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View Full Version : Anyone agree with my theory on rear noises...



e34.535i.sport
09-27-2007, 05:12 PM
Ok, this is my last try to diagnose the terrible noise i have coming from the rear before i take it to a shop (which i really don't want to do!).

The noise i have is a knocking over rough surfaces...it seems to have got worse, and i found today that i can reproduce it when i turn the wheel from side to side when driving in a straight line. This makes me think its the pitman arms (which i have recently replaced (200mile i think), but i can't see how i could have fitted these incorrectly? It sounds as though its from the general area of the pitmans too. But i was also thinking the trailing arm bushes, but they 'look' ok.

I also have a very loud and scary noise that sounds like one of those chinese gongs when i go on and off one of those big black speedpumps... It sounds high, like near the rear parcel shelf so i'm guessing the shock mounts? The shocks seem to be fine, no strange ride issues, pretty even on both sides and when i bounce it with my hands it react as i'd expect.

The car sounds like an old banger at the moment and its really embarrassing. The loud gong noise is also very worrying it makes me think the shock will pop through the bodywork!

Any thoughts?

bmwrp8
09-28-2007, 12:33 AM
i saw in an old post before the same issue that you have. it has a crack in the shock mount area...just take out your rear seats and probably the headboard and take a look... inspect for cracks

e34.535i.sport
09-28-2007, 08:12 AM
I was under the impression you accessed it through the boot... I looked but the board behind the seat was well secured so i didn't want to mess too much. I'll be inspecting that tonight, dreading changing them but i was dreading the brakes when i done them and that wasn't a big deal... Famous last words.

leicesterboy15
09-28-2007, 08:23 AM
My friends e30 had the same kind of noise, it was scary, I thought it was going to come through the bodywork as well!

Turned out to be the rear shock mounts. The bentley manual also says you access it by removing the rear seat, do you have a copy? I can send you one if you don't.

Robin-535im
09-28-2007, 08:43 AM
I was under the impression you accessed it through the boot... I looked but the board behind the seat was well secured so i didn't want to mess too much. I'll be inspecting that tonight, dreading changing them but i was dreading the brakes when i done them and that wasn't a big deal... Famous last words.

Just pull off the bottom of the rear seat, then unfasten the plastic nuts and the bottom of the upright part and it should pull out. Then you can sneak in under the rear parcel shelf and inspect the top of the shock mount.

Rear subframe bushings also can clunk when the direction of torque on the drive train changes, like letting off the gas abruptly. You can pull off the cover plate on the underside of the car with 2, 13mm nuts and one 22mm (?) and inspect that visually. Otherwise I would suggest backing up on ramps, giving the underside a good cleaning and wiggling things / prying things to see if there is any excess movement of signs of wear.

e34.535i.sport
09-28-2007, 11:50 AM
My friends e30 had the same kind of noise, it was scary, I thought it was going to come through the bodywork as well!

Turned out to be the rear shock mounts. The bentley manual also says you access it by removing the rear seat, do you have a copy? I can send you one if you don't.

Hey thanks, i'd really appreciate it if you could send me a copy I only have a haynes manual (sh*te i know)! Should i PM you with my email? Thanks again!!!

e34.535i.sport
09-28-2007, 11:57 AM
Hey guys i've just took the seat off thanks for the advice, and took the top rubbery covers off (the spherical ones are a b*tch to get off!), and found something suspicious...

On the left hand side one it seems to be well off alignment and this is the side thats making all kinds of noises (although they do sound closer to the floor - could be related?). I don't know much about the shock mounts but theres the plate where the three nuts are, and then a gap and then a big washer and then a gap and another big washer then a nut. The washers are not aligned on top of each other but at an angle - whereas on the right side the washers are all on top of each other straight up in a line. I'm guessing this is a bad thing? What should i do?!!!!! Any more help/advice/links seriously appreciated.

