[devioushaikuzero]

Hello bimmerpost,

I have a 2013 328i Sport. The rear struts had failed and required replacement. I had replaced the rears with Bilstein B6's, while leaving the front at factory B4s. I kept the stock springs, as was recommended.

Now, when I drive, the car is super bouncy. It feels oversprung. It sort of makes the ride unpleasant. I want to understand why. When you drive over a bump or small, but short, elevation change, your stomach drops and it feels very intense.

Do I need to upgrade the front to B6s? Does the higher dampening of the rear vs front throw the weight off and cause the bounciness? Is it possible they improperly installed the rear struts?

Or is this the intended behaviour of these struts? Any advice is greatly appreciated. Thank you.

Edit: I just replaced the wheels and tires. 18x8 Sparco Pro Corsa DRK TITAN with 225/45ZR18 Continental ExtremeContact Sport for the front. For the rear:
18x9 Matte Dark Titanium Sparco Pro Corsa with 255/40ZR18 Continental ExtremeContact Sport.
I had an alignment when installed the rear struts and balance when installing the tires. Thanks again

[cfm56d7b]

devioushaikuzero How many miles does the vehicle have? What's the condition of front shocks? Does the rear bounce more than the front?

Mixing struts with different performance specifications is not generally a good practice.

B6 struts are much stiffer than B4 struts.

[devioushaikuzero]

The car has 98k miles. When it was in the shop (April 2023), they said the front suspension was good. I am thinking maybe that is less true now.

Would the solution just be to have the b6's installed on the front? Or would just finding the m-sport suspension at a good value be sufficient?

[Polo08816]

Originally Posted by cfm56d7b

devioushaikuzero How many miles does the vehicle have? What's the condition of front shocks? Does the rear bounce more than the front?

Mixing struts with different performance specifications is not generally a good practice.

B6 struts are much stiffer than B4 struts.

I've found that B6 struts are much stiffer than factory/B4 struts on the F25 X3.

If I had to do it all over again, I would opt for B4 struts/shocks if I'm using factory springs.

However, the B6 struts paired well with Swift springs on my 2008 Subaru Legacy GT.

I'd be cautious of using B6 or B8 struts/shocks on a vehicle that does not have a stiffer than factory spring.

[devioushaikuzero]

Would you advise just going back to b4's on the rear (stock) or finding springs and front b6 struts?

[cfm56d7b]

Originally Posted by devioushaikuzero

Would you advise just going back to b4's on the rear (stock) or finding springs and front b6 struts?

A few suggestions.

It's doubtful that at 98K miles the suspension (which consists of many parts) is "good" as described by the shop in April 2023.

By the way, are the front shocks still OEM at 98K miles?

The suspension parts - for example controls arms - contain rubber bushings which do wear out. I suggest to take the car to a more qualified shop to inspect all suspension parts and identify any part with worn rubber bushings.

Replacing these parts would be the first priority.

https://www.turnermotorsport.com/BMW...ushings-mounts would be helpful to review and appreciate all the parts with bushings.

Potential options to consider.

If you like OEM suspension handling:

- Bilstein B4 shocks: front and rear
- New OEM springs (at 98K miles, the springs are inexpensive to replace and match with new shocks)
- Plus any other worn parts such as control arms with rubber bushings

There are other options to consider:

- Koni Special Active shocks + Eibach Pro springs; all credit goes to johnung for his expertise. Please search for his posts.

- Coilovers such as KW Street Comfort

[devioushaikuzero]

I was looking at fortune 500's but they are kind of expensive.

Here is what they did for the rear:
PARTS QTY EACH TOTAL
Shock Absorber 2.0 $222.76 $445.52
Shock Bump Stop w/ Cover 2.0 $32.03 $64.06
Shock Mount 2.0 $76.80 $153.60
Shock / Strut Mount Gasket 2.0 $29.31 $58.62

I do think they are woefully incompetent as I've had to go back 3-times for them to fix my brake light when I have payed for repair of the whole assembly. Yet, I still get a stage 2 brake light error.

I will look into it. Thank you for your help!

[cfm56d7b]

Originally Posted by devioushaikuzero

I was looking at fortune 500's but they are kind of expensive.

