[Ageispolis]

So as I understand it, there are 3 kinds of suspensions offered on the f30: Base, Adaptive M, and M sport. From what I understand, the M Sport suspension is standard on all M Sports, except the XDrives. Is that right?

I have an XDrive M Sport. Am I limited on what I can do to the suspension? I'm really only looking for very modest mods like maybe just some strut/sway bars. Different springs wouldn't be terrible either.

What do most people in my situation do?

[alohasurftoad]

Eibach Pro-kit springs, E10-20-031-05-22 with F80 bumpstops. provides just enough lowering to enhance appearance without risk of half axles on the front transfer case, while providing a comfortable ride, just 10% stiffer than OEM.

shorter, F80 bumpstops, are required so you don't engage the bumpstop earlier than necessary due to the slight lowering of the eibach springs.
bmw part 31-33-6-859-768, fronts
bmw part 31-33-7-847-662, rears

depending on age and mileage of your suspension, i suggest changing the strut mounts, spring perches/rubber bit/etc and one use bolts.

wiechers front strut tower brace

monoball upper & lower control arms vastly improve steering feel. VAC, Millway, Turner

you can do aftermarket sways, however since the subframe needs to be removed for access to the sways, a majority of the swaybar cost is labor.

[cfm56d7b]

Ageispolis What is your budget for the suspension upgrade?

[danb1979]

Originally Posted by alohasurftoad

Eibach Pro-kit springs, E10-20-031-05-22 with F80 bumpstops. provides just enough lowering to enhance appearance without risk of half axles on the front transfer case, while providing a comfortable ride, just 10% stiffer than OEM.

shorter, F80 bumpstops, are required so you don't engage the bumpstop earlier than necessary due to the slight lowering of the eibach springs.
bmw part 31-33-6-859-768, fronts
bmw part 31-33-7-847-662, rears

depending on age and mileage of your suspension, i suggest changing the strut mounts, spring perches/rubber bit/etc and one use bolts.

wiechers front strut tower brace

monoball upper & lower control arms vastly improve steering feel. VAC, Millway, Turner

you can do aftermarket sways, however since the subframe needs to be removed for access to the sways, a majority of the swaybar cost is labor.

Agree with the ARBs (sway bars); considered it on my F31 but the faff of having to remove all the subframe for access outweighed the actual benefits, for me personally anyways.

Shame really as the rear sway bar upgrade on my E39 touring to the M5 one made a good difference (however that's on SLS and that's where it needs firming up a touch)

Re bump stops; I've fitted B4S shocks with Eibach pro kit springs to my F31 and stuck with OEM bump stops as they really don't lower much at all over OEM M Sport ride height and just back from the Highlands with a very full car (there & back) and not once did the car come anywhere near to bottoming out (and the motorway and bypass to the Highlands is terrible in places with some serious undulations/potholes etc); so it gave the new suspension a really good shakedown...

However, this is a RWD car; not sure if the ride height is different on xDrive M Sport



Re the front strut tower brace; do you think they make a difference on the F3x cars?

I ran them a lot on previous Jap import Honda's to reduce the front flex, more so when lowered on coilovers; but the BMWs are much stiffer in that sense

[alohasurftoad]

Originally Posted by danb1979

Re the front strut tower brace; do you think they make a difference on the F3x cars?

i have one on my 428i F36 and tbh i barely feel any difference. some members in the strut brace threads reported otherwise, so it seems to be kind of 50-50 between yays and nays.

i suggested it because it is relatively inexpensive, easy to install and something to "check the box" for suspension mods.

[danb1979]

Originally Posted by alohasurftoad

i have one on my 428i F36 and tbh i barely feel any difference. some members in the strut brace threads reported otherwise, so it seems to be kind of 50-50 between yays and nays.

i suggested it because it is relatively inexpensive, easy to install and something to "check the box" for suspension mods.

Yeah; thought that might be case...

On track; probably worth it (it certainly made a huge difference back in my Honda days (EF8 CRX, EG2 Del Sol, EG6 SiR-S, EK9 etc).

But BMWs are much stiffer up front; think it'd be lost on an every day car...

Still look good though

[Ageispolis]

Thanks for all the suggestions. Honestly, I don't know how to start putting together a budget for this. Admittedly, I'd like to start small and low-impact to see how I feel. My mind went to sway bars just because that rigidity has always been an instant bonus on every car I've driven. And they were cheap/simple enough to make an impact right away. But springs and dampers are an option too (not crazy about coil overs). I just don't know how that translates to the Xdrive.

[johnung]

Originally Posted by alohasurftoad

i have one on my 428i F36 and tbh i barely feel any difference. some members in the strut brace threads reported otherwise, so it seems to be kind of 50-50 between yays and nays.

i suggested it because it is relatively inexpensive, easy to install and something to "check the box" for suspension mods.

