Base 128i suspension upgrades w/ minimal drop

[gjm120]

First a thanks for all posters for the great info on this forum. This site has really made me comfortable that at least routine maintenance on my car is quite doable.

I recently bought a 128i and really like it. The one regret is that I got the AT after driving manual cars for about 23 years. There were reasons for that. One being it was the right car otherwise.

The car is non sport but has the sport seats- big plus. I’ve been contemplating suspension mods for when the run flats need to be changed – or sooner. I’m after good handling with minimal drop in ride height.

Damper/ spring options I’m considering:

1. Swift Spec–R with Bilstein B6
2. B12 Pro Kit.
3. BMWPS - maybe a little more money than I want to spend and right or wrong I think there are better damper options.
4.Stock Sport suspension - maybe not stiff enough to bother with.
5. Is there a Dinan or BMW spring set that will give a high spring rate with little drop and can be paired with say B6’s?

I know someone will say use the search feature. I have done that many times to be able to ask at least half intelligent questions.

Any input will be greatly appreciated. Thanks

[asbrr]

Originally Posted by gjm120

First a thanks for all posters for the great info on this forum. This site has really made me comfortable that at least routine maintenance on my car is quite doable.

I recently bought a 128i and really like it. The one regret is that I got the AT after driving manual cars for about 23 years. There were reasons for that. One being it was the right car otherwise.

The car is non sport but has the sport seats- big plus. I’ve been contemplating suspension mods for when the run flats need to be changed – or sooner. I’m after good handling with minimal drop in ride height.

Damper/ spring options I’m considering:

1. Swift Spec–R with Bilstein B6
2. B12 Pro Kit.
3. BMWPS - maybe a little more money than I want to spend and right or wrong I think there are better damper options.
4.Stock Sport suspension - maybe not stiff enough to bother with.
5. Is there a Dinan or BMW spring set that will give a high spring rate with little drop and can be paired with say B6’s?

I know someone will say use the search feature. I have done that many times to be able to ask at least half intelligent questions.

Any input will be greatly appreciated. Thanks

Congrats on the new car. There are a lot of threads back and forth on this, will add my 2 cents below:

1. Swift spec R should be run with Bilstein B8 due to drop, but some have run it successfully with B6. From "non-sport" suspension the drop will be 40mm+, while not slammed, it's not a "minor" drop

2. The B12 theoretically gives you similar drop, but after just installing mine I think it's quite mild compared to M sport, I would say only 10mm max more than M-sport. I also have Dinan camber plates up front which reduce the drop by 5mm so the front may have only come down 5mm from M-sport

3. Also a mild drop, similar to B12 maybe a few mm higher. I'm sure it's a decent setup w/ OEM quality, but the price is steep considering what you get.

4. May be worth it if you get a bargain on a lightly used set, it will be a noticeable difference than non sport, but it kind of depends what you want out of the car and what you're used to. The B12 kit I put in reduced roll by say 25% from M-sport, and has a stiffer but more controlled ride - some say it rides "better" than stock which it does because it has better body control but make no mistake it's stiffer overall. Don't forget to grab the upgraded anti roll bars front and back that go with this kit. Non sport 128i doesn't have a rear anti roll bar even.

5. Dinan stopped making springs for our cars due to low demand now. The B12 kit uses eibachs which are quite close in rate and drop. Swift spec R are a bit stiffer in relation to Dinans and Eibachs. The BMW PS springs are somewhere in-between Msport and the Dinan/Eibachs in drop and rate. You could get the yellow BMW PS springs and pair them with Bilstein B6 or B8 or Koni STR or Yellow

Overall I would suggest choosing based on your use case, go more conservative if it's a daily driver, or if you plan to have some track time you can go a bit more aggressive. In either case I'd strongly recommend you get upgraded anti-roll bars from the Msport package at least.

And last but not least, do the rear subframe bushings...massive improvement and will let the suspension do it's job. You can go M3 (expensive, harder to install) or aftermarket like whiteline 2 piece (I have them) which are cheaper and easier to install but perform just as well.

