M42club.com - Home of the BMW E30/E36 318i/iS

DISCUSSION => Suspension => Topic started by: John W on October 20, 2007, 11:41:28 PM

Title: m3 springs on e30 318?
Post by: John W on October 20, 2007, 11:41:28 PM

Considering buying a 91 318i. Do e30 m3 springs fit this car front/rear or must other components be retrofitted from an m3 as well to make this possible?

Thanks

Title: m3 springs on e30 318?
Post by: eric ^__^ on October 21, 2007, 01:17:50 PM

Good question! *waits*

Title: m3 springs on e30 318?
Post by: gearheadE30 on October 21, 2007, 01:38:23 PM

Yes, they fit. The ride hight should even be about right, considering that the balance of an m42 car is close to that of the m3. I am fairly sure that the 318i has the 51mm struts like all the other e30s, save for the m10 318i. This means that shocks and springs are interchangeable.

M3 springs are not very stiff, so if you are looking for a big increase in mechanical grip I would go with H&Rs or something.

Title: m3 springs on e30 318?
Post by: John W on October 21, 2007, 03:46:10 PM

Thanks. I want to refurb the suspension a bit (new shocks and struts) and if I can find these springs used for a reasonable price I'll throw them in at the same time. I want something that looks stock -- even if you physically look at the spring from underneath the car.

Title: m3 springs on e30 318?
Post by: christophbmw on October 21, 2007, 04:25:42 PM

they will fit like stated above, it will drop the car about 1/4" in the front.....not to noticible though. and they have a better spring rate.

Title: m3 springs on e30 318?
Post by: eric ^__^ on October 21, 2007, 05:39:54 PM

this is exactly what I'm looking for in upgraded springs

If I could get my car to handle like a stock M3 I'd be more than pleased :)

Title: m3 springs on e30 318?
Post by: christophbmw on October 21, 2007, 07:31:48 PM

Quote from: eric ^__^;36237

this is exactly what I'm looking for in upgraded springs

If I could get my car to handle like a stock M3 I'd be more than pleased :)

thicker sway bars (from an M3, the ones on the car are way to small), bilstein shocks, and some M3 springs should get you close to its handling. the M3 has different front control arm bushings giving the car different front end alignment. it might have a different wheelbase width, but our car is more than 100lbs lighter so that should make no difference.

Title: m3 springs on e30 318?
Post by: gearheadE30 on October 22, 2007, 09:42:11 AM

Sawybars from the M3 do not fit, though. M3's have the mount on the strut, ours are mounted to the control arms. You would either have to get some M3 struts or weld the mounts onto the factory strut housings.

As for the bushings, they are about $60 and are offset to increase castor (sp?). The factory concentric bushings are not solid, so there is a lot of steering play and alignment change around corners. Put the car up on jack stands and push the tire foreward with your foot. The bushing will bend close to an eighth of an inch with that little bit of force.

Title: m3 springs on e30 318?
Post by: eric ^__^ on October 23, 2007, 01:23:04 PM

I just replaced the bushings, so :(

Title: m3 springs on e30 318?
Post by: christophbmw on October 23, 2007, 07:22:00 PM

Quote from: gearheadE30;36275

Sawybars from the M3 do not fit, though. M3's have the mount on the strut, ours are mounted to the control arms. You would either have to get some M3 struts or weld the mounts onto the factory strut housings.

did not know that.....:o

Title: m3 springs on e30 318?
Post by: ducatipaso on October 23, 2007, 08:10:29 PM

I have E30 M3 springs in my cabrio with just a basic set of Bilstein Touring... a huge improvement over stock, and suited for my driving style just fine. I'm still looking around for a mild anti-roll setup.
 
Here's before and after with the springs. You'll see it's quite subtle.
 
(http://row10.net/d/15164-2/IMG_1064.jpg)
 
(http://row10.net/d/15075-2/IMG_1274.JPG)

I bought 'em used off s14.net for $100 shipped
 
Here's the front springs. The wire is heavier, the spring is shorter
 
(http://row10.net/d/13519-3/IMG_1270.JPG)
 
here's the rear
 
(http://row10.net/d/13531-3/IMG_1273.JPG)
 
it all goes together like stock
 
(http://row10.net/d/13523-3/IMG_1272.JPG)
 
hope this helps out

Title: m3 springs on e30 318?
Post by: jpod999 on October 23, 2007, 08:51:10 PM

Wow, your convertible is SO nice.

Title: m3 springs on e30 318?
Post by: eric ^__^ on October 24, 2007, 01:57:29 PM

cool, this is probably what I'll do eventually

Title: m3 springs on e30 318?
Post by: tony92ic on October 25, 2007, 09:13:16 AM

I've got e30 M3 springs and Bilstein sports on my cabrio as well and love the handling. I went with the rubber bushings because on a cabrio I didn't want to stiffen everything up too much.  The chassis on a cabrio can't handle it.

If I am not mistaken the M3 sway bar is actually thinner than the standard 318 one. The way it is mounted must make it more efficient. Don't go to the M3 sway bar set up unless you are doing a complete suspension swap for the hubs and brakes as well. You actually have to weld reinforcements on to it, because with aggressive driving they tend to tear off the strut. Its not worth the hassle just for the sway bars.

If you want to lower it even more, pull out the rubber spring pad. I replaced my spring pads front and rear with some heavy gauge vinyl sheet. I probably got 1/2" drop (if the red cabrio pictured is 1/4").

No problems so far.

Title: m3 springs on e30 318?
Post by: gearheadE30 on October 25, 2007, 07:24:02 PM

The M3 one is the same size as ours iirc. It is more efficient because it is mounted to the strut instead of halfway down the arm. This means that the bar moves roughly twice as far on the m3 as on our cars for a given suspension movement. It's kind of hard to explain without a drawing.

Title: m3 springs on e30 318?
Post by: busbeagle on October 27, 2007, 08:48:05 PM

I have M3 springs on a 318is with Bilstein HDs and love it.  It also has the factory offset top sturt bearings which provide a little more neagative camber.  It rides slightly softer than my E30 M3 and corners well.  At track days it performed well.

Title: m3 springs on e30 318?
Post by: ducatipaso on October 30, 2007, 07:35:33 PM

Quote from: jpod999;36434

Wow, your convertible is SO nice.

thanks. I might pull out the pads to drop mine a tad more, but my driveway is steep and eats iS lips.