E90Post
 


 
BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > All-Wheel-Drive (Xi / xDrive) Talk > Quick xi Suspension Review - Bilstein + Eibach



Reply
 
Thread Tools Search this Thread
      05-12-2014, 10:23 AM   #199
instigat0r
New Member
0
Rep
25
Posts

 
Drives: 2007 328xi coupe
Join Date: Dec 2012
Location: Pittsburgh

iTrader: (0)

I replaced the old tophats since they had a little bit of play in the bearings but the new ones also had the same amount of play. I guess this is normal for the tophats' bearing to have a little play in them. But yes, I agree, the tophats caused the extra heigth. The old tophats have been tossed.

I did put the eibach springs on this weekend (front only) and I'm back to a 3 finger fender gap (down from 4 fingers). Hoping once the springs settle, I'll be down to a 2 finger gap, which is exactly what I'm after.

To me, the ride quality it great! And the Eibachs have only marginally stiffened up the ride in the front. The bilstein HD's attribute to the stiffer ride more than the springs IMO. I haven't taken it on the highway yet, but for driving around the city, I love this setup... firm but still very comfortable over small and large bumps/potholes. Passed the wife test easily.

Next Iím going to install the HDís on the rear with stock springs and see how it handles. I donít want to add the eibachs to the rear as I like the height the way it is with a 2 finger gap.

Here's a pic with the eibach pro springs with bilstein HD's (front only). Rear is all stock.
Attached Images
   
Appreciate 0
      05-12-2014, 10:24 AM   #200
instigat0r
New Member
0
Rep
25
Posts

 
Drives: 2007 328xi coupe
Join Date: Dec 2012
Location: Pittsburgh

iTrader: (0)

the first pic is without the eibachs on and the last two are with the eibachs.
Appreciate 0
      05-12-2014, 11:17 AM   #201
Nonecure
Second Lieutenant
Nonecure's Avatar
United_States
2
Rep
248
Posts

 
Drives: 2009 335xi E90 LCI
Join Date: Nov 2012
Location: Dayton, Ohio

iTrader: (1)

Nice wheels, but that is some serious gap!
__________________
OFT Wedge Tuned, VRSF 7" Intercooler, BMS DCI, Eibach Pro-kit/Bilstein
Appreciate 0
      05-12-2014, 12:36 PM   #202
ajsalida
Lieutenant Colonel
ajsalida's Avatar
20
Rep
1,737
Posts

 
Drives: 95 M3, 02 R1150GSA, 09 335xi
Join Date: Aug 2010
Location: SW USA

iTrader: (2)

Yeah I think something is wrong with that gap.

You want to make sure two things were done:

1. What bumpstops were used if any? Bilstein sports have internal stops, not sure about HD's. If OEM stops are supposed to be re-used they need to be cut at least 1". Most folks use e36 M3 stops. If the HD strut rod is about the same diameter as stock you need to use some kind of external stops. If it is huge diameter compared to stock none should be used.

2. The struts have to go all the way down into the steering knuckle hub/cup thing. They should stick out the bottom approx 2". Look under the front of the car with the wheel turned out as far as you can. Look under the hub you should see the bottom of the strut sticking way out. If not it needs to be pushed down snug into the cup.

If either of these things were done wrong you'll be riding far too high. I have Eibach pro kit in front and OEM ZSP D2 rear, koni sports, nowhere near that front gap. No amount of settling will fix that.

Last edited by ajsalida; 05-12-2014 at 12:45 PM.
Appreciate 0
      05-13-2014, 03:25 PM   #203
instigat0r
New Member
0
Rep
25
Posts

 
Drives: 2007 328xi coupe
Join Date: Dec 2012
Location: Pittsburgh

iTrader: (0)

Thanks for the tips ajsalida, but I really think the combination of the new tophats and HD shocks are causing the huge gap. HD's supposedly raise your heigth about .5 inches and the tophats definitly raised it up another .5 of an inch. I am almost certain that I did the install correctly and this is just how any similar XI will look with brand new HD's and Tophats on freshly installed eibach pro kit.

The HD's have internal bumpstops so I removed the stock ones during the initial install. And you are correct, the strut rod on the HD's are about twice as thick as the stocks. So yes, internal.

The HD's do not extend past the steering knuckle like the Koni's do, and I triple checked that they were all the way down when I put them in. It actually slides down easily with a thunk when it hits the bottom of the knuckle. This is the third time I've removed the shock/stprings (once for the HD's, once for the tophats, and once for the prokit), so I'm pretty good at this now and (i think) know what I'm doing. Each side took me only about 1 hr.

