as much handling as possible from inherent balance and optimum suspension geometry; high spring and sway bar rates foul Griggs' goal of meaningful weight transfer to the rear tires on corner exit.

Another recent development is 315/35-17 Hoosier tires at all four corners. This immense tire size has long been popular at the rear of AIX cars, but by November 2003 they showed up on the front of some cars. With an 18 percent gain in contact patch area over a 275 tire, the huge rubber answers nagging Mustang questions-namely how to handle such a nose-heavy weight bias. Bruce put off fitting the 40 car with the big front tires, because they are difficult to fit, but they work so well he went to the trouble and expense during the car's refit last summer.

As one glance shows, the rest of the chassis, including the interior, the seating, the instruments, the bodywork, and so on are, hmmm-let's say part of this thoroughly tested race car. To clear the huge front tires, the fenders have been cut and the flares pie-shape-enlarged for the second time. And because the fender doesn't have a chance of mating with the rest of the bodywork at the rear, a business-like gap has been generated. A natural exit for high-pressure fenderwell air, the fender openings-along with the air filter bursting through the hood-personify the 40 car's purposeful demeanor.

Griggs Road Racing Mustang Engine Compartment

The latest, all-aluminum habitant of Old Blue's engine compartment makes a rousing 600 hp from 345 inches. Bruce Griggs says there is plenty more power in the exhaust, but with the car so low and the 3-inch exhaust so big, he doesn't feel like-or need to-invest in trick headers or pipes only to smash them against race track curbs. Engine-plate mounting best handles the big power, while many of the accessories follow circle track practice. The MSD coil on the now-useless right shock tower has been in the car since day one. It's about the only thing under the hood that has been there all along.

Many powertrains have visited this chassis, from its original four-cylinder automatic combination to the mild bolt-on 302 and stock T5 transmission of American Sedan days, to the current AIX booster rocket and synchro-less crash box we drove for this story. The current engine snarls out just over 600 flywheel horsepower and is a conjunction of an aluminum racing block and a set of heavily ported Trick Flow Street Heat heads breathing through an Edelbrock Victor Jr. intake and an 800-cfm Holley carburetor. The 4.145-inch bored and 3.250-inch stroked Sonny Bryant-forged crank gives 345 ci. Compression is proprietary in typical Griggs fashion, but let's just say we've seen Bruce run 13:1 combustion chambers on street cars. Obviously, the reciprocating parts are the best American forgings Carrillo and Ross can supply, and the clutch is a 7-inch, three-disc light switch from Quartermaster.

Bruce is keeping what are clearly stratospheric cam specs to himself, but he lamented that the current engine is "too drag racy" to work as well as it could. That means the cam specs have changed since we visited anyway.

Behind all this excitement is a Jerico four-speed transmission. As is everything on Old Blue save the prototype pieces, the non synchro, lightning-fast, practically unused Jerico was something Griggs already had in the shop; cobblers kids have no shoes, and development hacks, even one as successful as this car, are last in the budget line.

We're afraid we took whatever new may have been left out of the gearbox during our practice session in Old Blue, but we're getting ahead of ourselves. To tell that part of the story, we should note this is one of those beasts for which we bothered suiting up all the way-fireproof underwear, crash hat, gloves, the works. It's that kind of car.

Griggs Road Racing Mustang Interior

Everything in Old Blue's hot and noisy cockpit is laid out to make the driver's job easier. That includes seating, steering, and shifting moved back 7 inches, leg and torso extensions on the well-worn Kirkey seat to combat crash loads and cornering g's, and a hose for ducting fresh air to the driver's helmet. Seating is low and the hood bulge is high, so spotting right-hand apexes is occasionally a challenge, and heat is noticeable on warm days. We found the switches too hot to touch without gloves by the end of our practice session.

Getting in and comfortable was easy. Bruce and I are almost the same size-well over 6 feet tall-and the 40 car is about the only Mustang in the world I truly fit in. As the only parts of Old Blue that are original Ford include the roof, the windshield, and the door handles, it's no surprise to find the driver has been moved back 7 inches, with the steering wheel and shifter even more so. Done to aid weight distribution, the movement was engineered by fitting a spacer to the stripped-but-otherwise-stock '93 steering column, using a deep-dish, large-diameter Schroeder circle-track steering wheel, and placing the Long shifter right where Bruce wanted it. There's a distinct feeling of being back from the windshield, but not quite like you're sitting in the rear seat. The naked interior, the five-pane rear view mirror, the rollcage tubes everywhere, and the dry sump tank in the right footwell make the interior an all-business sort of place.

