1979-1993 & 94 Conv [Subscribe to Daily Digest] |
Short answer: Don't bother changing your springs.
Long answer:
As you've learned, springs can sag and "take a set"; however, their rate does not change, only what's called their "free length."
Spring rate is determined by some, but not all, of the spring's physical dimensions: number of coils, coil diameter, spring diameter, and metallurgical properties (modulus of steel). Note that I excluded free length from the list of attributes.
These physical characteristics are all constant over time (unless you compress the spring so much that you de-activate a coil, which is highly unlikely). (On c900 springs, there are "dead" coils at each end, to facilitate positioning/securing the spring between its perches. These dead coils are not related to the rate.)
So, regarding the front springs: if they are not sagging, and I've neither seen anyone write that theirs have nor seen a c900 with sagging front springs, then there is no reason to replace them. Furthermore, unless you have the Saab spring compressor tool, a front spring job can be a total PITA, not to mention scary, when you pull a spring out of the wheel well that's compressed by some cheap-ass hokey Chinese-made spring compressor.
Finally, I have read that the Scantech springs aren't great, but have no direct experience with them. My experience with most Scantech parts is that they are neither well-made nor durable (exception: control arms).
But, wait, there's more. Saab fitted different spring rates and lengths over the years, depending on trim level, body type, and transmission type. There is certainly a chance that you would be replacing your OEM springs with ones of a different rate that could potentially change the car's ride height and/or handling characteristics (in fact, your stiffer rear springs probably will make the car understeer at the limit less).
Bonus: Shocks don't control ride height; springs do. Exception: some gas-charged shocks can slightly raise ride height.
Extra Bonus: For better handling, the two most significant changes you can make to the car are better tires and a front end alignment with about -1 to -1.5 degree camber. This, with an ultra-high-performance 205/50-16 so-called "summer only" tire will transform the car.
posted by 65.102.159...
A spring manufacturer's explanation of springs
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