The second and third pictures are with the eibachs on, and there's at tight 3 finger gap. Once this settles, I should be around 2, right? Even if it doesn't settle, I'll still be okay with how this turned out. I really like the ride and the height, as I intially just wanted to replace the blown front shocks and maintain stock height. A little more drop would be nice though!
Appreciate 0
      05-13-2014, 04:26 PM   #204
ajsalida
Lieutenant Colonel
ajsalida's Avatar
20
Rep
1,737
Posts

 
Drives: 95 M3, 02 R1150GSA, 09 335xi
Join Date: Aug 2010
Location: SW USA

iTrader: (2)

OK well just glad you checked and seem to know what you're doing. I find it very odd pro kit + HD + new top hats leaves you at what appears to be stock ride height or higher. But as long as you are cool with it (and you did it right) doesn't matter what we think.
Appreciate 0
      05-15-2014, 08:13 AM   #205
instigat0r
New Member
0
Rep
25
Posts

 
Drives: 2007 328xi coupe
Join Date: Dec 2012
Location: Pittsburgh

iTrader: (0)

I wonder what exactly is the stock ride heigth on a brand new XI? It's problably somthing like the 4 finger gap that I had before putting on the Pro kit (or a little lower because of the stock shocks and not HD's).

I don't think the height that I'm at now is too odd because the Pro kit did lower my car about 5/8 of an inch and may settle futher (it's only been 3 days). Pro kit is advertised to only give like a 1-1.2 inches of drop. I've seen others report no visual lowering right after intstalling the Pro kit but then get a decent drop after a few weeks.

I could still put on some lowering perches if it doesn't settle any. I went with the 'I' tophats when I replaced mine, so they will fit even though mine is an XI.
Appreciate 0
      05-15-2014, 04:19 PM   #206
ajsalida
Lieutenant Colonel
ajsalida's Avatar
20
Rep
1,737
Posts

 
Drives: 95 M3, 02 R1150GSA, 09 335xi
Join Date: Aug 2010
Location: SW USA

iTrader: (2)

Several things to consider.

Eibach does not make springs for XI's, so what you are using is for non XI model (hopefully for the 328). The drop Eibach specs for pro kit is for non XI's. OEM XI springs are much stiffer than non XI, and Eibachs are about same overall spring rate as OEM non XI, just lower ride height.

For non-XI, non-ZSP sedan pro kit drop is 1.4 front and 1.0 rear, ZSP sedan or coupe is 1 front and .8 rear. But none of this matters because you have an XI with much stiffer springs, higher initial ride height, and a heavier car. You are replacing those springs with much softer ones that already give 1.4" drop on a lighter car using the SAME spring rate as the non XI car. Unlike the coupe vs non ZSP sedan on non XI, XI has no OEM sport suspension.

So point is drop should be more like over 1.5" on an XI in front, if you had only done springs. This is why me and others are scratching our heads. If it settles out that is great. Sometimes mcP strut front Bilsteins trap air in the bottom of the strut housing under the "rod" (which is actually the shock body), and this air farts out over time lowering the car.

Time will tell. Right now you have an interesting combo of stiff OEM XI rear springs and soft fronts, but the unusual ride height going on. Lot of folks (including me) who put on the full pro kit F&R found the rear too low WRT front, mainly due to weight issues and softness of rears. I put on a set of OEM D2 ZSP rear springs and that equalized the fender gap F&R to about 1-1.5 fingers. Before the rear looked too low which is the rake everyone talks about. No rake now. Have Koni sports as shocks, 335 e92.

Anyway I think your plan is good drive around see if it settles. Springs do not settle but rubber parts like spring pads, maybe new strut top hats, and excess trapped air does. The Bilsteins are high pressure gas monotubes so you will have some offset force due to internal pressure from inside the high pressure gas chamber in the shock body itself (this is what everyone talks about with higher ride height, not the trapped air under the strut housing) but that should only be 1/4" tops.

Many people are not pleased with the lowering perches, I'd read up on them before you try them. I am opposed mainly because they reduce travel, and lowering an XI w/o coil overs already reduces front travel considerably.

Last edited by ajsalida; 05-15-2014 at 05:25 PM.
Appreciate 0
      05-16-2014, 11:49 AM   #207
instigat0r
New Member
0
Rep
25
Posts

 
Drives: 2007 328xi coupe
Join Date: Dec 2012
Location: Pittsburgh

iTrader: (0)

Iím using the pro kit for a 328i sport coupe, part number 2091.140. I thought this would be the closest fit for my xi. Hereís the only picture I have comparing the front springs. Wish I had a better one. The Eibach spring is on the right. To me its hard to tell but I would guess theyíre pretty close to same size? Maybe pro kit even longer? Shouldnít they be noticeably lower/shorter? The stock spring on the right is labeled i2.

