David Haggas wrote:
> 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.
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!
> 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.
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.
> 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.
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.
> 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.
It'd sink to the bumpstops! I bet the 318i was an SE?
> 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.
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