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GR40 Kit For 2005+

’2005 to’2014 SN197 GR40 SLA Chassis kits are now in production!!!  

Note:  The photos shown of installed parts are not typical of finish as they are of a prototype test car.  All production parts are plated or powder coated. 

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Prototyping and Testing has been completed.  Orders are being taken for these kits now and judging from initial interest demand will be high.  Don’t be left out and have to wait for the next run, CALL TODAY!!

SN197 GR40SLA with Torque Arm and Watts is the latest addition to the Mustang chassis system lineup from Griggs Racing. The system incorporates all of the features of the renowned record setting yet venerable Griggs GR40 system that fits 79-04 Mustangs but with a little more wizardry.

Front end system:

Rigid.  Each kit includes a provision for solid mounting the motor in a way that greatly increases chassis stiffness, without using motor plates that are expensive to install; affording the serious enthusiast nearly the same rigidity as full motor plates, but can be installed without touching the engine, or even removing it from the car during installation. The rear plate is shaped to accommodate all known long tube header combinations

Quiet Option:  For the street driver that wants a sweet smooth street ride, or that has not installed a perfectly balanced flywheel and clutch, rubber mounting is available at no extra charge. Solid or Rubber mounting should be specified when ordering.

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Proven Performance:  The geometry is nearly identical to that of the proven AIX National Championship winning GR40SLA systems already on the market, with the exception of minor changes due to track, wheelbase and CG differences between the ‘05s and earlier cars.  

Low:  The inherent design of the S197 chassis allows us to make the car be very low in appearance; while maintain the well know “ Griggs Stance” as low as 2 ½ inches at the rear K member mounting plate.  The resultant low center of gravity is FAST!

Simple & Complete:  The system replaces everything in the front end from steering to spindles to K member, along with the #1 cross member or radiator cowl support.  Delivered from Ford this is a heavy part and a separate piece from the K member, but integral in the GR40 unit which weighs just 42 pounds complete.  Since the integral design combines the two members, it no longer resembles a letter of the alphabet so we refer to it as the “Front Cradle”.

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Light weight, easy access:  The complete GR40 system saves considerable weight as well, and makes working on the car a breeze.  Using GR40 Alum spindles and Griggs 13.5” Sport Brake Kit, total OEM parts weight removed is 261 lbs.  Total installed GR40 front end weight removes 30 pounds from the front of the car, most of which is un-sprung.

Rear weight bias obtainable.   Our test car yielded a 50.2 % rear weight bias full of fuel and with 210# driver, this was a GT in street trim, battery in stock location all systems stock except for the GR chassis and brakes.  Other mods and/or track prep could move the weight back further.

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BIG TIRES FIT: The unique GR40 SLA design allows us to fit under the stock sheet metal 285-18 tires on 10” rims, are standard Front and Rear. Larger sizes will fit.

Easy Installation:   All parts bolt on except for two small stiffener plates that need to be welded to the rear shock mounts on the rear axle.  In the front, four 7/16” holes must be drilled to facilitate the installation. 

Incredible feel, input and response.  The first impression of all drivers that have tested this chassis is the car drives and feels like it weighs half of its real weight. All SN197 GR40SLA cars require a steering rack change due to dimensional differences, and two racks are offered.  Recommended for vehicles driven primarily on the street is the variable ratio unit with gearing as used on 03-04 Cobras.  For those that demand quicker response, we also offer a very quick responding steering rack for those that want fast response and this is recommended for autocrossers, experienced road racers, and drifters.  This system steers faster and more accurately than any GR40 system to date.    We also supply a larger competition suitable steering fluid cooler with all fittings and hoses to replace the extra long power steering hoses that are in the way of a clean installation, and to ensure long life of the PS system. 

Rear End System:

Since we build cars and parts for SPDs (Serious Performance Drivers) little time was spent discussing the merits of developing an IRS for the car.  We have proven many times that IRS, low down-force, front engine, rear drive, high powered cars are not as user friendly, reliable or as fast as a TorqueArm equipped stick axle car with good geometry.  It is also heavier.  Therefore we decided to retain our venerable GR40 Torque Arm and Watts Link design for our SPD customers and at a minimum retain the 3-link and/or Panhard bar while improving the geometry of it for the masses.

Lowering the SN197 chassis improves the geometry of the OEM Panhard bar, but destroys forward bite geometry and induces excessive rear steer.  To remedy this we have anti-squat correction brackets which double as a mounting for a unique bind free adjustable rear anti-roll bar.  This bar is provided for those desiring a tuning tool for chassis balance while running the OEM Panhard bar geometry.  

Not shown in these pictures is the Watts Link which is soon to be available.  The Watts assembly will be a simple bolt on unit and will allow adjustment of rear roll center height as in all other GR40 Watts Link assemblies. This will be released soon.

Rear Koni coil-overs are standard and an axle mount reinforcement bracket kit is supplied to strengthen and make rigid the somewhat flimsy OEM shock brackets on the rear axle. 

Track testing exceeded even our expectations for the new car which was first tested with the OEM third link in place.  Then it was removed and the TorqueArm installed this proved superior as the car then exceeded the performance level attainable with the three link especially over track irregularities and when cresting hills while cornering.  These are similar conditions that would be found on a city street.  Also, launch was improved, wheel hop was eliminated and consistency was easy to attain.  Due to its predictability at the limit all testing drivers expressed more confidence in the TorqueArm than the 3 link.  However, unlike the leaf springs or the four link of prior Mustang chassis the three link can be retained and have a balanced and fairly predictable car if rules or budget require, or the driver so prefers.

The system has spent some serious time on track at the hands of a variety of highly skilled drivers as well as many miles of street driving.  It truly is a joy to drive fast, and feels as solid and accurate as any car from anywhere, yet it has a surprisingly light feel, most drivers saying it feels like it weighs about 2000 lbs. 

GR40 equipped SN197 cars are a major improvement in Mustang quality and performance.  We believe that over time they will prove to be an incredible performance value.  Performance numbers from independent testers will be published as soon as completed. Call today to arrange a demonstration in the New GR40 Mustang

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