Starting the carbureted small-block is easy. Flip the usual master, ignition, and fuel-pump switches and crank away. Rrrrrap! The engine flies to life and proves ultra-eager to rev. Even with mufflers and helmet, the gloriously crackling exhaust requires ear plugs, so we were glad to have them.

Getting started from rest is decidedly not easy due to the feather-weight clutch and flywheel, a torque curve that starts about where a stock Mustang hits the rev limiter, and a First-gear ratio that felt like Second. Told to use 3,000 rpm and not slip the clutch, I found it actually took 3,500 rpm and a series of quick jabs of clutch engagement coordinated with some fancy throttle work to get the beast moving. And, yeah, I stalled it about five times and never got the hang of it.

Once on the track, however, there isn't a driveability care in the world, although self-preservation may cross your mind. This car is mind-bendingly fast-more fleet than our guardian angels, we decided, as the pavement uncoiled and flung itself through the windshield. Without benefit of recent racing experience, it was faster than we could think in the manhood test of Turn 10 at Infineon, so the throttle magically self-levitated off the floor there every lap. And while ours was a warm day, we wager this machine can leave a dry and pasty taste in your mouth during the coldest winter race meeting.

There are no vices, no tricks up the 40 car's fenders. Its handling is completely benign, even while tuned to the razor's edge. Bruce is an exceptional driver and prefers his cars to be quite neutral-that's a tightrope walk on the edge of oversteer for the rest of us, but once you learn to trust this tremendously capable chassis, you see how it points with economy. There's never a need to hustle this car, but rather a continuous need to relax and simply guide it as necessary.

This effect is multiplied by the way Griggs has fitted the car with long throttle-pedal travel and slightly slow steering. Both are deliberate and done to give maximum control. We especially loved coming out of the turns, feeding in more and more throttle, and having the nuclear reactor under the hood pull more and more strongly in direct proportion to the throttle position. And when you thought that had to be about it, there was still plenty more throttle travel-and power-to go.

Griggs Road Racing Mustang Quarter Master Clutch

Accommodating the Jerico transmission-which is tucked up tightly under the car thanks to the minuscule Quarter Master clutch and bellhousing has meant a hand-fabricated section of the transmission tunnel, while the switch panel, dry-sump oil tank, and ignition boxes have been laid out wherever convenient.
Whipping the Jerico through the gears is another pleasure center overload. All it takes is a quarter lift of the throttle, lever the manly-but-precise shifter, and mash the gas. Forget the clutch-it's absolutely not needed and only slows the process. With the engine delivering its hand-of-God power from the high sixes to 8,000 rpm, up shifting through three gears might as well be a narcotic. There's no perceptible interruption of thrust or engine note, which simply wails afresh with each change.

Downshifting is another story. Again, the clutch is not needed, but precise matching of engine and road speed is before the shifter slips seamlessly into the next gear. Here's where we were too excited to tickle the throttle and finesse the transmission. Instead we resorted to the clutch and larger throttle blips more than necessary. But clearly, with a bit of practice, downshifting could be as rewarding as up shifting.

What truly has to be felt to be believed is the way Old Blue turns in, carves the line, and can still react or correct in mid corner. This is the SLA and 315 tires at work, as we've never felt another Mustang-race car or not-with the front end grip this one has. And those huge tires are obviously being presented flat to the pavement, as they do not pull or twitch, and until the tire's grip is exceeded, the front-end simply keeps tracking or turning in as commanded. So, for the first time in our 17 years of testing Mustangs, rear grip, not front grip, is the limit with this car.

"Amazing" is the only-yet lame-word I can summon to describe how relaxed, stable, and responsive this car was in the corners. Cornering as hard as I dared, Old Blue clearly had more in reserve and awaited only my courage to put it to use. Corner exit traction-even with all the power-was excellent as well.

