[MaverickBMW]

Here are a couple of photos of my E91 and the stock Xi ride height and measurements. It is getting to be crunch time because my car is going to the shop on Tuesday morning, so I need to make a decision.

After all said and done, I actually don't mind how the rear springs feel and the ride height. So now I am leaning more to only changing the front springs to ZSP. Hopefully this would also eliminate some of the rake.

From the very beginning, I was never looking to lower my vehicle (maybe 0.5") because I am always in the mountains in the winter and need the extra ground clearance. I just wanted a slightly firmer ride to get rid of the float and better control of pitch and sway. I believe the Bilsteins will solve most of that in terms of feel.

Also the OEM rears springs of the Xi wagon are likely as stiff or stiffer than a ZSP rear spring. And I am worried that the E93 rear ZSP spring will not work because it is meant for a vehicle that is 230 lbs heavier in the rear that my E91. It will most likely end up raising the rear end 0.5".

[andy_06xi]

Originally Posted by MaverickBMW

Did your vehicle lower even a little? When you say a little too high are you referring to what you had expected from the drop or did the springs actually raise the front end from stock?

Also is your vehicle a standard or automatic?

My vehicle is a manual. I think my rear dropped about 1/2 in. My front dropped maybe 1/4 inch. Where previously the difference between front and rear height was between .75" and 1" -- now it between 1 1/8" and 1 1/4". My current rear 'gap' between the the fender and and tire is about 2 of my fingers. In the front it is almost 4 of my fingers.

[MaverickBMW]

I contacted Tischer this morning to ensure I had the right combo for the front springs and interesting enough here is what they send me for a e91 non-xdrive zsp sport with steptronic. It looks like my vehicle has the same spring number as a 335i ZSP.


31336767377 $145.67 $0.00 $116.54
Front suspension - Suspension components - Spring - W/sport package
335i w/twin power Either Side - W/o m3 2011
W/sport package Either Side - 328i, 335i, 335is 2011

[wagonmeister]

I am interested in doing the same thing with my 07 wagon. Looks like we even have the same wheels. The aftermarket lowering kits are too low for me, i would actually be happy if the front was lowered to match the rear. Please let us know how this turns out

[MaverickBMW]

I will try to explain my thoughts as clear as possible so others who are looking to achieve the same results can relate to my rationale:

1. Why Change the OEM Setup

I originally had a 2006 E90 330i with sport package. I loved how that car felt and the way the suspension handled. But due to family circumstances I needed more space along with an automatic. I traded the vehicle in for a 2011 E91 Steptronic X-Drive. Fully fully loaded. I love the wagon and always wanted to have a wagon since I am consistently throwing outdoor gear and bikes in the back.

The only disappointment in changing vehicles was the suspension. The OEM Xi suspension is in my opinion a real let down by BMW. I have owned several BMWs in the past and the new vehicle didn't live up to the handling dynamics I expected with a premium brand. My largest complaint wasn't the ride height but how the car felt on the highway and around town. It wondered on the highway and just felt 'loose'. It would also sway side-to-side and pitch front to back with imperfections in the road. In other words the ride wasn't and didn't feel planted.

2. Why ZSP/Bilstein Combo versus Alternative Aftermarket Choices

I chose the ZSP springs because I was really happy with the setup on my E90 330i. I liked the way it handed and it felt solid. I also liked the ride height. It was the perfect mix of performance, looks and act as a daily driver.

Another big reason that I went with the ZSP setup it that the Service Manager at my local dealer said that lowered vehicles were prematurely wearing out the CVs and ball joints. He said it wasn't the stiffness of the springs but the amount it lowered the vehicles that caused them to wear excessively. Knowing this I wanted to retain as close to stock ride height especially since my vehicle is still under the factory warranty.

I chose the Bilsteins because I had them in a past Audi and VW. It was more a personal preference and I knew how they would feel. Also, the Service Manage said they would still warranty other parts of my OEM suspension if all I did was change my struts and shocks. It was a no brainer.

3. Which ZSP Springs did I finally use on my E91 Wagon

To give you some specs to compare my vehicle is a 2011 E91 328xi Steptronic fully loaded with every available option except the HK Stereo. I also changed the wheels to 18" OEM Style 189s. I had the sport option so mine had come stock from the factory with a staggered setup.

The most difficult decision wasn't the choice of shocks but which springs I would use to achieve what I was looking for. After much debate and after countless hours of researching on this board...I took the plunge.

I used the following for my vehicle:
ZSP Front Spring: D7 (OEM stock I2)
ZSP Rear Spring: D8 (OEM stock C7)

Trying to find a proper setup that matched the weight balance of the wagon was a difficult task. My number one concern wasn't ride height but improper sag. I didn't want the use springs in the front or rear that were made for a lighter vehicle just to get a lower stance. I wanted the proper suspension travel with the right spring rate.

