Ballaratcastle
Well-known member
- Joined
- May 29, 2018
- Messages
- 161
- Reaction score
- 0
- Location
- New Zealand
- My Car
- 1973 Mustang Convertible. Just imported from the USA as an unfinished project.
[url=https://ibb.co/gXU4Qy][img]https://preview.ibb.co/f0tW5y/Mustang.jpg[/img][/url]
Hi team
I have a 73 vert with a 351W and C4 transmission.
Put the car together and discovered that the speedo is reading 75mph when I am doing 100km (62mph) using a gps speed app on my phone.
I discovered when adding an LSD to the 9 inch diff that the gearing wasnt the 2.79 as on the tag but 3.25 and my rims that came with the car are non standard 16 inch mercury grand marquis wheels.
The tyres on them are 225/60/16s.
I have no idea which speedo driven gear is on the cable and am not sure which size I should get to bring the indicated speed down to reflect the real speed as my mileage is obviously going up quicker than necessary.
Is there a formula from wheel size and diff ratio to get the correct speedo driven gear?
Cheers
Steve
I have a 73 vert with a 351W and C4 transmission.
Put the car together and discovered that the speedo is reading 75mph when I am doing 100km (62mph) using a gps speed app on my phone.
I discovered when adding an LSD to the 9 inch diff that the gearing wasnt the 2.79 as on the tag but 3.25 and my rims that came with the car are non standard 16 inch mercury grand marquis wheels.
The tyres on them are 225/60/16s.
I have no idea which speedo driven gear is on the cable and am not sure which size I should get to bring the indicated speed down to reflect the real speed as my mileage is obviously going up quicker than necessary.
Is there a formula from wheel size and diff ratio to get the correct speedo driven gear?
Cheers
Steve
Last edited by a moderator: