Yeah, the later 140s already had the perch that's needed, but our early 68's don't. But about the springs, putting cut 245 springs on the back is a lot stiffer than a stock rear 142 spring... I haven't heard about this worrying about putting a non matching setup on the car either. I mean I know it isn't optimal, but since when does someone not increase a spring rate for one end of the car in relation to the other end? Normally you'd want to increase the rear spring rate more just because it's conservative from the factory. Here's an example of Volvo's doings, the '79 GT came with R-Sport front springs, and kept the same rear springs.

I can't find the stock spring rates for a 245 and a 164, I'd like to take a look at them so I might know just what we actually are dealing with. I know I won't be flipping my car though...

PS. I'm getting the 164 springs and 245 springs for $20. The rear springs are already cut for a 142 fitment, and I know some people who can cut another coil or two off of the 164 springs(they've already had one coil cut off).
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Kyle E.
VP of Membership and Website Administrator
Oregon Volvo Tuners
Portland/Corvallis, OR - 1968 142 - 71b20b SUs, m40, ask me for more info...