Creaking sound from drivers rear at low speed

[28firefighter]

Hi friends,

I noticed today that I’m getting a creaking noise from the drivers rear at low speeds. I notice it most when slowing to a stop, say less than 15 mph and immediately after I stop.

A lot of work has been done to the suspension front and rear, but I only have records for the front.

Any thoughts?

[ZHPizza]

I chased this exact issue and never resolved it from changing bushings/spring pads/etc. I am working on reinforcing the RACP now (had a crack in the LR wheel well seam) so hoping it was the movement there making the noise.

[28firefighter]

I really hope it isn't the subframe cracking...

[t.er]

I really hope it isn't the subframe cracking...

You could get under there and check, if it's truly the RACP that is creaking then more than likely you have some major cracks. FWIW I had 1 fairly long crack, and a split seam in the LR wheel well and did not have any noise

[28firefighter]

I got under there and did not see anything cracking. For what it's worth, I gave the upper strut mounts, control arms, and some of the bushings I could see a squirt with silicone spray just to see if that helped, and I'd say it reduced the noise by 75% - which leads me to believe that it has something to do with worn out bushings.

Going to take it in next week so someone much more experienced than I can take a look.

[ZHPizza]

The LR wheel well is a good spot to check:
https://uploads.tapatalk-cdn.com/20200711/4ace74e12337ef9b202c20385541ef3d.jpg

If you don't see cracking along the seam there or next to the LR mount then you're probably fine. That's where the shitstorm starts on non-m cars.

[Will]

Could the squeaking be from sway bar bushing? I changed my sway bars to other BMW OE bars and I noticed there was a creak/squeak afterwards. The noise was very apparent when my rear seats were folded down, whereas I didn't even notice when the seats were up. This noise was noticeable at low speeds (parking lot speeds), but that may be a function of being drowned out by road noise at higher speeds.

I've been meaning to get under there and spray the mounts /bars with some lube.



The LR wheel well is a good spot to check:
https://uploads.tapatalk-cdn.com/20200711/4ace74e12337ef9b202c20385541ef3d.jpg

If you don't see cracking along the seam there or next to the LR mount then you're probably fine. That's where the shitstorm starts on non-m cars.

Damn, that's a bummer! Not to derail this thread, but what's your plan for the fix besides welding? CMP Bar + plates, VinceBar?, Reddish Plates + a bar? CCE46M3 bolting method?

[28firefighter]

My running suspicion is what you say or possibly a loose left rear upper shock mount. I’m trying to get it into my Indy later this week to diagnose.

[ZHPizza]

My running suspicion is what you say or possibly a loose left rear upper shock mount. I’m trying to get it into my Indy later this week to diagnose.

Oh man sorry to scare you when I read your first post I thought you said you had been through all of the bushings and stuff. #1 culprit would be sway a sway bar bushing.

Does it happen on (1) regular dips or (2) off-camber dips where the suspension kind of twists?

If (1), then I'd try to test it by putting a jack under the subframe right in front of the differential (don't jack on the differential!) and lifting to extend/compress everything and trying to track the noise

If (2), then lift on the LR jack pad and try to torque that corner and recreate it



Damn, that's a bummer! Not to derail this thread, but what's your plan for the fix besides welding? CMP Bar + plates, VinceBar?, Reddish Plates + a bar? CCE46M3 bolting method?

I thoroughly cleaned and inspected the underside and don't even have any pulled spot welds, so not going to waste my time with plates. I'm hoping to address the root cause from above and bandage the crack in the wheel well with some seam sealer + rivets where the spot welds pulled.

For the front mounts, I'm bolting through like CCE46M3 did. For the rear mounts, I'm making some brackets out of aluminum to tie the subframe mounts to the the chassis rail. Similar to the Vincebar design, but will still allow me to install an X brace (https://www.s-m-eng.com/product-page/e46-racp-brace).

If I hadn't already cut open the floor and ground/flattened the T area on top of the mounts, then I would just be bolting through the front mounts and installing the x brace for the rear. That way the force that pulls down on the LR mount (and causes all of the cracking to start) will be anchored to the shock tower, which is integrated into the chassis rail. Easy peasy lemon squeezy.

I'll try to post some pics if I ever finish the damn thing!

