Adds 750cc of diff oil capacity and external cooling fins to tame chronic heat build-up in the Series 1 RX8 differential.
$690
The Mazda RX8 diff cover from REVOLUTION targets a genuine structural weakness in the Series 1 driveline. The RX8 differential runs hot by design. The transmission tunnel is tight, and the muffler and rear bumper block airflow. Heat has nowhere to go.
Add a weaker case than the FD RX7 it shares some DNA with. The result is a differential prone to lateral case flex, elevated oil temperature, and degraded side-bearing preload. This finned, high-rigidity cover addresses each of those problems directly.
For RX8 enthusiasts running a Series 1 car on track days or demanding back roads, this diff cover works silently but meaningfully. Heat soak shortens fluid life and accelerates wear inside the differential. More fluid absorbs heat. More surface area releases it.
A thicker, correctly located housing keeps bearings and gears in their intended geometry. It is the kind of improvement you feel in sustained confidence rather than a single moment. As a Mazda RX8 diff cover upgrade, it stands apart from simply refreshing the OEM unit.
Pair this with the R-MAGIC Super Magnetic Gearbox Drain Plug to capture metallic debris at drain intervals. It keeps your driveline fluid cleaner between services. The GREDDY TRUST Super Magnetic Oil Pan Sump Plug rounds out a thorough driveline maintenance refresh.
For front-end rigidity at the same time, the AUTOEXE Lower Arm Bar (Front) is a natural complement on a car being driven hard. Read more about the REVOLUTION range at revolution.jp.
| RX8 Model |
|---|
Related RX8 Upgrades
The REVOLUTION Big Cooling Diff Cover is designed for the Mazda RX8 Series 1, covering the 2003 to 2008 model years. It is not listed as compatible with Series 2 cars, so confirm your build year before purchasing.
The REVOLUTION diff cover adds 750cc of differential oil capacity over the standard cover. That additional volume slows heat build-up during sustained hard driving by giving the fluid more thermal mass to absorb heat before temperatures climb.
The external fins increase the cover's surface area, allowing heat absorbed by the differential oil to dissipate into the surrounding air more quickly. The two mechanisms work together: the extra 750cc of oil slows the initial heat rise, and the fins then shed that heat more effectively between corners or long runs.
The REVOLUTION cover averages 5 to 10mm wall thickness compared to the 3mm OEM casting. The added material increases housing rigidity at the rear of the driveline, which helps maintain side-bearing preload and correct gear contact geometry under load.
The integrated service hole allows an external oil cooler to be plumbed directly to the differential if the build demands it, such as for dedicated track use. It is an optional provision rather than a requirement for normal installation.
Yes. The upgraded bolts on the REVOLUTION diff cover also function as knock pins, providing precise cover location. This helps maintain consistent side-bearing preload and correct gear contact geometry, which matters most under the lateral loads generated during hard cornering.
Occasional track use still generates sustained heat in the differential that the standard cover is not optimised to handle. The increased oil volume and finned housing reduce fluid degradation and accelerate wear, so the cover is a practical upgrade for any Series 1 owner who pushes their car hard, even intermittently.
Yes. Replacing the differential cover requires draining the existing oil, removing the OEM cover, fitting the REVOLUTION unit with its upgraded bolts, and refilling with fresh differential fluid to the correct level. It is a straightforward service-type job that can be completed at home with the right tools and a workshop manual.
