Help me decide on springs, E34T content

[moroza]

This is *not* for a track car, but some of the same ideas still apply, so I'd like some input from more experienced folks. I'm rebuilding an E34 525iT (Touring, wagon) suspension, setting it up to be a loafy cruiser on 15's, but with less understeer. Here's what I've got:
- Slight rear weight bias, maybe 48/52
- Swaybars are for an E34 sedan (23mm front, 15mm rear), not the normal 25/15 of a wagon
- Rear track width is 14mm over stock. I realize that won't help understeer; it's for looks. Front track width is stock now, but I might space it out later to match. Wheels are 15x7 with squishy tires.
- Rear springs are the stiffest full-height (not MTech or any other lowering) available, 33531138721. These are fitted to optioned-up 525iT and stock 530iT.
- Rear shocks are Bilstein B4, on the firm end of the soft range
- Front shocks are Sachs, on the soft end of the soft range

And here's what I'm trying to do: decide on a front spring
- Choice 1 have a rate of 18.1N/mm, the same as a 525iT, but are ~30mm lower ride height.
- Choice 2 are stiffer, 20.0N/mm, the same as a 530iT, and also ~30mm lower.
- For reference, Vogtlands are ~55mm lower than stock, 18.5N/mm, and ride great but barely keep an E34 off the ground even with stiffer shocks (while I'm running pretty soft shocks).

In favor of Choice 1: correct rate for the weight, correct rate for the shocks, softer ride, less understeer. In favor of Choice 2: better match for the rear springs, less likely to bottom out, stiffer is appropriate with lower, ride will be ok.

One thing I'm not sure of is whether soft shocks with a lowered setup will last longer with a stiffer spring (keeps them from compressing as much), or with a softer one (easier to control on rebound).

Opinions?

[CSBolger]

Realistically, you're probably still within the thresholds they calculated when valving the shocks. Longevity will probably end up being affected more by your planned spirited drives than the slight increase in bump harshness.

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