And I see what youíre saying about me using the pro kit made for the lighter non xi 328, and how that should have exaggerated the drop even more than the suggested 1.4 inches. So now Iím scratching my head a little on this too. BTW, I did check and make sure the part numbers were correct before I installed them.

Next weekend Iím going to install the HDís on the rear with the pro kit springs and see if I get a similar non-lowering effect. If I do get a big drop in the rear, then maybe there is something wrong with my front install? If I donít get much of a drop, then maybe itís the HDís reducing my drop? The good thing is I enjoy working on my car and donít mind if I have to things over again or try different spring comboís. I read about how you have the zspís on the rear of your car before I bought the pro kit and was initially looking for them but couldnít find any below d6.

Question about settling. Will driving more help settle the car faster? Or is it just a time thing? I take public transportation all week to work and only drive about 5-15 miles on the weekend. Could be waiting a while for this to settle. Might be time for a road trip!
Attached Images
 
Appreciate 0
      05-16-2014, 11:51 AM   #208
instigat0r
New Member
0
Rep
25
Posts

 
Drives: 2007 328xi coupe
Join Date: Dec 2012
Location: Pittsburgh

iTrader: (0)

edit: stock spring is on the left, eibach on the right.
Appreciate 0
      05-16-2014, 03:10 PM   #209
ajsalida
Lieutenant Colonel
ajsalida's Avatar
20
Rep
1,737
Posts

 
Drives: 95 M3, 02 R1150GSA, 09 335xi
Join Date: Aug 2010
Location: SW USA

iTrader: (2)

Hard to tell what a spring will do WRT ride height by looking unless you have some background. A shorter spring is not necessarily going to lower your car.

You can vary only a few things on coils and still fit into factory spring perches in front BMW type struts. # of coils, wire diameter, dead length. Hard to vary coil diameter due to form factors. Coil springs actually work like a torsion bar, just all wound up. The spring force comes from twisting the metal all along the coil as it compresses. Those parameters determine how stiff the spring is but also what the static ride height will be when loaded. You can have a shorter dead length spring but thicker wire and not lower at all, or even be raised.

Because of the way the front strut is set up, you can only get a small number of spring coils into one. This is why the top diameter is huge, to get more length of metal in there. On BMW it is like 4 total (active coils). If you reduce the number of coils to make it shorter you stiffen it, but you get into a situation where now there is too much torsional load on the metal and may go past deformation limits in full compression. You can trim maybe 1/4 to 1/2 coil off the top and that is it. You'll get some lowering but a lot of stiffening. The bottom diameter tapers to fit the lower perch and there is some progressive effect, but you can't trim off that end.

So the way Eibach makes a lowering spring in front is to make slightly thinner wire and same number of coils, slightly shorter overall dead length. If you did the compressor yourself you probably noticed how much stiffer the stock XI spring was even though shape is nearly the same. That is nearly all only from thicker wire. Stiffness (torsional) goes proportional to diameter to the 4th power on wire, so a small increase is a lot stiffer.

I measured the wire diameters and the Eibachs were definitely thinner than OEM XI. Other people have measured them on spring testers and found Eibachs to be about same spring rate as stock non-XI, just lower. Both front and rear.

In back there is not as much constraint fitting into stock form factor. The rear Eibachs are shorter dead length, fewer coils, and thicker wire than either OEM XI or non XI. OEM XI is much thicker wire in the rear than OEM non XI. But here is where looks are deceiving, Eibach has same linear spring rate as stock non-XI in lbs/in but lower ride height. Unfortunately I think you will find you get a larger drop in back than you want by a lot.

Part of this is due to the heavier car at both ends than non XI. Part is due to the fact that in front the lower spring perch on an XI is HIGHER above the axle than on non XI, so while the drop from stock XI height is whatever it is, even more than the non XI, it is still higher up than non XI. XI rear suspension is same as non XI but the car is heavier so rear will drop MORE than non XI and you get a funny rake effect with rear looking too low. That is even without the unusual higher than normal front gap you got. So I am afraid you might be disappointed when you put the rears on.

One thing to check, just to make sure. Did you in fact get XI Bilsteins? Since they do not, as you have said, have the lower part that sticks down past the lower hub, just want to make sure on that.

Also on the pic, is the lower-most end of the installed spring flush up to the notch in the rubber pad? Can't tell. It is on the top pad not sure on the bottom.

