E30 325iS & M3 spring comparison (pics)

[Garageaholic]

The black is from my 89 325is. The red, I purchased as used M3 springs.

The M3 springs look slightly thinner, yet shorter (for the slight drop).

Can you guys confirm that these are M3 springs? They just don't feel any stiffer than the 325is springs.

[PNWDan]

M3 springs are black and same wire diameter. Just 1 coil less in length.

[Garageaholic]

I found this on an old forum

The color doesn't bother me. They were powder coated. Also, I looked up the P/N on my red springs and they are BMW 1130046. As confirmed by an old forum lookup I found on Google below (This guy had the same exact question I had on June of 2001, my springs are certainly M3 springs...

QUESTION:
> My question is, are these really E30 M3 springs? I went to install them
> last night and discovered that they are just as tall (free coil length) as
> the stock E30 325is springs (stock OE springs) I have now. On the front,
> both sets of springs have the same number of coils (seven) and I thought
the
> E30 M3 springs had six coils. In addition, the E30 M3 springs have a
> smaller diameter wire than the E30 325is springs currently installed. In
> total, these E30 M3 springs were longer and would be softer than the E30
> 325is springs so I do not believe they are E30 M3 springs.
>
> Am I correct or not? Any ideas or can anyone identify what springs these
> are?


ANSWER:

K(spring rate) = Gd*4/8ND*3 where G = 11.5x10*6, d = spring wire dia, N =
total turns-1.5, D = spring dia.


E30 M3 front spring BMW part # 1130046
D = 5.09"
d = 0.484"
Free length = 12.69"
Total turns = 6
Spring rate 132 lbs/in

E30 M3 rear spring BMW part # 2226147
D = 5.04" (in center)
d = 0.590 (in centr)
Free length 8.38"
Total turns = 6 1/4

E30 325is 12/88 front spring BMW part # 1132742
D = 5.09"
d = 0.502"
Free length = 13.81"
Total turns = 7
Spring rate 125 lbs/in


E30 325is 12/88 rear spring BMW part # 1134702
D = 5.09" (in center)
d = 0.504" (in center)
Free length = 9.88""
Total turns = 7 3/4

[Tanktheory]

Just what I was looking for, hooray for science!