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Speedometer and Differential Ratios

HB Chris

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Huntington Beach, CA
The e9 coupes came with three differential ratios and could be found both open or unlocked and locked or LSD. The speedometers were matched to the car based on which differential was fitted.


The differential ratio is expressed as a fraction and is stamped on the right lower side of the differential on a flat boss. The presence of a stamped or painted S indicates locked or LSD.

3.25 = 39/12
3.45 = 38/11
3.64 = 40/11

These differentials were typically found on these models:

3.25 Open - CSi
3.25 LSD 25% locking - CSi and CSil
3.45 Open - Euro 3.0CS/CSA
3.45 LSD 25% locking - CSL, Euro 2800CS/CSA and 3.0CS/CSA and US 2800CS/CSA
3.45 LSD 40% locking - Euro 2800CS/CSA and US 2800CS/CSA
3.64 Open - Euro 2.5CS/CSA and US 3.0CS/CSA
3.64 LSD 25% locking - 2.5 CS/CSA

The LSD could be ordered as an option as well.


The speedometer ratios are as follows (numbers stamped on the speedometer are rounded and include a mm/yy build date):

3.25 KPH W= 0.679
3.25 MPH W= 1.078
3.45 KPH W= 0.7125
3.45 MPH W= 1.14
3.64 MPH W = 1.2164

Note: MPH includes not only the US market, e.g. the 3.25 MPH speedometer


3.45 Locking differential identified by the stamped S
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