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Sounds From the Rear: Explained

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315K views 441 replies 134 participants last post by  GermanAutobahn 
#1 ·
I think I've gone through pretty much all of the problems you can have with the rear end of the car that will make distinctive noises, so I'm going to lay some of them out for anyone who has problems in the future.

I'll start with the most severe:

My car sounds like...

...a helicopter:
Pull over now!!! The most probable cause of the sound is one or several loose lugs. Stop the car, bust out the BMW tool kit (the tire iron is actually over on the battery cover) and tighten all of the offending lugs. While you're at it, go ahead and check all of the rest of the lugs too. If the lugs work their way out far enough, the sound will get worse and the shaking will pick up. Eventually the lugs will snap and you'll note you'll be riding a bit lower on that side. By then, it's generally a bit too late - your car's on the ground.

...it has metal scraping around in back:
It might be that the rear shock mount (RSM) has failed. This failure, however might not have occurred at the shock mount itself, unfortunately. The metal scraping and knocking could mean the failure occurred at the frame mount. This is going to require some metal work to fix. Plan on spending a good amount on fixing it.
To prevent this, upgrade your shock mounts and re-enforce them! Re-enforcement plates are available at BavAuto, among other BMW parts shops.

...there's a slight knocking or squeak in back:
As mentioned above, there is probably a problem with the RSM. A knock means that the RSM has probably failed and the upper mount of the shock is just knocking around freely. Squeaking generally only occurs when the roads are wet, but can occur at other times, and generally means the same thing. Both the knocking and squeaking should co-incide with suspension actions, such as driving over bumps, or rough roads. This problem isn't as urgent as the above-mentioned, but since the mount has failed, it's possible that moisture can now get into the car, which can cause other problems. Get new rear shock mounts. Meyle makes a heavy-duty RSM that resists push through failures (most common type), yet retains the stock feel, unlike many of the urethane upgrades. If you're going performance, now is a good time to upgrade to urethane. When you replace the shock mounts, don't forget to buy a re-enforcement plate! Replacement RSMs are available at most all BMW part shops, and re-enforcement plates can be found at BavAuto, and maybe Pelican.

...it's running on off-road tires:
This is most likely a failure of the rear wheel bearing (RWB). The rear wheel bearing failure's sound can range from a grumble, to a growl, to a roar. When it gets bad, it will sound like you're riding in a Jeep with huge off-road tires. The sound will follow your car's speed, not the engine RPM. Generally, as you get faster, the sound gets louder. This is not always the case, however, as sometimes there is a point at which the sound will die down some. To check the speed correlation, bring the car up to highway speed and press the clutch pedal (if you're an AT, put the car in N - this is illegal in many states, so watch yourself) to let the engine spool down to idle, while your speed remains relatively high. If the sound remains strong, it's most likely the bearing. If the sound dies with the engine RPM, you've got something else wrong.
RWB fixes are nasty! They aren't super-urgent, but be aware that if the bearing finally fails completely and locks, you're not going to be getting anywhere very quickly and you'll probably need to replace the tire that just got dragged until you stopped. I drove on mine for a while before I replaced it; some 4,000mi, I think. That's not the smartest option, but I needed to save up for the parts and tool.

DIY GUYS: This fix is time-consuming and expensive! The tool to remove and press the bearings is around $250 itself. The bearings are around $30 each. If you have a while (and the patience!!) to do this job, this is your best option. You can do both bearings on the rear axle for the price of what most garages charge for one. Expect hang-ups if your car has not had much service in the rear. Frozen bolts, hubs and rotors all slow progress and are a general pain. Once you get it done, however, your car will sound like new again. The tool and parts are available at Pelican Parts (they have the best prices on this job, believe you me!).
You will need:
2 RWBs, 2 Circlips, 2 New Rotor Screws (one-use part, don't re-use the old one!) and the bearing press. A Bentley Manual is an absolute must! If you don't have one, PM me and I'll send you my write-up with alternatives, should one of the options not work.

NON-DIY GUYS: This fix is expensive! Expect the shop to charge around $300-350 (that's at independent shops). It will be a bit less on the second bearing if you're getting both done. BE AWARE that some BMW specialty shops may try and screw you. One BMW shop that I trusted quoted me at 7 hours of labour, plus over-priced parts, so watch yourself. I could've gotten the job done in 1 hour a side if I had a lift and shop tools. Seven is about what it took me in the end with socket wrenches, jack stands and a rubber mallet.

...it's hissing:
First, check and make sure you don't have a hole in your tires. If that's not the case, and it sounds more sandpaper-ish than high-pressure air, then it's probably something rubbing. More specifically, the brake rotor shields. If it's very light-sounding, it's probably fine. If it's more gouging or metallic-sounding, you should probably try to re-bend the shield so it's not rubbing so intensely. The best bet, however is just getting them replaced. The shields themselves are not too expensive, but the job is similar to the rear wheel bearing job, as the rotor will need to be removed and the hub will need to be pressed off to get to the brake shield. I haven't gotten a quote from a shop, but I'd expect labour to be the main cost in this fix.

I hope this clears up some of your sound worries. Good luck with the fixes!
 
