Restore 1991 318is to stock height - Much confusion, PLEASE ADVISE

[BHT2109]

Hey everybody! Got a (long-winded) question regarding shocks and springs, and I really need some advice. I know that this sort of topic has been covered before in other areas, but I really can't seem to find any up-to-date, definitive answers. Here's the dilemma:

I need to refurb the suspension on my '91 318is in order to better suit the NYC roads that I'm commuting on. It is currently lowered on Vogtland springs and Bilstein B4s (by previous owners), and both the ride height and stiffness are intolerable on these Brooklyn streets. WAY too many potholes and speedbumps around here - the roads are really just awful. I want to raise the car up as much as possible (which I guess means "stock"), and also soften up the ride a bit. Every time I go over even the slightest imperfection in the road, it reverberates throughout the entire frame and shatters my teeth. Additionally, I'll be rehabing lots of spring pads/end links/bushings/etc, so no real issues there.

Problem is, most of the information online seems to be aimed at lowering springs; these discussions are only minimally useful to me. And all the info that pertains to my specific needs is either out of date or contradictory.

Also, parts availability seems to be an issue. Springs-wise, the only options that I've found seem to be new OEM BMW springs from ECS ($$$, and only fronts available), used BMW stock from Ebay (but I'd rather buy new), or H&R "OE Sport" (rather than the straight-up "Sport"). Everything else seems geared toward lowering. Anyone have any other ideas for "stock" springs?

As far as shocks, Sachs/Boge seem like the option I'm hunting for, correct? BavAuto/Pelican/ECS still appear to have these in stock. Adjustible Konis seem intriguing, but pricey. Any other suggestions (remember, my old man bones are looking for a softer ride)? Haven't read great things about KYB or Meyle...

So I guess what I need from you guys is this:

1. Will the H&R "OE Sports" fit on the 318is? ECS says No, Turner says Yes, and the guy on the phone at H&R said that part# 50404 ("Sport Springs") and part# 50404-55 ("OE Sport Springs") are essentially the same thing, and that they will fit. Confused? I am! Does anyone have experience putting these "OE" springs under an E30 318is?

2. As far as matching springs and shocks, what should I watch out for? Will the H&Rs and the Sachs/Boge play well together? Do I need to pay close attention to spring rate and load weight and whatnot?

Any advice is most appreciated. I'm pretty new to the E30 game (just bought my baby a few months ago), so I hope you'll forgive rookie mistakes. If the answers I'm looking for are already published, kindly direct me there.

Here's a photo of the current ride height for reference:



Thanks all!

[nrubenstein]

Bilstein B4s are a fairly stock analogue shock. They are slightly stiffer than Sachs, but not much. I'd recommend leaving them on, unless they are old.

H&R OE Sport springs still lower the car a lot from stock. If you want stock height, suck it up and buy used, or suck it up and go to the dealer. OE Sport springs are also close to double the stock stiffness in front.

If you want a slightly lowered compromise spring, find an E30 M3 set.

[5Toes]

Bilstein B4 is awesome for your application. People literally give away their factory springs, why do you think you need new ones?

[BHT2109]

Bilstein B4s are a fairly stock analogue shock. They are slightly stiffer than Sachs, but not much. I'd recommend leaving them on, unless they are old.

H&R OE Sport springs still lower the car a lot from stock. If you want stock height, suck it up and buy used, or suck it up and go to the dealer. OE Sport springs are also close to double the stock stiffness in front.

If you want a slightly lowered compromise spring, find an E30 M3 set.

Oh man, I was hoping to avoid the dealership prices, but I'll pay them if it gets me what I want. I suppose I might as well try to source used OEM before going to the dealership.

That bit about the M3 springs is a bit confusing: what does that mean, exactly? When I search for parts on ECS (for example) as an M3 owner, the OE H&Rs come up, as well as new BMW springs (part# 31331130046). But when I identify as a 318is owner, the OE H&Rs are gone, and the BMW springs are exactly the same. Do you mean that I should try to source used E30 M3 springs from some dude whose also doing a suspension refurb?

Bilstein B4 is awesome for your application. People literally give away their factory springs, why do you think you need new ones?

I think I need new ones for three reasons: 1. The bone rattling sensation every time I go over anything but perfectly smooth tarmac; 2. I can see that the car sits lower that I want it (I'm a stock purist at heart), and; 3. I'm attracted to the idea of attacking an entire system (i.e. suspension) rather than plugging in new parts piecemeal as they fail. I bought this car from a standup guy who is quite mechanically inclined, but I still want the piece of mind that goes along with overhauling an entire subsystem myself.

Perhaps I don't truly understand what is happening when my car is violently bottoming out? When a Buick LaSabre goes over a bump, it bounces like you're driving a sofa - is that due mostly to shocks or springs (or both)? This is not to say that I want to turn my baby into a Buick - far from it. I'm just trying to understand the underlying concept.

Thanks so much for your input guys! Keep the suggestions coming!

[nrubenstein]

Well, a Buick LeSabre has inches more suspension travel that you will ever have. That said, the higher you get your car, the better it will cope with bumps. The bone rattling sensation is because the lowering springs that you have (like most lowering springs) are crap. The shocks may have been trashed by your springs (how old are they?), but B4s ride very nicely.

H&R OE Sports will fit on ANY E30. They are a lowering sprig and higher rate than stock. They are in no way whatsoever a stock equivalent. They merely don't lower the car as much as most lowering springs.

If you want a stock-like spring that sits a little lower, E30 M3 springs are a nice option.

If you want to be stock, you need stock springs. Period.

I have Bilstein B4s with E30 M3 springs on my 325is. It's a great setup. The ride is very good (I live in Washington, DC and drive around NYC frequently), handling is acceptable, and it doesn't have the skyjacker look. If you need a little more suspension travel, GC Touring plates will gain you an extra half inch or so of travel.

[nrubenstein]

Attached is a random picture that I just happened to have of my 325is on E30 M3 springs and Bilstein B4s.

[BHT2109]

Attached is a random picture that I just happened to have of my 325is on E30 M3 springs and Bilstein B4s.

Lovely! I've never really been partial to brilliantrot, but man you're turning me around on that!

As far as the ride height, it still looks a little lower than what I think I'm after, particularly in the rear (but with the angle, who's to say definitively?).

I came across this photo randomly on this site this morning (while researching aux fan switches, of all things), and I liked the look:



Shall we speculate as to it's setup? Simply stock? Also, I think I may have cleared up my "What exactly are M3 springs" confusion by going on BMW of South Atlanta's website and simply searching for springs for an M3. Much more accurate and comprehensive than an ECS search!

Anyway, I came up with Part# 33539061510, which is a rear spring set, and seems widely available. Now, I just need to deduce if they will allow the rear to sit a bit higher than the Vogtland Sports that are currently on there. According to spring rate charts I've seen floating around, the M3s are a bit lower (which is what I'm aiming for), but does spring rate translate directly to overall height? Like, the lower the spring rate, the taller the spring?

Eventually, I'm going to just have to bite the bullet (drink the Buillet?) and get to wrenching, but I just wanted to make sure that I was making the most informed decisions possible. Thanks so much for your assistance!

[varg]

Perhaps I don't truly understand what is happening when my car is violently bottoming out? When a Buick LaSabre goes over a bump, it bounces like you're driving a sofa - is that due mostly to shocks or springs (or both)? This is not to say that I want to turn my baby into a Buick - far from it. I'm just trying to understand the underlying concept.

A Buick LeSabre bounces because it is underdamped, the shock valving is inadequate to control the motion of the body so it oscillates as any undamped sprung mass will. I don't know why people are convinced that bouncing and floating is a "nice ride", but it seems that's what people are conditioned to think, but I digress. For us, spring rates are in lb/in, 200lb/in means for every 200lbs on the spring it will compress an inch. The higher the rate the stiffer the spring. If you have a lot of suspension travel you can use a softer spring and not bottom out, less travel means more spring rate will be required to stay off of the bumpstops. If you have a 10" spring rated at 200lbs/in with 400lbs on it and an 9" spring rated at 400lbs/in with 400lbs on it they will compress to the same height. It does get more complicated with wheel rates and motion ratios but that's not necessary to get into for this discussion.

In your case I'd just buy a set of used oem 325/318is springs. I tossed mine in the scrap when I converted to coilovers figuring nobody would ever want them, and many people here have done the same. Put a wanted ad up, people are always swapping springs for performance and/or lowering.

E30 spring rate reference:

http://e30performance.info/viewtopic.php?t=1357

[AndrewBird]

For looking up stock part numbers, use RealOEM.com. Just copy and paste the part numbers into ECS/BluntTech/BMA etc to purchase.

Honestly though, just get a set of used springs from someone. They might have sagged slightly over the years, but they will still give you what you want. Stick with the struts you have now and if it is still too harsh, get some OEM non-sport struts.

[nrubenstein]

Lovely! I've never really been partial to brilliantrot, but man you're turning me around on that!

As far as the ride height, it still looks a little lower than what I think I'm after, particularly in the rear (but with the angle, who's to say definitively?).

I came across this photo randomly on this site this morning (while researching aux fan switches, of all things), and I liked the look:



Shall we speculate as to it's setup? Simply stock? Also, I think I may have cleared up my "What exactly are M3 springs" confusion by going on BMW of South Atlanta's website and simply searching for springs for an M3. Much more accurate and comprehensive than an ECS search!

Anyway, I came up with Part# 33539061510, which is a rear spring set, and seems widely available. Now, I just need to deduce if they will allow the rear to sit a bit higher than the Vogtland Sports that are currently on there. According to spring rate charts I've seen floating around, the M3s are a bit lower (which is what I'm aiming for), but does spring rate translate directly to overall height? Like, the lower the spring rate, the taller the spring?

Eventually, I'm going to just have to bite the bullet (drink the Buillet?) and get to wrenching, but I just wanted to make sure that I was making the most informed decisions possible. Thanks so much for your assistance!

One major issue that I've found with aftermarket springs is that they are surprisingly prone to blocking (that is 100% compressing). This makes the ride terrible, as you've effectively got no springs at all in front when this happens.

The rear doesn't need to be particularly high to have adequate travel (although I understand the desire for more height for other reasons of practicality).

Net-net, the solution that you will probably be happiest with is a set of good used OE 318is springs.

[BaltimoreBimmer]

I'm not going to lie. It's pretty depressing there are no aftermarket OEM equivalent springs for these cars. Especially with their cult following.

On the flipside though, it's cool that BMW still offers them and honestly, they don't seem that ridiculously priced. ~600 bucks for all 4 springs manufactured with BMW's QA seems very reasonable. I mean, how cheap should they be?

What is the going price for a set of used 25+ year old springs? I'm willing to bet is depressingly higher than I would expect? (thinking of all the absolute crap old OEM e30 stuff for sale on craigslist as if they were like-new parts)

[nrubenstein]

I'm not going to lie. It's pretty depressing there are no aftermarket OEM equivalent springs for these cars. Especially with their cult following.

On the flipside though, it's cool that BMW still offers them and honestly, they don't seem that ridiculously priced. ~600 bucks for all 4 springs manufactured with BMW's QA seems very reasonable. I mean, how cheap should they be?

What is the going price for a set of used 25+ year old springs? I'm willing to bet is depressingly higher than I would expect? (thinking of all the absolute crap old OEM e30 stuff for sale on craigslist as if they were like-new parts)

A hundred bucks or less, depending.