[relative4]

Hi, I have an '08 E90 335xi manual, and I'd like to improve its cornering. Not looking for a lot of lowering, just out to decrease body roll and improve road holding and keep some of the current bump handling and comfort. What have people found works well? Thanks!

[dpaul]

1) get rid of stock struts- kwv1 coilovers are a conservative choice that will provide modest lowering and a comfortable but controlled ride.

2) get decent, non-all season, non-run flat tires. Continental DW are a relatively inexpensive choice.

These changes made an enormous difference in my 6MT AWD 335

[relative4]

Thanks! What about an upgraded rear sway bar? I'm reading the M3 can be used on these cars, have people had good results with those?

[dpaul]

Changes in sway bar should be made with a specific purpose in mind, for example to correct an observed understeer or oversteer condition. The M3 rear bar could be a worthwhile change but you have to consider the full context (what size/type of tires, what size wheels, what rate springs and damping, ride height, AWD vs RWD etc), what current handling issues actually need to be addressed and what kind of driving you wish to optimize the suspension for. One size does not fit all, particular in regard to the last point.

I could easily be wrong but I doubt a sway bar replacement is going to be useful first step.

Small changes, one at a time, is a safe policy. Start with tires. Particularly if you've got oem run-flats.

[relative4]

Yes, unfortunately the DPO put on run-flats only 2000 miles ago. I'm planning to put a year on them before throwing them away. At that point, I'll put on my beloved Conti ExtremeContact DWS-06s.

On my previous 3 toys, all the glorious '05 Subaru Legacy GT, the bigger rear sway bar was the first step to all cornering improvements. I take it the E90 did not come out of the factory with such a glaring imbalance.

[dpaul]

No. The glaring problem in the rwd E90 was the lack of a factory limited slip differential. The glaring problem with the awd E90 are the awful, awful struts (search "pothole explosion") and the increased ride height (compared to the rwd).

Anyway, in regards the M3 sway, replacing the rear bar in the E9x requires a LOT of disassembly, not fun at all. In addition, the larger bar will add oversteer - you might enjoy that or you might not.

Again, I'd dump the RFTs. I'd take them off immediately and sell them. Try driving a while with the DWS and reassess.

You might also want to carefully inspect all the rubber bushings in front and rear suspension. In particular, the "hydrobearings" in the lower control arm (what BMW calls the traction strut) are filled with fluid which can leak out when the rubber cracks.

If after that you need more, do the coilovers and don't waste time with cheap ones.

Then if you still think there is too much understeer, you could mess around with sway bars.

[relative4]

Thanks. I do enjoy oversteer. I already replaced all the front LCAs, the bushings were shot.
Will add coilovers to my tire budget plan. Man, those suckers are a bigger investment than putting Konis or Bilsteins on a Subie...

My wife's 335xi has the Contis, brand new, and honestly I'm not feeling much difference in the corners. In general ride quality and feel, there is definitely a difference.

[JeanCa]

Some decent coilovers like KW, ST, Bilstein etc... would significantly improve handling. But they would be a rougher ride. Another option would me Dinan springs, they only lower the car 0.5inches in the front and nothing in the rear while improving handling. Next, replace the stock strut bar with the m3 strut, since it's stiffer and tightens up the front end. Some m3 control arms would also improve steering feel and handling, if you are on a budget you could do the fronts only. Furthermore, to improve the rear you could swap out the subframe bushings for some steel ones. You could also target unsprung mass (which improves handling exponentially) like going for some flow forged or forged wheels which are lighter, also the front f30 brakes mount right up to the 335, I saw in some other post that the f30 calipers are about 7.5pounds vs the e90 12.5pound calipers and if you go for 2pcs rotors then you will also save weight. Finally, some good tires would make a night and day difference on how the car handles. If you're looking for street tires then the best choice would be some Michelin Pilot super sports or son Pilot sport 4s. I have heard good things about the Firestone indy 500s, they are good in dry but are not as capable as ps4s at wet, they are allot cheaper tho. If you really want to go at it maybe you can consider some extreme performance summer tires like the RE71-R and RS4 which have more dry grip than the michelins but will wear faster and will be less capable in the wet.

