[aleph-one]

Originally Posted by cky

I have installed the following and I'd say most of them improved the handling but in different %:
1. MSS lowering springs
2. Spacers
3. Lighter wheels and PS4S tires
4. X3M/ X4M sway bars & lower strut bar
5. CPM strut plate: http://cpmtech.jp/product/?cat=1#%EF%BC%9CCSRP-B401
6. Dinan tension strut ball joint (G20 one works on on my MY21 G02): https://www.dinancars.com/products/s...arts/D280-0022

I would say spacer, X3M/X4M lower strut bar, CPM strut plate and dinan kit improved the steering handling feeling quite a lot

Can you share part numbers for the X3M/X4M sway bars and lower strut bar and/or where you sourced them from? Thanks!

[djmcbride1980]

Originally Posted by aleph-one

Can you share part numbers for the X3M/X4M sway bars and lower strut bar and/or where you sourced them from? Thanks!

Bump for this?

Thank you!

[Rhdlife]

Originally Posted by aleph-one

Can you share part numbers for the X3M/X4M sway bars and lower strut bar and/or where you sourced them from? Thanks!

Bump for this?

Thank you!



I second this

[earlgsxbusa]

I'll post up in a few weeks. Waiting for KW3 coilovers. But had similar questions on this thread. I'll see how KW3s go see about adding the under braces.

[abbike18]

Originally Posted by Rhdlife

Bump for this?

Thank you!



I second this

RealOEM is your friend....

Front sway bar: 31308093412
Source: https://www.realoem.com/bmw/enUS/sho...diagId=31_1666

Rear Sway Bar: 33508746456
Source: https://www.realoem.com/bmw/enUS/sho...diagId=33_2461

Also...the rear swat bar for the X3M is a very different shape than the rear sway bar for the M40i. It also mounts on the end links to a different location on the suspension. I would be surprised if it fit.

The front bar looks to have a very similar shape and might swap over.

[abbike18]

I replaced the rear sway bar bushings on my M40i. Why? Well I looked at the bushings when the car was flat (see picture 1) and then I looked at them when I simulated a little body lean by jacking one side of the car up slightly (see second picture).

Notice how soft the bushings are, and how much the sway bar moves in the bushing. I made some measurements of the deflection and they showed that if you could reduce the deflection to 0, the effective stiffness of the bar would increase about 15%. Poly bushings it is as an experiment.

So I measured the sway bar - it is a 22mm sway bar. I ordered a new set of universal links from Whiteline - P/Ns w21301 and w21047g. I also got some M8 fender washers.

See third picture for a comparison of the old and new.

Used a E14 wrench to work in the tight space to remove the old bushings. Note - this is a really tight job without dropping the subframe, but totally doable. You'll learn some tricks about reach around the sub frame with two hands etc to get it done. I did bend the wrench a bit to help fit.

Picture 4 shows the finished product. You will notice that I put a small piece of sheet metal between the bushing and the sub frame. This was to take up the space caused by the nut insert in the sub frame, and ensure no play.

On drive, you can definitely feel the back end is more responsive, and the car is more balanced on hard corner (rather than being slightly biased towards understeer). It's not a night and day difference, but its definitely noticeable and was worth it to me.

Plan is to do the same to the front, and then alter the rear sway bar to have a shorter lever arm to restore the nice balance. Let's see how far I get...this is all experimentation for the sake of experiments.

[ContactPatch]

Join your local SCCA sanctioned Autocross and learn from people that have been doing it for years. There is more to it than one would believe, watch your course times improve and find out from seasoned drivers what mods will help improve lap times. Word of caution: this is highly addictive and more fun than just about anything you can do with a car.

This past weekend I witnessed lightly tuned Miatas (with a great driver) destroy new corvettes and a 22 Porsche 911 GT3 by 3 to 4 seconds, it was brilliant.

[abbike18]

Got all the parts to do a front sway bar bushings change out. Should be quick and easy because the front bushings are way easier to access.

Wrong! The front bushings are bonded to the sway bar. Did some experimentation to figure out the stiffness of the bushing (how much torque they apply) vs the stiffness of the bar. Makes it a tough choice because the bonded nature means they also make the sway bar act like a torsion arm spring...but seems to be relatively low force as compared to the springs/bar.

Anyone have any experience with bonded sway bar bushings?

[dmicah]

Originally Posted by abbike18

Got all the parts to do a front sway bar bushings change out. Should be quick and easy because the front bushings are way easier to access.

Wrong! The front bushings are bonded to the sway bar. Did some experimentation to figure out the stiffness of the bushing (how much torque they apply) vs the stiffness of the bar. Makes it a tough choice because the bonded nature means they also make the sway bar act like a torsion arm spring...but seems to be relatively low force as compared to the springs/bar.

Anyone have any experience with bonded sway bar bushings?

I've never heard of bonded bushings. Are you sure they're bonded at the factory, or is it that they've become bonded over time?

In any case, maybe this is the universe telling you to do both the bushings and switch to the X3M bars?

[abbike18]

Originally Posted by dmicah

I've never heard of bonded bushings. Are you sure they're bonded at the factory, or is it that they've become bonded over time?

