Supercharger Service – Eaton M45

When the engine was first started, I could hear a rattle coming from the supercharger.  The supercharger on this engine is a Eaton M45, that is common to many vehicles throughout the years (mini cooper s, pontiac gran prix/am?, etc.)  From my reading online, there are two general causes of the rattle.  Those are failing bearings (which there are many in the supercharger) and worn coupler.  For general diagnosis, with the supercharger belt off, turn the snout pully, if there is play when rotating back and forth, the coupler is likely worn, if it is rough and grindy, bearings are likely the problem.  On mine there was play when rotating, but it rotated smoothly, implicating a worn coupler.  Lucky for me, this is the easiest of fixes.  Drain supercharger fluid, remove snout, replace coupler, reinstall snout, fill with new fluid, done.  I purchased kit similar to those found on this site (  From what I’ve seen online, replacing bearings requires more care and expensive tools (presses, etc).


Eaton M45 – Supercharger had to be removed from the engine in order to remove the snout.


Snout off, smelly oil (muenster cheesy) removed, and coupler coming off. Take care not to pull the next section of supercharger off which supports the rotor/fan shafts as this will be loose too.




Brakes and Clutch

Prior to performing the first drive, the brakes and clutch were made operational. For the brakes, the lines were installed, filled with fluid and bled. Started bleeding at the furthest brake caliper and made our way up to the closest to the master cylinder, then repeated until there were no more air bubbles. Luckily none of the bleeder screws/valves on the calipers were seized shut. A Wilwood brake proportioning valve was installed in the line that I purchased from Flyin’ Miata (

For the clutch, the existing slave cylinder was seized and had to be replaced with new one I picked up from a local auto parts store. Once replaced, the master was filled with fluid and line was bled.

New clutch slave.
Old seized clutch slave.
Factory service manual clutch slave diagram.
Service manual clutch slave mounting torques.
Bleeding brakes.
Bleeding brakes. Rims and tires need cleaning.