Various Harmonic Balancers were used over the years. No clear information on what the differences are.

Model Years Part number Color Engine number  
928 1978-1979 928.102.120.14 black M28.01  
928 1979-1983 928.102.120.15 red M28.11/12  
S 1981-1983 928.102.120.16 blue/green M28.11/12  
928 1980-1983 928.102.120.17 grey M28.09/10  
S2 1984-1985 928.102.120.22 ? M28.21/22  
S2/S3/S4 1983-1989 928.102.120.23 orange M28.19/20 M28.43/44 M28.45/46 M28.41/42  
S4/GT 1990-1991 928.102.120.23 black/grey M28.42/47  
GTS 1992-1995 928.102.120.24 green M28.49/50  


This is the S4 vibration damper (GT/GTS are green). Notice the TDC marker and the -2 degree, -1, 0 +1 and +2 degrees mark

Damper with the Porkensioner fitted .... and what the damper should look like in your car.

This is what it looks like when the damper is placed reversed.

and here's another one.... installed backwards, COMPLETELY WRONG, and setting the timing will be hard as the markers on the damper are reversed.


This looks good. Marker on 45 degrees.