Here is what they did for the rear:
PARTS QTY EACH TOTAL
Shock Absorber 2.0 $222.76 $445.52
Shock Bump Stop w/ Cover 2.0 $32.03 $64.06
Shock Mount 2.0 $76.80 $153.60
Shock / Strut Mount Gasket 2.0 $29.31 $58.62

I do think they are woefully incompetent as I've had to go back 3-times for them to fix my brake light when I have payed for repair of the whole assembly. Yet, I still get a stage 2 brake light error.

I will look into it. Thank you for your help!

It appears a new partnership with a more qualified shop will produce better results. :-)

Glad to help and keep us updated!

[johnung]

Originally Posted by cfm56d7b

A few suggestions.

It's doubtful that at 98K miles the suspension (which consists of many parts) is "good" as described by the shop in April 2023.

By the way, are the front shocks still OEM at 98K miles?

The suspension parts - for example controls arms - contain rubber bushings which do wear out. I suggest to take the car to a more qualified shop to inspect all suspension parts and identify any part with worn rubber bushings.

Replacing these parts would be the first priority.

https://www.turnermotorsport.com/BMW...ushings-mounts would be helpful to review and appreciate all the parts with bushings.

Potential options to consider.

If you like OEM suspension handling:

- Bilstein B4 shocks: front and rear
- New OEM springs (at 98K miles, the springs are inexpensive to replace and match with new shocks)
- Plus any other worn parts such as control arms with rubber bushings

There are other options to consider:

- Koni Special Active shocks + Eibach Pro springs; all credit goes to johnung for his expertise. Please search for his posts.

- Coilovers such as KW Street Comfort

Great stuff! Just a couple things to add:

1) Eibach recently started selling OEM height springs which are high quality and probably less expensive than Genuine BMW. They can be found in the Eibach Germany catalog. Just look up Eibach Spring Kits for a particular model and they’ve added OEM height springs at the bottom of the listing.

EIBACH GERMANY CATALOG
https://web2.carparts-cat.com/defaul...6279004&12=100

Eibach probably isn’t distributing them in the US. I’ve been buying European parts for years from a retailer in Germany named Andreas who FaRKle! originally recommended. His email is:
andreas.schade@gmx.de

2) I’m actually refreshing my suspension this weekend. Attached is a photo from realoem website showing the stock suspension bits that I’m replacing. It’s been 9 years since mine were installed at the factory. Even if they appear okay they have obviously lost their original cushioning. I expect my suspension comfort to feel like new again. FCP sells kits like Meyle which are cheaper than buying everything a la carte.

[Oksamit78]

I've installed front Eibach Pro XDrive springs a months ago, only replaced the hats (#1, OEM by Lemfoerder 5 bolt version) and bump stops (#4, Dinan). The rest of the items were in pristine condition.

[devioushaikuzero]

Originally Posted by johnung

Great stuff! Just a couple things to add:

1) Eibach recently started selling OEM height springs which are high quality and probably less expensive than Genuine BMW. They can be found in the Eibach Germany catalog. Just look up Eibach Spring Kits for a particular model and they’ve added OEM height springs at the bottom of the listing.

EIBACH GERMANY CATALOG
https://web2.carparts-cat.com/defaul...6279004&12=100

Eibach probably isn’t distributing them in the US. I’ve been buying European parts for years from a retailer in Germany named Andreas who FaRKle! originally recommended. His email is:
andreas.schade@gmx.de

2) I’m actually refreshing my suspension this weekend. Attached is a photo from realoem website showing the stock suspension bits that I’m replacing. It’s been 9 years since mine were installed at the factory. Even if they appear okay they have obviously lost their original cushioning. I expect my suspension comfort to feel like new again. FCP sells kits like Meyle which are cheaper than buying everything a la carte.

How do I know which ones to buy for a 2013 328i (RWD) (n20 2.0l) f30, from Eibach?

[devioushaikuzero]

Could you link the parts you used? Did you use B6 struts with them?

I've installed front Eibach Pro XDrive springs a months ago, only replaced the hats (#1, OEM by Lemfoerder 5 bolt version) and bump stops (#4, Dinan). The rest of the items were in pristine condition.

