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      05-11-2013, 11:02 PM   #1
thegrinchboy
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Koni Yellow/Eibach Pro on Xi - Jittery rear axle

Hi Guys ~ Need some help here.

Just upgraded my '11 335xi to Koni Yellow/Eibach pro. The handling is great but the back-end seems to shift when I drive over an uneven surface e.g. manhole cover, potholes, cracks, etc. For example, drive over manhole cover on passenger side, rear of the car shimmies left then back to the right. Same on the driver side but not as prevalent. It feels like the body is moving, as the wheel/tire are planted to the road. The car was aligned by the installer after the upgrade. My local BMW dealership has also checked out the install and reported everything to be tight and realigned the car (again) in trying to resolve the issue, but it's still there. The car is riding on 18" staggered Michelin PSS RFT.

Any thoughts or suggestions would be greatly appreciated. Thanks!
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      05-12-2013, 06:07 AM   #2
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Quote:
Originally Posted by thegrinchboy View Post
Hi Guys ~ Need some help here.

Just upgraded my '11 335xi to Koni Yellow/Eibach pro. The handling is great but the back-end seems to shift when I drive over an uneven surface e.g. manhole cover, potholes, cracks, etc. For example, drive over manhole cover on passenger side, rear of the car shimmies left then back to the right. Same on the driver side but not as prevalent. It feels like the body is moving, as the wheel/tire are planted to the road. The car was aligned by the installer after the upgrade. My local BMW dealership has also checked out the install and reported everything to be tight and realigned the car (again) in trying to resolve the issue, but it's still there. The car is riding on 18" staggered Michelin PSS RFT.

Any thoughts or suggestions would be greatly appreciated. Thanks!
What are the rear shocks set on?
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      05-12-2013, 07:24 AM   #3
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That's because of our crappy subframe bushings on non-M cars. Getting better shocks simply revealed the deficiency that was already there.
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      05-12-2013, 08:35 AM   #4
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Originally Posted by ajsalida View Post
What are the rear shocks set on?
The rear are set at 1/2 turn from full soft (out of 1.5 turn range). The fronts are set 1 turn from full soft (out of 2.5 turn range). Any thoughts? Thx!
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      05-12-2013, 08:38 AM   #5
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Originally Posted by ashmostro View Post
That's because of our crappy subframe bushings on non-M cars. Getting better shocks simply revealed the deficiency that was already there.
That was one of my thoughts as well. e.g. stiffening up the rear, but others have gone the Koni/Eibach combo without issues. So wanted to get feedback before possibly spending more $.
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      05-12-2013, 08:50 AM   #6
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Originally Posted by thegrinchboy View Post
The rear are set at 1/2 turn from full soft (out of 1.5 turn range). The fronts are set 1 turn from full soft (out of 2.5 turn range). Any thoughts? Thx!
That sounds right. Unfortunately the only thing I can suggest is something was not put together properly. I know you said the dealer looked at it but unless they removed the rear carpet and took apart the upper strut mounts (for example) I don't know how they can say that. IIRC there are are two pieces to the bushings and they have to go in in the right order. Plus there are some washers and a spacer and so forth.

Also were the rear bump stops trimmed? You need to take 1" off them in back. Fronts need to be trimmed too or use e36 M3 stops. You could be riding on the stops (this just occurred to me).

All kinds of shit could go wrong that would not nec be apparent from casual inspection, springs not seated properly, missing/misaligned spring rubber pads, improperly assembled under-tightened shock mounts. etc etc.

Not sure who your installer was or how well he knows BMW's. If this were my car I would take it all apart and start over.

As for the rear subframe bushings, yeah they are "weak" but that only shows up on hard launches and super hard cornering. Over ordinary road imperfections you should not be experiencing what you're describing.
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      05-12-2013, 02:15 PM   #7
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Originally Posted by ajsalida View Post
That sounds right. Unfortunately the only thing I can suggest is something was not put together properly. I know you said the dealer looked at it but unless they removed the rear carpet and took apart the upper strut mounts (for example) I don't know how they can say that. IIRC there are are two pieces to the bushings and they have to go in in the right order. Plus there are some washers and a spacer and so forth.