I’m a proponent of the front upper strut brace on the F3x. Since it’s an inexpensive DIY part, I think the benefit that it provides is definitely worth the cost.

It’s true that these modern day chassis are stiffer. Think of the strength of the front of the F3x as a “U” shape with the subframe across the bottom and the strut towers on the sides.

There is a stock strut brace but it’s a weak design that angles back towards the firewall. The stock brace may do something, (I’ve never driven without it to know if there’s a difference), but it definitely doesn’t do enough to prevent chassis flex at the top.

A few years ago I was on a product development team investigating new potential designs for a front strut brace. The two engineers on the team both agreed that there was benefit. One held up his arms bent at the elbows to show how the strut towers were straight up & parallel in a neutral position when driving down the road.

He demonstrated with his arms that without a strut brace connecting the tops of the towers, the force when entering a curve would act on the inside and outside towers differently. They would flex and at different rates, so they would no longer be parallel.

Drivers get used to the characteristics of the car that they are driving so this momentary chassis flex wouldn’t be perceptible. It would just feel normal.

Here is a good test that demonstrates the benefits of a strut tower brace. First, drive a local circuit of roads with a lot of turns and curves of varying speeds. Then install a strut brace. And immediately go out and drive the same familiar road circuit.

To the driver, the difference with a strut brace installed can be felt upon first entering the turn. Most people describe it as if the steering has improved.

This is what has actually happened. With the car stock, the driver is used to a curve approaching, beginning to turn the steering wheel, feeling the chassis momentarily flex and then the car responds by moving into the turn.

But with a strut brace installed, that momentary flex is reduced/eliminated because the strut towers can no longer get out of parallel. So the driver turns the steering wheel and it feels quicker, like the car instantly moved into the turn. It actually did because that momentary delay when the chassis was flexing has been eliminated.

Note: IMO the best strut brace designs are multi-piece. They are adjustable for exact distance between the towers. They are installed with the chassis in a neutral position. And their brackets are installed once on the strut tower and never removed. So the stretch bolts on the towers don’t get constantly reused every time the crossbar is removed for engine servicing. I use the German Weichers Strut Brace. See photo of strut brace in my engine bay, installation video and product link.

Hope this helps!

https://youtu.be/eP9Jyr2v93s?si=qLK-XQRkOsUOy9f8

https://www.kiesmotorsports.com/prod...4&_ss=r?aff=22

[johnung]

Originally Posted by Ageispolis

So as I understand it, there are 3 kinds of suspensions offered on the f30: Base, Adaptive M, and M sport. From what I understand, the M Sport suspension is standard on all M Sports, except the XDrives. Is that right?

I have an XDrive M Sport. Am I limited on what I can do to the suspension? I'm really only looking for very modest mods like maybe just some strut/sway bars. Different springs wouldn't be terrible either.

What do most people in my situation do?

Before diving into potential aftermarket parts it’s important to identify your goals and identify exactly what your car has now. That’s how you’ll discover your options.

Exactly what year and model XDrive do you have? What mods have you already done? Is this just your daily driver or do you have plans to track it etc? Do you have a long commute? Are you more oriented towards wanting a comfortable ride, sporty ride or both?

Often M Sport refers to the bumper appearance package and not necessarily other things like suspension or brakes. It’s important to put your full VIN into the mdecoder website to get a listing of the packages installed on your car. Especially look for line items for Adaptive Suspension, M Sport Suspension, M Sport Brakes, etc.

What are the last 7 digits of your VIN so I can look up sway bars, etc?

[Ageispolis]

I have a 2015 335i XDrive with the Adaptative M Suspension. When I was shopping around for it, I found out from this board that only the RWD comes with the M Sport suspension. I could never find out why, so I'm trying to figure out what that limitation is exactly and how that translates to aftermarket parts too.

This car is my daily and the only things I really want to do to it are drivability and longevity. So far, just a charge pipe, intercooler, strut/sway bars and maybe that's it. If I could swap in OEM parts like the big brake kit, the M Sport suspension, etc, that would be ideal but idk what my limitations are there. I love how it drives and I just want to tighten things up a bit and improve it, not turn it into a different car.

[vcx]

My post on another thread, that could help you:

Hello guys,

Just a quick review of my last chassis upgrade.

For the record, I have a 340 xdrive sedan, with adaptative suspensions. I already installed VAC monoballs front control arms, which were great to give more feeling in the steering wheel and more responsive/sharper turns.

Recently, I installed Eibach springs (06.22 version, as I didn't want to go very low), H&R sway bars, and a f-32 V-brace and f-80 reinforcement plate under the chassis.

