Help Please? Banging Noise In Rear Suspension

johnung · 08-02-2019, 08:01 PM

I'm suddenly getting a banging noise in my rear suspension every time I hit a bump. There is nothing at all in the trunk. I checked to make sure the battery bracket is tightened down, so that isn't moving. I called my independent BMW shop and they speculated that it could be a rear shock mount (see #8 in the attached diagram). Has anyone had a rear shock mount go bad and did you get this same symptom? If that is it, are there any heavier duty replacements that I should consider? Anyone have any other ideas as to what it could be?

Thanks in advance for any advice.

Car details: 2015 335i x-drive, auto trans, non-adaptive suspension, 30k miles on car

Rear Suspension Mods: only 15k miles on Koni Special Active rear shocks, Eibach mild lowering springs (0.6" drop in rear) and H&R rear sway bar.

FaRKle! · 08-02-2019, 08:07 PM

How tight did you tighten the nut that holds the shock to the top mount (item 11)? If you take the shock out do you still hear the noise? Are the end link nuts still tight?

johnung · 08-02-2019, 08:19 PM

Quote:

Originally Posted by FaRKle!

How tight did you tighten the nut that holds the shock to the top mount (item 11)? If you take the shock out do you still hear the noise? Are the end link nuts still tight?

Shocks, springs and sways were installed last year by an experienced BMW tech. (I don't have tools or garage any longer to do much work myself.) Other than what I already mentioned, no other troubleshooting has been done yet. Taking it to the Indy next week. Any parts I should order ahead of time?

Billfitz · 08-02-2019, 09:27 PM

Don't order any parts until and unless you find out what the problem is.

johnung · 08-03-2019, 03:40 AM

Quote:

Originally Posted by Billfitz

Don't order any parts until and unless you find out what the problem is.

Good advice, Bill. I was thinking in terms of if there was a likely part that had an upgrade. For instance, if I had a problem and the likely culprit was a DV, then I'd order a DV+ to have on hand to install while they had it apart.

A stock part like the rear upper shock mounts that BMW might list for $105 each and I might be able to get for $75 in three days. There is no telling what the local dealer's price might be since they don't have to follow BMW list price. They once quoted me, with a straight face, $40 each for an N55 spark plug.

I'd like to have any likely parts on hand for when the Indy has the car in the air and I'm paying for their labor. I wouldn't order anything that I could not return.

Billfitz · 08-03-2019, 08:08 AM

Murphy's Law corollary #69 guarantees that whatever parts you order in advance won't be needed, while you'll fail to order the parts that are needed.

08-02-2019, 08:01 PM	#1
johnung Major General 4528 Rep 5,392 Posts Drives: 2015 BMW 335i x-Drive Auto Join Date: Oct 2017 Location: New Jersey/Philadelphia iTrader: (1) Garage List 2015 BMW 335i XDriv ... [8.67]	Help Please? Banging Noise In Rear Suspension I'm suddenly getting a banging noise in my rear suspension every time I hit a bump. There is nothing at all in the trunk. I checked to make sure the battery bracket is tightened down, so that isn't moving. I called my independent BMW shop and they speculated that it could be a rear shock mount (see #8 in the attached diagram). Has anyone had a rear shock mount go bad and did you get this same symptom? If that is it, are there any heavier duty replacements that I should consider? Anyone have any other ideas as to what it could be? Thanks in advance for any advice. Car details: 2015 335i x-drive, auto trans, non-adaptive suspension, 30k miles on car Rear Suspension Mods: only 15k miles on Koni Special Active rear shocks, Eibach mild lowering springs (0.6" drop in rear) and H&R rear sway bar. Attached Images
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08-02-2019, 08:07 PM	#2
FaRKle! Brigadier General 4017 Rep 3,540 Posts Drives: 328d Wagon, M2 Comp, i4 eD35 Join Date: Sep 2016 Location: Bay Area, CA iTrader: (4) Garage List 2023 BMW i4 eDrive 35 [0.00] 2017 BMW 328dx Wagon [0.00] 2021 BMW M2 Competi ... [0.00]	How tight did you tighten the nut that holds the shock to the top mount (item 11)? If you take the shock out do you still hear the noise? Are the end link nuts still tight? __________________ -328d Wagon Build Log (with helpful reference links) -My YouTube Channel for some of the best DIYs and in depth information Please don't PM me for suspension recommendations unless interested in paid private consultations.
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08-02-2019, 09:27 PM	#4
Billfitz Lieutenant General 8245 Rep 16,088 Posts Drives: '15 328iX GT Join Date: Jan 2015 Location: New Hampshire iTrader: (0)	Don't order any parts until and unless you find out what the problem is.
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08-03-2019, 08:08 AM	#6
Billfitz Lieutenant General 8245 Rep 16,088 Posts Drives: '15 328iX GT Join Date: Jan 2015 Location: New Hampshire iTrader: (0)	Murphy's Law corollary #69 guarantees that whatever parts you order in advance won't be needed, while you'll fail to order the parts that are needed.
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