Also were the rear bump stops trimmed? You need to take 1" off them in back. Fronts need to be trimmed too or use e36 M3 stops. You could be riding on the stops (this just occurred to me).

All kinds of shit could go wrong that would not nec be apparent from casual inspection, springs not seated properly, missing/misaligned spring rubber pads, improperly assembled under-tightened shock mounts. etc etc.

Not sure who your installer was or how well he knows BMW's. If this were my car I would take it all apart and start over.

As for the rear subframe bushings, yeah they are "weak" but that only shows up on hard launches and super hard cornering. Over ordinary road imperfections you should not be experiencing what you're describing.
The bumpstop were replaced with E36 M3 ones, and the rear were trimmed per your recommendation and the Eibach notes. The installer is someone who has done many BMW installs and comes highly recommended by various people on this forum. So I am not sure what's up....

I do agree that the dealership most likely did a superficial check. Therefore my next step is to bring the car to a local BMW specialty shop and them take a look. I will provide an update after the visit. Thanks again for the input!
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      05-12-2013, 02:31 PM   #8
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Quote:
Originally Posted by thegrinchboy View Post
The bumpstop were replaced with E36 M3 ones, and the rear were trimmed per your recommendation and the Eibach notes. The installer is someone who has done many BMW installs and comes highly recommended by various people on this forum. So I am not sure what's up....

I do agree that the dealership most likely did a superficial check. Therefore my next step is to bring the car to a local BMW specialty shop and them take a look. I will provide an update after the visit. Thanks again for the input!
Glad to help, hope you get it sorted out. The other thing to check is that the shocks are set properly. Then check again. I went through it several times before I was sure they were set the way I wanted. The rears esp since you have to take them out. I have SA konis on another car and they adjust the opposite way so it is easy to get confused. Plus front and rear go opposite directions. Easy to be on full stiff when I thought it was full soft.

There are procedures on line @ Koni's website make sure you are looking at the right one for your car and then the right end of the car. Rears esp are hard to get the rod fully compressed and seated into the adjuster mechanism, and then held there while turning.
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      05-12-2013, 06:25 PM   #9
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I respectfully beg to differ re: subframe bushings. I feel them squish sound all the time in normal driving conditions and cause exactly the same feeling the OP described... On stock zsp suspension.
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      05-12-2013, 07:44 PM   #10
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I respectfully beg to differ re: subframe bushings. I feel them squish sound all the time in normal driving conditions and cause exactly the same feeling the OP described... On stock zsp suspension.
You could be right, but to be clear, you do not have an xi, you do not have koni/eibach, and you have not replaced rear subframe bushings yet?

I'm not seeing how you can conclude bushings are at fault on OP's car when you haven't even verified bushings are the problem on your own car.

My car does not do this, I am running koni/eibach 335xi, 18" OEM staggered wheels but non RFT conti DWS tires.
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      05-13-2013, 12:19 PM   #11
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I got the eibach/koni combo. I can tell you the car still feels a little unstable over bumps like those you describe. Sometimes it feels like the car hydroplaned, sometimes its like a shake (like when a dog tries to shake water of its body). Cant really give you a better description. Car is not as planted as my old STI.

I just attributed this to the subframe bushings that seem to be fluid filled ones, rather than solid ones.
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      05-13-2013, 12:45 PM   #12
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I got the eibach/koni combo. I can tell you the car still feels a little unstable over bumps like those you describe. Sometimes it feels like the car hydroplaned, sometimes its like a shake (like when a dog tries to shake water of its body). Cant really give you a better description. Car is not as planted as my old STI.

