[OpenAir]

I'm unhappy with the ride quality on my 228 cab. I've been driving a 235xDrive which has the adaptive suspension and it feels more in control over poor roads compared to the M-Sport suspension.

So, it's time for fresh rubber all around my car, which I want to run 235/255/40/18's and this will require new wheels as I have the square 7.5" wheels...which max out at 225. I will also be ditching the run flats. Now for the question, while I'm in there, I'm thinking I should upgrade the shocks with something that has better dampening abilities. Since the cab is 400lbs heaver than the coupe, should I lean on the "tight" side as the weight will compensate for this, or would some yellows be just fine?

I'm at a total loss, this is a dd that I frequently drive stupid on back roads...I normally have my foot up her A$$ multiple times daily, but when I take mother for a ride, we just cruise so suppleness is a factor also.

I'm rambling now, this is such a hard decision...

[mdputnam]

I would suggest, with suspension changes, you do one thing at a time. First, get rid of the run flats and you will notice a significant change. Then dive it for a few weeks before making any other change.
Our 135i convertible had run flats and the M Sport suspension and I hated the ride and handling. After switching to Michelin Pilot Super Sports it was a different car. I would be careful with stiffer shocks as the convertible body is not as stiff as the coupe. Most people think stiffer is better, but I run my track car with relatively soft shock settings it keeps the tires more firmly planted when going over the aprons on the apexes allowing for a faster exit speed (that's on a proper unequal wishbone front suspension, unlike most BMWs) Anyway, the point is, especially on a road car, stiffer is not necessarily better and setting up a suspension is complicated.

[Viffermike]

Originally Posted by mdputnam

I would suggest, with suspension changes, you do one thing at a time. First, get rid of the run flats and you will notice a significant change. Then dive it for a few weeks before making any other change.
Our 135i convertible had run flats and the M Sport suspension and I hated the ride and handling. After switching to Michelin Pilot Super Sports it was a different car. I would be careful with stiffer shocks as the convertible body is not as stiff as the coupe. Most people think stiffer is better, but I run my track car with relatively soft shock settings it keeps the tires more firmly planted when going over the aprons on the apexes allowing for a faster exit speed (that's on a proper unequal wishbone front suspension, unlike most BMWs) Anyway, the point is, especially on a road car, stiffer is not necessarily better and setting up a suspension is complicated.

+1. The springs on the 2 Series -- even the M235 and THP 228i cars -- have relatively low rates and are not very stiff. This is done as a compromise for all-around street pliability and control. It's a reason non-THP 228is like mine have a bit of body roll (my biggest complaint about the M Sport suspension); the non-THP dampers have rebound and compression settings that are fairly low and, of course, static. Meanwhile, the damper settings on the M235i are firmer (higher) overall and adjust themselves for conditions -- and are, thus, not as prone to as much roll.

Another thing to consider: the predictive dampers are tuned for non-run flat tires, while the static suspensions are tuned for run-flats. Basically, a non-RFT has a significantly higher damping effect because of the less-stiff sidewalls. When you switch, part of the 'different car' effect will be this. Simply put, your tires will absorb more light to middle road shock and will bend to keep the contact patch on the road more readily -- which translates to a smoother ride, a more planted feel and higher adhesion limits, but won't translate to less body roll and more supple handling over undulating or broken pavement.

[OpenAir]

Originally Posted by mdputnam

...Most people think stiffer is better, but I run my track car with relatively soft shock settings it keeps the tires more firmly planted when going over the aprons on the apexes allowing for a faster exit speed (that's on a proper unequal wishbone front suspension, unlike most BMWs) Anyway, the point is, especially on a road car, stiffer is not necessarily better and setting up a suspension is complicated...

Understood, the only reason I mentioned a "stiffer" aspect is that the convertibles weigh 400lbs more than a cab, and as such "may" off-set some of the harshness, it was a question.

As for the difference moving from run flats to non-run flats, the 235 xDrive I've been driving has the same run flats as mine, with non of the sloppiness.

I'm skeptical about picking up a set of wheels and tires as I'm not sure they will really change the ride that much.

Thanks for the input !!!

[OpenAir]

Originally Posted by Viffermike

+1.

I get what your saying, but I spent an entire weekend and then some playing with a 235i cab running MPP's and a 235i xDrive cab running the same RFT's as mine.