Before I was ready, I realized I was tired. Like piloting the Millennium Falcon through an asteroid field, the 40 car had me whipped with its mind-bending speed and strenuous cornering loads. I pulled in and talked it over with Bruce. I said the car felt similar to a modern Trans Am racer, with nearly the same thrust but not quite the same precision. He agreed, noting the Trans Am car has a more rigid chassis and the benefit of purpose-built racing slicks. As for my being tired-especially in the long, accelerating right-hander leading to the carousel-Bruce said that was from trying to sit upright, "a bad habit from sitting in lousy street car seats." He then delivered his rather sangfroid advice: "I just let my head lean against the rollcage, relax, and sort of slump against the side of the seat and steer." Easier said than done when accelerating through 100 mph like a dragster while cornering.

Ultimately I noted that while lapping this monster was a real gas, racing it against similar cars might give me pause. Bruce replied, "Yeah, it's so fast it's not fun any more," and in a way I know he's right. But I'm sure you could get used to winning in it. He certainly has!

What Are You Going To Do With Your Car

With so many Mustang parts on the market, choosing the right ones can be a daunting task. Our own huge parts list is no exception, and to jump-start your GR40 parts decision process we need to ask you what your Mustang plan is.
Begin by answering the following questions.

1. What is the ultimate goal of my car?
2. Will my car remain street legal?
3. Is my car an occasional-use toy or must I drive it everyday?
4. How important is ride quality?
5. Is my priority straight line or cornering performance?
6. How much power will I end up with in the long run?
7. Do I realize my demands on my Mustang's chassis will increase as I add power and traction?

We know it can be surprisingly difficult to answer these questions, but you've got to start thinking about what your goal for your car is.
Buying parts piece meal usually results in a hodgepodge of components that, acting together, don't address the inherent problems of the chassis for your particular application. We have developed systems and sub-systems to assist you in developing the chassis you not only want, but need, in a step by step method that keeps the car balanced and usable between steps, and precludes buying things twice.
The only way to achieve the Mustang of your dreams is through the proper selection of parts that compose a system that properly affects the car's handling characteristics for the specific use of the car. If you have not made a definite determination as to the usage of the car you will have a difficult time building it correctly the first time. We have broken this catalog down into sections that address the majority of applications. If you read the descriptions of the parts and systems thoroughly you should be able to make a determination that will save you a lot of time, money and grief. Starting with late model (1979-current Mustangs and 1983 to 1988 T Birds), which are all variations of the GR-40 Suspension Package, they are:
• Strictly Street or Daily Driver. Where safety in handling and wet weather is coupled with good ride as the primary parameter, along with a lowered look. The bonus in this GR40 combination is a Mustang capable of taking freeway onramps as well as some of the finest European sport sedans. If you want a strictly street toy–or what some call a “Sunday Driver”– a car capable of delivering high doses of horsepower to the ground, and performing incredibly on an offramp, you need to build to the Street/Autocross/Open track specification listed below. If you want a stoplight racer, build a Street/Strip car.
• Street/Strip, where the car is (streetable) usually driven daily but straight line launches and an occasional trip to the drag strip is called for.
• Street/Autocross/Opentrack. If you want to drive your Mustang to work still your primary interest is high performance handling, both in a parking lot around cones and on open road racecourses, this is for you. This car could also be called a “Canyon Runner.” Some call them “Porsche Hunters.” Generally the cornering speed capability is nearly double that of a stock Mustang chassis and cornering surpasses everything you come across.
• Drag Race only, for serious single purpose drag race cars. Weight savings is unsurpassed, and safety is immensely increased over any other system due to the improvement in high-speed stability and response.
• Road Race Only. If you are a serious wheel to wheel road racer, we have a full line of products to prepare your Mustang for a national championship.
• GR-350 Vintage Mustang. This section addresses 1964 through 1971 Mustangs prepared for serious open track use. If you own a high powered vintage Mustang and want to eliminate the white knuckle ride and add incredible world-class handling performance to your prize, this system is for you.

Cant Stand to Get Passed?

