The Dreaded Vintage Ferrari Leaf Spring
This week’s job was to install the leaf springs on the blue GTE I have at my shop. Vintage Ferrari leaf springs are strange beasts. They are very tricky to install and I often feel it’s one of the most dangerous things to fit these cars because of the amount of tension involved.
Vintage Ferrari leaf springs are pre-tensioned, so when they are removed from the car, they form the shape of a U when relaxed. To get the spring shackles to line up with the frame of the car, the spring has to flattened out with a strong tool that can pull the ends down.
Besides not lining up with the frame mounts, the shackles need to be in the correct orientation so the car sits at the proper ride height. If you look at my illustration, the top figure shows when the shackles are incorrectly orientated. This will force the car to sit too high and ride stiffly. Flattening the spring out further allows the shackles to sit in their correct orientation and proper ride height. To keep the spring properly flattened, there are limiting cables than have to be properly anchored to the frame to keep the axle from dropping too far down when the car is raised by the frame. Without these limiting cables installed, the curve of the leaf spring will pop (usually very violently) inwards back to the incorrect position.
The anchors to secure the limiting cables were missing on this car, so I machined a set out of some round stock. I don’t have easy access to a Bridgeport milling machine, so I had to grind the pockets out for the cable ends. Someday if I have the space, skill, and opportunity, I’ll get a Bridgeport!
New Delrin bushings were also machined for the rear suspension, so everything was finally going back together. I took my time getting all the parts in place, and gingerly installed the parts, making sure the whole time I stayed safe while things were tensioned. Not only do all these spacers and bushings have to go in, there are locating arms that have to line up with their bolt holes. I let you know when I survive the installation!