My point is that the RFT's rode nicer than the MPP's. This threw my original argument of RFT's being crap right out the window. So, here I sit complaining yet not really having an answer or idea and my current tires are running out of tread. Really don't want another set of 225's as I'd like to add a little bit of sidewall, hence the 235's but they require new wheels...which if they don't correct some of the issues I'm experiencing, could have been used for a down-payment on the 235i...

I do appreciate your thoughts, I'm just a mess...SIGH

[jnu]

It might help the thread if you described in more detail what it is you don't like about the ride quality in your 228i cab. You mentioned you thought the M235i PSS "rode nicer" than the M235 RFT. But you also mention you're considering firmer dampers, which would likely make the ride more harsh.

For comparison, I also have a 228i Msport cab and feel that the ride is a little harsh over choppy pavement. A big bump or pothole can really throw the car off balance. The first thing I'm likely to change is the tires (softer, non RFT). I probably wouldn't consider firmer shocks.

[OpenAir]

Originally Posted by jnu

It might help the thread if you described in more detail what it is you don't like about the ride quality in your 228i cab...

Thanks,

So I've been on this journey for some time now looking at how I can improve the driving and handling on my cab. I have the Sport Line w/analog dampers and no THP.

I have several "favorite" roads where I can bottom "it feels like bottom" the suspension due to road irregularities. Additionally, small sharp road bumps cause havoc with the RFT's, to the point where I've been wondering if it could be a dampening issue. I've driven over these same roads with the adaptive suspension, 235i rwd and MPSS and also with a 235ix with RFT's. One specific corner is especially brutal on my car, and I can only take it at ~30mph or the outside front wheel gets slammed hard, whereas both of the adaptive suspension cars can handle it much faster with no issues.

OK, so originally I thought to remove the RFT's and this should clear up most of my issues) along with adding a slightly taller tire (235 vs 225) to increase my sidewall. What threw me off this path was that the adaptive suspension with the RFT's didn't have the issue. My point being that if I can't correct this, I'd rather put the money for wheels, tires and dampeners towards a 2 series with adaptive suspension.

So, after several threads and lots of input from a long list of forum members, I've made step one and purchased some lighter wheels (OZ Racing LEGGERA HLT with 235/40/18 DWS-06's. They should arrive this Friday which gives me the weekend to clean and apply some Quartz to protect the finish. I have no doubt that this will quiet the car and add some compliance to the overall ride. After that, maybe some dampeners at 30K.

[Viffermike]

Originally Posted by OpenAir

Thanks,

So I've been on this journey for some time now looking at how I can improve the driving and handling on my cab. I have the Sport Line w/analog dampers and no THP.

I have several "favorite" roads where I can bottom "it feels like bottom" the suspension due to road irregularities. Additionally, small sharp road bumps cause havoc with the RFT's, to the point where I've been wondering if it could be a dampening issue. I've driven over these same roads with the adaptive suspension, 235i rwd and MPSS and also with a 235ix with RFT's. One specific corner is especially brutal on my car, and I can only take it at ~30mph or the outside front wheel gets slammed hard, whereas both of the adaptive suspension cars can handle it much faster with no issues.

OK, so originally I thought to remove the RFT's and this should clear up most of my issues) along with adding a slightly taller tire (235 vs 225) to increase my sidewall. What threw me off this path was that the adaptive suspension with the RFT's didn't have the issue. My point being that if I can't correct this, I'd rather put the money for wheels, tires and dampeners towards a 2 series with adaptive suspension.

So, after several threads and lots of input from a long list of forum members, I've made step one and purchased some lighter wheels (OZ Racing LEGGERA HLT with 235/40/18 DWS-06's. They should arrive this Friday which gives me the weekend to clean and apply some Quartz to protect the finish. I have no doubt that this will quiet the car and add some compliance to the overall ride. After that, maybe some dampeners at 30K.

Superb choice on the wheel! If price were no object I'd have either those or Ultraleggeras on mine ...

What you're running into is almost certainly the predictive damping at work. The biggest advantage of the system is being able to adjust compression and rebound damping on the fly, in milliseconds, to smooth out the ride and suspension behavior over less-than-perfect pavement. Predictive damping doesn't do all that much good on great pavement -- that's why you frequently don't see it on true performance cars (Best example for our purposes? The M2). It's on the everyday stuff 'in the wild' that the system really shines -- and you have absolute empirical and tangible proof of that from your drives in different cars on the same route.