Lowering an XI evenly without true coilovers is very tricky.

edit: one thing bilstein advises WRT install of their shocks is to fully compress them by hand before you install. In front this helps to get the air out of the housing. As far as driving a lot sure, esp try driving slowly over things which tend to cycle the suspension in front fully, like speed bumps. Not to bottom out but to compress the front shocks as much as you can maybe fart some of that air out. Your plan on the rears is good, install it all see how it looks. Take it from there and replace if you need to. Any ZSP rear should work in case you need to find some. Read the thread "i springs on XI" in this section for more info.

Last edited by ajsalida; 05-16-2014 at 03:22 PM.
Appreciate 0
      05-19-2014, 09:50 AM   #210
instigat0r
New Member
0
Rep
25
Posts

 
Drives: 2007 328xi coupe
Join Date: Dec 2012
Location: Pittsburgh

iTrader: (0)

Thanks for all the great info! Based off of what you said about the rear springs, I might just do rear bilstein HD's with stock springs for now. I really don't want the rear any lower than the current 2 finger gap.

I did get XI specific Bilstiens, and the eibach springs did line up perfectly, top and bottom, to the end of the rubber of the perches.

I did not know that Bilstein recommends that you compress the shock completly before installing! Do you think that is why my ride height is kind of high? Guess I'll have to find some slow bumps to try and compress some of the air out.

As far as ride quality, I'm still really enjoying how it is right now. I find myself actually hitting small bumps somtimes instead of avoiding them! And the front has settled about 1/8 inch over the last week. I'll post back with pics if it goes any lower after a few weeks.
Appreciate 0
      05-20-2014, 01:14 PM   #211
ajsalida
Lieutenant Colonel
ajsalida's Avatar
20
Rep
1,737
Posts

 
Drives: 95 M3, 02 R1150GSA, 09 335xi
Join Date: Aug 2010
Location: SW USA

iTrader: (2)

I have not installed any Bilsteins on e9x but on other McP strut cars (like my e36 M3) they always said in the instructions to compress struts fully by hand before assembly/install. Below is a pic of the way a front bilstein monotube looks like inside, you can see where air gets trapped inside at the bottom, you want to get all that out if possible. Based on what you're saying about settling you are probably burping that air out already.

I would do what you suggest and just install the rear bilsteins for now, see how it goes. If the front settles a lot re-evaluate. Installing rear springs is mostly unrelated and you will not need to re-align after just shocks. The only thing that may be a little off is the spring rate in back is going to be stiffer than ideal WRT front, but it shouldn't be an issue and besides you'll not need a bigger sway bar.

BTW in the pic below, the high pressure gas chamber is the orange shaded region at the top inside of the strut on the left. There is a floating piston there that separates the gas and oil volume, it has to move in order to compensate for fluid displaced by the piston rod movement inside the shock body. You can see the other "rod" visible from the outside that slides up and down on a monotube strut is actually the shock body with the fluid. The high pressure gas is what causes the additional ride height in monotube struts and shocks. You'll get some of that in back too. The air trapping thing is unrelated to that.

You can calculate the offset force due to the high pressure gas pretty easily, it is merely the lower piston rod cross sectional area in sq in times the gas pressure in PSI. Last time I did this for another car it was 40-50 lbs per corner pressing UP. So like nearly 200 lbs whole car of static force in the vertical direction, enough for 1/4" or so additional ride height depending on each corner's effective wheel spring rates (with motion ratios etc.). The gas chamber acts like a mini air shock IOW. But the benefits usually far outweigh the small increase in ride height vs other types of shocks in same price range.
Attached Images
 

Last edited by ajsalida; 05-20-2014 at 01:54 PM.
Appreciate 0
      05-22-2014, 09:00 AM   #212
AWD Addict
Chief Executive
AWD Addict's Avatar
36
Rep
2,483
Posts

 
Drives: 2008 335xi 6spd Coupe
Join Date: Dec 2007
Location: Boston

iTrader: (1)

Garage List
2008 335xi  [0.00]
Quote:
Originally Posted by Nonecure View Post
Nice wheels, but that is some serious gap!
I'd be concerned running the car in that stance (front only), and lowering springs installed on the HDs in general. The valving on the HDs isn't designed to be constantly compressed as they will be with the lower spring. Normal driving with the piston partially dampened is going to throw everything off.

