I read the article in June's issue about using math formulas to get a good baseline for spring rates for autocross and track days. One of the formulas require corner weights for your car. Did anyone do corner weights on a factory E36? I have a 328i, but if someone did one for a M3 or 325i, that will be close enough. No, I'm not finding much when I look it up on Yahoo.
Factory curb weight and weight distribution divided by 2 should get you in the ballpark.
In reply to bgkast:My number is coming out really odd. To get the rear suspension frequency to a 2, I need to use 1600 lb/in rear springs. 
That doesn't sound right. Post your math?
Check my e36 M3 build thread. I am sure I put it on my scales.
Its there on the first page. Its a 6 cyl though.
E36 motion ratio: front .88 rear .46
E36 wheel rate Front: 67.37 Rear: 44.44
E36 curb weight approx. 3174 lbs corner weight approx. 793.75 lbs with 50:50 weight dist.
Front factory suspension frequency: .915
Rear factory suspension frequency: .743
Front suspension frequency w/500lb in springs: 2.19
Rear suspension frequency w/1600lb in springs: 2.05
Corner weight- front: 809.37 lbs rear: 777.63 with 51:49 weight dist.
Front factory suspension frequency: .906
Rear factory suspension frequency: .751
Front suspension frequency w/ 500 lb in springs: 2.17
Rear suspension frequency w/ 1600 lb in springs: 2.07
I went off a couple of people on a BMW forum that said the front motion ratio is .88 and the rear motion ratio is .46. I also went with an online source for factory spring rates of a M3. I should have dropped the spring rate by 10% since I have a regular one, but it should be close enough. I can post the formulas if someone needs it.
http://www.uucmotorwerks.com/html_techtip/techtips/e36_m3_spring.htm
You'll need to log in to post.
