Changing suspension and lowering a car - a good idea?

[RobM77]

A few months ago I bought a lovely '98 BMW 328i sport coupe to go alongside the Elise to handle longer distances in more comfort, carry my cello around and just to make a change when commuting now and then. At 70k miles, the suspension is a bit tired and I'd like to replace it. I've been quoted well over £1,000 for original equipment BMW springs and dampers, but a well respected specialist has recommended a Bilstein B12 kit as a better alternative. He says that this kit will lower my car by 30mm at the front and 25mm at the rear. This makes me worry somewhat; I don't want to ruin my car's lovely handling by messing up all the roll centre / CofG etc. On the one hand, BMW no doubt spent months perfecting my car's ride and handling, but on the other hand I'm sure cost saving measures are made in every area of a £30k coupe, and I doubt the standard springs and dampers are top notch.

Obviously I'll raise my concerns with the specialist, as I trust them completely, but does anyone have any opinions on this? I'm leaving price out of this decision as I just want the best thing for my car.

[EDLT]

Don't buy OE suspension if it costs too much. There is nothing wrong with third party parts imo.

[Mars]

I agree with you Rob. Isn't there anyone who can sell you some cheaper-than-OEM kit without lowering it? There simply must be. There's a ton of BMW specialists out there.

[parapaul]

Bilstein do make good kit though, and you should be able to get OE replacements (or very nearly) from them or any other performance/tuning company.

[PJR]

Springs don't wear out as such. There is likely nothing wrong with them? I would get all the bushes replaced. Perhaps with upgraded ones. And put decent shocks in. Koni FSD's would be great, if available for your model. if not, theres plenty of other good alternatives. A 4 wheel alignment check/correction can work wonders too.
Lowering looks great though, granted. But in my experience can make cars rather impractical on our crap roads. Still, just replacing the shocks alone can work to great effect with little or no drawbacks, when selected carefully.

P,

[Colonial]

Billies are great

My 318is runs on the standard set up. A mates runs on billies

Miles ahead in terms of handling

[vano]

Most likely source of the problem is worn bushes and/or balljoints and dampers.
I would invest in the set of PowerFlex bushes
http://www.powerflex.co.uk/products.asp?cat=0003&a...
for Dampers, do not go to BMW - you can get same shock absorbers much cheaper from GSF or Euro Car Parts. The only difference will be Boge/Sachs logo instead of BMW logo - they are all made in the same factory:
www.eurocarparts.com
www.gsfcarparts.com
Once the parts are fitted it is a must to do proper computerised 4-wheel alignment - "Laser" alignment is not enough for E36.
You can find the closest center on this website:
www.alignmycar.com

Hope this helps!

[stew-S160]

RobM77 said:

A few months ago I bought a lovely '98 BMW 328i sport coupe to go alongside the Elise to handle longer distances in more comfort, carry my cello around and just to make a change when commuting now and then. At 70k miles, the suspension is a bit tired and I'd like to replace it. I've been quoted well over £1,000 for original equipment BMW springs and dampers, but a well respected specialist has recommended a Bilstein B12 kit as a better alternative. He says that this kit will lower my car by 30mm at the front and 25mm at the rear. This makes me worry somewhat; I don't want to ruin my car's lovely handling by messing up all the roll centre / CofG etc. On the one hand, BMW no doubt spent months perfecting my car's ride and handling, but on the other hand I'm sure cost saving measures are made in every area of a £30k coupe, and I doubt the standard springs and dampers are top notch.

Obviously I'll raise my concerns with the specialist, as I trust them completely, but does anyone have any opinions on this? I'm leaving price out of this decision as I just want the best thing for my car.

as i dont know you, ill ask bluntly, do you know anything about suspensions?
Bilstein make alot of suspension systems for production road cars. actually, Bilstein has some of the best 'tech' in their dampers compared to just about every other brand going.
30mm and 25mm are nothing much and wont upset the balance. the rear suspension as standard on road cars is set soft so there is plenty of compression to deal with heavy loads in the luggage area and rear passengers. these new springs will be slightly stiffer.

the B12 kit will be a 'sporty' kit, but not hard. i guess the standard spec stuff is basically set to be soft and comfortable. ride comfort might actually improve with the bilsteins.


just my take on things.