I just attributed this to the subframe bushings that seem to be fluid filled ones, rather than solid ones.
Exactly! That's what I noticed as well. I was going to PM you to verify your experiences as you and I both have the same setup and installer :-)

One of the things I did try yesterday, per Ajsalida's recommendation was to review Koni's specification and install procedure. What I found was that the rear shocks actually have 2.5 full turn, not 1.5 full turn (per the installer's verification during the install). Assuming that is the case, 1/2 turn from what I thought was "full soft" is actually 1.5 turn for the "real full soft" baseline. Short of removing the rear and restarting, I firmed up the front end to match e.g. 1.5 turns from full soft. This seemed to have made the car better, but now makes me wonder if both rear shocks are set up identically. Next step is getting it checked out by an independent BMW shop, when I get new tires put on.
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      05-13-2013, 01:15 PM   #13
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Quote:
Originally Posted by thegrinchboy View Post
Exactly! That's what I noticed as well. I was going to PM you to verify your experiences as you and I both have the same setup and installer :-)

One of the things I did try yesterday, per Ajsalida's recommendation was to review Koni's specification and install procedure. What I found was that the rear shocks actually have 2.5 full turn, not 1.5 full turn (per the installer's verification during the install). Assuming that is the case, 1/2 turn from what I thought was "full soft" is actually 1.5 turn for the "real full soft" baseline. Short of removing the rear and restarting, I firmed up the front end to match e.g. 1.5 turns from full soft. This seemed to have made the car better, but now makes me wonder if both rear shocks are set up identically. Next step is getting it checked out by an independent BMW shop, when I get new tires put on.
This is getting interesting. One thing about the Konis is they are not linear in the adjustment range so if your rears are 1.5 turns off full soft they are effectively close to full stiff. The fact that both you guys have the same installer may mean he set them both up that way. I read an article somewhere where a "pro" was suggesting this.

However I am not ruling out the rear (subframe) bushings, enough people have complained about them, it is something I've read about and considered doing if I ever kick the power level up beyond where my car is now (Cobb stage 2+). It's just I drove my car a lot looking for what they were describing and I just could not feel it. And believe me I live in an area with some pretty rough roads.

One question for both you guys, or all you guys reporting this who have K/E. What kind of tires? RFT or not, and then independent of that, what wheel sizes and widths. Finally what pressures?

I also found 2.5 turns available and set them to 0.5 turns off full soft. Next time I have them off I want to try 1 full turn. I run 18" staggered with non RFT conti DWS, OEM sizes, set at 38 PSI F/R. The rear feels very planted esp on sharp transitions (like tucking back in after an aggressive pass), or getting on throttle coming out of a turn.

edit: last thing, I forgot to mention. When I first installed these and did an initial alignment (I do my own), I did notice a jiggling at the rear. Then I went back again after a few miles of settling and did a full alignment, and also released the binding on all the rear bushings. Meaning I fully loosened the main control arm and the two rear suspension adjuster bolt/nuts, and let the car visibly settle full weight, tightened it all back up again, then completed the alignment off that base. Two things happened. The rear dropped another 1/4 or so, and the jiggling went away. If you do not do this the bushings are twisting against load at rest.

Last edited by ajsalida; 05-13-2013 at 01:24 PM.
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      05-13-2013, 02:25 PM   #14
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Originally Posted by ajsalida View Post

One question for both you guys, or all you guys reporting this who have K/E. What kind of tires? RFT or not, and then independent of that, what wheel sizes and widths. Finally what pressures?

I also found 2.5 turns available and set them to 0.5 turns off full soft. Next time I have them off I want to try 1 full turn. I run 18" staggered with non RFT conti DWS, OEM sizes, set at 38 PSI F/R. The rear feels very planted esp on sharp transitions (like tucking back in after an aggressive pass), or getting on throttle coming out of a turn.

edit: last thing, I forgot to mention. When I first installed these and did an initial alignment (I do my own), I did notice a jiggling at the rear. Then I went back again after a few miles of settling and did a full alignment, and also released the binding on all the rear bushings. Meaning I fully loosened the main control arm and the two rear suspension adjuster bolt/nuts, and let the car visibly settle full weight, tightened it all back up again, then completed the alignment off that base. Two things happened. The rear dropped another 1/4 or so, and the jiggling went away. If you do not do this the bushings are twisting against load at rest.
My current set up: Michelin PS RFT staggered. F: 225/40/18 @ 36 PSI 18x8. R: 255/32/18 @ 41 PSI 18x8.5. These are OEM sizes and inflation.

