How do aftermarket springs improve handling?

[sunnydays]

Hey all,

So I am presently having a set of Eibach Pro springs fitted to my 35is. These offer a 0mm rear/10mm front drop over m sport springs.

What I am curious about is given BMW spends millions on development, R&D, research etc on suspension setups for their cars exstensively testing in all scenarios, how is it that aftermarket springs can be considered an upgrade so to speak.

Ie are they as exstensively tested, how do they quantify wether spring is an upgrade? Do they utilise G force sensors to measure body roll for example. Do they spend as much on R&D? Given that the eibachs seem to reduce rake by lowering the front of the car more what is the overall aero effect of this on the cars speed, downforce, handling and traction etc...

Apologies if this has been asked before just genuinely curious.

Thanks!

[john-e89]

'Upgrade springs' generally are progressive, meaning the the harder the load that's put on them, e.g. cornering, the stiffer they become as the load increases. You can often see this by the coils becoming more tightly wound on the top mounting end. Lowering is done to reduce car body roll or to give a different stance for aesthetics. You won't notice any difference in aero or speed, I guess if you put very sensitive measuring equipment on the car and measure aero there might be a very slight difference at high speed but so miniscule you'd never notice.

[cj10jeeper]

I would take the word 'upgrade' out of any advert to do with parts to add to a car.

That said there is nothing wrong with your logic that BMW spends a fortune on development of springs, shock absorbers, etc., but what they fit is a compromise for dozens of countries, driving styles, roads and to a price.

With careful selection and more money you can buy parts that better suit what you want, lower/higher, more/less comfort, better cornering, etc. Equally with poor selection you can really mess up..

[mr wilks]

I would take the word 'upgrade' out of any advert to do with parts to add to a car.

That said there is nothing wrong with your logic that BMW spends a fortune on development of springs, shock absorbers, etc., but what they fit is a compromise for dozens of countries, driving styles, roads and to a price.

With careful selection and more money you can buy parts that better suit what you want, lower/higher, more/less comfort, better cornering, etc. Equally with poor selection you can really mess up..

Hard to disagree with any of the above "sunnydays " & to simplify don't expect £170 of Eibachs to offer any improvement to the car other than visual

[sunnydays]

'Upgrade springs' generally are progressive, meaning the the harder the load that's put on them, e.g. cornering, the stiffer they become as the load increases. You can often see this by the coils becoming more tightly wound on the top mounting end. Lowering is done to reduce car body roll or to give a different stance for aesthetics. You won't notice any difference in aero or speed, I guess if you put very sensitive measuring equipment on the car and measure aero there might be a very slight difference at high speed but so miniscule you'd never notice.

Thanks John, this makes sense

I would take the word 'upgrade' out of any advert to do with parts to add to a car.

That said there is nothing wrong with your logic that BMW spends a fortune on development of springs, shock absorbers, etc., but what they fit is a compromise for dozens of countries, driving styles, roads and to a price.

With careful selection and more money you can buy parts that better suit what you want, lower/higher, more/less comfort, better cornering, etc. Equally with poor selection you can really mess up..

Ahh so you could say the standard BMW Springs are "General" one size fits all springs that aim to be good in all scenarios, where aftermarket springs can narrow down to one particular segment and be more focused at that, IE race springs that offer increased corning ability at the expense of comfort

Hard to disagree with any of the above "sunnydays " & to simplify don't expect £170 of Eibachs to offer any improvement to the car other than visual

Thanks, agreed as it does make sense. One last thing that is confusing me is you state that I should not expect the Eibachs to offer any handling improvement only visual. Their are various reviews by users on here that state it has improved handling, road holding, reduced crashiness etc... Would you say that it is placebo?

Thanks Guys appreciated!

[mr wilks]

Its jmo so may not match anyone else's but the 5 cars ive had lowering springs fitted to all handled worse afterwards simply they did not ride the bumps as well as on OEM springs
2 cars were V6 TTs which to be fair wallowed into bends on stock springs , afterwards they still wallowed only looking a lot cooler
ZMR on OEMs drive far better than on Eibach's to me , others may disagree

[john-e89]

Eibachs on my old MR2 were superb, much improved, however on an M roady I tried they were awful, way too hard and crashy, so as CJeeper says it's easy to ruin a cars feel. Tread carefully imo, I wouldn't put aftermarket springs on a 35is unless I'd tried one beforehand, easier said than done I know but there it is, you may get bitten.

[cj10jeeper]

Ahh so you could say the standard BMW Springs are "General" one size fits all springs that aim to be good in all scenarios, where aftermarket springs can narrow down to one particular segment and be more focused at that, IE race springs that offer increased corning ability at the expense of comfort

Yes - I'd agree with the summary above
I wouldn't say BMW get it right all of the time for all drivers, but for most, most of the time

There's 115,000 E89's running around, of which I'd guess 99% are every happy on OEM set up of tyres, springs, shock absorbers, suspension and other related components

If however you know what you want to achieve and make a series of correct well informed decisions, knowing the compromises, you can improve things to better suit your needs.
Reality is that much of the time people make poor decisions, or at least ill informed and while gaining one benefit compromise many other aspects.

[Maniac]

Personally I'd look at struts and anti roll bars first as an upgrade over springs. Adjustable struts will help you find a good compromise on handling and anti roll bars will help with the lean and wobble characteristics.

[sunnydays]

Thanks for the input everyone. The situation was a rear spring had snapped on my 35is and came back at approx £130. So rather than just replacing the 1 I read around online and saw the good reviews for the eibach and slight drop in ride height. They are currently being fitted so will just have to wait and see.

Hopefully they feel good will find out tommorow

[eff1guy]

Looking forward to the pics and the forthcoming review with interest

[mr wilks]

Thanks for the input everyone. The situation was a rear spring had snapped on my 35is and came back at approx £130. So rather than just replacing the 1 I read around online and saw the good reviews for the eibach and slight drop in ride height. They are currently being fitted so will just have to wait and see.

Hopefully they feel good will find out tommorow

I think 90% of the time (depending on your driving style , speeds , roads ) you will be happy enough but its the other 10% when they disappoint its knowing how to avoid those situations or simply put up with the deficiencies for improvement in stance

[sammyz]

Some very good sense and opinion being said on this thread

[sunnydays]

Update for all interested:

The springs have been installed and fitted for a week now. The car has dropped by 10mm up front and 0mm on the rear as expected. The 10mm front drop is noticeable and looks much better.

In terms of driving:
It feels similar to the stock springs. Maybe their is a more noticeable difference on track where you can really push the car etc.... for day to day driving they feel similar and improve the stance of the car.

Thanks all for your input!

[alex]

Do they make the car less crashy at all? Definitely something I wouldn't mind improving on mine, tends to get unsettled easily as well, but 19" wheels definitely don't help....