[devioushaikuzero]

Originally Posted by johnung

Great stuff! Just a couple things to add:

1) Eibach recently started selling OEM height springs which are high quality and probably less expensive than Genuine BMW. They can be found in the Eibach Germany catalog. Just look up Eibach Spring Kits for a particular model and they’ve added OEM height springs at the bottom of the listing.

EIBACH GERMANY CATALOG
https://web2.carparts-cat.com/defaul...6279004&12=100

Eibach probably isn’t distributing them in the US. I’ve been buying European parts for years from a retailer in Germany named Andreas who FaRKle! originally recommended. His email is:
andreas.schade@gmx.de

2) I’m actually refreshing my suspension this weekend. Attached is a photo from realoem website showing the stock suspension bits that I’m replacing. It’s been 9 years since mine were installed at the factory. Even if they appear okay they have obviously lost their original cushioning. I expect my suspension comfort to feel like new again. FCP sells kits like Meyle which are cheaper than buying everything a la carte.

Sorry if I missed something. What is the groups of parts called?

[johnung]

Originally Posted by devioushaikuzero

How do I know which ones to buy for a 2013 328i (RWD) (n20 2.0l) f30, from Eibach?

Are you asking which springs for stock height or which springs to lower the car? Eibach tailors springs to axle weight based on factory equipment installed on the car. So it would help me to help you if you provide your VIN number so I can look up the factory build sheet

[johnung]

Originally Posted by devioushaikuzero

Hello bimmerpost,

I have a 2013 328i Sport. The rear struts had failed and required replacement. I had replaced the rears with Bilstein B6's, while leaving the front at factory B4s. I kept the stock springs, as was recommended.

Now, when I drive, the car is super bouncy. It feels oversprung. It sort of makes the ride unpleasant. I want to understand why. When you drive over a bump or small, but short, elevation change, your stomach drops and it feels very intense.

Do I need to upgrade the front to B6s? Does the higher dampening of the rear vs front throw the weight off and cause the bounciness? Is it possible they improperly installed the rear struts?

Or is this the intended behaviour of these struts? Any advice is greatly appreciated. Thank you.

Edit: I just replaced the wheels and tires. 18x8 Sparco Pro Corsa DRK TITAN with 225/45ZR18 Continental ExtremeContact Sport for the front. For the rear:
18x9 Matte Dark Titanium Sparco Pro Corsa with 255/40ZR18 Continental ExtremeContact Sport.
I had an alignment when installed the rear struts and balance when installing the tires. Thanks again

Someone gave you poor advice. You’ve got old weak springs all around and you added strong B6 Sport shocks to the rear. Total mismatch.

Mdecoder shows the 2013 factory build list from your VIN as pretty basic. I did not see code S2VFA which would have meant that you have the Adaptive M Suspension . And I did not see S704A for the M Sports Suspension.

Your car did have code S7AC which means that it is a Sportline model. That typically means enhancement like steering wheel, color accents, etc. BMW seems to have had different Sportline features in different model years. I couldn’t tell if maybe that included the M Sport Suspension which would mean different model springs from the factory.

So you have some options to fix your current situation. All include replacing your springs.

Option #1
You sounded like you wanted to keep the rear B6’s that you bought and add new B6’s to the front. Those are Sport dampers that are setup stiff/harsh at the factory compared to B4’s. You would probably need heavier springs like H&R or Dinan to match best with the B6’s. The result would be the worst scenario making your ride more stiff/harsh than it was.

Option #2
Sell the rear B6’s. Install B4’s all around or a better option would be Koni Special Actives all around. Wouldn’t be idea with the original springs but should ride better than now.

Option #3:
Same as Option #2 except replace old stock springs with Eibach stock replacement springs. Eibach lists two possible fronts and four possible rear springs so you would have to speak with Eibach tech support to determine the correct ones. Probably have to purchase from Germany. (Contact German retailer andreas.schade@gmx.de)

Option #4
Install Koni kit that includes Eibach springs. This setup is matched for your car. See photo.

