I just checked my '71 240Z speedometer against my GPS. It seems to be almost exactly 10% off (reads 60 acutaully doing 66.3). It has been changed to a 5 speed and I don't know about rear end changes or how much change there is in existing tire diameter and original.

I can live with it but is there an easy fix?

John

I just checked my '71 240Z speedometer against my GPS. It seems to be almost exactly 10% off (reads 60 acutaully doing 66.3). It has been changed to a 5 speed and I don't know about rear end changes or how much change there is in existing tire diameter and original.

I can live with it but is there an easy fix?

John

Hello John:

"IF" the difference is caused by a differential change, you can replace the speedo gear with the correct one for the diff that is in your car now. This gear goes into the transmission where the speedo cable connects.

This has been discussed many times on this forum, so a "SEARCH"

using "Speedo gear" I come up with http://www.classiczcars.com/forums/search.php?searchid=62079

and within those results I found the following that may be of interest to you:

http://www.classiczcars.com/forums/showthread.php?t=6997&highlight=Speedo+gears

http://www.classiczcars.com/forums/attachment.php?attachmentid=1978

http://www.classiczcars.com/forums/showthread.php?threadid=1957

Thanks and thanks for not blessin' me out for not searching. I did search but I don't wear a Speedo and wasn't able to finnd just what I was looking for.

Note: "blessin' me out" - Southern phrase for "blessing me out" equivilent to northern "cussin' me out" for "cursing me out.

Thanks,

John