Although my vehicle is a 328xi Auto, I decided to use a ZSP front spring from a 335i Auto since the gross weight in front were relatively close. The rear was more difficult because the Xi wagon is heavier than a sedan or coupe, and I didn't want any rear sag - especially since I load lots of gear in the back when we go on trips. I decided to use a ZSP rear spring from a E93 335i Auto (convertible). The convertible is actually heavier than my vehicle in the rear by 230lbs (according to BMW specs).

My goal with the ZSP springs was to lower the front of my E91 by 0.6" and hopefully remove some of the factory rake. I figured by using the beefier E93 ZSP springs that my vehicle wouldn't really drop in the rear but I would get the benefit of a stiffer spring rate.

4. Did ZSP Springs Lower My E91 Xi

The Answer is Yes and No. By comparing the OEM versus ZSP side-by-side, the ZSP springs are about a full inch shorter than my Xi springs. It is definitely noticeable. So I was excited when installed I would achieve my desired objectives.

Well it didn't work out exactly as I planned and it had nothing to do with the weight calculations I was using. Although in theory the vehicle should have lowered by about 0.75" in the front, the ZSP springs only lowered the fronts marginally (by less than a 1/4"). In the rear I got a good 1/4" drop on both sides. The rears are perfect and it was exactly what I wanted.

So what happened in the front? Everyone on this board is so concerned with spring heights and which ZSP spring will work on an Xi vehicle. But ONE THING EVERYONE HAS OVERLOOKED is to compare the lower spring perch height on the front strut itself. The spring perch for the front struts on a Xi is actually higher than that found on a ZSP strut AND any aftermarket strut made for our vehicles will mimic what was originally on the vehicle. The shop happened to have a E9X ZSP strut lying around and we measured the difference. The bottom spring perch on a ZSP strut is lower by about 12-15mm.

This is why those who are trying to find ZSP springs that match vehicle weights with non-xi and xi are not seeing the expected drop. This is something I would have never thought about when trying to find the right combinations. Lessons learned - it is not just the spring but the strut itself can make a difference on ride height.

Ride Heights with ZSP from centre axle cap to fender:
Front Left 14.75" (14 7/8" stock Xi)
Front Right 14.5" (14 7/8" stock Xi)

Left Rear 13.5" (13.75" stock Xi)
Right Rear 13.75" (14" stock Xi)

4. Ride Quality and Feel

Although I wasn't able to reduce the brutal OEM rake, the ride and feel of the new setup is very subtle but definitely night and day. The annoying sway and pitch is gone and the best part is the car feels solid. SOLID Just what it should have been from the factory. Rebound is quick and controlled and the ride is not firm or jarring. That soft plushy and disconnected feel you get from the stock suspension has totally disappeared.

One thing I did notice it that the steering feels lighter now with the Bilsteins? I have no clue why and I had expected the opposite. Maybe it is because the mono tube shocks are stiffer laterally and vertically so it transmits less road feel? I saw others post of this before and now I understand what they were talking about.

5. Overall Assessment

Definitely a must do for all those riding on the stock Xi suspension. No questions asked. Even my girlfriend prefers the ride and how it drives. I am just hoping that once the shocks break in a little the front end will maybe lower ever so slightly. That said, I don't think it will happen. On that note, I guess I could have used ZSP springs from a 328i and it would lowered the front more but the shop guy said then you would get weight sag and I would lose suspension travel. This would put more stress on the damper to cure the problem. He said, he wouldn't change the front springs and if I decided to go that route to get a proper spring made for the weight of the vehicle.

So I hope this helps those with either a touring wagon or an Xi vehicle that have been contemplating making a change and don't want to steer too far from the stock setup and ride height.

[wagonmeister]

This is great info, but unfortunately dissapointing news. I was really hoping i could get the sportier stance of the non-xi's with sport suspension. Plus everything else i see out there does not seem to cure the rake problem. After looking at some pics of the H&R sport springs

http://www.e90post.com/forums/showthread.php?t=493976

i wonder if i would be happy with the h&r sport in the front, and your 335i springs in the rear. It is really the rear that looks like it sags too much on these cars. Thanks for the help

[rbeck]

I wonder: since the hub carriers and therefore the strut attachment differs, would that account for the spring perch difference? And, my Owner's Manual says that an e90 335xi/AT i has an allowable axle weight 50 kg more than the e91 328xi over the front axle. Would this account for the higher than expected ride height?

Maybe the zsp springs from a 335d would be another choice for the front? Only a 20 kg difference.