whiskychaser
09-28-2007, 01:16 PM
Any more help/advice/links seriously appreciated.
Maybe you could get the mobile phone camera working and post a pic? I wouldnt know if it was right or wrong but I'm sure someone will. Take up Robin's suggestion and check the subframe bushes too. Mine are fkd and this is how I checked them: in gear and handbrake off. Grab hold of a back tyre and rotate it forwards. When all the slack is taken up with a jolt watch the front of the trailing arm. If it dips noticeably they are probably toast. Try rotating the tyre backwards to be sure-the front of the arm will probably go up!
Safety tips:1. dont do this on a hill 2. Dont put your head near the wheels even if you are curious 3. always have a mate that can phone 999 standing by

e34.535i.sport
09-28-2007, 01:52 PM
Sorry Robin i meant to reply earlier, been rushing around a bit tonight... I changed the rear sub bushes myself about 4 thousand miles ago because of a similar (yet less frequent noise). They were TOAST! I checked the new ones again recently because i thought i might have ripped them out by driving a bit too sprightly one day when i managed to loose my cool. However they look fine and i replaced the four little bolts and the two big nuts while i was there and cleaned the plate and sprayed it with and undercarriage protector.

Thanks Whisky (could just go for a JD right now!), i'm hoping there's someone experienced in the art of shocks/mounts as it looks grim on the passenger side (RHD) who can give me some more hints/tips.

leicesterboy15
09-29-2007, 04:19 PM
I can send you a copy if you like but its 44 meg, not sure how email would handle it. You can download a really useful cd from this link (use the one on the 2nd page), it has the manual plus loads of other useful stuff:

http://www.bimmer.info/forum/showthread.php?t=32324&highlight=bentley+download

You can download just the manual from here (2nd link is better - searchable):

http://www.bimmer.info/forum/showthread.php?t=31447&highlight=bentley+download

Its a really useful bit of kit. BTW thanks for the advice on the tie rods, did them today, will get the alignment done tomorrow.

e34.535i.sport
09-30-2007, 03:34 AM
I can send you a copy if you like but its 44 meg, not sure how email would handle it. You can download a really useful cd from this link (use the one on the 2nd page), it has the manual plus loads of other useful stuff:

http://www.bimmer.info/forum/showthread.php?t=32324&highlight=bentley+download

You can download just the manual from here (2nd link is better - searchable):

http://www.bimmer.info/forum/showthread.php?t=31447&highlight=bentley+download

Its a really useful bit of kit. BTW thanks for the advice on the tie rods, did them today, will get the alignment done tomorrow.

Hey no problem, glad the tie rods went well, and cheers for the links!!!! I'll check them out today.

I got your metal hub rings, but didn't make the post office because the guy that sells them isn't a morning person. By the time he opens up shop everyone else is shutting theirs!!! Will get them sent Monday for you if all goes to plan, if not Tues. Put mine on yesterday, they felt a lot better than the plastic ones as soon as i went to put the wheel back on. Can't wait to test them out but taking the shock off today to see whats happening with that!

It never ends!!!!

e34.535i.sport
09-30-2007, 03:36 AM
Hey there i'm not that technicalogically advanced at the moment having some phone issues too! Gonna tak the shock off today and charge the digi up... Thanks!

leicesterboy15
09-30-2007, 03:40 PM
Thanks for the rings man, really appreciated as discussed on PM! Don't worry about posting, whenever you get time and whenever its convenient! Thanks again.

e34.535i.sport
09-30-2007, 04:04 PM
Don't mention it. Thanks for the Bentley link by the way, haven't managed to download it yet but my connection can have its moments. Glad to hear the tie rods went well! I done the half on half off nut trick today with the thrust arm ball joint... It resisted arrest for a while but i took it down in the end!

e34.535i.sport
10-01-2007, 02:27 AM
I don't want to jinks this but after doing a bit of work on the front of the car yesterday (thrust arm replacement/tightening up of the sway bar link nuts), all noises seem to have stopped? I can't figure out what i could have done to stop the noise from the rear... ALso, after jacking the corner up with the angled strut, it seems to have corrected itself? I have been taking it very easy over speed bumps since then obviously!

Its a strange one, but i'll keep listening... THanks for the help so far, i hope this one's over!