[sigtwenty]

Dropped on Bilstein B14 coilovers. front lowered to the max
rears about 1/3 lowered, and will test lowering a tad more (rubbing possible if rear goes much lower)

as for the ride....2015 RWD 328i, 73k miles on original suspension.

I'm on 19 inch wheels with runflats 90% new that were installed a day after the coilovers were installed so I test drove with the stock 17s (second post will show before pic of the car stock)
So driving this for 5 days now and here are my daily use findings.

Vegas roads are absolute trash. over the same rough roads I have no choice to drive on every day I feel absolutely no major difference in ride quality, in fact it feels the same as my E38 on 19s did, and compared to the original 17s on the car only thing I tend to feel different is the shorter tire profile, but not ride quality.
on decent roads, the ride is not "harsh".... it's a tad hoppy on some road imperfections, it's not rough or jittery in a sharp sense. it's noticable, in a typical of coilovers way.
on the freeway. rougher freeway/construction zones again like above....stable smooth and nothing overall wishing I didn't have them.
on smooth freeway, smooth, slightly more noticable hop feeling over imperfections.

on a freeway on ramp to another freeway that is about 2 miles long and a fairly sharp curve on stock doing over 55 felt unstable, leaning hard, planted but felt pushed. on these coilovers I did it today at 80, and passing another car on the curve area and felt like I was doing 30.

the car handles incredibly well. city street right hand turns from a right lane into a right lane are precise, even at 30mph compared to stock you felt pushed to the side of the car at 20 with the body leaning to the side.

I still have not 100 percent settled on ride height so alignment hasn't been done yet and I can feel that once it gets done it will feel even more precise.

speed bumps. harsh. can bottom out (my setup I have zero bottoming out already tried it but it did bottom out on my 17s immediately)

I may consider the softer springs (comfort springs iirc I forget the name of them made for these ) later on. as it sits now, I'd happily drive on a road trip with confidence and comfort. even my son didn't really notice much comfort difference, right after we spent 3 hours in the car on the freeway the day before.

for $1044 you can't go wrong with these. especially for oem quality. the ride quality did improve and the handling more when I slapped the 19s on the car.

[sigtwenty]

stock form

[FaRKle!]

Originally Posted by sigtwenty

I may consider the softer springs (comfort springs iirc I forget the name of them made for these ) later on.

Bilstein doesn't have a "comfort" version of the B14, only B16. If you found a B16 Comfort owner who wanted to trade springs you could do that though. Personally, I wouldn't bother with the Comfort rear springs as they're the same spring rate as some of the M-Sport rear springs. You can convert the rear to use standard 60mm coilover springs (out of the Hyperco/Swift/Eibach catalog) easily though.

[sigtwenty]

3 month review.

no complaints, pretty compliant, rear end really bouncy over a speed bump. handles around corners well, at 100-110mph it feels smooth, over rough roads its fine, just have to be concerned with bigger dips (like any lowered car you would have to). not very jarring or uncomfortable. took it on a 3 hour road trip and it felt 95% "stock comfort"...those that pay attention to their suspension and their cars will notice that little difference, where as the average every day driver prob wont notice anything other than its cosmetic appearance, and how it handles, but not notice the little differences on a highway trip.

these are a great buy, for the money.

[SantaEugence]

Surprised you kept the runflats. Biggest difference I noticed was switching to MPS4S. Night and day! Until I lowered on HR then the head splitting bangs were back...

[johnung]

Originally Posted by SantaEugence

Surprised you kept the runflats. Biggest difference I noticed was switching to MPS4S. Night and day! Until I lowered on HR then the head splitting bangs were back...

I agree with you. When I ditched runflats for Michelin PS4S, half of the teeth jarring stock suspension issues were suddenly gone. I had expected better handling, especially going from stock 225/45-18 to 245/40-18. But I was surprised how much comfort I gained. The jolt from sharp pothole edges was rounded off. The same for those road seams on freeways. It made taking the car on a longer trip more palatable.

The H&R springs might be 30% stiffer than stock along with the dampers that you used. Bilstein's would be especially stiff. Koni Yellows not as much with their adjustability. That has to ride more harsh.

I went with Eibach springs with a moderate drop that are only about 10% stiffer than stock. I paired them with Koni Special Active dampers. The KoniSA's use technology developed with McLaren that uses dual valves at different frequencies. So they act as both a Sport shock and a Comfort shock depending on road conditions. Best of both worlds. It's not marketing hype. They act as promised.

This Eibach/KoniSA combination got rid of the other half of the stock suspension's teeth jarring nature. The car can handle the fun curves with ease and it's a pleasure on long drives as well.

[sigtwenty]

Originally Posted by SantaEugence

Surprised you kept the runflats. Biggest difference I noticed was switching to MPS4S. Night and day! Until I lowered on HR then the head splitting bangs were back...

I didn't "keep" them so to say, I had stock 17s and I ditched them 4 months prior.

I got these wheels with nearly new tires for a steal at $600.

didn't really wanna drop $1000 on ANOTHER set of new tires. so I'll keep em for a bit.

[SantaEugence]

Originally Posted by sigtwenty

I didn't "keep" them so to say, I had stock 17s and I ditched them 4 months prior.

I got these wheels with nearly new tires for a steal at $600.

didn't really wanna drop $1000 on ANOTHER set of new tires. so I'll keep em for a bit.

