Frame / Springs: Truck spring interchange.

[oilnsteel]

Hi All,

SI has Champ 1/2 ton rear springs on sale. How do they differ from 3E rear springs?

Jim

[r1lark]

Not to give a short answer, but to answer that we need to know what part number springs SI has, and what spring is on your truck now.

[oilnsteel]

The springs SI has on sale are 1693361X. They are rear two stage HD 6E thru 8E models 5 and 7. My Truck is a 1957 3E7. It currently has rear springs of unknown origin. The leaf count does not match up with the springs in the parts catalog.
The correct HD spring for my truck is 1685100.

Jim

[r1lark]

Jim,

The 1693361 springs started being used on the 6E trucks. (BTW, I don't know what SI is designating with the "X" at the end of the part number -- you may want to ask them about that.) It is listed as a Heavy Duty spring for 6E5 and 6E7, with 8 leaves. (Didn't look in the 7E/8E parts catalog, but SI is already saying they continued thru to the 8E series.)

The 3E7 spring you noted, 1685100, was a Heavy Duty 12 leaf spring. The ride would probably be similar with the 1693361 spring. To me, less leafs are a plus because that means less friction between leafs so the ride may be somewhat better. Does your truck have the 12 leaf spring now, or does it have the standard p/n 681904 spring with 11 leafs? So if you have the 12 leaf springs now and like the ride, you would probably like the ride with the 1693361 spring.

Now the kicker, which may require some research on your part. Your 3E7 truck uses 12 total rubber bushings in the spring eyes. The 6E5/6E7 truck switched to 4 rubber & steel insert type bushings, similar to the '53 (maybe earlier) thru '66 car rear spring bushings. The shackle part numbers also changed with the 6E5/6E7 trucks. So whether you can press out the rubber/steel bushings and use the older style rubber bushings and shackles -- I don't know. And whether you can use the later 6E5/6E7 shackles with the attachment points on your frame -- I don't know.

An hour or so of sitting in your favorite chair studying the parts manual(s) may give you the answer as to whether you can use the newer shackles on your frame. Or, even better someone who has had these trucks side-by-side may be able to tell you whether this swap is possible.

If needed for comparison, I have my completed 8E frame in the basement with all the suspension on it, so would be happy to take pictures if needed. Let me know if you need pics (or measurements) -- and what exactly you need photographed/measured.