For reference, here are some popular spring rates:

BMW M sport = 120/350 lbs/in.
Dinan = 144/490. ----> no longer available
Eibach/Cobb = 148/457 ----> these are the springs used in the B12 kit
BMW performance = 160/420 ----> these are the BMW yellow springs, plus or minus slightly for different years
Swift Spec-R springs = 201/ 503

Good luck!

[gjm120]

asbrr - many thanks for the good input.
The car will likely not see a track, but, I like road feel and responsiveness and am not too comfort oriented.
It seems that the B12 kit will be a 25mm drop for me if I got it correct that sport v non-sport is ~15mm. I could start shopping for BMWP springs to pair with aftermarket dampers. The good thing I've noticed about BMWP springs is that they can be 'tailored' to your car. The bad thing is they cost somewhat more than alternatives.

The other thing I'm considering is picking up a used sport suspension. There was one on here just today that might work.

I'll certainly take the advice on sway bars and rsfb. From what I have read previously the 2 piece are quite good and can be done with a minimum of aggravation or money.

[asbrr]

Originally Posted by gjm120

asbrr - many thanks for the good input.
The car will likely not see a track, but, I like road feel and responsiveness and am not too comfort oriented.
It seems that the B12 kit will be a 25mm drop for me if I got it correct that sport v non-sport is ~15mm. I could start shopping for BMWP springs to pair with aftermarket dampers. The good thing I've noticed about BMWP springs is that they can be 'tailored' to your car. The bad thing is they cost somewhat more than alternatives.

The other thing I'm considering is picking up a used sport suspension. There was one on here just today that might work.

I'll certainly take the advice on sway bars and rsfb. From what I have read previously the 2 piece are quite good and can be done with a minimum of aggravation or money.

No problem. A low mileage stock M-sport with bars and upgraded RSFB is still a nice upgrade from non-sport.

One other quick note, I think M-sport is 25mm lower than non sport IIRC? That means the B12 would be like 35mm lower than non-sport roughly. Either way I have a roughly "2 finger wheel to fender gap" (slightly less in the rear because of the dinan camber plates up front) with my B12 kit.

[HP Autosport]

You could get OE sport suspension springs and match them to either Koni Yellows or Bilstein Sport. Koni's are rebound adjustable so you can dial in the damping to your liking.

[gjm120]

Just pulled the trigger on a used OE sport suspension. Seems to have everything except rear SB.
I'll see how I like a little drop and maybe later get more aggressive with springs or just upgrade dampers as suggested. It also made sense as it's OE and I still am under BMW CPO wtty. Question - Will I likely need an alignment? If so I may consider doing the front M3 control arms.
(I'm sorry I found this forum as now have a bee in my bonnet to do stuff with the car)

What about the M3 control arms? I'm thinking front

[HP Autosport]

Originally Posted by gjm120

Just pulled the trigger on a used OE sport suspension. Seems to have everything except rear SB.
I'll see how I like a little drop and maybe later get more aggressive with springs or just upgrade dampers as suggested. It also made sense as it's OE and I still am under BMW CPO wtty. Question - Will I likely need an alignment? If so I may consider doing the front M3 control arms.
(I'm sorry I found this forum as now have a bee in my bonnet to do stuff with the car)

What about the M3 control arms? I'm thinking front

M3 arms will be a good upgrade for performance and handling, but not for ride quality. You will also want to get rid of the run flats with the M3 arms, otherwise you will feel every bump on the road and more.

http://www.hpashop.com/E82-1M-E9x-M3...-E9xM3-FCA.htm

[asbrr]

Originally Posted by gjm120

Just pulled the trigger on a used OE sport suspension. Seems to have everything except rear SB.
I'll see how I like a little drop and maybe later get more aggressive with springs or just upgrade dampers as suggested. It also made sense as it's OE and I still am under BMW CPO wtty. Question - Will I likely need an alignment? If so I may consider doing the front M3 control arms.
(I'm sorry I found this forum as now have a bee in my bonnet to do stuff with the car)

What about the M3 control arms? I'm thinking front

You'll definitely need an alignment after the install....slipper slope indeed

[gjm120]

I had pretty much decided to do the M3 front control arms when changing out springs and dampers. However, after reading more on here and the 3 series site I’m starting to wonder about a few things.