[t.er]

I'll try to post some pics if I ever finish the damn thing!

How long has your car been on stands? I remember the pic you posted of your dropped subframe on E46F in April or May, and assuming that pic of the split seam sealer is recent, man that's quite long downtime.

But, given the current situation now would be the best time to carry out all this car work, especially if WFH :innocent

[28firefighter]

Good questions. It’s really only at lower speeds when I take my foot off the accelerator - particularly in first gear. I’m thinking it’s probably #1 more than #2.

[ZHPizza]

How long has your car been on stands? I remember the pic you posted of your dropped subframe on E46F in April or May, and assuming that pic of the split seam sealer is recent, man that's quite long downtime.

But, given the current situation now would be the best time to carry out all this car work, especially if WFH :innocent

Since March 7 :(

I also thought I would have some extra time to work on it when Covid got here but the opposite happened. I've been working my ass off (at work) and haven't the time or energy to work on the car. If I'm not working on a weekend, then I'm usually resting to try to recover from the week. Shit has been miserable and I haven't had my go-to stress outlet of sliding that red car around town.

I'm going to try to find an hour to work on it tonight. About 30 more of those and she'll be back on the road!


Edit: recent pic [emoji52]https://uploads.tapatalk-cdn.com/20200714/750d3ed87c607037456060deda447ec3.jpg

[ZHPizza]

Good questions. It’s really only at lower speeds when I take my foot off the accelerator - particularly in first gear. I’m thinking it’s probably #1 more than #2.

Ok so probably not a sway bar bushing. Could be any other rubber bit back there (diff bushings, csb, rtabs, shock mounts, etc etc etc)

[28firefighter]

You nailed it - RTABs are shot and the left side completely fell out, so the rear trail arm is just resting on the chassis accounting for the noise. I'm obviously having them do both sides. They need to order parts, so will be fixed next week.

[Will]

You nailed it - RTABs are shot and the left side completely fell out, so the rear trail arm is just resting on the chassis accounting for the noise. I'm obviously having them do both sides. They need to order parts, so will be fixed next week.

Glad you found it!! Do you mind taking a few photos and sharing what it looks like?

Did you notice a "droop" or feel a "collapse" on that side? I had a RTAB fail - it pushed itself out of the hole in the arm somehow - and it felt like I had a flat tire where that corner just dropped an inch or so.

[28firefighter]

My shop took a few photos - I'll ask them for them when it goes back next week.

That appears to be exactly what happened, but it doesn't feel like what you describe - I'd say I get a "thunk" periodically on that side and just the creaking at low speeds as I approach a stop. Back maybe wanders a bit more, but I suspect it has been this way since I got the car 6 months ago.

[Will]

Since March 7 :(

I also thought I would have some extra time to work on it when Covid got here but the opposite happened. I've been working my ass off (at work) and haven't the time or energy to work on the car. If I'm not working on a weekend, then I'm usually resting to try to recover from the week. Shit has been miserable and I haven't had my go-to stress outlet of sliding that red car around town.

I'm going to try to find an hour to work on it tonight. About 30 more of those and she'll be back on the road!


Edit: recent pic [emoji52]https://uploads.tapatalk-cdn.com/20200714/750d3ed87c607037456060deda447ec3.jpg


Damn, I know that feeling of getting too busy and spending the free time to rest and do other activities than to work on the car ; it's a curse on the DIYer. Hope you muster up the motivation for it. Are you skipping the Vincebar or CMP bar and just going with X-brace instead? (also, pics aren't working for me).

Edit: photo shows now.

[ZHPizza]

lmao holy shit I bet that thing was allover the place

[ZHPizza]

Damn, I know that feeling of getting too busy and spending the free time to rest and do other activities than to work on the car ; it's a curse on the DIYer. Hope you muster up the motivation for it. Are you skipping the Vincebar or CMP bar and just going with X-brace instead? (also, pics aren't working for me).

Edit: photo shows now.

