330xi suspension, mods to improve softness

[Susie520]

I know the suspension on the "Xi" is softer than the sport suspension that comes on the "i". I want to improve upon the suspension I have and am trying to weigh my options. When people refer to the Xi suspension as being softer, what elements are really contributing to the softness. Would the H&R coil over kit that incorporates (bilstein) shocks and springs that are engineered together benefit me most? This will drop my car down to about "i" ride height because the minimal drop is 1.2". Would the front and rear sway bars Racing Dynamics offer show me a dramatic improvement in handling? Would I notice much if I upgraded my standard tires from the "eh" Goodyear Eagle RS-A's to the Michelin Pilot Sports in a lower profile perform a lot better?
I am trying to determine the root of the softness in my suspension - what did the i come with (or what is upgraded) that makes it somewhat firmer?
I am detecting some understeer (diagnosed by my SA after explaining what I am experiencing) and a loose feeling in handling on highway ramps.

 

[frolf]

What I am trying to correct is understeer in my rear tires .

that doesn't make sense to me.

but all those things you listed wil lmake a huge difference, i think a shocks/springs or a coil over kit will make a huge improvment for you, because i have an iS, i think i'd do sway bars myself, but thats cuase my car is already fairly low. tires are one of the best modifications you can have, but i think for your situation you should start with shocks/springs, then do tires, then sway bars,....but i really don't know anything about the RS-A's, so maybe they are shadey.

 

[bmwrocks]

What she meant there frolf buddy was the definition of understeer. As you know it is the tendency of your rear tires to want to go in front of the front tires.......hence her reference to the "understeer in my rear tires".....

 

[sidney]

Why don't they offer the sport suspension with the XI? Is there a technical reason that it can't be offered?

 

[MightyMouse]

my xi should be here next week. I my first mod will be the h& r coilover kit. anyone have this in there XI?

 

[Average Jae]

my thought on the xi: the whole reason for bmw offering xi is for those wanting to get into the entry level luxury car in the snow belt for those that does not want a rwd car. because it is a common knowledge that rwds are bad in winter. [roll] (altho they dont' even mention that snow tires make a huge difference.)

anyway, the sporty 3er is the coupe or regular i. i doubt they care as much for the xi's performance, since awd system weighs them down, and also think the main reason for awd is for winter driving. and for winter driving, higher the ground clearance the better. (i got stuck in my driveway thanks to my low clearance last week..)

besides, if you want better performance, you'd get rid of the A/S M&S tires first. (all sports package comes w/ high perf tires right?) but having summer tires on a car that is supposed to be equipped to handle the winter snow, doesn't make sense now does it? i'd say that's the reason why they didn't offer a sports package for the xi, and stiffer springs that lowers the ride height.

 

[Bmw 325i 7803]

Whats wrong with the Eagle RSA's? I don't understand why everyone complains, I mean I wouldn't replace my current eagles with new ones but they came with the car and after 5k miles I see no problem...

BTW, if she wanted performance AWD she should have purchased an Audi 3.0 quattro..
BMW and its 3series AWD stinks, when buying my 330i even the salesman (who owns a 330i himself) advised against the 330xi instead suggesting slower, more careful winter operation...

 

[aNoodle]

I think Average Jae hit the nail on the head. You may want to give some thought to ground clearance...people think they want the car extra crazy low, until they are bottoming out on every shopping center entrance.

 

[Average Jae]

well, you can't say much after someone made a purchase, and i believe the 330xi is a capable machine. quatro is pretty much legendary when it comes to awd system, so it is hard to compare the two, but here is me: i live in michigan w/ plenty of snow, i drove both the 1.8t and the 3.0 quatro and was more impressed w/ the 1.8t. and then i walked into the bmw dealership and after figuring out some numbers, picked up a 330i. i never drove the xi, since i didn't want to get an awd bmw. (because a bimmer just isn't one unless the rears are pushing you around imo)

while having a rwd in the snow isn't the best, snow shoes are saving my ass more often than not, (and given the choice of rwd w/ snows or awd w/ A/S tires, i'll take the rears w/ snows on em, every time!) it's just the ground clearance that's killing me.. oh well. i think one needs to know what they are getting into before choosing a car, not just the hype about it, like, "awd, x-drive, quatro blah blah" but really know about it. (i'm still learning, but at least i made a somewhat educated decision.) but xi is still a nice set up, and while you wont' get all of the bmw performance, at least you won't get stuck in snow as much

 

[MightyMouse]

does anyone know if your drop a bmw if you need a camber kit? if i put on h&r springs are my rear wheels going to be toed in?

 

[Bmw 325i 7803]

Well on that hand I agree with you being it's better to be raised an inch and get stuck in the snow less... But isn't the zhp lower than the regular 330i as I have never had a ground clearance problem.. when I need to go up a ramp I make sure it's done carefully and on the appropriate angle if necessary. It sounds like your local roads are suited for an SUV not a perf 330i, and I thought NY was bad...

 

[Kirby]

Getting back to Susie's question:

Start with a freebie - Tire Pressure. Find the normal tire pressure information and then add 4 lbs. Try that tire pressure setup and see how it changes the feel.

The RSAs are not bad tires (I have them from the factory on the 330) but they are definitely softer and flex more than the Pirelli P Zero Neros on my 325. You may need to change tires to get the feel you are looking for. Tires can change the feel ALOT.

Sway bars won't provide a dramatic change, noticeble but not dramatic. The primary purpose of sway bars (actually anti-roll bars) is to reduce and control body roll in corners. That does have an effect on handling, but changing bars is primarily for fine tuning handling AFTER getting the rest of the suspension dialed in. Bars should be the last change, not the first.

The biggest noticeable change will be springs/struts, then tires, then bars.

My recommendations in order:
Tire pressure tests
new tires
struts/shocks
bars

 

[Kirby]

does anyone know if your drop a bmw if you need a camber kit? if i put on h&r springs are my rear wheels going to be toed in?

Rear Toe In is adjustable. After changing out major suspension components you should always get a 4 wheel alignment and they will check rear toe in.


Reading a few articles below will shed some light on a lot of this thread's questions and suspension tuning in general:

European Car

Bimmer World

Tire Rack Tests