Springs for heavy E30

[Ekohn04]

Hi everyone, I have a 1987 325ic that I have recently added a lot of weight to. I would love to get it on the scales, but as of now it’s slammed on its nuts courtesy the previous owner, so much so I can’t drive anywhere. My estimate is that the car weighs around 3100-3200 pounds, a 3-400lb increase from the curb weight. What springs should I get for this car? I want to be lower than stock ride height but I don’t want to scrape on speed bumps either. I’ll be driving on some curvy mountain roads, hopefully with some speed. I don’t know a lot about springs and shocks in general, so any recommendations will be much appreciated. Thank you!

[Panici]

It sounds like you'll be into a set of coilovers with custom spring rates.

What have you done to bump up the weight so much?

Big V8 and huge car audio system?

[Ekohn04]

A big motor and a huge battery pack actually :) I've estimated I removed about 700lbs, and the motor and batteries weigh around 1,000lbs. It is rear biased as well, probably around 60% rear 40% front. I really want to avoid coilovers. Any other option you can think of for me?

[varg]

Gotta weigh the car first. Otherwise you're just guessing, IIRC a 325i convertible weighs about 3,000lb even. Did you buy that tesla powered convertible or something? I also want to know how so much weight was added, 3-400lbs on an E30 is tough... An LS+T56 swap would only gain ~150lb over an M20, an iron block "LS" would add another 100ish to that. That's still only 250lb. Springs intended for a convertible exist, there's a thread somewhere on r3v about convertible suspension options.

[Ekohn04]

You're right, I should probably get a proper weight before I get springs -- especially if it means I might have to go custom. I built the car myself, I'm almost finished. I've added an appropriate amount of chasis reinforcement for the added weight (and torque). I'll definitely look for that thread on convertible suspension options, but this is an unusual case so I wanted to get advice specific to my situation. Thank you!

[digger]

the change in stiffness should be directly proportional to the stiffness of a known setup that you are happy with at stockish mass.