As all those mods were installed at the same time, the effect of each component is harder to distinguish but, as expected, here is what I found:

-less squat and nose dive during acceleration/braking ;

-almost no harshness add, a pleasant surprise (thank to adaptative suspension ?) ;

-much less body roll in corners, the car keeps cornering flat and is much more confidence inspiring. Combined with the more rigid chassis, it almost looks like you could take any turn at any speed without losing control!

Even my girlfriend, who knows nothing about cars, notice how cornering have been improved, when she drove the car.

-car is more composed and flex less when climbing on a sidewalk or things like that.

-visually, the difference is not very noticeable. Maybe the springs will set up and go a bit lower next weeks, we will see, but if one wants a low-rider look, this won't be enough.


Overall, I 100% recommend these mods, as they are relatively cheap and bring a lot of improvement to the soft-floating chassis of the f30 xdrive.

Many thanks for the interesting imputs found on this forum, that helped me chose the right components !

https://f30.bimmerpost.com/forums/sh...599564&page=11

[Ageispolis]

Thanks for the writeup. Wow, what a beautiful car. How did you find out about the OEM parts swaps? I wonder what options there are for the F30. Again though, gorgeous car. I wish they were available in the US!

[johnung]

Originally Posted by Ageispolis

I have a 2015 335i XDrive with the Adaptative M Suspension. When I was shopping around for it, I found out from this board that only the RWD comes with the M Sport suspension. I could never find out why, so I'm trying to figure out what that limitation is exactly and how that translates to aftermarket parts too.

This car is my daily and the only things I really want to do to it are drivability and longevity. So far, just a charge pipe, intercooler, strut/sway bars and maybe that's it. If I could swap in OEM parts like the big brake kit, the M Sport suspension, etc, that would be ideal but idk what my limitations are there. I love how it drives and I just want to tighten things up a bit and improve it, not turn it into a different car.

You are making the assumption that the “M Sport Suspension” is some big deal that you are missing out on. “M Sport” is a BMW Marketing term that they slap on many things. Some are significant like M Sport Brakes, but others are not so much.

If you look at realoem and the difference in part numbers between having an M Sport Suspension or not, it is very subtle. For example the rear sway bar is 13mm in diameter instead of 12mm. It would be a complete waste of time swapping out the 12mm for 13mm, thinking that a difference could be felt. It would make a difference to swap in the BMW 15mm rear bar where there would be an improvement. See photo.

Same goes for springs. BMW doesn’t publish a lot of data on production springs. But from what I’ve found the “M Sport Springs” maybe 10mm shorter. But it would be a waste of time trying to track down actual “M Sport Springs” because they would probably have spring rates for the axle weights of RWD cars anyway. It would be a lot smarter to install an Eibach Spring Kit (E10-20-031-06-22) with correct XDrive spring rates that would lower the car: Front 0.8” (20mm), Rear 0.6” (15mm). See photos for comparison of BMW XDrive springs vs Eibach -06 kit.

You already have Adaptive Dampers which are great so nothing to change there.

So you can make aftermarket suspension changes that are actually better than whatever bits an “M Sport Suspension” may have had. Not missing out on anything.

[Ageispolis]

Thanks for the write up. I took a look at the Eibach springs and I like the price point. Plus everyone I've seen review them like them.

A wrinkle in all of this is I found one of my struts leaking now. So I probably should get that fixed. And if I'm doing one, I might as well do them all. But they're not cheap and I'm not sure what aftermarket struts to replace them with. B8s? Aftermarket adjustable?

The first question wasn't really about specific springs, etc. A better way to put it is "Why did BMW limit suspension options on the XDrive and what does that mean overall, including aftermarket options"

[alohasurftoad]

for aftermarket adaptive replacement, Bilstein B4 Damptronic. however you will not be able to find any available.

if replacing the OEM adaptive damper, buy a pair. if you can afford all four, why not. otherwise just change a pair, f or r.

[Airwick604]

[QUOTE=alohasurftoad;30919620]

depending on age and mileage of your suspension, i suggest changing the strut mounts, spring perches/rubber bit/etc and one use bolts.

wiechers front strut tower brace

QUOTE]

Hi!

I have a strut tower on order and I was wondering if you knew the part number of the hardware (13mm bolts) used on top of the tower used to anchor the brace.

Are these supposed to me "one time use" only?

I tried to look on RealOEM but had no luck

Thanks!

[chuncomunco]

Originally Posted by alohasurftoad

for aftermarket adaptive replacement, Bilstein B4 Damptronic. however you will not be able to find any available.

if replacing the OEM adaptive damper, buy a pair. if you can afford all four, why not. otherwise just change a pair, f or r.

FYI, anyone who needs the left side B4 adaptive damper FCP has it in stock right now: https://www.fcpeuro.com/products/bmw...b4-37116793869


I've been slowly collecting my way to an entire set of B4 adaptive shocks since November. It's crazy!