w markings on back of speedometers

[pmansson]

It might be useful to line up the various w values on the speedometers when it comes to changing the final drive unit (as I like to do).
I read in the Blue Book that the 2800 CS has w=0,69. I take it that this is tied to the 3,45 diff. that it came with on the European market.
Anybody got more input on this subject?

 

[Gosch]

As I know, there are 2 Types for 3,45 or 3,25 Diff.
w = 0,7125 for 3,45 Diff and
w = 0,68 ( early Version ) w = 0,67 ( later Version ) for 3,25 Diff
The stock Tyres in Germany was 175 R 14 or 195/70 R 14
The Rolling circumference of
175 R 14 is 1,935 Meter and
195/70 R 14 is 1,93 Meter ( metric )

For example

W = 0,67
Diff = 3,25
Speedodrive at Tranny is 10 : 4 = 2,5
Rolling circumference is 1,93 Meter

The correct Formula for calculating is :

3,25 x 4 / 1,93 x 10 or
3,25 / 1,93 x 2,5 = 0,6735751

~ 0,67

It´s clear ?
gosch

 

[pmansson]

Very clear Gosch

I might just add that the US spec 3,0 CS with a diff ratio of 3,64 had w=1,21 on the back of the speedometer, according to the original parts list.
So when cars get new gearboxes and matching final drives as well as new wheels and tyres, this Forum Thread might be of interest to those who wish to have a fairly accurate speedometer in their cars.