[RobM77]

Thanks for your thoughts guys. When I bought the car I had the front bushes replaced and a full geo done. The main issue that I can feel is that the dampers are tired. In my experience, dampers start to get tired at around 30k miles, and you begin to think "this really needs doing" at around 60k. My first E36 was a deathtrap at 90k miles on original dampers, and I had the springs and dampers replaced (original spec by Bilstein), utterly transforming the car. I want to do the same with this one, but I don't want to ruin it by "uprating" them.

Would compression due to a load aboard the car really lower it that much? And surely the car's set up to deal with more compression at the rear (full boot & rear passengers), whereas this kit lowers the front by more than the rear (presumably to quell understeer?).

The other thing that worries me is how much testing Bilstein do with their kits. BMW must spend months setting the damping and spring rates.

I should add that the car is only for motorways, carrying stuff around and commuting now and then. I don't take it on drives for the sake of it, or use it on track.

[robemcdonald]

Based on what you have said; If I were in your position I would just replace the shock absorbers with standard ones. That should improve things without ruining the ride quality.
Since you're not taking the car onto a track there is little to be gained from lowered / uprated springs (which would then require uprated shocks)

[AdamMX-5]

Fraid my knowledge stops at the E30 but didn't 325 Sport's of that era come with Billies on as standard?

Seem to remember my old man's Saab 99 running on Billies as OE as well.

Good kit as far as I'm concerned and what I'd want on a Beemer personally.

[BlueEyedBoy]

I have been thinking about updating my cars suspension for 2 years. What I want is to test it before and after, to see if I like it, sadly, I don't want to spend 1K doing this testing I like you, don't want to ruin things, the good news for me, is that in a 9-3, things must only be able to get better, just how better puts me off as to whether it is worth it or not

[RobM77]

Standard dampers from BMW for are horrendously expensive. Bilstein do an original equipment range I think though? That's what I fitted to the 325i. I want to retain whatever was "sport" about my sport coupe though (the 325i was an ordinary saloon.

There is obviously some potential improvement to be made, as I so rarely have any more than just me and an overnight bag in the car, and possible a cello or a passenger. OE is obviously designed for four people and suitcases; mind you aftermarket probably is too...

[Otto]

As has already been mentioned, what you need in your situation is blueprint shocks from GSF or Eurocarparts.

Looking quickly at GSF, their 'best quality' shocks are about £65 each (these will be the boge/sachs/Bilstein branded shocks, as used originally by BMW but with a different sticker on them).

I wouldn't start messing around with lowered suspension for what you plan on using the car for. It will no doubt also cost more as you will need to buy springs at the same time.

[MikeyMike]

Changing my suspension on my MR2 was the best modification I've done, the car handles beautifully and holds the road really well.
A 30mm drop isn't as big as you may think, so I wouldn't be overly concerned about that.
It is worth doing some research first though before you opt for a certain setup, I'm sure there must be a wide range of kits for your car varying from near standard to race-spec.
I got a set of Tein coilovers for my MR2 which allow 12 different levels of damping and a large range in terms of ride height adjustment, I paid about £700.

[Vauxcrayzee]

People often just do springs and DAMPERS (they are not shock absorbers, common myth). However don't overlook wishbones, anti-roll bar links and track rod ends. They all play their part in the dynamics of the car!

[RobM77]

Vauxcrayzee said:

People often just do springs and DAMPERS (they are not shock absorbers, common myth). However don't overlook wishbones, anti-roll bar links and track rod ends. They all play their part in the dynamics of the car!

The dampers are definitely worn, thus the question. I will be getting a full check of all related components when the work is done. I had such a check when I bought the car, and as a result have already had front bushes replaced.

[Vauxcrayzee]

Good call

Might be worth asking other owners of your particular car what works best, as for example Spax (top brand) is not as good as a Gmax (budget) kit on a Calibra... so results are not always as you'd expect. As a rule though, Spax or Koni are full of win.

[Mr POD]

http://www.freudenberg.com did you know that 85% of the worlds shock absorber seals are made by one company ?