-Assuming I’m willing to live with the harder ride until going away from run flats, will the stiffer M arms shift forces elsewhere and cause problems?
-Will alignment become a problem? Can the camber be kept within reasonable range so as not to eat up tires ? (don’t care much about the run flats but thinking later on).
-Is doing just the tension strut, aka upper arm, an option as I think the negative camber comes from the lower arm?

Sorry for all the questions.

[squidge]

Speaking to your second two questions, the negative camber you get from the M3 arms is minimal and a good thing. I got -1.0 exactly from punching the pin and doing the M3 arms (and tension struts). That -1.0 is just enough to improve handling and help with tire wear when cornering aggressively, but not enough to cause problems.

As to your first, you'll feel some extra NVH, but it's also a good thing as you're increasing communication from the road to your hands, as well as responsiveness. No downsides here either IMO.

[gjm120]

Originally Posted by squidge

Speaking to your second two questions, the negative camber you get from the M3 arms is minimal and a good thing. I got -1.0 exactly from punching the pin and doing the M3 arms (and tension struts). That -1.0 is just enough to improve handling and help with tire wear when cornering aggressively, but not enough to cause problems.

As to your first, you'll feel some extra NVH, but it's also a good thing as you're increasing communication from the road to your hands, as well as responsiveness. No downsides here either IMO.

Thanks.
So if I don't remove the alignment pins, camber will be something closer to -0.75 deg ?

[asbrr]

Originally Posted by gjm120

Thanks.
So if I don't remove the alignment pins, camber will be something closer to -0.75 deg ?

Probably in that range. It varies a little car to car....you could go the other way and save the money from the control arms and just do the pins and arrive at roughly -0.75 as well....

[gjm120]

Originally Posted by asbrr

Probably in that range. It varies a little car to car....you could go the other way and save the money from the control arms and just do the pins and arrive at roughly -0.75 as well....

Likely will do the control arms and think about more camber by pulling the pins later. I really like the idea of more steering response and feedback and it seems the m3 front control arms accomplish that. The TRW arms are available for just over $300 + another $42 for the installation hardware. This seems like a good deal.

[asbrr]

Originally Posted by gjm120

Likely will do the control arms and think about more camber by pulling the pins later. I really like the idea of more steering response and feedback and it seems the m3 front control arms accomplish that. The TRW arms are available for just over $300 + another $42 for the installation hardware. This seems like a good deal.

Yes you will gain better response due to the better bushing design. If you have the suspension apart for your install of the new struts, you might as well yank the pin. Sometimes depending on the guide support/upper front mount manufacture date, the pins are not actually removable externally and are a moulded part of the guide support. In that case you have to simply grind/hacksaw them off and that's much easier when everything is apart. So just do it in one shot. You will still have a small range of camber adjustment since if the pin is gone, you can move the strut bolts in the strut tower along their eccentric openings and adjust camber by up to + or - 0.5 degrees roughly....

[gjm120]

Originally Posted by asbrr

Yes you will gain better response due to the better bushing design. If you have the suspension apart for your install of the new struts, you might as well yank the pin. Sometimes depending on the guide support/upper front mount manufacture date, the pins are not actually removable externally and are a moulded part of the guide support. In that case you have to simply grind/hacksaw them off and that's much easier when everything is apart. So just do it in one shot. You will still have a small range of camber adjustment since if the pin is gone, you can move the strut bolts in the strut tower along their eccentric openings and adjust camber by up to + or - 0.5 degrees roughly....

Good idea. I'll probably do that. I'm probably going to purchase new strut mounts to minimise the time the car is not put together.

[bimmerboyE92]

Just ordered the B12 kit for my 128i non-sport. After a bit of reading, and looking at the spring rates listed here. It almost seems like the aftermarket (not BMW) springs are based on a non-sport suspension. The reason I say this is that the spring rate difference is around 300lbs. The BMW springs have a spring rate difference closer to 250lbs. Depending on how you calculate it, that's kinda what a rear bar would do to this car in terms of spring rate... no?

[chris82]

Originally Posted by gjm120

Good idea. I'll probably do that. I'm probably going to purchase new strut mounts to minimise the time the car is not put together.