If I had a 1K budged I would go with tires.

If I had a 2K budget I would go with tires, m3 front control arms, Dinan springs or tires and coilovers.

It all depends on your budget, but tires would be the first thing I would go for.

[relative4]

Originally Posted by JeanCa

Some decent coilovers like KW, ST, Bilstein etc... would significantly improve handling. But they would be a rougher ride. Another option would me Dinan springs, they only lower the car 0.5inches in the front and nothing in the rear while improving handling. Next, replace the stock strut bar with the m3 strut, since it's stiffer and tightens up the front end. Some m3 control arms would also improve steering feel and handling, if you are on a budget you could do the fronts only. Furthermore, to improve the rear you could swap out the subframe bushings for some steel ones. You could also target unsprung mass (which improves handling exponentially) like going for some flow forged or forged wheels which are lighter, also the front f30 brakes mount right up to the 335, I saw in some other post that the f30 calipers are about 7.5pounds vs the e90 12.5pound calipers and if you go for 2pcs rotors then you will also save weight. Finally, some good tires would make a night and day difference on how the car handles. If you're looking for street tires then the best choice would be some Michelin Pilot super sports or son Pilot sport 4s. I have heard good things about the Firestone indy 500s, they are good in dry but are not as capable as ps4s at wet, they are allot cheaper tho. If you really want to go at it maybe you can consider some extreme performance summer tires like the RE71-R and RS4 which have more dry grip than the michelins but will wear faster and will be less capable in the wet.

If I had a 1K budged I would go with tires.

If I had a 2K budget I would go with tires, m3 front control arms, Dinan springs or tires and coilovers.

It all depends on your budget, but tires would be the first thing I would go for.

From the research I've done so far, it is my understanding that some of the suggestions you're making are incompatible with the 335xi. Do you have experience modifying AWD suspension, or just RWD?

Regarding the tire suggestions, you'll note my profile specifies I'm in Colorado, where the tire requirements are vastly different from the ones in Puerto Rico.

[JeanCa]

Originally Posted by relative4

From the research I've done so far, it is my understanding that some of the suggestions you're making are incompatible with the 335xi. Do you have experience modifying AWD suspension, or just RWD?

Regarding the tire suggestions, you'll note my profile specifies I'm in Colorado, where the tire requirements are vastly different from the ones in Puerto Rico.

Ahhh yeah my bad, totally forgot about Xi, so that means no control arms. I don't know much about colorado but if it gets cold at some point then you must already know that you will also need a pair of winter/all season tires laying around. Apart from that everything else is ok.

[Raptor04]

Originally Posted by relative4

From the research I've done so far, it is my understanding that some of the suggestions you're making are incompatible with the 335xi. Do you have experience modifying AWD suspension, or just RWD?

Regarding the tire suggestions, you'll note my profile specifies I'm in Colorado, where the tire requirements are vastly different from the ones in Puerto Rico.

Let me know any questions you have. I'm in Colorado too and have tried many different suspension setups on the E90 335xi.

[relative4]

Originally Posted by Raptor04

Let me know any questions you have. I'm in Colorado too and have tried many different suspension setups on the E90 335xi.

Great! What have you found to provide a balance of excellent cornering with decent comfort?

[Raptor04]

Originally Posted by relative4

Great! What have you found to provide a balance of excellent cornering with decent comfort?

Lol. I haven't found it yet. Best setup I've had to date was coilovers with Fortune auto struts in the front and TC Kline Double Adjustable in the rear with Swift springs all around. Now I'm back on springs and shocks and looking for a good combo. I can tell you the Eibach RWD springs on a 335xi are garbage. I am installing h&r sports this weekend and will report back on how it feels.

[dpaul]

OP:
I ran on OEM 17" run flats (Conti, can't remember the model), installed square 225/40-18" Conti DW. Profound difference in grip!. Eventually settled for 225/255 staggered 19" Conti DW. I think extra contact area is a good idea but most feel staggered setup induces understeer and serious trackers seem to like square setups. I'll admit I like the way the staggered set looks.