I would have gone with just the x brace if I hadn't already cut open the floor and made some brackets to attach the subframe mounts to the chassis rail (like the vincebar does). I fabricated them weeks ago and finally found a few hours tonight to install them with panel bond and an unnecessary amount of rivets. I also did an aluminum plate tying the floor and rails all together. It was really just a convoluted way to get the same result as the vincebar but will still allow me to install the x brace.

https://uploads.tapatalk-cdn.com/20200718/1653bee3a5b9b3106dd8101c9e68919b.jpghttps://uploads.tapatalk-cdn.com/20200718/9456b6ca8745feca96abd91ef90c76e3.jpghttps://uploads.tapatalk-cdn.com/20200718/9203bf9581e12cc561887ec7c8d948b4.jpghttps://uploads.tapatalk-cdn.com/20200718/25471eee6e45441f7968e09b520f6c7f.jpghttps://uploads.tapatalk-cdn.com/20200718/cd2a9de0e63a2db89fce6683f027b180.jpghttps://uploads.tapatalk-cdn.com/20200718/047c0d9b4d1357f437632c9aa2deec3d.jpg

[t.er]

unnecessary amount of rivets.

:eyetwitch what are we doing here, building airplanes?!

[ZHPizza]

:eyetwitch what are we doing here, building airplanes?!Lol I actually got a rivet spacing equation from an aircraft design book...I went with the minimum...

...And used massive headed rivets

It's obnoxious, but uhhh pretty strong

[johnrando]

Wow!

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[Will]

You nailed it - RTABs are shot and the left side completely fell out, so the rear trail arm is just resting on the chassis accounting for the noise. I'm obviously having them do both sides. They need to order parts, so will be fixed next week.

Glad the culprit was found, otherwise I'd feel real bad about derailing this thread.


I would have gone with just the x brace if I hadn't already cut open the floor and made some brackets to attach the subframe mounts to the chassis rail (like the vincebar does). I fabricated them weeks ago and finally found a few hours tonight to install them with panel bond and an unnecessary amount of rivets. I also did an aluminum plate tying the floor and rails all together. It was really just a convoluted way to get the same result as the vincebar but will still allow me to install the x brace.

...

https://uploads.tapatalk-cdn.com/20200718/047c0d9b4d1357f437632c9aa2deec3d.jpg

Wow, amazing. What's all that black stuff, POR15? Also, will you be writing it up? I'm fascinated with your approach to this problem. Did you have to do any welding?

I have too many questions. lol

[t.er]

Wow, amazing. What's all that black stuff, POR15?

My guess is structural adhesive, this man is building an airplane

[ZHPizza]

Wow, amazing. What's all that black stuff, POR15? Also, will you be writing it up? I'm fascinated with your approach to this problem. Did you have to do any welding?

I have too many questions. lol




My guess is structural adhesive, this man is building an airplane

Yep, 3M panel bond. That's why I sanded all of the mating surfaces before install - that stuff bonds hard to unprepped surfaces so I'm sure it's in there for good now.

I did no welding. The idea was based on Vince's epoxy kit, with a lot of design and fab on the fly as I went along. I'll try to post all this in my build thread so we can discuss it there instead of continuing the massive hijack here!

[28firefighter]

Good news: RTABs took care of the creaking. Car rides great.

Bad news: After an alignment, now have a DSC and Yellow Brake light illuminated. Was not on previous and car was never out of alignment. Did the alignment to make sure things were straight after the bushings. Drove it about 20 miles, tried taking the steering wheel lock to lock, nothing. So, back to the shop it’ll go.

[t.er]

Good news: RTABs took care of the creaking. Car rides great.

Bad news: After an alignment, now have a DSC and Yellow Brake light illuminated. Was not on previous and car was never out of alignment. Did the alignment to make sure things were straight after the bushings. Drove it about 20 miles, tried taking the steering wheel lock to lock, nothing. So, back to the shop it’ll go.

I wonder if it is the steering angle sensor requiring calibration. During my DIY alignment woes, that was something that I came across during my research

[28firefighter]

That was my thought too. I decided to order the Foxwell NT510 from amazon. I figure I need an OBD reader anyway and this will cost only a bit more than taking it to the shop for diagnosis.

[28firefighter]

And for what must be a first in BMW history, the light turned itself off this morning....go figure.

[ZHPizza]

lol probably the steering angle sensor. The foxwell should be able to pull/clear it.

[johnrando]

Good news.

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[Will]

Nice! Congrats.