Now the bad news: you won't be able to replicate that on your car with upgrades since everything you'd be able to get has static settings. Even coilovers with adjustable dampers will be static once you're driving.

[OpenAir]

Originally Posted by Viffermike

Superb choice on the wheel!

Thanks! I'm hoping the color looks great on my Deep Blue.

Originally Posted by Viffermike

...Now the bad news: you won't be able to replicate that on your car with upgrades since everything you'd be able to get has static settings. Even coilovers with adjustable dampers will be static once you're driving.

I know, hence all my concern regarding $5k or better on wheels, dampeners and tires for something that will never get there, I could use that money and purchase a M240i at LCI and call it a day...but I like my color and mods that I've already done, so I figure this is a venture in the right direction.

Thanks again!

[jnu]

I can definitely agree with this statement you made: "small sharp road bumps cause havoc with the RFTs". Interesting to hear that the M235 with adaptive dampers performed better on the bottoming out scenario too. I've only noticed the bottoming out issue in one particular spot with a devastating dip in the road. I probably just need to slow down.

We both have essentially the same setup, so I'm very interested to hear how the wheels + tires work for you. Please let me know! Since you're changing both at once, it could be tough to say whether the wheel weight or tire swap is really the key factor. Did you go 18x8 all around? One other option might be 17-inch for even more sidewall height.

Originally Posted by OpenAir

Thanks,

So I've been on this journey for some time now looking at how I can improve the driving and handling on my cab. I have the Sport Line w/analog dampers and no THP.

I have several "favorite" roads where I can bottom "it feels like bottom" the suspension due to road irregularities. Additionally, small sharp road bumps cause havoc with the RFT's, to the point where I've been wondering if it could be a dampening issue. I've driven over these same roads with the adaptive suspension, 235i rwd and MPSS and also with a 235ix with RFT's. One specific corner is especially brutal on my car, and I can only take it at ~30mph or the outside front wheel gets slammed hard, whereas both of the adaptive suspension cars can handle it much faster with no issues.

OK, so originally I thought to remove the RFT's and this should clear up most of my issues) along with adding a slightly taller tire (235 vs 225) to increase my sidewall. What threw me off this path was that the adaptive suspension with the RFT's didn't have the issue. My point being that if I can't correct this, I'd rather put the money for wheels, tires and dampeners towards a 2 series with adaptive suspension.

So, after several threads and lots of input from a long list of forum members, I've made step one and purchased some lighter wheels (OZ Racing LEGGERA HLT with 235/40/18 DWS-06's. They should arrive this Friday which gives me the weekend to clean and apply some Quartz to protect the finish. I have no doubt that this will quiet the car and add some compliance to the overall ride. After that, maybe some dampeners at 30K.

[x233]

It's going to be very hard to replicate the adaptive suspension road manners on a non-adaptive suspension.

Comfort and better grip? Non-RFT tires are an obvious first move in that direction.

I'd look if there are any progressive springs with not too much lowering (unlike H&R) available for your car. I've no idea if there are but a progressive spring with minimal lowering might be a cheap solution while a wrong choice wouldn't hurt your pocket too much.

If you're into coilovers, I'd forget about Bilsteins because that's not what you go to if you're looking for comfort. They're usually quite stiff and bouncy.

KW might be more appropriate. They are usually very comfortable (sans the Clubsport variety). I don't know how that works on a 2-er but most users are happy. What I don't like about KW is they usually lower the car a bit too much and are usually too soft for my liking (but that might be just what you're looking for) and they are not very easy to adjust (usually you have to take the rear shocks off the car).

I haven't heard about Ohlins offering anything for this vehicle.

One other option would be to talk with AST Suspension folks and see if they can make you a custom solution. They have 5100 series for F20/F21 but I don't know for a fact if it fits your vehicle. Because they are a rather small shop they do custom coilovers for specific applications frequently.

Of the Bilstein, KW and AST coilovers I've tried AST are by far the better coilovers in terms of grip and usually at their default settings they are much more comfortable than Bilsteins and at the same time not as sloppy as KW. Fantastic grip and stability on the road, a different level entirely. They do know how to tune their shocks, use double digressive pistons, proper springs and... helper springs (which helps both comfort and grip on bad roads). Easy to adjust, too.

[OpenAir]

Originally Posted by x233

It's going to be very hard to replicate the adaptive suspension road manners on a non-adaptive suspension...