I am surprised that you find little difference between run flat and non-run flat tires. Maybe run-flats have improved since I last tried them (~6 years). I have dedicated summer and winter wheels and tires (staggered Conti DW, not DWS-big difference and Bridgestone LM001 - noisy and vague feeling but they really stop you in the cold). Have Michelin PS3 on my E90 M3

I tried Koni FSD shocks, then Fortune Auto coilovers, then KWV1s. It is to some degree a matter of personal taste and what kind of driving you do. I found the fortune auto struts too stiffly sprung with the recommended spring rates for an urban setting. Nice on a track perhaps. The Koni's alone don't do enough. KWV1 was the sweet spot for me, with about double the stock spring rate and adequate damping. I do not find having adjustable damping to be very important - I'm not tuning the chassis for Nürburgring.

I tried increasing the size of the front bar because it was cheap and easy, even tho I knew it was the wrong thing to do. I didn't find it to be an improvement - quite the opposite. At least with the KWV1s and staggered wheels - car pushed too much as it was. The coilover stiffened things enough.

I also tried poly bushings (front only) which for me made little difference in street driving as long as the original rubber was in good shape. However, there's a great youtube video showing how much better poly is than the hydrobearing at controlling traction struct movement during driving - it's impressive and if I was going to track a lot, I'd have kept the poly. I just got annoyed with the groaning noises it developed. I think most of the remaining instability might be in the rear suspension - it might be beneficial to swap out the rear bushings for aftermarket or M3 pieces. This is somewhat difficult work best done with special tools that can be rented. I'll probably never do it.

After all this, my E90 335xi is still not an M3. My E93 M3 (extra heavy due to convertible top, stock except for intake, with Michelin PS3 tires) is more balanced and confidence inspiring at the limits (which I reach very very rarely). Even though my FBO 335i is significantly faster, I find the M more fun to drive.

[relative4]

Excellent info. Thanks!

[HawkeyeGeoff]

I ended up with Bilstein B8's + Dinan springs on my E90 XDrive. They're basically the only springs that keep it reasonable and are made for the XDrive. Very comfy....Do not go with eibachs if you want to keep it civil. I also live in Detroit area, so worst roads in america. lol

[relative4]

Originally Posted by HawkeyeGeoff

I ended up with Bilstein B8's + Dinan springs on my E90 XDrive. They're basically the only springs that keep it reasonable and are made for the XDrive. Very comfy....Do not go with eibachs if you want to keep it civil. I also live in Detroit area, so worst roads in america. lol

Thanks. That looks like a very effective setup; also very reasonably priced considering the Dinan name is involved.

Now to start comparing merits of this setup versus the KW coilovers.

[dpaul]

A principal difference is that you can adjust the ride height with the coilovers. If you don't like where the Dinan springs put you there is little you can do.

[relative4]

Originally Posted by dpaul

A principal difference is that you can adjust the ride height with the coilovers. If you don't like where the Dinan springs put you there is little you can do.

Good point, thanks.

@HawkeyeGeoff, don't suppose you have a side-on pic of your ride?

[HawkeyeGeoff]

Originally Posted by relative4

Good point, thanks.

@HawkeyeGeoff, don't suppose you have a side-on pic of your ride?

A little late....but yes.

https://drive.google.com/open?id=1NR...g90w5sENBvcwRS

It looks lower than it really is. Might be the angle, but it strikes a good compromise between lowered and suspension travel. Like I said it's significantly more comfy than the eibachs because of the extra travel.

[relative4]

That looks like a pretty reasonable height. Thanks!

And nice wheels, what are they?

[blau808]

335xi

255/35/18 square. 9" ET30 Apex Arc 8's in hyper silver on Michelin PSS.

KW V1's on their highest (tallest) setting, no fender roll, no rubbing, speed bumps or driveways not an issue at all.

Going from stock 225/45/17 to this setup has totally transformed the car.

Highly recommend, though I would go a different route than the PSS next time, the wear was uneven and road noise became an issue, though they grip great in wet and dry conditions, ymmv.