The Stovebolt Site Forums The Parking Lot '60-'66 Trucks 3/4 ton rear springs on a 1/2 ton 66

has anyone ever installed 3/4 ton srings on a 1/2 ton in an attempt to gain greater load capacity?

I assume your talking about rear coil springs. Yes I have and you gain a little bit but the overload springs are what make the most difference. Once the overload springs touch you can just about put anything in the truck and the bumper height wont change. The coil springs are a bolt in swap. Another option you might consider is air assist bags. These are air bags that fit inside the coil spring and you fill just like air shocks. They are available from JCWhitney or your local truck accessory store.

I have a '65 C20, and let me tell you, I now know where the old saying "it rides like a truck" came from!! I'm sure you'll gain a little load capacity but you'll pay for it in ride quality. Other things to consider: tires play a big role in how much a truck can carry. Also, 3/4-ton wheel bearings are heavier duty than 1/2-ton. The front end of the truck also carries load weight, so you don't want to carry so much of a load that your front suspension is compromised. Brake are another factor.

All things to think about.....

This is a great way to go. You get the smoother ride that a 1/2 ton provides, but when you need temporary extra capacity you air up the coil assist bag. This also puts the extra load where it was designed to go, into the frame and the trailing arms. Unlike air shocks which attempt to hold up the load via the shock mounts, which were not designed to see these loads.

Here is a photo of an air spring in one of our era trucks: http://inlinethumb30.webshots.com/47517/2104497230103882008S600x600Q85.jpg

Email the folks at Airlift Company, they make a living selling these and can steer you in the right direction.
http://www.airliftcompany.com/products/air-springs/air-springs-overview