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#72 ·
Rear end noise

I'm going under today to find out if my noise is my rebuilt M3 LSD or wheel bearings. 175K miles on the car. I don't know how long wheel bearings tend to last, and I don't know if the bearings where changed when the diff was rebuilt. (bought off ebay or craigslist) Any comments?:dunno:
 
#73 ·
I´ve got a noise coming from the rear (of E46, not E36, but that´s not important I guess) after my brother hit a curb (must have been on very low speed, judging by the place where it happened, and I beleve it was, as he is driving carefully, just don´t understand how could he accelerate while going around a corner) with left rear wheel. The wheel was a little bit deformed, changed that but there is still some noise that is coming most (not always, however) of the time. It depends on the speed- the faster I go, the "faster" is the sound. It´s like rrrrRRrrrRRrrrrRRrrrrRRR (RR being louder :) ). I can´t really hear it on highway, but I think that´s becuase the soudn is "too fast" but it´s still there. It´s the rear wheel bearing I suppose, right?
Thanks
 
#77 ·
Rear end noise not covered yet...Large clunk when making sharp turns!

My 1994 e36 325iC has a brand new Bilstein sport suspension all the way around and Eibach Sportline springs with new front and rear shock mounts. It has develope (and continues to worsen) a "thunk" that can be quite loud at times when turning hard right or left and sometimes when turning while backing out of parking spaces. Check all of bushings nothing seems bad. Any ideas....it is irking me greatly.
 
#78 ·
.there's a slight knocking or squeak in back:
As mentioned above, there is probably a problem with the RSM. A knock means that the RSM has probably failed and the upper mount of the shock is just knocking around freely. Squeaking generally only occurs when the roads are wet, but can occur at other times, and generally means the same thing. Both the knocking and squeaking should co-incide with suspension actions, such as driving over bumps, or rough roads. This problem isn't as urgent as the above-mentioned, but since the mount has failed, it's possible that moisture can now get into the car, which can cause other problems. Get new rear shock mounts. Meyle makes a heavy-duty RSM that resists push through failures (most common type), yet retains the stock feel, unlike many of the urethane upgrades. If you're going performance, now is a good time to upgrade to urethane. When you replace the shock mounts, don't forget to buy a re-enforcement plate! Replacement RSMs are available at most all BMW part shops, and re-enforcement plates can be found at BavAuto, and maybe Pelican.



^Check them anyways. New parts aren't necessarily always perfect
 
#84 ·
Thanks for this thread OP. Had an increasing rumble at the back - thought it was wheel bearings, sounded likely after reading this and confirmed at $250 a side, but all great now. Did think about tackling it myself but after watching a trained BMW mech struggle for 3 hours I am so glad I didn't! :yikes:
 
#85 ·
Hello. I have 2 irritating noises coming from my rear. The first one sounds like a proppeller airplane landing when I down shift to my second gear and the noise goes with my RPM, not speed. Could this be coming from my diff or from my tranny? Second, I have a constant squeak that goes with the car's speed. I was told it could be my rear e-brake pads which kinda makes sense since I have to pull my e-brake up to the max or else it will roll. Please help!! Wanna fix all this before bimmerfest.
 
#86 ·
The propeller sound is more than likely your center carrier bearing, the mount fails, and it hits the tunnel in the center of the car. I had to replace mine right after I got my car. Check out Eight Thirty's guibo thread, as you will need to do the two of them together. The squeak seems like it could be the wheel bearing, they tend to fail fairly regurally with these cars. There are a lot of DIY's out there where you can replace the wheel bearing without a bearing puller, just search on google. Good luck, keep us posted!
 
#88 ·
The center bearing is hidden behind some of the shielding around the exhaust system, half way between the transmission and the rear drive. For a good view check out your car on realoem.com or pelicanparts. You can key in the last 7 characters of your vin to id your vehicle.
 
#89 ·
The parts for the driveshaft would be less than $100 dollars, then figure about 2-3 hours for labor. The wheel bearings are about 3 hours I think, and i'm not sure about price for parts.
 
#92 ·
hell everyone.. heres my problem. i have a weird knocking noise coming from the rear wen accelerating on first gear, only sometimes. it almost sounds like im running over those small reflectors that the city puts on the road to indicate the road lines at night..also im hearing that squeeking coming from my shock towers starting hearing them right after i installed my new shocks . guess there mad old already or didnt tighten them by hand tight enuff, cus i remember using the air gun on one but the other i did by hand and a vise grip..
 
#95 ·
I think the z3 1997 convertible id the same as the e36 right?
I have a really bad metal grinding sound comimng from my rear and i cant even go more then ten feet forwards or backwards without it getting really loud almost stopping the car somehow almost even propelling the car in reverse after going forwards it sounds very loud and happens suddenly i had to get the car towed home any ideas anyone i have no idea and dont think i can afford to get it fixed right now and i love the thing to death
 
#97 ·
I have the same symptoms as the "slight knocking or squeak in back" description. However, when I brought it to my mechanic, he said that I needed new shocks. Is there any way to tell for sure, or should I just replace the shock mount myself and see if it works?
 
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