Project EJ Civic, Building the Drivetrain


To further make the diff quieter, longer lasting and smoother on the street we subjected our diff’s clutches to WPC treatment as this had made our noisy and rough Nismo LSD silky smooth on our Project 350Z.  These changes should give us a clutch type diff that is much more positive than a helical gear type without the disadvantages of spin under wheel lift or spin breakaway while still being smooth and streetable with minimal contribution to turn in understeer.

The squared off pinion shaft slot has a steeper ramp for a quicker and harder lock up curve.  The more gradual one is the one M Factory modified for us to reduce understeer with a lower powered NA car.

Howard assembled our transmission using new seals.  The bearings were carefully inspected and found to be in excellent condition and were reused.

The pinion shaft cam in the fast lock slot.  You can see how the pinion shaft wedges the pressure rings apart to put more clamp load on the clutches.

The next parts that had to be upgraded was the slipping clutch.  If Annie drove hard for any length of time it would start slipping and she would have to drive it easy for a few hundred miles to deglaze the clutch to the point where it would grip again.  By doing this she had been nursing her clutch for years.  It was time to take care of this once and for all!  We called upon ACT to give us a heavy duty clutch that was track capable but daily driver friendly for our projected power levels.

 Here is the pinion shaft cam in the more gradual lock up slot.  We used this slot.

The ACT clutches’ HD pressure plate has a torque capacity of 245 lb/ft which should be more than enough for our intended use.  It has a thicker diaphragm spring with 55% more clamping force than the stock Honda pressure plate.  One of the cool things is that the pressure ring has a reengineered fulcrum point so that the engagement travel is softer and longer.  This means that the clutch has a nice and easy pedal effort and an easy to modulate engagement even though its clamp force has been greatly increased.  The pressure plate diaphragm spring’s finger tips are induction hardened to resist wear from rubbing on the throwout bearing, a nice OEM type feature that helps guarantee long service life.

We gave the pressure rings and the clutch discs the WPC treatment as we have had good luck with this smoothing out clunky clutch type diffs on other projects.


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