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BMW 3-Series (E90 E92) Forum
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Koni Yellow/Eibach Pro on Xi - Jittery rear axle
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05-21-2013, 01:10 PM | #23 |
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Please post up pics after the install ...very interested in how it turns out!
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05-21-2013, 08:50 PM | #24 |
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I get the same thing in my e91 xi with just H&R springs. To me it definitely feels like a shifting subframe. Same exact feeling that is felt in older Mustangs with a small panhard bar.
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05-22-2013, 08:28 AM | #25 | |
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One guy replaced all the rear subframe bushings with M3 ones and still says it is happening. Others (mainly with high TQ cars) say it helps but many go to a diff lockdown kit and delrin or solid bushings. Going to guess that higher mileage cars that have been beat on a lot will have more of a problem, as will same with high TQ and many hard launches. PROBABLY (caveat) it is a function of the weakest link phenomenon. It is a 5 link rear (with a bushing at each end each link) with subframe bushings, diff bushings etc etc. You stiffen up something in that whole complicated system (like shocks or springs), then the next thing starts to flex. edit: in my case the Eibachs are at the softer end of lowering springs (vs H&R sport or race), plus the shocks are set near full soft (for a reason). I plan to mess with that setting for summer, maybe then some of this rear wiggling will start. |
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05-27-2013, 09:07 AM | #26 |
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I felt it on mine with the stock springs as well. I have a set of whiteline subframe bushings on order with Turn in Concepts to see if they help. These bushings are inserts bushings that should help increase stiffness in the rear without having to do a full m3 subframe bushing swap. Should take less than an hour start to finish. Used something similar to this on my sti and loved the results.
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05-27-2013, 09:12 AM | #27 | |
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edit: Jeez those are only $50 and look easy to install, great find if they work! http://www.whiteline.com.au/product_..._number=KDT918 Last edited by ajsalida; 05-27-2013 at 09:25 AM.. |
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05-27-2013, 08:16 PM | #29 |
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Yeah I also ordered a set, they were so cheap. 45 shipped. Figured why not try it. Plus I have a M3 rear sway bar to install too, while I'm under there.
One thing, you look at the PDF for intstall instructions it looks like maybe they are going to be a bit thicker/taller than stock, so maybe it will raise the rear a bit. Which may not be bad just something I'm going to keep an eye on. |
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05-27-2013, 08:39 PM | #30 | |
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Anyhow would definitely would like to know the outcome of your guy's experiment with the subframe bushing, e.g. if they solve the issue and raise the rear as well. |
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05-27-2013, 09:02 PM | #31 | |
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I did look closely at my car on a level paved surface. The rear is low but the tire is not tucked under as I thought it was. I think without spacers it is easy to get an angle that looks tucked. With the spacers pushing the wheel faces out flush there is still clearance of a finger or so. I will take some before/after pics & measurements on the bushings. |
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05-27-2013, 09:10 PM | #32 | |
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05-27-2013, 09:21 PM | #33 | |
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edit: do you have any pics of your car, showing the excessive drop? |
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05-27-2013, 09:34 PM | #34 |
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It's probably not excessive. Most people would probably call it a perfect drop. I just wasn't expecting this much, since as noted I drive up to ski country every wknd during the winter time. From the pictures, at tire level, it doesn't look too bad, but standing next to the car the rear tires looks tucked into the wheelwell.
Last edited by thegrinchboy; 05-27-2013 at 09:40 PM.. |
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05-28-2013, 05:02 AM | #35 | |
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05-28-2013, 10:01 AM | #36 |
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Drives: 2008 335xi Sedan
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I got the rear tucked look too after my install last weekend. I didn't expect the Eibach drop to be this low in the back.