Everything from handling to braking will be all tossed into the lottery on how it will settle in and perform when cornering and braking.
Appreciate 0
      05-28-2014, 10:08 AM   #213
instigat0r
New Member
0
Rep
25
Posts

 
Drives: 2007 328xi coupe
Join Date: Dec 2012
Location: Pittsburgh

iTrader: (0)

I agree whith what you're saying, but since my front is still at a tight 3 finger gap, IMO the HD's are not being over compressed (I could be wrong though) and seem to have enough room work properly. The ride quality is still great and the pro kit/HD set up is very similar to just having HD's on the stock springs but just a tad stiffer.
Appreciate 0
      09-04-2014, 04:02 PM   #214
TxWolf
Registered
TxWolf's Avatar
0
Rep
3
Posts

 
Drives: 2008 BMW 335xi
Join Date: Aug 2014
Location: Austin, TX

iTrader: (0)

I've followed jackb "My upgrade path so far, Eibach Pro kit, Staggered 19 inch wheels on Hankook V12 K110" and have questions regarding the Eibach Pro Springs/Bilstein Sport Shocks-Struts combo.

For those who have an e92 (I own a 2008 BMW 335xi) did you have to purchase the XI specific Bilstein Sport (B8) Shock-Struts?
http://www.turnermotorsport.com/p-21...-set-of-4.aspx

If so, since my car has 80,000 miles on it, will I have to include the Strut/Shock Mount kit?
http://www.turnermotorsport.com/p-11...9x-xi-awd.aspx
__________________
2008 BMW 335xi Cobb V3 Stage 1
Appreciate 0
      09-04-2014, 07:04 PM   #215
AWD Addict
Chief Executive
AWD Addict's Avatar
36
Rep
2,483
Posts

 
Drives: 2008 335xi 6spd Coupe
Join Date: Dec 2007
Location: Boston

iTrader: (1)

Garage List
2008 335xi  [0.00]
You want the xi specific shocks/struts.

Not sure on the mount kit. i didn't need it, but I had the setup installed quite a bit earlier than you.
Appreciate 0
      09-11-2014, 12:41 PM   #216
SLOWER
Captain
SLOWER's Avatar
6
Rep
680
Posts

 
Drives: 2010 E90 335ix
Join Date: Apr 2013
Location: MA

iTrader: (5)

Garage List
Quote:
Originally Posted by TxWolf View Post
I've followed jackb "My upgrade path so far, Eibach Pro kit, Staggered 19 inch wheels on Hankook V12 K110" and have questions regarding the Eibach Pro Springs/Bilstein Sport Shocks-Struts combo.
http://www.e90post.com/forums/showthread.php?t=857285

Please read this thread if you haven't already.
Appreciate 0
      09-30-2014, 04:06 PM   #217
Emozoo
Captain
Emozoo's Avatar
21
Rep
629
Posts

 
Drives: 2010 328xi premium package
Join Date: May 2013
Location: Eastern Long Island

iTrader: (1)

Garage List
2010 328 xi  [0.00]
XI on D5/D4

__________________
2010 FBO e90 328xi. Suspension: ZSP i springs, m3/z4 bump stops, 12mm front spacer, 15 mm back, Michelin Sport As3
"Just because you are a character doesn't mean that you have character." -The Wolf
Appreciate 0
      11-14-2014, 05:46 PM   #218
jezzy
Captain
jezzy's Avatar
Canada
7
Rep
611
Posts

 
Drives: 06 E91 325xi Black Wagon
Join Date: May 2014
Location: Montreal, Canada

iTrader: (10)

Looking at buying a set of bilstein b8 xi struts.. They have 335i eibach pro springs installed on them oddly enough.. Will these springs fit my 325xi wagon??

Bought kw v1s instead. Looking forward to installing them.

Last edited by jezzy; 11-30-2014 at 02:50 PM.
Appreciate 0
      11-30-2014, 02:44 PM   #219
butanmist
Registered
0
Rep
2
Posts

 
Drives: '11 329xi 6MT Prem, Sport
Join Date: Feb 2014
Location: Portland, OR

iTrader: (0)

Garage List
2011 BMW 328xi  [0.00]
My '11 328xi is at 89940 atm and yes suspension is overdue so getting ready to address this. I live in the in the NW and average 1400 miles a week with around 600lbs of tools and supplies (mobile furniture specialist, yes I can fix your crappy Ashley sofa and no you shouldn't have CL free'd your grandma's couch) over a lot of different surfaces. I often have dirt/gravel roads, potholes that look suspiciously like an M252 made them, snow, rain and ice of all kinds. After reading several novels worth of posts on this I think the b12 from blistien is my best option, so I pulled out my bently manual, searched you tube and perused the DIY forums and still not sure how much of a pain in the ass this would be to do myself. My time is valuable and after a certain point it is worth more to me to pay someone to do the work. For those that have done the job themselves how long (and how much swearing, occasionally flying tools) did it take you?
Appreciate 0
Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -5. The time now is 10:42 PM.




e90post
Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST