Speedometer question?

Glad you asked! My work is not for naught.

HB Chris

Thread 'Speedometer and Differential Ratios'

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%...
  • Like
 
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
 
Also there is a little visual outside difference of dots/markings location depending on engine/diff, example:

s-l1600.jpg
509366602_1123600973147991_5327788791971390728_n.jpg
 
I've thought about this many times, but I've never found a source that discusses about these dots.
The dots refer to speedometers in kph, there is no dots on mph speedometers.
Not sure, this may refer to gears shift recommendations (as some more modern cars) or some sort of limits markings.
 
it doesn't make sense with different diffs as at 50kph they would all be much closer together and further apart at higher speeds. i think it might have more to do with redline with different diffs, but ... in reality there are only 2 different diffs in Euro cars - the 3.25 and the 3.45 as i think 3.64 was only used in the USA (i could be wrong)
 
You must log in or register to reply here.
Back
Top