Packard Forum Index » Pre-War (1899-1942)

Is there anyone on the forum that understands spring load and rate ratings? I want to replace 37-120 front springs, with sidemounts, and want to understand the difference between 1570x75 and 1570x90 springs. Thank you.

DAF

Here's a place to start:

eatondetroitspring.com/spring-rate-vs-load-rate/

I pretty much understand that. In fact, I spoke with Mike Eaton at Detroit Spring twice regarding making me a pair of springs. Problem is, unless you buy at least 50 pairs, the setup cost would be quite painful. So unless there are 49 other guys out there wanting a set of springs for 120c's with sidemounts to original specs, (and I wanted a slightly taller ride height to compensate for modern tire diameters....) I am pretty much dead ended with having some custom made. I am now researching what NOS springs are out there, and if one reviews the parts book, its almost as complex as shock absorber options...

So here's the question. How can two different spring numbers with similar ratings (1435x70 , and 1450x100; 115c and 40-110 sedan) result in such different ride heights? 8 3/16" vs. 9 5/16".

I'd like to raise the nose slightly so I can run the same 31" tires I have on the rear, but I sure don't want to raise it too much....

Is there enough room in the cradle or nest in the lower A frame to add a shim or spacer? If so you might want to inquire what the specs are on the Kanter repro springs or a stock spring from Detroit. I've never asked Fred as to whether their springs are "generic" or available in each of the original spring calibrations - perhaps James will come along with the answer, or perhaps you might call them to inquire. Or perhaps you've already been down this road.

You might want to check with ESPO Springs 'N Things, www.springsnthings.com. I dealt with them a few years ago and I was happy with their price and their product. As I understand it, they wind coil springs to order and their system is computerized. I'm sure they can make adjustments to give the desired ride height and they won't make you buy 100 of them to get the 2 you want. Keep in mind compressing those coil springs can be challenging as modern spring compressors are useless in respringing our Packards.

I don't think anybody has answered your question yet.

What those numbers mean is the first number is the load rating for the spring and the second number is the rate.

The rate is the weight required to deflect the spring one inch.

The higher the rate number the harsher the ride.

So for the above numbers 1570 90 is a harsher riding spring than a 1570 75.

Now I'm just taking these definitions from my reference manual. Packard of course loved to use their own systems so it may not fit these numbers.

As well the original Packard springs may have been variable rated and I don't have any of that information.