In any case, maybe this is the universe telling you to do both the bushings and switch to the X3M bars?

Yes I'm sure they are bonded from the factory. They are extremely evenly stuck on there. And now I know why the single P/N on real OEM is for bar and bushings.

Going X3M bars is a good idea, but I really don't want to drop the subframe...I don't think there is any other way to get the bar out. Anyone who knows please chime in.

[dmicah]

Originally Posted by abbike18

Yes I'm sure they are bonded from the factory. They are extremely evenly stuck on there. And now I know why the single P/N on real OEM is for bar and bushings.

Going X3M bars is a good idea, but I really don't want to drop the subframe...I don't think there is any other way to get the bar out. Anyone who knows please chime in.

I hear you on the subframe, that sounds like a nightmare. Maybe you don't wanna mess with the front. Your rear bushings have probably increased oversteer marginally in the back. That sounds good to me.

[pchao2]

In Sport mode setting, the SAV feels very bouncy on smooth highways at 70 mph or more with body-roll when changing lanes at this high speed. Can exchanging out the X3 m40i OEM front and rear anti-sway bars for the X3M OEM version reduce the bouncy and body-roll ???
Also, is the exchange a simple "plug & play" transplant or not?

[Rottweiler]

Originally Posted by pchao2

In Sport mode setting, the SAV feels very bouncy on smooth highways at 70 mph or more with body-roll when changing lanes at this high speed. Can exchanging out the X3 m40i OEM front and rear anti-sway bars for the X3M OEM version reduce the bouncy and body-roll ???
Also, is the exchange a simple "plug & play" transplant or not?

News to me that the X3 M40i has factory f/r bars…

[HighlandPete]

Originally Posted by pchao2

In Sport mode setting, the SAV feels very bouncy on smooth highways at 70 mph or more with body-roll when changing lanes at this high speed. Can exchanging out the X3 m40i OEM front and rear anti-sway bars for the X3M OEM version reduce the bouncy and body-roll ???
Also, is the exchange a simple "plug & play" transplant or not?

If across the axle, springs and/or dampers are responsible for any bounce. Anti-roll bars with not change that, as they are neutral for cross axle bumps. If single wheel bounce, the stiffer the anti-roll bars, the more single wheel bumps will be amplified. Stiffer bars will help with roll control.

[abbike18]

TLDR:
Code your VDC module fields AusgabeSollstromVA_Zug_VDC2, AusgabeSollstromVA_Druck_VDC2, AusgabeSollstromHA_Zug_VDC2, AusgabeSollstromHA_Druck_VDC2 to a value of 1100 (from 900), or even higher if you want, to stiffen the sport setting of your adaptive suspension.

Long Version:
After Dinan released the springs for our car, I was curious if they would be working on a Shockwave software upgrade. This upgrade essentially tunes the adaptive damping algorithm. Turns out they aren't, so naturally I tried to figure out what I could do myself.

I did some logging on the adaptive damper valve in our car, and found that it seemed that higher currents led to a stiffer shock. Look at the "comfort" mode and "sport mode 900ma target" plots below. That is the same road driven with the same aggressiveness. It's clear visually as well as from the average current that sport mode has more current.

I did some research, and found that historically the BMW EDC system was the opposite - no current was stiff and more current was softer. Hmmm...so I found a press release saying that Tenneco is the supplier for BMW X3: https://www.businesswire.com/news/ho...hicle-Platform

It is their CVSAe platform, so I scoured around for an explanation on how they work. Found this video:

Check out the 2 minute mark - 1.6amps for sports driving and 0.29 amps for comfort. Brilliant - exactly what I was seeing in the data.

So I looked at the VDC module, and it turns out you can increase the current target (but it is still capped at 1.6 amps) for the EDC system with the following coding parameters:
AusgabeSollstromVA_VDC1
AusgabeSollstromVA_Zug_VDC2
AusgabeSollstromVA_Druck_VDC2
AusgabeSollstromHA_VDC1
AusgabeSollstromHA_Zug_VDC2
AusgabeSollstromHA_Druck_VDC2

All of the 'VDC1' parameters are set at 400, whereas the VDC2 are set at 900. So VDC2 = Sport and VDC1 = Comfort. I changed all the VDC2 values to 1100.

Then I went for a drive, and you can see the last plot with the 1100ma target current. Much more dampening applied from the data, and felt firmer as well. Felt flatter in corners, and like it had less understeer.

I used Bimmergeeks ProTool for all the logging, investigation and coding: https://www.bimmergeeks.net/protool

I found a specific engineering reference in German wrt Druck and Zug, seems to be compression/rebound, respectively. Which might make sense: https://www.proz.com/kudoz/german-to...zug-druck.html

VA seems to be front, where HA seems to be rear: https://www.air-suspension-parts.de/...-1-F20-M-140-i

Anyone else want to try and comment on what it does for them?

[deladude]

Originally Posted by abbike18

After Dinan released the springs for our car, I was curious if they would be working on a Shockwave software upgrade. This upgrade essentially tunes the adaptive damping algorithm. Turns out they aren't, so naturally I tried to figure out what I could do myself.

