A four day drive from Key Largo to Connecticut in a nearly 50 year old car requires proper preparation. Making sure the car is running properly is one of themost important requirements. The 1973 Giulia Super developed a clunking sound coming from the differential. This could be minor or possibly lock up the rear wheels on the interstate, so replacing the “diff” was decided the best option. The original engine in the car was a 1.3 that was replaced with a 1.6. With the added power a higher ratio rear-end designed for the 1.6 was located. The original ratio diff was 43:9 – The replacement is a 41:9 ratio and will give the car more speed at the same rpms as the original differential.
Fitted into the rear end were new inner bearings and seals and new wheel bearings. The old ones where showing signs of serious wear.
Final results of RPM to MPH in 5th Gear
3,500 rpm = 63mph
4,000 rpm = 71mph
3,500 rpm = 67mph
4,000 rpm = 76mph