dIfferential ratio

[estepona1999]

I have followed some information to find out my differential ratio and it seems it is 4:2:1,my question is,is this a standard ratio for my 1958 traveller? My reason for asking is will I need to have my speedo re calibrated or not?
Finally I will have a ribbed gearbox fitted and a 1098 engine (should be originally a smooth case box and a 948cc engine) will this affect the speed reading? Thankyou

[bmcecosse]

The FINAL DRIVE ratio on your 1958 car should be a 4.55:1, matched to a 948 engine and smooth gearbox. The engine/gearbox makes no change - the 4.22 final drive ratio (correct for a 1098) should be matched to a 1408 tpm speedo...your car would originally have a 1504 tpm speedo - but the speed reading if you have the old speedo won't be too far out. Compare it to a GPS (perhaps on your phone) or just the 'speed reading' signs as you enter a village....

[estepona1999]

Thankyou for that,you certainly have a lot of knowledge,I appreciate your advice.