Speedometer question?

[Ed G]

Are all speedometers the same CS, Csi, Auto? Were all gearing ratios manipulated in the gearbox?

 

[Ian C]

Speedos are geared to suit differential. There is a FAQ on the board which explains identification

 

[HB Chris]

Glad you asked! My work is not for naught.

Thread 'Speedometer and Differential Ratios'

Jul 28, 2020

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.

Differentials

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%...

• HB Chris
• Replies: 5
• Forum: FAQ - Frequently Asked Questions

• 

 

[Ed G]

Thank you all!!!

 

[Ives]

Ed,
Once someone knows what the rear end is in their Coupe or Sedan they can send away to someone like Palo Alto Speedo and have it clocked to the correct ratio. I did that on a switch to a 3.25 LSD and by using an Apple Ap to measure they got the mechanical speedometer to within less than 1 MPH. I'm guessing this would work for all of the speedos.
Regards, Jon