Speedo drives

[GTRMikie]

If I change from 10 inch to 12 inch wheels but keep the same diff (3.44) what speedo drive gears should I use to avoid having to recallibrate the speedo? I know there is a magic formula one can use to calculate this, but it would be a lot easier if someone out there knows the answer already!! Since my engine/gearbox is out at the moment it is probably easier to change the gears than send the speedo away for recallibration.

[guru_1071]

as long as its the later type speedo - i.e in front of driver, or non mk1/2 centre type then you need a six tooth drive spindle (2A3720) which is standard in all ten" wheel cars and a 16 tooth pinion (DAM2905) which is found in some 84 on cars.

if you are running a mk1 or 2 speedo you will need to get it calibrated.