Mazda RX-7 parts list, 79-85
Thank you for your interest in Ground
Control Suspension and the quality parts we sell. The following is a fairly
complete list of what is available for the early RX-7, both for the racer and street
enthusiast. This list is organized starting at the front of the car, and moving to the
rear. Many of the parts listed also require choices to be made, either because of a rules
restriction or to suit a budget. If you have any questions regarding these choices, please
do not hesitate to call.
Front suspension bushings
Front strut rod bushings, urethane replacement with new center sleeve $
20.00
Front strut rod bushings, steel spherical bearing (Monoball), welding
required for installation, I.T. only Dec. 95
Front lower control arm bushings, centered urethane, new center sleeve $
14.50
Front lower control arm bushings, steel spherical bearing, weld to
install, I.T. only $ 150.00
Front MacPherson strut components:
Strut cartridges (dampers, strut inserts), two needed per car, priced individually.
Tokico HP, primarily street use, # APEX 69 $ 59.00
Tokico HP, performance street use with Camber/Caster plates, or will fit
stock upper mounts with our adapter, sold below. # APEX 86 $ 59.00
Tokico "Illumina 5" Five position externally adjustable for
high performance street use, average road racing use, # APEX B69 $ 124.00
Tokico "Racing 5" Five position adjustable for road racing,
will only fit our Camber/Caster plates or Camber plates from Mazda Motorsports, # APEX B99
$ 124.00
KYB Gas Strut cartridge, nice, inexpensive strut for the wife’s car,
# APEX K1 $ 44.00
KYB Gas 4 way adjustable, a nice street shock, not suitable for racing, #
APEX K4 $ 75.00
Bilstein Racing strut insert, non adjustable sport valving, 1 1/2 inches
shorter than the standard length insert. Primarily used where additional travel is
absolutely necessary.
Cutting and welding required, but directions are included. Use with Camber/Caster plates
only. # APEX B91 $145.00
Bilstein Racing strut insert, same as above but with custom valving $235.00
Koni Racing strut insert, this insert DOES NOT fit the stock housing and
must be used with our custom struts, the only real advantage to this insert is that it can
be custom valved in our shop, call for details. $175.00
Adapter bushings for struts listed above, sold individually. $6.00
Front springs and spring kits
Eibach Pro-Kit, set of 4 springs for street use, lowers the car one inch,
non-adjustable $224.00
Ground Control NON-adjustable height front spring kit
Specifically made for racing classes where the spring origin is unlimited, but threaded
collars and perches are specifically prohibited, this kit allows a large choice of spring
rates. The small upper diameter of the spring also allows greater camber adjustment than
the stock spring for classes where the strut towers can be modified, but not replaced.
each kit includes a billet aluminum upper spring perch, which can be used instead of, or
in addition to, the stock perch according to your rules. $68.00
each
Ground Control Adjustable Height Front Spring Kit 
Commonly called a “Coil-Over kit”, this kit has all the pieces
needed to convert the front struts on your RX-7 to 2 1/2 inch I.D. racing springs. In
addition to the ability to set the ride height almost wherever you want, you can also
adjust corner weights, roll center height and change spring rates quickly and easily.
These kits come with an Eibach race spring (your choice or our recommendation), a two
piece threaded height adjustment sleeve machined from 7075 T-6 seamless aluminum tubing,
and a billet aluminum upper spring perch. The existing lower spring perch (welded to the
strut) remains as stock on the street kits, but is replaced with a lower profile version
on the race kits. This minor welding takes about 5 minutes per strut.
Street Adjustable Height Front Spring Kit$ 97.50 each
Improved Touring and Street Prepared Adjustable Height Spring Kit$ 92.50
each
Eibach 2 1/2 I.D. race springs
Additional springs are available from our large inventory for testing or different track
setups. Available are: 275 lbs./in., 300, 325, 350, 400, 450, 500, 550, 600, 650, and 700.
We also have 175, 200, 225, 250, 375, and 475 available in other brands.
Prices range from $ 45.00 to $ 62.00
depending on spring rate and quantity.
Bump Stops
We sell three different types of bump stops for MacPherson Struts. All three are closed
cell urethane foam, and vary in density. We can recommend the most appropriate length and
density for your setup. $ 12.00 each
Camber
/ Caster plates
Adjustable upper strut mounts have been known as “camber plates” for over 20
years. All this has changed with the introduction of our Camber / Caster plates.
Our Camber / Caster plates are the culmination of 10 years of making improvements on
existing camber plates. By starting with a clean sheet of paper, we have significantly
increased the adjustment options for the serious driver.
One our finest and best selling products are the Camber / Caster plates which replace the
upper strut mount, and bolt into the existing holes with virtually no modifications to the
sheetmetal needed. These plates allow fast and accurate adjustment of camber and caster
from under the hood. Useful for initial setup, and essential for keeping up with changing
conditions at the track, our exclusive design uses a spherical bearing to eliminate
binding of the strut shaft, with a separate needle bearing assembly for the spring. When
used with 2.1/2 I.D. springs, up to 4.5 degrees negative camber can be achieved. Sold as a
complete set with directions and setup sheet for your type of racing or driving style.