The first car I drove was a ¼ midget at Yeakle Brothers Oldsmobile in 1956. They were doing a sales promotion in their West Los Angeles sales lot using a hay-bale lined oval track so folks could bring their kids down for a free 10 lap session. I was around seven or eight, and my Dad dropped me into the cockpit of the little car and told me to drive around the outside of the track so I could get a longer ride. I did that until all the other kids started passing me on the inside of the corners, and I immediately turned hard left in pursuit of the shorter inside line. I could not stand being passed. Well over 40 years later I still can not stand being passed, and that is what fuels my passion for American muscle car performance, and a passion for perfecting that performance.


To me, perfection is extreme performance easily controlled. I raced a long time and spent innumerable hours figuring out how to make an engine deliver adequate power and live a long time. However, I soon learned that power alone did not win races. I had to be able to use that power, and that meant even more innumerable hours figuring out what made a good chassis work. Back then there were few books on the subject, most good cars were put together by accident if anyone knew how they were not talking. Much more information is available today, but none really solve the problems of what to do with a high-powered front engine car in all areas of competition while still providing a good ride. Applying my engineering education, and working full time in this pursuit, I did learn a lot; I was privileged to work as a consultant for world class teams, and I did win a few races of my own. Griggs Racing Products is the result of that life long pursuit.


Today it's never been easier or more cost effective to build a truly high performance car. This is especially true of Ford's Mustang, which while wonderfully affordable and blessed with a stout powertrain, is notorious as the most poor handling performance automobiles on the road. I have applied all of our energies at Griggs Racing to the Mustang's shortcomings, so that using parts from this catalog, you can easily transform your pony car into a world-class street and track performer while avoiding the dead ends and detours that are inevitable when developing such parts and packages yourself. At Griggs Racing Products we pride ourselves on making customers happy by delivering products that truly perform as advertised.


My partner and son, John Griggs, grew up in my high-speed environment, and developed the same desire for excellence. Today I am proud of his tenacity in trying to solve all our customers' needs. He heads a team of employees that are all dedicated to producing excellence in the American-built products delivered to you. I am proud of them too, and they all seek the same common goals, that is to make our customers call us after installation of a GR-40 chassis system with a story of how a car costing 3 to 10 times as much could not keep up with their Mustang. We have heard hundreds of such stories, and we never get tired of them because all of us at Griggs Racing Products can not stand to get passed.


R. Bruce Griggs
President and CEO

Some helpful definitions

The world of automobiles can be a strange and frightening place before you even think of donning fire proof coveralls, helmet, and a Hans device. So to make this a little bit easier on all of us here are some helpful definitions which should come in handy when reading our tech articles. We wont blame you for correcting your friend when he mistakes understeer with roll steer. Go ahead be smug. You are welcome.

• Roll Center - Both front and rear suspensions have a Roll Center. This is an imaginary point around which the body of the car will rotate in a turn. The attachment points of the suspension components determine the Roll Center.
• Roll Axis - A line between the front & rear Roll Centers.
• CG (Center of Gravity) - The center point of the vehicle's mass.
• Understeer - When the front tires lose traction first.
• Oversteer - When the rear tires lose traction first.
• Neutral Steer - The ideal balance when the front & rear tires gradually give up traction at an equal rate.
• Spring Rate - Expressed in pounds per inch, it is the force necessary to compress the spring, i.e. a 200 lb spring requires 200 lbs to compress it 1 inch, 400 lbs to compress it 2 inches, etc.
• Motion Ratio - Specifically we usually refer to the relationship between the motion of the wheel and the motion of the spring; i.e. If the spring is half the distance from the control arm pivot as the wheel is, the motion ratio relative to the wheel is .5 to 1.
• Wheel Rate - The combined effect of spring rate, motion ratio, friction and/or binding of other suspension components measured at the wheel
• Roll Bind - Any binding of suspension components that occurs as the body of the car leans over in a turn
• Roll Steer - Generally refers to a steering effect on the rear axle as the car leans over in a corner. Caused by the rear control arms pivoting around their forward mounting point, drawing the axle forward as the arm moves up or down.
• Bumpsteer - Toe change as the suspension moves up & down
• Ackerman - Or in other words Toe out in turns. When turning the inside tire must turn more than the outer tire because it is turning on a smaller radius
• Camber - Expressed in degrees, it is how much the tire leans in or out
• Caster - The forward inclination of the spindle or strut - like the forks on a bicycle
• Toe - The difference in the distance between the leading and trailing edge

Safety Is Our Primary Concern!

