Open Diffs

[HB Chris]

Thanks for the stamping location. Now I know where to look to see what LSD is in my car. About 3000 RPM was 80 MPH ,and 4000 RPM was 100MPH in 5th gear.

With a 3.45 in fifth at 3000 rpm I’m doing 77MPH, my speedo has been calibrated. You most likely have a 3.64 so it sounds like your speedo is reading fast, I would expect 73/74mph At 3000rpm.

 

[rsporsche]

Chris, according to the gearing calculator, a 3.45 at 3000 rpm with 225/50-16 rear tires with a 5th gear ratio of 0.81, you are doing 79 in 5th. for comparative purposes, i have attached the 3.64, 3.07 and 3.25

 

[HB Chris]

Pretty darn close. I use Waze to confirm speed as every tire can be slightly different. Also confirms that BMW speedos generally read fast, the 3.64 says 75 too, not 80.

 

[rsporsche]

excellent point.