The Stovebolt Site Forums The Shop Area Driveline How to tell if my leaf springs have lost their arch?

Question: how can you tell if the springs have lost their arcs? Can it be done “on” the truck?
For your information my truck is 1948 ½ ton.

For the rear springs you can use the attached excerpt from the 1948 Vehicle Info Kit as an indication. Note that it's a "loaded" dimension, so if your tailgate is less than 25-3/4" above the ground with the truck bed empty, then your rear springs are definitely sagged.

Here is the GM information packet, https://www.gm.com/content/dam/comp...hevrolet-trucks/1948-Chevrolet-Truck.pdf about midway through it is the information on springs. It doesn't really tell you waht you are asking, but it does have some good information to use if you go shopping for replacements.

Ask around and find a few other trucks equipped like yours and get a measurement from frame to top of axle. If yours is setting lower, chances are you have weak springs.

If you are willing to get to work, you can pull the springs apart and re-arch each leaf yourself, if you have press it goes easier. Lay each leaf on cardboard and trace the arch, then making small bends, increase the arch in a smooth curve. The next leaf should follow the same new curve you just made. Stay out away from the center bolt area. No heat is needed. Lots of DIY video's showing how to do this.

$200 each. I`d say if the springs are original to the truck, they need replacing.
but this.... Ask around and find a few other trucks equipped like yours and get a measurement from frame to top of axle.
If yours is setting lower, chances are you have weak springs.

Doing a cold re-arch is a temporary fix at best. Once a spring has sagged, it will return to that shape pretty quickly. The proper way to re-arch a spring leaf is to anneal it, re-establish the correct arch and then retemper it. Very few spring shops and virtually no hobbyists have the equipment or the metallurgy experience to do that.
Jerry

The spring leaves also wear. I have some sitting in the shop with notches worn maybe 1/8" into the leaf where the spring leaf above it sat slight slightly misaligned. When I have them apart for whatever reason I lube them with open gear grease used on mining equipment etc. Smooths out the ride considerably and reduces wear.

My originals were also notched from wear, I rounded the ends over so they would slide up over the notches. My old truck was plumb wore out from the old heating & plumbing companies hard use.