KR 40 Track 2 – Koni Rear Coil-Over Kit, Rebound Adjustable, Compression Firm, w/o Spring (’79-’04, ’83-’88 T-Bird)


Quick Facts

  • Allows for easy adjustment of ride height and corner weights. (1 turn is equal to 1/8 of an inch change in ride height)
  • Allows for
SKU: KR-40-Track-2 Categories: , ,


Quick Facts

  • Allows for easy adjustment of ride height and corner weights. (1 turn is equal to 1/8 of an inch change in ride height)
  • Allows for lighter weight K-member, control arms and other front end components to be used reducing both unsprung weight and overall vehicle mass.
  • Decreases motion ratio (how much the spring moves in relation to tire movement)
  • More predictable spring action.
  • Griggs coil over hardware components are made in USA form the finest aircraft quality aluminum, and sleeve is hard anodized for durability. 
  • A Torrington thrust bearing at the top provides friction free steering in spite of spring load applied to the camber plate.

Coil-overs perform two primary functions: Reducing the unsprung weight (the coil-over springs are lighter do to there more outboard location) and it allows for the infinite adjustment to ride height. 

Secondary benefits are decreasing the suspensions motion ratio, the expression of how much the spring moves in relation to how much the tire moves.  By relocating the spring outboard to the strut in the front, or to the shock in the rear, and employing high quality materials, lighter weight and lower rate springs and spring seats and load supports can be used with increased roll control. This results in a far better performance package.

We use Koni shocks almost exclusivley for these reasons:

Quick Facts

  • Available in dual adjustable and lightweight aluminum dual adjustable configuration so you can adjust ride quality or transitional handling characteristics
  • Requires little to no service over an almost indefinite lifespan.
  • Griggs race winning custom valving

The two most important elements in a performance chassis are the tires and shocks (or struts).  Dampers are a better term as their primary purpose is to dampen motion of the suspension movement of the chassis.  So far only Koni provides the quality and performance we demand of dampers to be included in a GR40 Kit.  And then in units that we have custom built to our specifications. 

Proven by over 50 years of international competition including Formula One, and the only part of our GR40 systems not made in the US, The Dutch company is owned by the US conglomerate, ITT automotive group.  Griggs Racing has worked closely with Koni in developing shocks and struts over the years that do exactly as required in delivering a serious performing chassis while improving handling, traction, ride quality, tire life, and safety.  Also, they last virtually forever with very little service required.  Koni’s are an investment you will have for a very long time.  They are not “throw away units”.

Most replacement shock offerings usually “feel” pretty good upon installation, but after a short time their “low speed” characteristics degrade with subsequent handling degradation.  Plus all other aftermarket units available are made with inadequate low speed damping, or digression, especially on compression (bump or jounce).  The adjustability of your Konis is easy, if you follow our instructions.  All but the struts are shipped pre adjusted on our shock dyno and most customers never need to adjust them to attain the ride quality or race winning performance they desire.

Most Griggs Racing standard offerings for GR40 Mustangs are not found in the Koni catalog under Mustang.  These shocks are derivatives of the Koni oval track program and the struts are originally from the Koni showroom stock racing program. With valving perfected to suit our standards, and the win record of GR40 cars to prove the point, these are a necessary step to tuning any Mustang chassis to perfection.

Single adjustable shocks came in various fixed compression valvings with adjustable rebound. 

Soft – Street use when the best ride is the requirement.

Medium – Most popular for cars driven hard on the street and road courses, autocross track as well as American Iron race cars. These are also the most popular street-strip rear shocks

Firm – These are generally used on the rear of high powered drag cars and with sticky slicks.  They are valved to afford better launch control and oppose tire shake.

Double Adjustable rears (and SLA front DA shocks) are usually for track cars.  They have a more digressive compression curve and simple on car adjust-ability of rebound makes them the serious club racer’s choice.  The lighter aluminum body reduces un-sprung weight for better handling and the special valving is a big improvement in corner exit adhesion.  Dual adjustable shocks are an excellent choice for use on the rear of serious drag cars.

Link to Double adjustable rear shocks