Help With "Black Betty's" Suspension

[TrentW]

I’m replacing the control arms, CAB’s (E30 M3), and tie rods on my wife’s 1988 325 (aka “Black Betty”) and while I’m in there I’m thinking of upgrading the struts, but have some questions.

I’m going to keep the car relatively stock and retain the original springs, as it needs to retain close to stock ride height and comfort. She doesn’t want the harsh ride of my car with H&R Sports/Bilstein Sports. While I would ideally prefer to get rid of some of that front fender gap, (may add some E90 drop hats just for good measure) remember, this is my wife’s car and since I’ll be adding an “is’ front lip soon, I don’t want her tearing it off on a parking barrier the first time she pulls into a parking space. I measured the clearance with the stock lip and there’s a good 8 ½”, but the “is” lip is 1 ½” thicker at the widest point, so I’ll already be down to 7” of clearance, and just over 6 ½” if I add the drop hats, which may actually be too low. Maybe I can get her to promise to back into any space with a curb. ;)

I’m considering replacing the front struts with slightly sportier ones, and was thinking of going with Bilstein HD’s, but found out the damping is the same as the Sports, which will be too harsh. I’m considering Koni adjustables—any advice on this? Checking realoem.com for part #’s so I can also order new upper strut mounts, I noticed there are two different upper spring pads (item 10), a 3mm, or a 9mm that is to be used with “red springs”. The springs currently on the car have a red stripe on them—see photo. What are these red springs? Since a taller spring pad would compress the spring more, are these some type of OEM sport spring pad or something? I’m curious because the rear shocks are yellow Sachs E30 M-Techniks, with #’s 81 4901 556 757 (see photo) and am wondering if someone upgraded the suspension at some point. I searched for a way to identify different stock springs but found nothing but a listing of spring rates.

Any knowledgeable advice on the Konis and/or the “red springs” is appreciated.

http://www.realoem.com/bmw/showparts...11&hg=31&fg=10

http://www.flickr.com/photos/59243816@N07/6332977364

http://www.flickr.com/photos/59243816@N07/6332226165

http://www.flickr.com/photos/59243816@N07/6332977060

[Balleristic31]

I wouldn't waste the money on konis for a stock sprung car. Just get some new KYBs or something. Those should be sufficient.

[TrentW]

I know, they're a little pricey, but I've read that the KYB's are no better than stock.

[M-technik-3]

Bilstein Tourings, they offer a nice ride and are a budget minded shock. Or look for some used Bilstein HD's.

[jlevie]

I've used Koni SA shocks on cars with stock springs and have been quite happy with that combination. Set the Koni's for 1/2-1 turn from full soft initially.

[TrentW]

Looks like the Bilstein Tourings are almost half the price, but are they any sportier than stock?

What about the red stripe on the springs guys--is there anywhere that lists the visual identifiers between the stock spring types?

[M-technik-3]

About the same as stock Boge's. The later date models had Bilsteins.

[Hellabad]

I know, they're a little pricey, but I've read that the KYB's are no better than stock.

Sometimes, but there are a few KYB's that are much better than stock, and e30 is one of them, particularly the rear.

I have found that the KYB struts designed and specced in the late 80's are better than the new stuff. I am quite sure that the damping designer back then knew what he/she/they were doing, and maybe they retired?

I would choose KYB over Bilstein Touring, for the reasons stated.

I like Koni the best, because you can upgrade, and I love to adjust shocks, but the price diff can't be ignored.

[TrentW]

My tech guru buddy recommended Sachs Advantage struts. Says the KYB's are junk and even said he had a used pair of KYB's that I could have for free if I wanted. Thinking the Sachs might just be the ticket for the money.

He also informed me that OEM springs with a red stripe are the softest, while green stripe springs are the stiffest, with pink and white somewhere in between. Said he has a few sets of springs that I can look through, so gonna check that out and see what I can find.