Thanks, at this point I'm going with the wheels and tires, i.e. loose some weight and trash the RFT's!

After that I'll see but most likely I'll just pick up a M240xi Cab during LCI, in which case I can still use my wheel purchase.

[jnu]

Looks like you've put on your new wheels/tires. Can you comment on how that changed the ride?

[OpenAir]

Originally Posted by jnu

Looks like you've put on your new wheels/tires. Can you comment on how that changed the ride?

I can say that the ride quality has improved dramatically. The car is much more compliant and expansion joints and sharp impacts no longer wreck havoc with the suspension. Additionally, road noise has decreased to the point that I don't really hear them, even with the top down.

I haven't "thrashed" it much yet as I'm breaking in the tires, but at this point I'm tickled with the decision.

[jnu]

Great news! I'm considering a similar upgrade but maybe in conjunction with the M4 LCAs, which reportedly push the wheels out about 10mm. Between the ET40 wheels I'm looking at and the 10mm LCA poke, my setup would be 15mm closer to fender than your setup. I'm not convinced it'd fit, and I may need to find ET45 wheels like yours but in 17". I know from your other thread that you're quite close on the strut side. How much clearance do you have fender-side? 15mm?

[OpenAir]

Originally Posted by jnu

Great news! I'm considering a similar upgrade but maybe in conjunction with the M4 LCAs, which reportedly push the wheels out about 10mm. Between the ET40 wheels I'm looking at and the 10mm LCA poke, my setup would be 15mm closer to fender than your setup. I'm not convinced it'd fit, and I may need to find ET45 wheels like yours but in 17". I know from your other thread that you're quite close on the strut side. How much clearance do you have fender-side? 15mm?

I would say I have a max of 7mm to be flush, but that is not from a measurement. I ran 12mm spacers in the front and 15mm in the back and I was starting to see issues from the tires kicking up rocks and the such, as such, I'm just tickled that the OZ offset brought them back in slightly.

Try this link to Will It Fit. It helped me a lot.

[Viffermike]

Originally Posted by jnu

Great news! I'm considering a similar upgrade but maybe in conjunction with the M4 LCAs, which reportedly push the wheels out about 10mm. Between the ET40 wheels I'm looking at and the 10mm LCA poke, my setup would be 15mm closer to fender than your setup. I'm not convinced it'd fit, and I may need to find ET45 wheels like yours but in 17". I know from your other thread that you're quite close on the strut side. How much clearance do you have fender-side? 15mm?

Keep in mind that LCAs also push the hub forward (toward the nose of the car) about 23mm. That's almost an inch. You'll need to account for that relative change, too, in terms of the wheel-to-well relationship when playing with offset. I'd hate for you to bottom out, or have the sidewall rub something hard and metal at full lock ...

[jaboyd]

New tires and light wt rims will almost always improve ride quality. IMO, if you wanted to retain the improved ride and improve handling I'd go the swaybar route. It is less expensive than doing a full coilover upgrade (though not cheap on a 2 series), and it will assist the tendency for roll in the corners on the heavier cab w/o trading off much ride quality. It will be noticeable at turn in and aggressive cornering.

[OpenAir]

Originally Posted by jaboyd

New tires and light wt rims will almost always improve ride quality. IMO, if you wanted to retain the improved ride and improve handling I'd go the swaybar route. It is less expensive than doing a full coilover upgrade (though not cheap on a 2 series), and it will assist the tendency for roll in the corners on the heavier cab w/o trading off much ride quality. It will be noticeable at turn in and aggressive cornering.

It's on my list of things I "could" do...

[JoeyF228]

Have you considered the Koni FSD struts and shocks? It says they offer one set for without M sport suspension and one with, says coupe only but might send them an email or call and see why the won't work on the droptop.

http://www.koni-na.com/en-US/NorthAm...RFORMANCE/FSD/
part number 2100-4142

[jgoldstein2000]

OpenAir Im hoping you put on some coilovers because I am considering so on my XDrive and want your feedback! Thanks ��

[OpenAir]

Originally Posted by jgoldstein2000

OpenAir Im hoping you put on some coilovers because I am considering so on my XDrive and want your feedback! Thanks ��

That will never happen. I've been pushing the car hard over the last few days as the tires have broken in. All my previous issues have gone away.

Sway bars would be nice, but I'm not going to drop the engine to do that. This should hold be over till LCI.