The complete automotive resource for buyers, sellers, and owners like you.
Car, Truck and SUV Forums at Roadfly
+ Bentley Forums
+ BMW Forums
+ Cadillac Forums
+ Chevrolet Forums
+ Ferrari Forums
+ Jaguar Forums
+ Lamborghini Forums
+ Lotus Forums
+ Mercedes-Benz Forums
+ Maserati Forums
+ MINI Forums
+ Porsche Forums
+ General Discussion
+ Marketplace Forums
Speed Sensor (archive)
[ Follow Ups ] [ 8-series (E31) Message Board ] [ Msg. Board FAQ ]
Posted by Greg K on March 14, 2000 at 19:53:47:

In Reply to: Re: 850I rear axil ratios posted by Mark on March 14, 2000 at 17:17:41:

Good point and no harm in guessing, its what the board is all about. There's a pulse sensor for the speedometer that's mounted on the back cover of the 850 differential (PN 621 683 57 020 for all 850/840). It counts how many revolutions your axle has made using a pulse generating wheel inside the diff case, converts this into feet travelled using a constant for tire/rim size, and determines speed. Since axle rotations are a constant unless you change your tire or rim size, changing the differential doesn't effect the speedometer. You've changed engine rpm and driveshaft revolutions per each mph, not axle revolutions per mph. No recalibration necessary. You retain your current sensor and rear cover (which has e31 specific mounting points) and install it on the new differential casing. No additional cost.

Follow Ups:


[ Follow Ups ] [ 8-series (E31) Message Board ] [ Msg. Board FAQ ]
Questions, comments, or problems, please visit the Roadfly help desk.
Roadfly.com Logo © 1997 - 2009 Jump Internet Inc. All rights reserved.