Custom Bay: Turning Over a New Leaf

Jan. 1, 2020

Despite their strength and simplicity, leaf springs on a rear suspension don't last forever.

Replacing Leaf Springs on a Rear Suspension

rear leaf springs Eaton Detroit Spring Eaton Eaton Detroi leaf springs specialty parts vehicle customization Despite their strength and simplicity, leaf springs on a rear suspension don't last forever.

"All springs have an effective life," notes Mike Eaton of Eaton Detroit. "They can gradually settle down — like your kids growing older. Or they will break, usually when the vehicle is empty and the spring goes up and into rebound."

Replacing a worn-out or snapped spring is a fairly simple proposition and a high-volume business. Last year, Eaton Detroit shipped out 20,000 leaf springs, and that's just from one company. Applications include everything from older cars to newer trucks and SUVs, as well as trailers and off-road equipment.

Replacement springs are just one aspect of the business. Lowering springs for street rods comprise nearly half of Eaton Detroit's orders. Even though some restoration projects modernize an older chassis with the latest suspension technology, that's not necessary or even desirable for all cars, particularly a collectible. Sometimes simply replacing worn leaf springs or adding lowering springs in the rear can give a street machine a whole new feel. Not only that, using leaf springs looks original, so you won't change the appearance of a classic or muscle car.

For instance, on the 1967 Chrysler C-body station wagon shown in the accompanying photos, the left side was starting to sag (probably because of the extra weight of the driver and gas tank), impacting both the ride and handling. Metal fatigue and/or worn bushings usually are the cause. (Eaton points out that the type of mounting, such as a rubber one that allows movement, affects spring life.)

Replacing old leaf springs with new ones is a straightforward, bolt-on deal, using only shop tools and preferably a lift. The one shown here, however, was done in a home garage, so for safety's sake, we used several jack stands and protection for both eyes and hands.

Actually, the hardest part of replacing or installing lowered leaf springs is determining the right size. That's why Eaton's Web site provides detailed info on how to measure springs. Alternatively, you need to provide the following info: year, make and model of vehicle, engine size, body style, whether it's air-conditioned or not and ride height (stock or lowered). Then the company can identify the correct size with no measuring needed.

Typically the entire install procedure can be completed in a few hours. Your customer should notice an immediate difference compared with their old springs. Not only that, you'll also be able to say that you've turned over a new leaf!

Steve Temple is a freelance technical writer and photographer with more than 25 years' experience. He has served as director of sales and marketing for Shelby American and as online editor for major magazines such as Hot Rod, Car Craft and Rod & Custom.