At 10:52 PM 10/05/98 EDT, DPowell126 wrote:
I am under the impression the gear ratio for the speedo is controlled by the
90 degree adaptor at the transmission. different gears are available. Is this
No, I don’t think it is correct for the e-type (but is correct for an
XJ-S). There were 2 schools of thought for speedo calibration: Those
manufacturers who used the same transmission gear for all diff ratios (most
UK manufacturers until the 1970s) and those manufacturers who used the same
speedo head for all rear axle ratios (most US manufacturers, UK Ford, and
Jaguar from the 1970s).
Cars which vary the transmission gear (e.g. my XJ-S) typically have 1000
rev per mile speedos, my S3 e-type (3.31 diff) has a 1216 rev per mile speedo.
That is why Jaguar speedos have a 4 digit number somewhere on the face, to
itentify which axle ratio the particular speedo head is for. The number is
the number of revolutions per mile of the speedo cable. You could achieve
the same result by changing the transmission gear, but it is not how the
factory did it.