Yes, with the same spring and same preload length, the ride height will remain the same.herr_sparky wrote:distance between the spring seats:
OE:266mm mod:210mm
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again, a difference of around 60mm/2 1/2"...theres no way i'm going to try and compress the coils nearly 10" to get them in, so my question is this: if i make the stub's length from shoulder to shoulder (forget about the threads for a moment) 2 1/2" to preserve the same preload, won't i just be replicating the same ride height of the OE struts? and if, instead, i made the stub with a shoulder to shoulder length of 1" (ignoring the preload issue for a moment) wouln't that result in a lowering of the 1 1/2" i'm looking for? do i have the concept right? if i do, i dont see any way around relocating the lower perch in order to preserve sane preload...unless 8 1/4" between spring seats seems sane to anyone...
With the same spring and a shorter preload length (shorter rod), the ride height depends on the preload force compared to the car weight. Unloaded length minus loaded length equals droop travel. Droop travel is needed to allow the wheel to travel down instead of the body (i.e. inside wheel when cornering; wheel when dropping into pot hole). If the preload force is greater than the car weight, the ride height will be lower - the car is too light to deflect the spring at it's current preload and no droop travel results. If the preload force is lower than the car weight, the ride height will not change - the car deflects the spring beyond the preload just like stock but with less droop travel.
I would not be concerned about greater spring preload force because the spring gets compressed to this load during use. However, I am concerned about loosing droop travel.
Lowering the lower perch and/or shortening the spring will lower the car while retaining droop (and bump) travel. However, lowering the perch has limitations due to wheel clearance. I've found the BWM E30 M3 spring/Audi 4000 insert/Mazda spring plate bearing/aftermarket bump stop to be a good combination that lowers the front rocker panel about 5/8" compared to the rear.
Shown with 205/50's front and rear:
