E46 Coils and shocks

Looking at real oem there are common shock absorber part numbers for E46 coupe/saloon and for convertible/touring models. There are also differences
between 4 cylinder and 6 cylinder. I understand the spring rates/sizes vary for standard/sport/and Msport but do they vary much between the different models? The shock absorbers do but I'm not sure about the spring rates other than they are colour coded for the options fitted to the car.
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David Haggas wrote:

If you find the Sachs catalogue for springs it'll give you a gazillion different options for the E46. Boils down to weight (and stance, secondarily) so a 318i springs will differ from a 320d, which differs from a 330i, which differs from a 330d. And then there's the body it's in (coupe is lighter than a saloon, lighter than a touring.) And for each of these there's the choice of manual or autobox. And whether or not its got aircon. Then there's normal or sport ride heights.
So that gives you 4 x 3 x 2 x 2 = 48 different springs on an imcomplete list of possibilities! Of course there will be some overlap; a manual 330d may share the same springs as an auto 330i as an autobox is heavier while the petrol engine is lighter.
--
Scott

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Many thanks for all that information. Yes lots of different combinations but I wonder about the actual spring rate difference when we are talking about perhaps the difference between say a few bags of luggage and an extra person's weight over the axle. I suppose for real world differences there's no substitute for trying different set-ups. I have a 2002 330 convertible auto with M sports package 2 and my intention - after 5 years of being badly shaken on appallingly maintained British roads - is to soften the ride and make the car more pleasurable to drive over long distances.
I drove a friend's 318 coupe manual with the same 18 inch staggered wheels and tyres (255/35 and 225/40) as my car and it rode beautifully so I can rule out the wheel tyre combination, although I recognise changing these to 17 would improve things further. Ideally I want the same suspension 'feel' as the 318 transposing onto mine, but my car weighs probably 300kg more so simply using 318 components might not work ideally. I have obtained some standard 6 cylinder struts (springs with three red marks) part number 1096855/6 and some rear springs from a 323 coupe (two blue marks) all for GBP60 from a breaker in the hope that I can emulate that 318 ride.
David
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David Haggas wrote:

It is an odd thing to specify so many different spring rates when, as you say, the usage of the car affects its weight far more than whether or not its got aircon, but that really is how they do it!

The E46 Sport suspension is noted as being too bloody hard. I've got a 320d SE and that bashes and crashes more than I'd like sometimes so I can't begin to imagine what the Sport is like.

Not really. The big step difference for the effect of tyre size on comfort comes with sidewall shape. 50+ profile tyres with their curved sidewalls are inherently 'softer' than the flat sided 45-and-below profiles. For an E46 this is the jump between 16" and 17" rims - and I think 16s don't fit on a 330i because of the brake disc size (certainly the case for the 330d.) I've gone the other way on mine (16" to 17" rims) and, with the natural stiffness of the SE, it actually didn't make that much odds. With a Sport you'd have to go down to balloon sized tyres to find an improvement.

It'd sink to the bumpstops! I bet the 318i was an SE?

Be interesting to know how it works. Being a convertible and an auto, you've got one the of heaviest E46 going (330d conv auto being heaviest) so you might find it'll sit a bit low at the front and very low at the back. You'd be better off with the rear springs from a Touring. as Convertibles are about as heavy in the back as the Touring while Coupes are the lightest of the lot.
--
Scott

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I agree about the sport being too bloody hard that's for sure. BMW GB's marketing was so successful that it almost all well equipped 330 models were m sport package but for UK roads they are a nonsense.
My experience with the 318 shows that the 18 inch wheels can be fine. If I did go to 17's I would fit 225/50 all round.
When you say 318 springs would make it "sink to the bumpstops" it would be an interesting trial. I took 4 large adults in a 99 318 saloon and it rode better than when empty! These people's weight would add up to more than the 318/330 difference and most of it directly over the rear axle...The coupe I drove in is an 02 - they didn't have the 'SE' then but I think it will be the same ie standard suspension.
The struts I have are off a convertible but the rears are off a coupe. Should be getting them swapped so will let you know how I get on. If the rears are too soft I can get some touring/convertible ones easily enough. Do you know about the wishbone differences? M sport are not the same part numbers but I am assuming they are stronger (thicker?) rather than significantly different geometry-wise
David
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David Haggas wrote:

I use SE as being non-Sport really! It's a point about the weight thing; people are heavy. I may have exaggerated the bumpstop thing, but the car would sit lower for a given weight.

Oooh, that's a point. The wishbone differences will be geometry; from looking at them I'd be guessing the chief difference would the angle the rear lug (that mounts in the lollipop bush) meets the main part. I suppose with higher suspension from a lighter car the two could cancel out and ride height could end up back to what it is now - which would keep the wishbone geometry happy.
--
Scott

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Searched around forums and from what I've read you are right about the angle. Also better longer-lasting bushes in the sport versions. What you say about the higher suspension correcting the geometry sounds encouraging but do you think there is still a possibility of uneven tyre wear or other consequences?
Maybe its a case of try it and see.
David
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David Haggas wrote:

Tyre wear is mostly down to toe settings (which can be corrected, natch). My old E36 on MTech suspension had a hell of a camber on the back wheels but wore them evenly (when I got the rear tracking sorted!)
The alternative is to find someone with standard suspension and do a full swap.
Or try it and, in due course, replace the wishbones as the balljoints don't last forever anyway.
--
Scott

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Yes, will have a good look at the joints when replacing springs but the car feels well damped in spite of rigid ride. Ideally I need to find someone with an SE who wants to swap everything but its a little low cost experiment so if it works to mitigate things then I'm happy. Remaining M sport spec stuff (correct me if I'm wrong) would be rear shocks, anti roll bars/mounts and the wishbones. The convertible is also a very rigid beast but I am hoping that it will be the springs that will make the biggest difference, followed perhaps by 50 profile tyres.
Thanks David
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Changed the struts and the ride is a huge amount better. There do not seem to be any issues regarding the wishbones and everything feels tight. The rear is more problematic because although the ride is now superb, the standard spring is not any taller than the sport one it replaced with a consequent lowering of the ride height. The front is higher so the car does not look quite right. I need some taller (or slightly stiffer) rear springs. Perhaps saloon car springs are taller?
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David Haggas wrote:

Stiffer springs are what you've just taken off! I doubt the Saloon will be significantly longer than the Coupe ones. You might get away with Touring ones but your best bet is to find some off an SE Convertible - the rear end loading is all the roof and gubbins. It won't matter which engine size it is as the %age of engine weight at the rear won't be particularly significant.
Interesting to hear your experience.
--
Scott

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I have a few photos showing the strut and rear spring heights. The struts are from a 6 cylinder convertible. The springs with two blue markings were from a 323i Coupe and are the same size as the sport ones (two white) but softer so no good. Then I tried some from a 318i saloon (single blue) which were better but gave a slightly low ride height so not surprisingly too soft for the convertible. Finally the single white ones which seem a good compromise - they are stiffer than single blue but nowhere near as stiff as the sport ones. The breaker was unable to identify the donor car but thought it was a 330D saloon. It's been trial and error really but at least I have achieved a good compromise at low cost and can quickly swap the parts back should I sell the car. The car rides far better now - still very much BMW handling but compliant enough to level out road undulations where the sport springs would not give an inch and shook up both the occupants and the mechanical roof. I am going to have the alignment checked for the new struts.
https://picasaweb.google.com/101654477920713752469/BMWE46?authuser=0&authkey=Gv1sRgCK6Cj83P6c3eWA&feat=directlink
David
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David Haggas wrote:

All good stuff. Have you been swapping the rear springs yourself, that's quite a lot of changes? Is is a difficult job?
--
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Yes with a trial and error job like this I wouldnt like to have paid anyone for all the swapping and changing. Youtube tuition videos were the key to me being able to get it done. Rears are easy enough but stuts are more difficult but once you've done one they are OK - I have two OEM jacks which makes things easier. I'd certainly recommend it to those who dislike the hard sport ride. The only downside is that the headlights are now too low so will have to look into how to adjust those.
David.
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It's not that hard. Firm, but impressively compliant, in my opinion. "Bashing and crashing" is does not do at all. Just want I want, in a sports sedan. Certainly softer than what a true "sports car" has.
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Nothing wrong with the M suspension if the road quality is good. An ex racing driver drove my 330 convertible and liked it very much but admitted he would prefer his SE for everyday driving on the badly maintained roads in our area. I understand Alpina versions of the E46 actually have softer springing than the sport so there must be something in that.
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Of course, the tires matter. With the 16-inchers that came on my sport/premium-pack 323, I would call the ride plush. In the Summer I run 215/45-17's, and it's somewhat jiggly, but still not "bloody hard", even on rough roads.
An M3 with 19's, I don't think I would like. 8)
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