Below are photos of the results from an 100mph plus head-on encounter into a concrete barrier at Laguna Seca. Cause of the incident was deemed by SCCA officials as a "racing accident" contributed to by great speed differential between cars in the group. The contact car was a Miata. Other than pieces of wheels, remnants of right front fender and small shards of hood, this is exactly the way the car looked when it was brought off the track. We believe this is testimony to the integrity and efforts toward safety we at Griggs Racing put into every GR40 Mustang. However, it is also a lesson.

One of the reasons we race Mustangs is the incredible crash integrity Ford built into the tub of the car. However, it was never designed to take a hit at this kind of speed. So over the years we have carefully sought to improve the crash integrity along with the performance, building our parts strong enough to perform, yet light and soft enough to deform in a crash to reduce the potential for cockpit penetration or crush.

If you carefully look at the pictures, the cage and frame kit are not the least bit distorted, the engine and drive train was contained, and drivers compartment penetration was near zero, as was distortion to cockpit structure. The K member had been on this car for nearly 7 years, 5 of which as a daily driver and open track car before conversion to a race car. Although lightweight, it contained the engine, suspension and steering components. The quality American made tubing deformed and the ductile welds held. The part of the front control arm designed to break under collision to absorb shock did break. This design feature is to allow the tire to move backward against the foot-well bulkhead absorbing impact energy. However the tire and rim separated at the spokes, departing the vehicle allowing greater impact shock into the chassis. Still, we are very happy to say that the driver, wearing a Hans-device, walked away with a minor cut to the left ankle, a minor concussion and chest and rib bruising.

We learn each day, and we learned a few things with this one that will appear in our cars of the future.

1. We highly recommend head and neck restraints be used in all competitive events. We doubt the driver would be back at work this day had he not been wearing one.
   
2. We at Griggs Racing pride ourselves on safety and professionalism, yet the fire bottle broke loose from its mountings. The failure was on our end as we had mounted it with nutserts in the sheet metal of the tub. Fortunately, it was safely contained in the rear of the car and the lines and operating cable remained connected. It did remain functional had it been needed.
   
   The video camera broke its case but was retained by the SCCA required safety strap. Check the mountings of all objects in the cockpit. Had this or the battery or the cool-suit unit, or the Accusump, or any other object come loose in the cockpit and hit the driver it could have been a substantially worse incident.
   
3. We package all our electrical and plumbing within the cage on a race car to protect it all in advent of impact. However the crash removed large sections of body forward of the strut towers, and the dislodging of the left front apron yanked hard on the 00 gauge cable running from the safety switch to the solenoid mounted on the left front apron. The switch was mounted as it should be, just inside the drivers door mirror, within the cage and in reach of the driver.
   
   The safety switch pulled apart under the load, the housing separated from its mounts baring the terminals and allowing the hot battery cable bare terminal to bounce around loose inside the cockpit around the pedal box. No short occurred, but it could have been a big problem. Consideration should be given to the location and routing of cables from the switch, and perhaps a beak-away cable system should be employed that would allow the cable running to the starter from the safety switch to pull free without damaging the switch. A Fusible link mounted at the battery end of the main feed cable would also be of benefit.
   
4. The cause of the cut on the drivers leg was impacting the dead pedal we had installed with the pedal cluster. This will be re-shaped and padded in our future cockpit designs.
   
5. The Master cylinder reservoirs separated from their mounts. Had the direction of impact been from the rear this could have resulted in the driver being sprayed with a pint of brake fluid, which can be flammable, as well as a serious eye irritant. We will be using one-piece reservoirs of metal design in the future.

Besides the obvious body damage, three wheels, two brake rotors, the transmission, bell housing and clutch, the engine and everything attached to it were destroyed. However, the car could be repaired to race again.

Such catastrophic accidents are rare in road racing, and of course we dont ever want them to happen. But the reality is that it can happen to anybody, at any time, in any car. At Griggs Racing our years of experience are made available for many to bet their lives on, as we believe in safety as much as winning. Whether you do you own work, or take it to a professional, your safety is ultimately up to the decisions you make in preparing your car.

So always remember that you get what you pay for.