Sorry read it as, you bought them after they were installed.
Makes sense, well worth considering come new tyre time though 👍🏻

[sigtwenty]

Originally Posted by SantaEugence

Sorry read it as, you bought them after they were installed.
Makes sense, well worth considering come new tyre time though

yea ill probably ditch them for sure. but I'm not kidding these tires are brand new. so I'll tolerate them lol

[casualDIYer]

Originally Posted by johnung

I went with Eibach springs with a moderate drop that are only about 10% stiffer than stock. I paired them with Koni Special Active dampers.

I read somewhere that the Koni SA were not to be paired with lowering springs. I don't want an angry Dutchman showing up at my door telling me I didn't following the instructions.

He'll beat me good with a wooden shoe.

I guess you've had no issues so far. How long have you run this combo?

[casualDIYer]

Originally Posted by johnung

I agree with you. When I ditched runflats for Michelin PS4S, half of the teeth jarring stock suspension issues were suddenly gone. I had expected better handling, especially going from stock 225/45-18 to 245/40-18. But I was surprised how much comfort I gained. The jolt from sharp pothole edges was rounded off. The same for those road seams on freeways. It made taking the car on a longer trip more palatable.

The insane grip in the wet is kind of nice too.
PS4S +1

[johnung]

Originally Posted by menncars

I read somewhere that the Koni SA were not to be paired with lowering springs. I don't want an angry Dutchman showing up at my door telling me I didn't following the instructions.

He'll beat me good with a wooden shoe.

I guess you've had no issues so far. How long have you run this combo?

Ah, I call that German-speak for Bilstein and I guess Dutch-speak for Koni. The confusion is due to a cultural/language/translation issue.

Bilstein for the B6 and Koni for the Special Actives both have wording in the their translated to English product literature that says something like "for use with stock height springs only".

To an American reading that it seems very unambiguous. It appears black and white that you are not to use those dampers with lowering springs of any kind. But that's not what those European companies intended to say.

I know this to be a fact because for months prior to the Koni Special Actives release in the US I had numerous conversations and emails with Koni North America. They actually had done testing with a BMW F30 335i xDrive with their upcoming Special Active dampers along with Eibach Springs (-06 xDrive part number). The Eibachs drop the car Front 0.8" and Rear 0.6". They shared details of their testing with me. I have the same as their test car and ultimately I installed the KoniSA/Eibach combination literally the first day that they were released.

During my conversations with KoniNA, I happened to read some Koni European literature that translated to that line about "only compatible with stock height springs". I was immediately alarmed so I asked. Koni said basically "Yes, that's true." It took some more conversation to realize that Koni considers a mild drop of say an inch or less to be in the category of "stock height". They didn't really see any reason to change the wording on their literature because well, everyone should just know that that's what we mean. I have seen the exact same phenomenon with the Bilstein B6.

I tried a few different ways over the past couple of years to spread this knowledge and have now given up. The exact wording from Koni and Bilstein literature gets proliferated to all of the US retailers. Unlike about three years ago when you might call an ECS or Turner or TireRack, etc and actually talk to a knowledgeable car guy, now those calls are taken by call center people who are trained to read and tell the caller exactly what they read on their computer screens.

Haha, just try to call and get those conglomerates to correct or even to just add a useful detail to their website. Once I tried to get them just to add rotor sizes to their websites and it just fell on deaf ears.

So that was the long explanation. Yes, I've been running Koni Special Actives with Eibach Springs for 2 1/2 years and it's been great!

[johnung]

Originally Posted by menncars

The insane grip in the wet is kind of nice too.
PS4S +1

Absolutely! Driving the MPS4S in the rain is like dry pavement. Amazing!

[casualDIYer]

Originally Posted by johnung

Bilstein for the B6 and Koni for the Special Actives both have wording in the their translated to English product literature that says something like "for use with stock height springs only".

To an American reading that it seems very unambiguous. It appears black and white that you are not to use those dampers with lowering springs of any kind. But that's not what those European companies intended to say.

'stock height' would make sense only if BMW made a single version of each car, with no configurable options. They do not. There is a non M Sport version, which American buyers recognize as the 'stock' version but in Canada, you could not buy a 340i with anything less than M Sport. All 340i sold here in 2017 were M Sport with Performance being an option. 'stock' in Canada was already 10mm lower that 'stock' in other markets, including the United States.

Using the US market 'stock' reference for M Sport config'd cars, a front drop of 0.8-inch (20mm) and rear drop 0.6-inch (15mm) drop would mean a net drop of 10mm for the front, and 5mm for the rear. In other words, from stock, the fronts are equal to the BMW Perf front spring drop (20mm from 'stock') and a +5mm raise from BMW Perf springs in the rear.

Originally Posted by johnung

It took some more conversation to realize that Koni considers a mild drop of say an inch or less to be in the category of "stock height".

Considering the above info, 'an inch' (i.e. 25.4mm) is still more the BMW's perf suspension drop of 20mm. Koni and Bilstein are making a part that will fit BMW's lowest drop but won't go any further.

Given this, Dinan's 1.25 inch drop for the rear of the 340i with their Performance Spring kit is outside the planned 25mm drop from Koni/Bilstein

Originally Posted by johnung

I've been running Koni Special Actives with Eibach Springs for 2 1/2 years and it's been great!

I'm considering this combo as well. But since I track the car a few weekends a year, I may go Koni Sports instead of SAs. I read over Farkle's article on rebound etc. It's fascinating stuff that will take a bit of time to soak in. I may also go KW SC but it seems the best parts are things I'll set once then never touch again. My wonderfully adjustable suspension that I'm too lazy to adjust.