Anyone know how to determine the "spring rate" on rear suspension coil springs.
-The ones that I just took off my car appear to be the stock ones and I've heard are either 90 or 100lb springs.
-The aftermarket ones I have here feel stiffer to push down. They are painted yellow and I don't see any markings on them. They are also several inches shorter than the stock ones that came off the car.
-Any way of know what pound springs these yellow ones are?

https://www.thespringstore.com/spring-rate-calculator.html

I've used a 400 lb digital postal scale in a drill press. Weigh the spring first!

the old yellow ones were made by pacesetter and were rated at 120 lbs

The original stock springs were in the 50-65 lb/in range.

You can measure the spring rate; it is pounds of force divided by inches of compression. Put weight on it, measure how much shorter it gets.

--DD

Also take a look at the link in my signature on how to put together your own spring combo that is fully adjustable.