Manufactured from 7075 T-6 billet aluminum. Minor machining may be required on struts that
were not bought from Ground Control. Available in blue or titanium color anodized finish.
79-92 RX-7 Camber / Caster plates , both sides, includes any adapters if
needed. $ 265.00
Camber / Caster plates, special price when purchased with Coil-Over Kit. $
250.00
We have developed a 3rd link kit for 79-85 RX-7s. This is a weld-on kit, and is a bit
complicated to install, but can be well worth the trouble. We first built one of these
five years ago, and have a good track record with it. $ 175.00
complete
Rear Control Arm Bushing kits
Urethane rear control arm bushing
We do not sell these, and probably wouldn’t recommend them in any case. Many handling
problems and quirks of the RX-7 can be traced to the lack of free movement in the rear
suspension bushings. Stiffening the rear suspension bushing material by substituting
urethane, delrin or any other material more rigid than the stock rubber bushing will only
exaggerate the problems. Spherical bearing rear control arm bushing kits Installed into
your existing rear control arms, these kits replace two, four, or occasionally six of the
eight stock rubber rear control arm bushings with a steel spherical bearing which has
virtually no binding in rotation, yet is perfectly rigid from front to rear. Please call
for advice on which bushings (they are all the same) should be replaced in your situation.
$ 175.00/pair
Replacement aluminum rear control arm with rod ends These threaded
aluminum control arms REPLACE your existing lower control arms, however because the arm is
replaced (not just the bushings), these are not legal for SCCA I.T. or S.P.
classes. $ 170.00/pair
Replacement rear springs
Street rear springs see Eibach Pro-Kit, listed under front springs.
Racing rear springs
All of our rear springs are made exclusively for us, but the most popular by far is made
by Eibach as a 175 lbs./in. rear spring. This is a very clever design that allows fine
tuning of the rear ride height by trimming (if necessary) any of the five “dead”
coils at the upper end of the spring. These five coils are not active when the car is on
the ground (hence the term “dead”), so the spring rate is virtually unaffected
by the trimming. These five coils do however create preload when the car is jacked up, so
we have also solved the problem of loose rear springs when working on the car. 175
lbs./in., 200 lbs./in. $ 119.00/pair
Racing rear springs, 125 lbs./in., 150, 200, 225 $ 109.00/pair
Adjustable rear ride height kits
We can supply you with all parts needed to make either a rear coil-over setup or a NASCAR
style setup with weight jack screws. Extensive and somewhat skillful fabrication is
needed. These kits are only legal for G.T., Production
and Modified classes. Despite many requests, we have never figured out a
good I.T. legal way to do this.
Rear shock absorbers Priced individually
The sensitivity of the rear suspension of the RX-7 extends to the rear shocks. In most
cases the choices and decisions made regarding the rear shocks are more important than on
the front. We have tried, have sold, and currently use a disparate mix of rear shocks. Our
testing in this area is ongoing (like everything else actually), and after 10 years of
racing Mazdas, we still try different ideas. It is always best to just call for advice on
what parts are best for you.
Tokico HP, primarily street use, but surprisingly good for racing. #
APEX13 $ 39.00
Tokico “Illumina 5”, excellent for street use, most popular for
racing # APEX B13 $ 108.00
Tokico “Racing 5”, the best choice for some race cars, # APEX
B99 $ 108.00
Koni hydraulic, a surprisingly good setup for racing, adjustable rebound,
# APEX K1 $ 99.00
Koni 4PA gas, the latest race shock from Koni, sold w/ special mounting
kit 144.00
KYB gas, for use on the wives car only $ 29.00
RX-7 Panhard Rods
Our exclusive Panhard rod for the 79-82 RX-7 does more than just replace the factory Watts
linkage. By eliminating 5 rubber bushings, the axle is more consistently located from side
to side.
Some movement of the axle is always present when using a Panhard rod, but through 4 inches
of travel we have limited the total lateral movement to 0.060 inches. Another advantage to
our Panhard rod is that we have relocated the rear roll center approximately 31/2 inches
lower, which creates a more level roll axis.This is a bolt-in kit However, stamped steel
reinforcements are included and must be welded on before any hard driving. Constructed of
.120 wall, 4130 chrome moly with aircraft rod ends. $ 160.00
Proportioning Valve Virtually every race car eventually gets a brake
proportioning valve, usually on the rear brakes. We include directions for the easiest way
to slide in and adapt this valve to your car. A flaring tool and a new American brake line
are needed. $ 59.00
Toe plates first saw Richard Petty’s team use these years ago. there
is nothing more simple or foolproof. These plates are quality extruded aluminum and are
placed up against each tire. One person uses two measuring tapes, one across the front of
the tires and one across the rear, and measures the difference. Example: front tape is 67
1/4”, rear tape is 67 1/8” for 1/8” toe-out.
Simple, light, portable, repeatable, and they calibrate themselves every time. $
75.00
Future products: Many of the parts we sell are destined to be obsolete as
soon as we find something better, but be assured that what we sell now is CURRENT
state-of-the-art racing technology. Maybe in the future? Lower priced spherical bearings,
more Eibach rear springs, a better way to utilize custom valved front struts are all
things under consideration.