08-05-2019, 12:31 PM | #23 |
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awesome thread. reading through and looking at the video, our suspension ailments are not consistent (mine are passenger side, grinding noise when turning and metal-on-metal over most road imperfections).
subscribed and will continue to monitor. maybe i can drive to ann arbor so you can help diagnose mine? lol!
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08-05-2019, 01:15 PM | #24 | |
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08-10-2019, 08:45 AM | #25 |
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[COLOR="RoyalBlue"][SIZE="4"]Edit: Seems this test wasn't so repeatable. See a couple posts down for an update.[/SIZE][/COLOR]
Grabbed some old chassis ears from work for one last check before tearing the car apart again. Mic locations: Drivers tension arm Drivers tie rod Drivers stabar link Drivers coil spring Passenger coil spring Everything is quiet except the driver's coil spring, so it seems that the problem is between the swivel bearing and the strut tower sheet metal, adding further credence that the lag I discussed previously is causing the issue. I'm especially happy to find no noise from the tie rod, so I can probably rule out the steering gear for sure ($$$$). The new strut I ordered tested fine with no lag, and the swivel bearing spreader socket and strut puller tool came in yesterday, so hopefully by the end of the weekend I'll have the issue resolved.
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Last edited by Racer20; 08-11-2019 at 12:07 PM.. |
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08-10-2019, 09:11 AM | #26 | |
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08-11-2019, 10:32 AM | #27 |
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Gees Racer, deep dive indeed...
Every-time I've worked on the suspension on this car (remove struts, added camber plates, removed swaybar endlinks) the car has exhibited a clunk, every-time. Sometimes it appears right away or after a few miles on the road. And everytime I've either 1. torqued the strut top nut down more or 2. torqued the swaybar endlink while the car is loaded on the ground. Method: Car is naturally loaded, turn wheel to full load, get your impact driver in-between the tire and wheel liner so you can access the swaybar nut. Loosen it so there's a little play between the strut and the endlink then impact tighten it. Not torqued by a torque wrench, just using the impact itself. One of two ideas mentioned have always solved the issue for me. Even had to do it after replacing the struts themselves (so new struts had no impact on the issue). |
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08-11-2019, 01:15 PM | #28 |
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I'm not looking forward to the thought of swapping all the MPHAS hardware to a new strut and dealing with that whole mess just to put a new $1000 strut on the car and have it still clunk. So, I figured I'd do some more easy testing before I really dig in.
I got all new sway bar hardware (links, body bushings, and new nuts) so I removed all the underbody protection and pulled the bar off. Figured this was a good chance to see for sure if the bar was the source of the noise or at least a transfer path, so off to my test bump I went armed with my chassis ears. Things I learned: 1. The sway bar or end links aren't causing the clunk. The noise is still there, even with the bar and end links completely removed. It's maybe a bit worse than before since the suspension can now articulate more. 2. Chassis ears are a little bit fiddly. I moved the mic that I had on the coil spring to down a coil to avoid contact with the body. The mic must have been hitting something else last time, because there it's silent now. I clipped a mic on the pass. side spring to compare, and they sound the same. No noise. Sometimes it's tough to tell if the noise is actual noise or just the mic clip being jostled around. 3. The damper itself is pretty quiet too. I clipped a mic onto the "nub" that's formed into the bottom cap of the damper, assuming that anything that's transferred through the strut body will light that up. Nope, quiet as a mouse. 4. The tension arm is NOT quiet. I tried a few different mic placements on the tension arm (one example shown in the pic), and this seems like the most likely transfer path at the moment. The loudest is when I clip it to the extra threads at the bottom of the ball joint. Next is the bolt on the other end, and it can be heard faintly from the subframe just next to the tension arm bolt. Out of the 5 different mic configurations I tried, I could hear the noise through the tension arm in 4 of them. Conclusion: Ordered a new tension arm. I have to take it off anyway to replace the strut in order to fit the puller tool in there per BMW's instructions. My strut sill has lag, so I might replace it regardless, but I want to see how it sounds/rides after the tension arm replacement. I'd rather not do all that work for minimal benefit.
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08-12-2019, 02:58 PM | #29 |
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Did you check the torque on the tension strut bolt? In the past I've had two alignment shops forget to torque that bolt to spec (I have caster adjustable bushings there) which created knocking/creaking noises.
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08-15-2019, 08:55 PM | #30 |
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I did. It was tight. The new strut is in, waiting for the new tension arm to be delivered.
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08-18-2019, 01:08 PM | #31 |
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Update:
New strut, upper mount, tension arm, both stabilizer bar links and body bushings. Installed per BMW TIS with all new hardware and torqued to spec with calibrated torque wrenches. The clunk remains on the sharpest bumps at low speeds. I can drive on 95% of the roads by me with no clunk, and on those roads, the car feels pretty good overall. Either there's a major design problem with the structure of the vehicle or the dampers or the noise is coming from something other than the suspension. Either way, I've spent way too much time on this car, so I'm going to take a break to decide what to do next. If anyone has anything else to share or any ideas to add, let me know.
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08-18-2019, 04:25 PM | #32 | |
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Just do a 1/8 turn clockwise of the steering rack nut, see if noise goes away.
If anything, the steering rack is where the noise problem is. Quote:
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08-18-2019, 06:11 PM | #34 | |
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08-20-2019, 03:59 PM | #36 |
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https://f30.bimmerpost.com/forums/sh...d.php?t=876523
Interesting . . . here's a thread full of UK F30 owners describing the same problem, a noise over bumps that sounds like a suspension noise. The interesting part is that they also have it on the drivers side of the car, which for them is on the right. It sounds more and more like this is something related to the steering or at least the drivers controls (clutch, brake, throttle, etc.). BMW released a repair kit last fall to fix some lash in the steering gear of the F30, but the F8X gear is made by a different supplier and I'm guessing the repair kit won't fit. From this link, it looks like there have been at least 5 revisions of the F8X steering gear, most recently from July 2018. No way to know if the changes are related to this issue, but it would be interesting to know if anyone with the clunk has a car built after July 2018.
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08-21-2019, 12:58 AM | #38 |
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Mine was built June 2018 and I have the clunk. Typically when going over metal road covers (those 1" think steel plates covering holes on road) when making a turn.
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08-21-2019, 11:09 PM | #40 | |
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Do you think the clucking is more of inconvenience or will cause long-term risks or issues? |
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08-22-2019, 05:03 AM | #41 | ||
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09-05-2019, 06:32 AM | #43 |
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Quick Update . . .
Going through some video I took a couple weeks ago, I noticed some odd behavior when the front tire hits a bump. If you look closely (make sure you're viewing at 1080p/60fps), you can see that the wheel oscillates in the fore-aft direction more than it does up and down after the impact. This oscillation approximately lines up with what the clunk sounds like . . . the strut mount coming unseated from the tower and banging against it, either due to bolt stretch or tower deflection (see my post #10 in this thread). Stiff or lowered suspension would make this problem worse . . . if the wheel can't move up to get out of the way of an impact, it'll have to move rearward. In other videos, I can tell that the noise doesn't happen until the suspension stops moving upwards and continues to "rattle" as it rebounds in the negative direction. The dealer can't find anything and my buddy who works for Bosch calibrating this same steering gear on Corvette and V series says he's never seen a noise like this come from their gears. This has to be the problem. Now the question is . . . how to fix it?
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09-05-2019, 07:26 AM | #44 |
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