[MaverickBMW]

Originally Posted by rbeck

I wonder: since the hub carriers and therefore the strut attachment differs, would that account for the spring perch difference? And, my Owner's Manual says that an e90 335xi/AT i has an allowable axle weight 50 kg more than the e91 328xi over the front axle. Would this account for the higher than expected ride height?

Maybe the zsp springs from a 335d would be another choice for the front? Only a 20 kg difference.

Sorry, are you looking for your 335xi or for me? To my knowledge the 335d is heavier in the front than a 335i Auto. The 335d uses a D8 front spring while the 335i Auto uses a D7.

After my experience with my E91 and you are looking to use a ZSP spring for your 335xi AT, I would use a D7 from a 335i AT. The challenge I had is that the wagon is heavier all around than a 328i so I didn't want to use a D4 or D5 spring. In retrospect I should have used a D6 spring and maybe I would have got the results I wanted.

The variable I hadn't thought about was the lower spring perch height and/or carrier height on a Xi versus non-Xi. I may vary well have the right spring for my vehicles weight but due to other variables it affected the height difference.

That said, it drives fantastic. I was out last night again for a good spin and I love the way it now feels. So solid and planted on the road. Also little undulations and imperfections in the road are much much better controlled.

[rbeck]

I'm thinking about my e91. I got my weights from the owners manual. The 335d looks like a closer match v. a 335xi IMO.

[luckyu]

Originally Posted by MaverickBMW

That said, it drives fantastic. I was out last night again for a good spin and I love the way it now feels. So solid and planted on the road. Also little undulations and imperfections in the road a much much better controlled.

Hi Mav, I was real happy to read that your suspension is now how you wanted. You were really careful and it paid off. Also, I'm planning putting on Bilsteins and I think I share your taste in how a suspension should feel. So it's great to get that feedback. Thanks for the report!

[wagonmeister]

side question: are the bilstein shocks for e91 xi same as the e90 xi?

[MaverickBMW]

Originally Posted by wagonmeister

side question: are the bilstein shocks for e91 xi same as the e90 xi?

All Xi Bilsteins are identical. The only thing you need to know is whether you want the Sports or HDs. They are valved identical but Sports have a shorter stroke for vehicles lowered greater than 1.5".

[wagonmeister]

Originally Posted by MaverickBMW

All Xi Bilsteins are identical. The only thing you need to know is whether you want the Sports or HDs. They are valved identical but Sports have a shorter stroke for vehicles lowered greater than 1.5".

awesome thanks. After reading this thread and some others i am leaning towards doing the eibach pro-kit on the front, and zsp in the rear. This looks like it makes an even drop all around. The question is which one of the zsp springs do i use. I am sure those d8 springs are pretty hard to find used. Did you look into what spring is used in the rear of the 328i wagon with sport package? It seems like the rear weight shouldnt be much different from the xdrive. Your post above says oem c7 on the rear, maybe d7 for sport? And do happen you to know what spring is used in the rear of the 335i sedan? I don't load my wagon down much, so maybe this will be ok. Thanks again.

[MaverickBMW]

Originally Posted by wagonmeister

awesome thanks. After reading this thread and some others i am leaning towards doing the eibach pro-kit on the front, and zsp in the rear. This looks like it makes an even drop all around. The question is which one of the zsp springs do i use. I am sure those d8 springs are pretty hard to find used. Did you look into what spring is used in the rear of the 328i wagon with sport package? It seems like the rear weight shouldnt be much different from the xdrive. Your post above says oem c7 on the rear, maybe d7 for sport? And do happen you to know what spring is used in the rear of the 335i sedan? I don't load my wagon down much, so maybe this will be ok. Thanks again.

That would be a great combo and would work well. About the zsp rear - e90 sedan uses D4 spring. E91 uses K4 and e93 uses D8. It will be easier to find a D8 spring versus a K4. I posted a WTB ad and got four replies within a few days. Or the alternative is to buy new from Tischer and save time but more expensive

[MaverickBMW]

If anyone else needs part number for ZSP Sport Springs for a non-X Drive e91 touring wagon here they are. These are for ones equipped with the Steptronic.

Fronts 31336767377

Rears 33536773598

Check out this post:

http://www.e90post.com/forums/showth...hlight=E91+zsp

[thegrinchboy]

Originally Posted by MaverickBMW

If anyone else needs part number for ZSP Sport Springs for a non-X Drive e91 touring wagon here they are. These are for ones equipped with the Steptronic.

Fronts 31336767377

Rears 33536773598

Check out this post:

http://www.e90post.com/forums/showth...hlight=E91+zsp

Sorry to dredge up an old thread. Doing the same conversion for 335xi E90 MT non-ZSP to 335i ZSP suspension. Started with Koni Sport/Eibach Pro, but too low for my liking, thus moving to ZSP. Besides the actual springs, what other part did you have to get e.g. pads, etc. Thx in advance.

