E30 M3 Springs in a 325ic

[cavpilot]

Ok Suspension gurus, I've got a few questions for you...

First off, I bought a set of springs from a guy who sold them to me as M-Technic springs. When he bought them, he thought that they were M3 springs but now believes that they were actually M-Technic. Is there a difference? Here are the numbers:

Front-1130046 Rear-2226147

I was able to find this info somewhere online. However, without a reference I'm not sure I can trust it.

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

Of course, I have pictures attached.

Next question, control arm bushings. If these are, in fact, M3 springs is it imperative to use the offset M3 bushings? I know the M3 bushings change the caster but what about the camber?

Lastly, What about the ride height? Will I still have the reverse rake? Should I install E90 drop hats when I do the job?

Thanks!

[Chessmaster]

Yes those are e30 m3 springs (green paint markings). If you go through the vert suspension thread there a few folks running them. You should sell me them lol I needs some fronts for my vert.

[jeffnhiscars]

I put in e90 drop hats when I changed my inserts and it made a small dent in the rake but not enough (the consensus is about 3/8").

To get it to sit right you need to change the springs and I don't know if the M3s will drop it enough.

As for your CABs you can make that decision independant of what springs you use. The m3s will add castor and may tweak your camber but it's the lowering that really changes your camber. I put H&R Cabrio springs in, left the drop hats and the car sits great. Camber is barely out so not worth putting in camber plates.

[cavpilot]

Yes those are e30 m3 springs (green paint markings). If you go through the vert suspension thread there a few folks running them. You should sell me them lol I needs some fronts for my vert.

These Springs are pretty hard to find. I just kept checking Craigslist and eventually found these. The cabrio suspension thread has been a great resource.

[cavpilot]

I put in e90 drop hats when I changed my inserts and it made a small dent in the rake but not enough (the consensus is about 3/8").

To get it to sit right you need to change the springs and I don't know if the M3s will drop it enough.

Good point. I kind of figured that this would probably be a multi step process. I think I'll put the springs on first then go from there.

[guibo09]

I have a set of e30 m3 springs if anyone is interested.

[reelizmpro]

It's my understanding that M3 and M technic are the same springs. The easiest way to combat the reverse rake on verts in particular is to stack pads or washers in the rear to raise it up a bit. Even stock verts are relatively low in the rear with the extra weight and lower rear arch.



H&R Race/Bilstein sports, no spring pads in front, extra pads in the rear.

[M-technik-3]

here is my old vert on them, granted the tires are 205-50-15 vs 205-55-15 but you get the picture.

[jeffnhiscars]

Good point. I kind of figured that this would probably be a multi step process. I think I'll put the springs on first then go from there.

The only reason mine was multi step was that when I bought the car the front struts were totally blown so I bought the BS Tourings so I could drive it. For the $11@ the drop hats cost I just threw them in to try and make a dent in the rake (they didn't)

After the suspension upgrade I just left them in. IMO the difference they make is barely noticeable.

[cavpilot]

As for your CABs you can make that decision independant of what springs you use. The m3s will add castor and may tweak your camber but it's the lowering that really changes your camber. I put H&R Cabrio springs in, left the drop hats and the car sits great. Camber is barely out so not worth putting in camber plates.

Good point about the camber plates. I hate, Hate, HATE, negative camber. I was figuring that the mild drop that these springs provide would't require the use of camber plates. Also, I'm running Bilstein HDs all around I'm thinking that they should work fine with the M3 springs.

[jeffnhiscars]

Good point about the camber plates. I hate, Hate, HATE, negative camber. I was figuring that the mild drop that these springs provide would't require the use of camber plates. Also, I'm running Bilstein HDs all around I'm thinking that they should work fine with the M3 springs.

I did a will call on my Touring struts and picked them up at Bilstein east which is only 20 min from me. I sat with their tech rep and discussed lowering and valving etc. there's actually a surprising amount of range in the Touring (7 in of total travel) and I suspect the HD is not that different.

When I pulled the Tourings to do my suspension (swapped to sports) I put them in our 87 4 dr and lowered it perhaps an inch with no issues whatsoever so same long as your drop is modest I think you will be ok. Do cut the bump stops down though. I'd leave 1/3.

[cavpilot]

I finally got around to putting the M3 springs in my vert. I've spent the last couple of weeks doing the head gasket on my daughters Volvo (pain in the ass!) Here are the before and after pics. For reference, I'm running factory 14" weaves with 195/65r14 Falkin Ziex ze329s on Bilstein HDs.

Before:

[cavpilot]

After:

[M-technik-3]

it will settle down.

[cavpilot]

it will settle down.

It's hard to tell from the pictures, but the drop is noticeable and pretty much where I wanted the ride height to be. The biggest difference is in the ride comfort. These springs are definitely softer than the stock cabrio springs. That;s ok though since the stock springs with the HDs were a little too harsh for my liking.