[bootay]

My 2007 e90 AT with ZSP is a ton of fun, but at 400rwhp with current mods, the suspension is really showing some issues and it'll only get worse with my next step to 500+. But it cannot change from the stock character - even running with the stock RFT was too harsh, putting on PSS tires fixed that up.

So, what can I drop in to reduce some body roll, keep that rear end from floating, and improve turn response? I don't track, but I do race around town and hit the backroads with a friend that lives in the country...

I looked at the M3 suspension package, including subframe bushings, but not replacing springs/struts (I definitely don't want to be lowered). Can I/should I eliminate any of those parts if a primary goal is to keep the stock comfort level?

Thanks!

[bootay]

On closer inspection, it seemed to me that only part of that M3 package would be needed for my uses:

Rear subframe bushings
front e93 sway bar
rear e90/92 sway bar
front control arms/tension strut kit

and while I'm in there, add a quaife LSD

That seems like it would really tighten the car up without causing ride harshness - any thoughts on if those front arms/tension kit are recommended, and if anything is missing?

[cvc 22349a]

I replaced the front and rear control arms and subframe bushings with M3 parts before installing slightly stiffer springs. Those parts alone definately tighten up your chassis and work really well with PSS tires You'll still have some float though due to soft springs and dampers. I didn't install the M3 roll bars but wish I had at the time the subframe bushings went in. Everyone says they help reduce roll, but I don't think they'll help with the excessive dive/squat. Springs will.
LSD should of been your first mod.. You must be going though rear brakes like crazy

[bootay]

LSD is definitely going to be nice, brakes so far haven't been an issue but I'm eager to push out of turns significantly harder (and if I tracked I'm sure I'd have had to do that long ago).

Thanks for the feedback, sounds like it'll work for me!

[bootay]

Settling on:
Koni Yellow + Eibach Pro - minimal drop + maintained comfort level + reduced bounce/float
Front E93 M3 Sway + Rear E9x M3 Sway - reduce roll
Rear Subframe Bushings
Front Control Arm Kit
Rear Toe Arms
Quaiffe LSD

Gets all of the subframe dropping stuff done at once, greatly tightens suspension, shouldn't result in scraping on driveways/speed bumps or harshness over bumps.

And the LSD .

And all it takes is $4k in parts and ~$800+ in labor. Since it's all going on my new-to-me 2009 335, gotta add $1k for PSS tires and $2k for FBO power mods (tune + dci + DP + FMIC). Not too bad for taking a stocker to awesomeness @ $8k or so total.

[CJ421]

Sounds like some fantastic upgrades. As mentioned the LSD should have been #1. The M3 subframe bushings are a MUST. And combined with the adjustable rear toe arms (I suggest the Rogue Engineering ones, I have them on my car and they are well made), you'll keep that rear end in check. The M3 parts are all excellent upgrades; can't go wrong.

Research whether you'll need adjustable sway bar end links with the Eibach Pro springs. IDK if the stock ones have enough adjustment to maintain proper suspension geometry. But good choice with the Eibach springs, they are quality.

You will be one of the few "FBO" cars here with proper supporting mods.

I recommend VAC Motorsports for your differential build. PM me if you need help.

[mike-y]

good choice on the konis. Even on factory springs, they make a big difference to how the car feels. No more bouncyness and loose transitions.

[YvesD]

mike-y, were you thinking about the Yellows here?

Yves

Originally Posted by mike-y

good choice on the konis. Even on factory springs, they make a big difference to how the car feels. No more bouncyness and loose transitions.

[mike-y]

yes, the yellows (also called koni sports)

[The HACK]

Since you don't "track," I'm going to go against everything I've been saying here and tell you...

Sway bars are the best bang for the buck for you. Especially if your primary goal is to reduce roll without changing ride-height or firmness. It's the ONLY thing on your list that will do exactly that.

[bootay]

Originally Posted by The HACK

Since you don't "track," I'm going to go against everything I've been saying here and tell you...

Sway bars are the best bang for the buck for you. Especially if your primary goal is to reduce roll without changing ride-height or firmness. It's the ONLY thing on your list that will do exactly that.

Agreed - huge bang for the buck there.
The car also feels way more "floaty" than I'd like, even at low speeds. Which is what drives the springs/struts, even though that will drop me .5" from ZSP. The other items I just go with what people say is mandatory for: front control arm kit for responsiveness and bushings/rear toe arms to tighten that rear end up. The LSD seems to go without saying, any high-performance car should have one, tracked or not.
And while I don't track/auto-x today, who knows . But I definitely hit the country/mountain roads a bit.

[CALWATERBOY]

Originally Posted by bootay

The car also feels way more "floaty" than I'd like, even at low speeds.

Consider this: Koni FSD

Uses stock springs; excellent ride vs stiffer yellows....stiffer at any setting. Ladies'll love ya for FSD's, as will your bank account.

M arms + M bushings + M sways outstanding mods. LSD a prerequisite to M sways. Precision is yours.

[The HACK]

If the car feels "floaty" the best fix for it would be a set of sport dampers.

LSD is only really a requirement if you track the car, IMO. For all of your street driving the electronic "fake" diff does a good enough job. The brake simulated diff is more than capable of sending enough power to the outside wheel. It only fall short when you're literally got the car loaded way sideways, or compared to the magical ///M LSD which is capable of varying the amount of lock-up from 0-100% at any time.

[bootay]

Originally Posted by The HACK

If the car feels "floaty" the best fix for it would be a set of sport dampers.

Totally agreed, that's why the Koni Yellows (likely set close to max comfort). My only concern with all this is the ride height...I see pictures of Eibach Pro springs and some look slammed, some look perfect.

For example, this looks fine:
http://www.1addicts.com/forums/showp...53&postcount=4
But this one (same springs) looks too low:
http://www.1addicts.com/forums/showp...4&postcount=17

Guessing the second one is a tiny bit lower using a cup or the like.

[The HACK]

Keep the stock springs if you don't want a "drop."

[DaanBMW]

BMW perf springs (yellows) would be my suggestion.

A bit of a drop but no slamming. And if you go that route, contrary to many, I'd say don't pair w/ Koni yellows (despite the color coordination ). Use the BMW perf shocks (v2 for perfect match, or v1 like I did).

[CALWATERBOY]

Originally Posted by The HACK

LSD is only really a requirement if you track the car, IMO. For all of your street driving the electronic "fake" diff does a good enough job.

Point 1 true; point 2 not so much!

LSD install makes its benefit felt at all speeds, including driveway travel. Not required for the street, but much desired once experienced.

Also, the LSD effect is felt & appreciated in direct proportion to add'l power.

E-diff's best for gentle drivers.

[CALWATERBOY]

Originally Posted by DaanBMW

BMW perf springs (yellows) would be my suggestion.

Here it is....

I say FSD's are better than yellows for most of us, unless carefully matched to springs for the 3 being modded. Ground Control excels there. Advice from HP Autowerks might do as well.