SCPulley

Super Charger Pulley Replacement

John Moody

I saw your comments regarding the supercharger pulley replacement. No need to reinvent the wheel. I did all that a couple of years ago including redesigning the pulley & sourcing a fabricator.

I changed the pulley from a 36 teeth unit to 42 teeth (about 4.2 in dia) - this change reduces the drive ratio to 108/42 = 2.57 & the maximum SC speed to 14000 rpm @ 5450 engine rpm ( 2700 prop rpm) for the G3 PSRU

I assume that the SOHC H4's use the same 108 teeth drive pulley as the STi's.

Below are a series of photos I took during the removal/ replacement process:

1. The existing pulley is 2 pieces. A thick aluminium "bell" press fit onto the SC shaft with a thin "teeth ring"

pressed on to the bell. I didn't have any prior knowledge of what was there before I started cutting it off so I did it the hard way.

First step is to cut off the teeth ring - it is only about 3/32 in thick & the bell lip below is about 1/16 thick so go easy

with the dremel. See details in the second photo.

Second step is to cut-off the bell without nicking the shaft. The bell/ shaft overlap is 1 in. I used a series of parallel

cut to get down near the shaft. I then cut-off the thin part of the bell & used a cheap gear puller to pull off the bell.

I think Brian Meyette went straight to the gear puller & it worked OK.

The SC shaft is 20 mm dia (0.787in +/-)