Last edited by RX_AGENT; 05-28-2013 at 10:12 AM.. |
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05-29-2013, 04:32 PM | #39 | |
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I just went out to the car in my driveway (on uneven gravel + back sloping hill) and there is def at least one finger's clearance between the outside fender edge and the tire. More than that inside the fender well. However what got my attention now that I was looking closely was I doubt there is enough clearance between the inside plastic fender well and the tire shoulder at full compression of the suspension. I have had zero problems or rubbing so far but I think if you loaded 3 passengers in there and hit some big rolling bumps you might get some rubbing on the plastic inner fender. So maybe 15 mm on the rear was too aggressive. It also depends how the wheel tilts inwards at the top as the susp compresses, could be that is not a problem. Need to do this more carefully, and then do it again after I put the rear bushing gizmos in. They shipped today as did the M3 rear bar. If they arrive in time that might be my weekend project. But def hold off on 15mm rear spacers for non LCI e92 with Koni/Eibach and OEM staggered 189's. It looks great and BMS website said they'd fit fine but it may be the case that 12 or 10 mm is more what you'd want. Also I'm thinking with a lot of snow filling up the wells this would not work at all. edit: the other thing to keep in mind is I do my own alignments and so I tried to get the rear camber to match what I ended up with in front, which was about -1.2 deg. It wanted to be more, and it may be that going to -1.5 or even -2 is better for clearance purposes. However I will not mess with the camber until I take the locator pins out of the front struts and see how much more neg camber I get there, then try to get close to that in back. Regardless I am still thinking for winter the spacers may need to come off. Last edited by ajsalida; 05-29-2013 at 04:40 PM.. |
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06-01-2013, 09:52 AM | #40 | |
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Interestingly, per one of the posters the xDrive OEM spring ratings (page 3) are almost identical to Eibach Pro. I called Eibach and they confirmed the rating numbers posted and that their springs are linear with the rear length being 300mm (11.8"). Eibach CA is looking into the front length as those are made in Germany, so the guys in CA did not have the length info (??? - Not sure why that data is not in their system...) Either way, given Eibach are 148F/456R and xDrvie OEM are 145F/460R with rear length being 13", I may put the rear OEM springs back as an experiment. This won't happen until end of June, as my local installer is booked up until then. Will definitely update. |
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06-02-2013, 02:24 PM | #41 | |
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It could be that the rear Eibachs are close to same rate as stock, which opens up some interesting possibilities. If you can find out the dead length of the Eibach pro kit (and wire diamter & # of coils if possible), I have both the OEM 335 Xi and a set of ZSP (sport) springs lying around. Would make for a good comparison. I think the standard 335i ZSP would be better than going back to OEM Xi for rear. However you'd want to make sure by comparing the three springs first to make sure the height would be in between OEM Xi and Eibach. BTW for LINEAR springs it is pretty easy to calculate spring rates, if you know dead length, coil diameter, wire diameter (and material), # of coils. It is still a mystery to me why the Eibachs (and others) seem to drop the rear too much. I think part of it is the tuck look (optical illusion cured partially by spacers) but I did not measure before and after so who knows. It could also be the motion ratio is so high on the rear any slight miscalc on ride height would end up being multiplied by a lot. For the sedan non sport, the pro kit 2092.140 drop is supposed to be 1.4": front, 1.0" rear. For the coupe (has ZSP standard) 1.0" front 0.8 rear". But as we know (or suspect) the Xi has a different set of springs than either ZSP or sedan non sport. I think it is safe to say the drop is more than 1" in the rear. |
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06-03-2013, 09:12 PM | #42 |
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Well I can speak from personal experience that the sloppy feeling over bumps is most definitely the rear sub-frame bushings. Since I am a previous Mitsu Evo owner I was extremely dissatisfied with the xdrive handling. First I had Bilstein and H&R and it was way to stiff and the rear was too tucked. Then I got some Eibachs to match with the bilsteins. Much better drop and much better comfort. Handling was a little softer but still good but the sloppy "disconnected" feeling was getting to me. I had always pondered replacing the rear sub-frame bushings but the cost of the M bushings and rear sway cost a ton when you factor in the install cost. The install was a royal PITA. Everything in the rear must come down and getting the old bushings out and the new bushings in with no proper tool is not an easy task. I have had the bushings and sway in for 3 days and it is exactly the solution to the the problem. Now it feels like the shocks and springs take the hit and not the whole car. It is much more planted and connected to the road. The only complaint I still have is the steering rack ratio leads to not enough aggressive steering response that I enjoyed in my evo. If someone has a solution to that then this will be the perfect car. If you have the $$$ then DO this upgrade. If you think your car doesn't do the things the OP stated then find someone who has done this or come to South Jersey and take my car for a spin and you will realize what everyone was saying.
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06-03-2013, 10:13 PM | #43 | |
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06-04-2013, 08:27 PM | #44 | |
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BTW, I did do a search but couldn't locate anything concrete as far a link to parts or a part number to search. Tried going through Grinchboy's possible locations, but no one gave any specifics for a 3 ser. I found bushings online for a 3, but is there are particular set? Any info you can give would be helpful. Thanks! |
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