[putnampunk]

Originally Posted by MaverickBMW

I will try to explain my thoughts as clear as possible so others who are looking to achieve the same results can relate to my rationale:

3. Which ZSP Springs did I finally use on my E91 Wagon

The most difficult decision wasn't the choice of shocks but which springs I would use to achieve what I was looking for. After much debate and after countless hours of researching on this board...I took the plunge.

I used the following for my vehicle:
ZSP Front Spring: D7 (OEM stock I2)
ZSP Rear Spring: D8 (OEM stock C7)

Trying to find a proper setup that matched the weight balance of the wagon was a difficult task. My number one concern wasn't ride height but improper sag. I didn't want the use springs in the front or rear that were made for a lighter vehicle just to get a lower stance. I wanted the proper suspension travel with the right spring rate.

Although my vehicle is a 328xi Auto, I decided to use a ZSP front spring from a 335i Auto since the gross weight in front were relatively close. The rear was more difficult because the Xi wagon is heavier than a sedan or coupe, and I didn't want any rear sag - especially since I load lots of gear in the back when we go on trips. I decided to use a ZSP rear spring from a E93 335i Auto (convertible). The convertible is actually heavier than my vehicle in the rear by 230lbs (according to BMW specs).

My goal with the ZSP springs was to lower the front of my E91 by 0.6" and hopefully remove some of the factory rake. I figured by using the beefier E93 ZSP springs that my vehicle wouldn't really drop in the rear but I would get the benefit of a stiffer spring rate.

4. Did ZSP Springs Lower My E91 Xi

The Answer is Yes and No. By comparing the OEM versus ZSP side-by-side, the ZSP springs are about a full inch shorter than my Xi springs. It is definitely noticeable. So I was excited when installed I would achieve my desired objectives.

Well it didn't work out exactly as I planned and it had nothing to do with the weight calculations I was using. Although in theory the vehicle should have lowered by about 0.75" in the front, the ZSP springs only lowered the fronts marginally (by less than a 1/4"). In the rear I got a good 1/4" drop on both sides. The rears are perfect and it was exactly what I wanted.

So what happened in the front? Everyone on this board is so concerned with spring heights and which ZSP spring will work on an Xi vehicle. But ONE THING EVERYONE HAS OVERLOOKED is to compare the lower spring perch height on the front strut itself. The spring perch for the front struts on a Xi is actually higher than that found on a ZSP strut AND any aftermarket strut made for our vehicles will mimic what was originally on the vehicle. The shop happened to have a E9X ZSP strut lying around and we measured the difference. The bottom spring perch on a ZSP strut is lower by about 12-15mm.

This is why those who are trying to find ZSP springs that match vehicle weights with non-xi and xi are not seeing the expected drop. This is something I would have never thought about when trying to find the right combinations. Lessons learned - it is not just the spring but the strut itself can make a difference on ride height.

Ride Heights with ZSP from centre axle cap to fender:
Front Left 14.75" (14 7/8" stock Xi)
Front Right 14.5" (14 7/8" stock Xi)

Left Rear 13.5" (13.75" stock Xi)
Right Rear 13.75" (14" stock Xi)

4. Ride Quality and Feel

Although I wasn't able to reduce the brutal OEM rake, the ride and feel of the new setup is very subtle but definitely night and day. The annoying sway and pitch is gone and the best part is the car feels solid. SOLID Just what it should have been from the factory. Rebound is quick and controlled and the ride is not firm or jarring. That soft plushy and disconnected feel you get from the stock suspension has totally disappeared.

One thing I did notice it that the steering feels lighter now with the Bilsteins? I have no clue why and I had expected the opposite. Maybe it is because the mono tube shocks are stiffer laterally and vertically so it transmits less road feel? I saw others post of this before and now I understand what they were talking about.

5. Overall Assessment

Definitely a must do for all those riding on the stock Xi suspension. No questions asked. Even my girlfriend prefers the ride and how it drives. I am just hoping that once the shocks break in a little the front end will maybe lower ever so slightly. That said, I don't think it will happen. On that note, I guess I could have used ZSP springs from a 328i and it would lowered the front more but the shop guy said then you would get weight sag and I would lose suspension travel. This would put more stress on the damper to cure the problem. He said, he wouldn't change the front springs and if I decided to go that route to get a proper spring made for the weight of the vehicle.

So I hope this helps those with either a touring wagon or an Xi vehicle that have been contemplating making a change and don't want to steer too far from the stock setup and ride height.

Really appreciate the explanation and details provided. I'm looking for the same and originally was going to buy some Eibach Pro-Kit but ZSP seems much better for my daily (well, when I drive any more...)