Flywheels, Ring & Pinions, Driveshafts
Proper selection of a flywheel will improve both performance and driving ease. Most of the mass in a stock flywheel is concentrated near the outer edge, resulting in high inertia. This feature, combined with the relatively heavy weight of these stock components make them unfavorable for most high performance applications.
For street use, our Lightweight Steel Flywheel not only allows the engine to accelerate more rapidly, but it also eliminates much of the "rubbery" feel that occurs at clutch engagement when shifting. While the Lightweight Steel Flywheel is entirely suitable for race use, it is not as light as our aluminum flywheel. The aluminum flywheel is intended primarily for road racing and rallying; it is a bit too light for street use unless you use a very low rear axle ratio or have the engine/clutch assembly installed in a lightweight vehicle.
Flywheel or clutch components should ever be allowed to exceed 10,500 RPM under any condition. This same RPM limit applies to stock components. You must use an engine RPM-limiter to prevent excessive RPM. If your engine is capable of exceeding 8,500 RPM you must install a transmission scatter shield, or "ballistic blanket". Failure to implement the above may result in serious injury or even death.
Ring & Pinion Gears
The Ring & Pinion sets cannot be swapped from one "group" to another "group" although some other rear axle components (bearings, seals, differential) may be interchangeable. Aside from the alternate ratios listed for each group, there are a few additional choices available for groups I, II, V & VI. Groups III & IV have no alternate ratios available.
|RX-3 SP 1977-78||3.727|
|RX-7 12A 1979-83, Late 1983 & 1985||3.909|
|RX-7 12A early 1984||3.933|
|RX-7 1984-85 GSL-SE||4.076|
|RX-4 & Cosmo 1976-77||3.636|
|Rotary Pickup 1974-75||4.625|
|Rotary Pickup 1976 Man Trans||4.375|
|Rotary Pickup 1976 Auto||4.111|
|Rotary Pickup 1977||3.900|
|RX-7 1986-92 NT Auto||3.909|
|RX-7 1986-92 NT, Man Trans, Ex GTU||4.100|
|RX-7 1989-91 GTU||4.300|
|RX-7 1987-91 Turbo||4.100|
|RX-7 1993-95 Man Trans||4.100|
|RX-7 1993-95 Auto||3.909|
|Many factors impact the selection of a suitable gear ratio, including the specific application, horsepower, aerodynamics, etc. The standard formula that relates vehicle speed and engine RPM is as follows:|
Speed (mph) =
(TC x RPM) ÷ (1056 x AR x TR)
TC: The outside rear tire circumference measured in inches.
AR: Rear axle ratio (Ring & Pinion).
TR: Transmission gear ratio in any gear you want to use.
RPM: Engine RPM.
When setting the ring & pinion gear assembly, follow the Mazda Factory specifications. It is essential that the pattern of contact between the gears be correct to ensure expected gear life and minimal noise. The "pinion depth" settings are provided to establish the correct pinion shim. If you lack the requisite equipment for depth measuring, start with the old shim.
For best results in road racing, install both a differential oil cooler and temperature gauge. For the cooler, the oil exit point from the differential should be at the rear of the ring gear near the bottom of the housing, while the return point should be just above the "mesh point" of the ring and pinion. When plumbing your oil cooler pump, be sure to install a screen-type filter ahead of the pump and check the filter regularly for contaminants. Do not route any of the oil cooler or temperature gauge lines below the housing; they will likely be damaged during an off-course excursion.
When installing the differential temperature gauge, the sender is best mounted in a "T" fitting in the hose line leading to the pump. Most gear oils lose significant lubricating capability above 320°F. Keep the temperature below 220°F and change the oil frequently to promote gear life.
We recommend that the differential components be "broken in" using a 90W hypoid gear oil for approximately 300 miles. Drain the differential case, and replenish with a synthetic lubricant, such as Royal Purple Max-Gear Oil. In our experience, synthetic gear oil lowered the differential temperature 10°F when compared to a high quality mineral-based lubricant. Also, gear and bearing wear were very slight, clearly showing that synthetic gear oil achieved the aforementioned temperature reduction through decreased friction.
Inspect your rear axles and bearings regularly. While Mazda’s components are of very high quality, they are not unbreakable.
Do not attempt to use a driveshaft that has been modified unless it has been straightened and balanced. Rapid wear of the driveshaft yoke where it enters the transmission extension housing is frequently a sign of an unbalanced driveshaft. When running a rotary at very high speed, it is possible for the driveshaft to see more than 11,000 RPM. Experience has shown that harmonic vibrations are present in the driveshaft at the 8,000 to 11,000 RPM range, causing rapid wear of the universal joints.
1984 and later Mazda OEM driveshafts have non-replaceable U-joints, requiring the replacement of the entire assembly if a joint fails.
Copyright 2007-2021 Racing Beat, Inc ©