I did some logging on the adaptive damper valve in our car, and found that it seemed that higher currents led to a stiffer shock. Look at the "comfort" mode and "sport mode 900ma target" plots below. That is the same road driven with the same aggressiveness. It's clear visually as well as from the average current that sport mode has more current.

I did some research, and found that historically the BMW EDC system was the opposite - no current was stiff and more current was softer. Hmmm...so I found a press release saying that Tenneco is the supplier for BMW X3: https://www.businesswire.com/news/ho...hicle-Platform

It is their CVSAe platform, so I scoured around for an explanation on how they work. Found this video:

Check out the 2 minute mark - 1.6amps for sports driving and 0.29 amps for comfort. Brilliant - exactly what I was seeing in the data.

So I looked at the VDC module, and it turns out you can increase the current target (but it is still capped at 1.6 amps) for the EDC system with the following coding parameters:
AusgabeSollstromVA_VDC1
AusgabeSollstromVA_Zug_VDC2
AusgabeSollstromVA_Druck_VDC2
AusgabeSollstromHA_VDC1
AusgabeSollstromHA_Zug_VDC2
AusgabeSollstromHA_Druck_VDC2

All of the 'VDC1' parameters are set at 400, whereas the VDC2 are set at 900. So VDC2 = Sport and VDC1 = Comfort. I changed all the VDC2 values to 1100.

Then I went for a drive, and you can see the last plot with the 1100ma target current. Much more dampening applied from the data, and felt firmer as well. Felt flatter in corners, and like it had less understeer.

I used Bimmergeeks ProTool for all the logging, investigation and coding: https://www.bimmergeeks.net/protool

I'm also curious about the difference between Druck and Zug, and HA and VA. I found on specific engineering reference in German wrt Druck and Zug, seems to be compression/rebound, respectively. Which might make sense: https://www.proz.com/kudoz/german-to...zug-druck.html

Anyone else want to try and comment on what it does for them?

I am tempted to try this using bimmercode's expert coding feature. I have not messed with expert coding yet but this looks worth a try. I've always been a bit underwhelmed by the sport suspension setting.

I dont have time today but I will post back later this week

[Rottweiler]

Following this

I’d chance a venture into BimmerCode expert with step by step instructions

Thank you

[abbike18]

I'm not sure Bimmercode can do this - I'm pretty sure they don't give access to the VDC module.

You might need a more advanced, feature rich tool like Bimmergeeks ProTool for this type of thing.

[deladude]

Originally Posted by abbike18

I'm not sure Bimmercode can do this - I'm pretty sure they don't give access to the VDC module.

You might need a more advanced, feature rich tool like Bimmergeeks ProTool for this type of thing.

It appears you are correct. The ProTool looks like a good purchase for a few reasons so I'll probably pick one up soon.

I have the "chassis function limited message" popping up again so I should probably address that before tweaking things. If I ever get around to this I will let ya's know how it works out. Thanks for the info!

[abbike18]

Originally Posted by deladude

It appears you are correct. The ProTool looks like a good purchase for a few reasons so I'll probably pick one up soon.

I have the "chassis function limited message" popping up again so I should probably address that before tweaking things. If I ever get around to this I will let ya's know how it works out. Thanks for the info!

Do it! I've been running it now since my first post. It is definitely firmer. I ended up changing sport to 1300 (across front/rear and rebound/compression) and moved comfort up to 500. I really like it this way. Don't forget if you go off the standard values (400/900/1100) you have to enter custom values in hex.

I found that with a hybrid turbo in comfort if you nailed it to pass someone on the highway the suspension was just a tad soft and the car would really get unsettled from the quick torque hit. Upping the comfort setting helped with that a bit while maintaining the soft nature.

[IAmSpeed]

Have you considered spending those budgets to buy the car that you fit your style and taste better instead?

I used to spend $$$$ on mods to turn my X3 as sporty as it can be, but then eventually I traded in and get the Supra as my fun car.

Just my experience, and look forward to seeing you expand all the potential of this beast!

[abbike18]

Originally Posted by Iamthespeed

Have you considered spending those budgets to buy the car that you fit your style and taste better instead?

I used to spend $$$$ on mods to turn my X3 as sporty as it can be, but then eventually I traded in and get the Supra as my fun car.

Just my experience, and look forward to seeing you expand all the potential of this beast!

Good question, and yes I thought about it. It really comes down to this...we needed a family car and I wanted a car that was fun to drive/satisfy my urge to have fun driving. That leaves two options given a fixed total budget of about 50k, give or take:
1.) Buy a boring crossover/minivan and an older sedan
2.) Get only a X3 M40i

We chose #2 because when we go on family trips (often in the mountains) that means we have a car that is fun to drive.
If you look at what you can get for option 1 at $25k each, the family car is really not very inspiring.

When it came to X3 M40i vs X3M, it came down to gas mileage and the fact that my wife really hates busy rides, so the comfort adaptive setting of the M40i was much better.

Not the right choice for everyone, but it was right for us.

I've also learned that no matter what car I get, I will always mod it. I just like learning about the car I have and experimenting with it. At this point the mods are for the enjoyment of it, not to make the car in to some goal.