[devioushaikuzero]

Originally Posted by johnung

Someone gave you poor advice. You’ve got old weak springs all around and you added strong B6 Sport shocks to the rear. Total mismatch.

Mdecoder shows the 2013 factory build list from your VIN as pretty basic. I did not see code S2VFA which would have meant that you have the Adaptive M Suspension . And I did not see S704A for the M Sports Suspension.

Your car did have code S7AC which means that it is a Sportline model. That typically means enhancement like steering wheel, color accents, etc. BMW seems to have had different Sportline features in different model years. I couldn’t tell if maybe that included the M Sport Suspension which would mean different model springs from the factory.

So you have some options to fix your current situation. All include replacing your springs.

Option #1
You sounded like you wanted to keep the rear B6’s that you bought and add new B6’s to the front. Those are Sport dampers that are setup stiff/harsh at the factory compared to B4’s. You would probably need heavier springs like H&R or Dinan to match best with the B6’s. The result would be the worst scenario making your ride more stiff/harsh than it was.

Option #2
Sell the rear B6’s. Install B4’s all around or a better option would be Koni Special Actives all around. Wouldn’t be idea with the original springs but should ride better than now.

Option #3:
Same as Option #2 except replace old stock springs with Eibach stock replacement springs. Eibach lists two possible fronts and four possible rear springs so you would have to speak with Eibach tech support to determine the correct ones. Probably have to purchase from Germany. (Contact German retailer andreas.schade@gmx.de)

Option #4
Install Koni kit that includes Eibach springs. This setup is matched for your car. See photo.

Thank you, so so much!

[devioushaikuzero]

You had mentioned: "
Option #2
Sell the rear B6’s. Install B4’s all around or a better option would be Koni Special Actives all around. Wouldn’t be idea with the original springs but should ride better than now."

I found Koni Active for F30 Non-M-Adaptive Sportline. I feel that I should replace the springs while I am at it. Would the Eibach PRO-KIT Performance Springs - BMW F30/F32 be OK with those struts?

Thank you!

[johnung]

Originally Posted by devioushaikuzero

How do I know which ones to buy for a 2013 328i (RWD) (n20 2.0l) f30, from Eibach?

Eibach and Koni carefully choose the components in their kits to match the chassis and axle weights of various models. Make sure to choose the correct part number for your car shown in photos.

Koni Special Actives are shown in red. If you go with the Eibach spring kit make sure to trim the tops of the stock bump stops with a serrated knife. For Front trim about 1.0” and for rear trim about 0.75”

[devioushaikuzero]

So for the pro-kit, which has the least lowering, I would still follow the EDC/Xdrive recommendations even though I only have RWD non-edc? Sorry if this is dumb.

Would a competent shop be able to do this if I told them how much to remove on the bump stop? I don't have the tools/capacity to do this myself.

Also...finding a competent shop is challenging.

[devioushaikuzero]

Alright, I am 99.9% sure I have it right with tirerack from parts catalog, matching the manufacturer's part #.

Koni Special Active Front:
Manufacturer Part #: 8745-1318

Koni Special Active Rear:
Manufacturer Part #: 8245-1319

Eibach Pro-Kit:
Manufacturer Part #: E10-20-031-01-22

Questions?
Do I have to buy aftermarket bump stops or any other items when making this purchase? Also, how do I find the exact OEM springs for my VIN? I was thinking the OEM would give better ride quality. Thank you so much!

[E90lova]

I am not at all a fan of BILSTEIN at all. Also their B6/B8s are overrated and should not be considered for sport driving. Bilstein and H&R is very bouncy especially in the rear nowadays. I took my B14 coilover kit and installed a 700lb 10" spring in the rear and that made things a ton better. Took the stock crap BILSTEIN rear spring out. The 700LBs spring was even more comfortable but yet sportier than the supplied Bilstein spring.

[B50AteYourRide]

Really curious to see how you like the Koni Special Actives.
I came close to buying them for my wife's car several years ago, but ended up with Bilstein. Not bad, but they were a bit stiff for her. It was a 2008 Audi A3 S Line. Poor car ended up in the hands of a completely incompetent mechanic and I just ended up selling it.