So if you do the OE M-Sport suspension, you're getting slightly stiffer and shorter springs, plus new dampers. You will definitely need an alignment, so I would recommend if you're doing the M3 arms, do them when you put on the new suspension so not to need 2 alignments. I doubt even with run flats that the M3 control arms will affect ride quality, but you will have more precise steering and also more road feel. increased negative camber will be minimal if you keep the pins in, and will not significantly affect tire wear as long as the toe setting is correct. I think with the above mods, you are on the right track for a nice, fun, comfortable 128i.

[gjm120]

Originally Posted by chris82

So if you do the OE M-Sport suspension, you're getting slightly stiffer and shorter springs, plus new dampers. You will definitely need an alignment, so I would recommend if you're doing the M3 arms, do them when you put on the new suspension so not to need 2 alignments. I doubt even with run flats that the M3 control arms will affect ride quality, but you will have more precise steering and also more road feel. increased negative camber will be minimal if you keep the pins in, and will not significantly affect tire wear as long as the toe setting is correct. I think with the above mods, you are on the right track for a nice, fun, comfortable 128i.

I'm definitely doing the arms and dampers/springs at the same time for the reason you stated. Been ordering the parts and attempting to assemble the knowledge to diy. From this site, other sites and the E90 Bentley manual I think I have a good handle on doing it. Somewhat anxious to get to it but I'll probably not have time until end Aug.

Any suggestions on the order of removal and replacement would be appreciated (as well as any other things to consider). It seems (1)arms off, (2) r&r struts, then (3) new arms on makes sense !? I've also gathered that the car could be so far out of alignment that it's hard to drive. Any advice on getting it to a drive-able state to get to the alignment shop ?

[chris82]

Originally Posted by gjm120

I'm definitely doing the arms and dampers/springs at the same time for the reason you stated. Been ordering the parts and attempting to assemble the knowledge to diy. From this site, other sites and the E90 Bentley manual I think I have a good handle on doing it. Somewhat anxious to get to it but I'll probably not have time until end Aug.

Any suggestions on the order of removal and replacement would be appreciated (as well as any other things to consider). It seems (1)arms off, (2) r&r struts, then (3) new arms on makes sense !? I've also gathered that the car could be so far out of alignment that it's hard to drive. Any advice on getting it to a drive-able state to get to the alignment shop ?

I'm afraid I'm not much use here, I have only replaced rear shocks, which are a piece of cake. I think to try to get a similar alignment for the front, try marking the current position of the arms

[gjm120]

Originally Posted by chris82

I'm afraid I'm not much use here, I have only replaced rear shocks, which are a piece of cake. I think to try to get a similar alignment for the front, try marking the current position of the arms

I think front toe gets thrown off and creates the most wonky driving. There is a threaded tie rod with a clamping nut that is easy to adjust toe, but probably very easy to make a bigger mess as well.

Hopefully someone who has done this will chime in. I obviously need to do more research before starting the project.

[John_01]

Originally Posted by bimmerboyE92

Just ordered the B12 kit for my 128i non-sport. After a bit of reading, and looking at the spring rates listed here. It almost seems like the aftermarket (not BMW) springs are based on a non-sport suspension. The reason I say this is that the spring rate difference is around 300lbs. The BMW springs have a spring rate difference closer to 250lbs. Depending on how you calculate it, that's kinda what a rear bar would do to this car in terms of spring rate... no?

I'm not sure if I understand your question. The rear springs need to be a higher rate because they are mounted inboard of the hub carrier. It means the motion ratio is a lot lower than the springs used on the front struts that are mounted directly to the front hub carriers. It explains why the stock front springs are around 120lb/in, and the rears around 350lb/in, in the case of the 135i.

[bimmerboyE92]

Originally Posted by John_01

I'm not sure if I understand your question. The rear springs need to be a higher rate because they are mounted inboard of the hub carrier. It means the motion ratio is a lot lower than the springs used on the front struts that are mounted directly to the front hub carriers. It explains why the stock front springs are around 120lb/in, and the rears around 350lb/in, in the case of the 135i.

Trying to say that the BMW PS and M-sport are designed around having a read bar. Aftermarket kits are designed around not having a rear bar.