Aligned twice as noted. Not sure how it was done the second time, but the suspension was installed with the frame supported and components tightened, then moved to the alignment machine.
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      05-13-2013, 02:58 PM   #15
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Don't know what to tell you mon, inclined to think at the very least the rear shocks are at or near full stiff. If you could change one thing it'd be dial them back to 0.5 turns off full soft. Unfortunately they have to be taken out to do that.

Somebody here invented a way to only need to drop the top of the shock out, leaving the bottom still attached. Wheel removed, you unbolt the upper mount, drop the susp corner til it comes out of the upper fender well, take the mount and and the bump stop off the rod, and adjust while still bolted into the lower arm. Next time I do this I'll try that but I haven't done it myself.

Keep up posted and good luck.
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      05-13-2013, 03:02 PM   #16
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Quote:
Originally Posted by ajsalida View Post
Don't know what to tell you mon, inclined to think at the very least the rear shocks are at or near full stiff. If you could change one thing it'd be dial them back to 0.5 turns off full soft. Unfortunately they have to be taken out to do that.

Somebody here invented a way to only need to drop the top of the shock out, leaving the bottom still attached. Wheel removed, you unbolt the upper mount, drop the susp corner til it comes out of the upper fender well, take the mount and and the bump stop off the rod, and adjust while still bolted into the lower arm. Next time I do this I'll try that but I haven't done it myself.

Keep up posted and good luck.
Will do. Thx for the input and help.
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      05-14-2013, 07:12 AM   #17
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When I installed mine, I specified turns from full stiff, rather than full soft. So installer should have turned to full soft then to full stiff (counting) and then to the setting I wanted. This might have given me better knowledge of how they were set up (knowing how many turns are in the strut, which seem to vary)

I changed over to non-rfl (michelin) like 500 miles ago and the car feels way better now. This jitter is less pronounced. Tire pressure as defined in the car (i think its 38 back, 32 front).
I once read that the higher tire pressure is to fix the understear that it receives from the AWD. I have not tried it with lower pressure on back. I like my ride right now.

On a separate note. I got road force tire balance and it was awesome. Car was just gliding on the road. No vibration whatsoever.
Too bad it didnt last long, due to these damn roads
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      05-14-2013, 08:16 AM   #18
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Quote:
Originally Posted by vapore0n View Post
When I installed mine, I specified turns from full stiff, rather than full soft. So installer should have turned to full soft then to full stiff (counting) and then to the setting I wanted. This might have given me better knowledge of how they were set up (knowing how many turns are in the strut, which seem to vary)

I changed over to non-rfl (michelin) like 500 miles ago and the car feels way better now. This jitter is less pronounced. Tire pressure as defined in the car (i think its 38 back, 32 front).
I once read that the higher tire pressure is to fix the understear that it receives from the AWD. I have not tried it with lower pressure on back. I like my ride right now.

On a separate note. I got road force tire balance and it was awesome. Car was just gliding on the road. No vibration whatsoever.
Too bad it didnt last long, due to these damn roads
I had want to run down the RFT and buy some time, but my change to non-RFT may happen sooner than later. As for the Koni settings, I have been playing with the front, but not the back, as it too much of a pain (and $) to take out and adjust. I will adjust the back after the tires are swapped out. Glad to hear that the non-RFT have helped dramatically.
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      05-20-2013, 08:37 PM   #19
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My car does not do this, I am running koni/eibach 335xi, 18" OEM staggered wheels but non RFT conti DWS tires.
I have a e90 330XI and just ordered koni FSD w/ eibach prokit. i have the 18" OEM staggered wheels on non RFT conti DWS tires. Did you trim down your bump stops? Or use E36 bump stops? Is this absolutely necessary?
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      05-20-2013, 08:41 PM   #20
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      05-21-2013, 04:56 AM   #21
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Considering that I have a 330XI will the E36 M3 fit for the front? I would prefer purchasing new ones for the rear instead of trimming them down, anyone know which ones i can get?
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      05-21-2013, 07:40 AM   #22
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Considering that I have a 330XI will the E36 M3 fit for the front? I would prefer purchasing new ones for the rear instead of trimming them down, anyone know which ones i can get?
E36 M3 for the front and (probably) E85 Z4 for the back.
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