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
My 73 vert was originally a 302 coded car with a C4 and Axle 3 2.79:1 ratio
The car when I bought it and imported it to NZ just over 2 years ago had a 351W C4 and what I believe to be a 28 spline 9inch diff. The previous US owner purchased the car 6 years earlier with this engine in it.
When replacing the shocks, I also noticed the spring hangers had extra plates with an extra tounge and hole fitted which I believe are for a rear sway bar assembly.
I am about to remove the Diff carrier assembly as my mechanic is going to fit a 2nd hand rebuilt 28 spline LSD that I bought as she is a single spinner.
My question is I was wondering if I should change the crown wheel and increase the ratio.
I had noticed that the speedo is not accurate. Using a phone speed app 100km (62mph) is showing as 75mph on the speedo.
I wonder if the 9 inch is original or swapped out as some feedback is a 302 car would not normally be fitted with a 9 inch. I cant recall the tyre size but she is also on 16inch rims and 215 tyres (cant remember ratio). I doubt the speedo head on the cable was changed if the diff was changed when the 351 went in.
Would this error in speed be tyre circumference only or have I actualy got a different ratio diff than on the tag?
I will be taking the car down the 1/4 mile again hopefully in Sept again (if group events allowed) at our Fathers day drags hence why I am putting in the LSD.
I had traction issues with standard tyres and best ET was a 15.2 at 94mph
I am happy for it to remain a cruiser for mustang club runs and local car shows so dont need an accelerating monster as the engine HP is a modest 400 only so she isnt going to break any 1/4 mile records but a 14 and 100mph over the line would be nice!
My 73 vert was originally a 302 coded car with a C4 and Axle 3 2.79:1 ratio
The car when I bought it and imported it to NZ just over 2 years ago had a 351W C4 and what I believe to be a 28 spline 9inch diff. The previous US owner purchased the car 6 years earlier with this engine in it.
When replacing the shocks, I also noticed the spring hangers had extra plates with an extra tounge and hole fitted which I believe are for a rear sway bar assembly.
I am about to remove the Diff carrier assembly as my mechanic is going to fit a 2nd hand rebuilt 28 spline LSD that I bought as she is a single spinner.
My question is I was wondering if I should change the crown wheel and increase the ratio.
I had noticed that the speedo is not accurate. Using a phone speed app 100km (62mph) is showing as 75mph on the speedo.
I wonder if the 9 inch is original or swapped out as some feedback is a 302 car would not normally be fitted with a 9 inch. I cant recall the tyre size but she is also on 16inch rims and 215 tyres (cant remember ratio). I doubt the speedo head on the cable was changed if the diff was changed when the 351 went in.
Would this error in speed be tyre circumference only or have I actualy got a different ratio diff than on the tag?
I will be taking the car down the 1/4 mile again hopefully in Sept again (if group events allowed) at our Fathers day drags hence why I am putting in the LSD.
I had traction issues with standard tyres and best ET was a 15.2 at 94mph
I am happy for it to remain a cruiser for mustang club runs and local car shows so dont need an accelerating monster as the engine HP is a modest 400 only so she isnt going to break any 1/4 mile records but a 14 and 100mph over the line would be nice!