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How much arch in new or OEM front springs?

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bikinkawboy

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My '77 W100 parts truck had what must have been Tough Country front springs; 5 thick leaves, plenty of arch and bouncing my big butt on the front bumper wouldn't budge them. I removed the bottom 4 leaves and replaced them with 3 thinner leaves from the rear of a Chrysler LeBaron. Under load, they now have a slight upward arch to them and there is approximately 4" of clearance between the bottom of the rubber snubber and the metal stop on the axle. I've seen plenty of older trucks with factory springs having reverse arch, but I don't know how badly they were sagged. I would think they surely came from the factory with more than maybe 2 inches of travel. Incidently, I don't want a bunch of lift, just enough to run 31" tires. Thanks!
 
I have a set of used stock front springs that were in pretty good shape when I took them out of the truck and didn't have the reverse arch like so many of these trucks show after so many years . I could count the leaves and see how many there are if you think it would help . I could also give them a quick measurement but being out of the truck and not under load , I don't think that would be much help to you . With stock springs you can run 31's without any issues at all . Also with what you did , I would imagine that a rear set of springs out of a passenger car would have less of a load capacity then the front spring meant for a truck . So I'm not sure if that was a good idea or not ?
 
This is on the truck I'm converting from 2 wheel drive to 4. The front axle I bought had been removed with the trusty old blue tip wrench. What remained of the spring had 3 leaves, all very thick with the bottom one being extremely thick in the middle. As it now stands, measuring from the top of the spring ends, loaded the spring has approximately 1 inch of positive arch measured at the axle. Before I swapped leaves, it had something over 3" of arch. The rear axle also had a second 3" block under the rear springs. I used the original 3" block on the rear axle as well as swapping in 2 of the thicker leaves I removed from the front. This helped give the old springs a bit more positive arch, which I suspect have sagged over the last 38 years. Hauling plenty of heavy loads with the snubbers resting on the axle probably flattened them some as well. I don't have the bed on, but height wise it appears the frame should be fairly level if the rear springs sag an inch or so with the bed on. When it's all said and done, I'm hoping to have the ride height correct or maybe a bit higher and that the front springs will be a bit more compliant. And run 31" tires, no bigger. I know years ago my brother's '74, '77 and '79 power wagons all rode like log wagons up front. Oh, I did have to use the existing thick, stiff upper leaf on the front springs. And don't bother measuring your springs; I really appreciate the offer but as you say, unloaded won't tell a lot. Thanks!
 
Thanks Ramtough, that's exactly the information I needed. My present setup has about .5-1" of positive arch, meaning it's just a bit taller than stock. That's just what I wanted, a bit higher but nothing excessive. I appreciate you taking the time to reply.
 
If it helps . This is what the stock springs look like .

IMG_3395.jpg
 
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