Annoying rattle from the rear

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chris1984_99_99
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Annoying rattle from the rear

Post by chris1984_99_99 » Fri 05 Sep, 2014 14:29

Fortunately I am only talking about the car! Ive only ever been in 1 other Z3 so its difficult to compare, but there seems to be an awful lot of rattles from the back of my Z3, its very obvious when driving over an uneven road or surface, like something is very loose underneath the car. Ive had her up on ramps, had a look, infact any time im getting work done I always ask the guys to have a look for anything loose, but nobody has ever found anything obvious.

Im just wondering what other peoples cars are like and if they have ever come across any causes of annoying rattles?

Thanks in advance!
Chris
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Southernboy
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Re: Annoying rattle from the rear

Post by Southernboy » Fri 05 Sep, 2014 14:47

........ there has been chapters posted on the "rear rattle"...... and everything from handbrake components to stabilising ballast in the bumpers has been mooted...It's a PITA trying to isolate, and ultimately a process of elimination. Best advice is to do a topic search on the Z3 roadster pages... It'll short circuit having endless repeat guesses being logged here...again... :wink:
Perhaps it's time the mods added a "rattle in the rear" item to the knowledge base listing all the possible causes...that way anyone with your question can go directly to the list of items for checking... :roll:
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Cooper01
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Re: Annoying rattle from the rear

Post by Cooper01 » Fri 05 Sep, 2014 16:40

ditto to what southerboy says.... and pray that it isn't the return ball thingo in petrol tank. I saw a thread where a guy had to virtually pull the rear end of the car apart sourcing the problem. :D

Del
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Re: Annoying rattle from the rear

Post by Del » Fri 05 Sep, 2014 17:14

Rattles at the rear are not a usual/acceptable Z3 characteristic. As said already, there are several things it could be. Assuming it's not the exhaust, 2 common ones are firstly, the rear drop links can rattle when worn and secondly, the spring kit holding the rear handbrake shoes in position can become slack with age. On visual inspection the rubber bushes on worn/old droplinks will look old, perished and cracked.

An annoying rattle I also had was the complete corrosion of the metal exhaust bracket at the gearbox - but that tended to rattle in unison with the revs and one could detect it coming from the centre of the car.

The metal fuel tank straps can also make a noise if some of the padding between them and the tank falls out.

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Mouldy
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Re: Annoying rattle from the rear

Post by Mouldy » Fri 05 Sep, 2014 18:33

Many years ago when I first bought my Z3, I had a similar problem and eventually traced it to the handbrake. An easy way to establish whether you have the same problem is to pull the handbrake on enough to take up the slack in the cables whilst driving (and experiencing the rattling) and see if the noise stops.

If it does, you've found your problem, its simply a matter of adjusting the handbrake and if I remember correctly, there is a guide on how to do it by Mike Fishwick somewhere on the Forum.
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Beemer Man
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Re: Annoying rattle from the rear

Post by Beemer Man » Sun 07 Sep, 2014 22:43

My rear end rattle was traced to the fuel tank straps, where the pads had moved almost to the point of falling out. Fortunately a simple fix to loosen two bolts and re-position the pads.

Beemer Man

Hoppo1979
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Re: Annoying rattle from the rear

Post by Hoppo1979 » Sun 16 Nov, 2014 20:40

Hi everyone, I recently bought a Z3 3.0 Sport, and it has a rattle from the back end. It sounds like you haven't shut a door properly and happens over shuddery services. So far I have;

Replaced rear shocks and top mounts
Checked exhaust
Stripped boot completely (tools etc)
Removed spare wheel
Driven covering brakes and handbrake when it occurs to eliminate rattles from pads

I used to work at a BMW dealer and a mate who is a master tech spent an hour and a half on it to no avail. All bushes etc look fine.

Any ideas?

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Southernboy
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Re: Annoying rattle from the rear

Post by Southernboy » Sun 16 Nov, 2014 20:47

Did you check the weights in the rear bumper ?
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Del
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Re: Annoying rattle from the rear

Post by Del » Sun 16 Nov, 2014 22:46

Two possibilities:-
1) Rear droplinks
2) The spring kit holding the rear handbrake shoes in place can become weak/stretched (with age) and allow the shoes to rattle.
EDIT - just noticed I've duplicated my post above :oops:

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Re: Annoying rattle from the rear

Post by Joycey » Mon 17 Nov, 2014 08:01

Once i had put my car back together after removing my fuel tank i had a similar rattle develop only over uneven surfaces.

After hours of tapping things with a rubber mallet i found it to be the anti-vibration clips that hold the rear callipers in place, they had lost their elasticity. Also while you’re under the rear put your arm up behind the bumper and wobble the counter weights and see if they rattle.

Lee
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Hoppo1979
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Re: Annoying rattle from the rear

Post by Hoppo1979 » Tue 18 Nov, 2014 16:26

Guys thanks for the responses. Weights in rear bumper? That sounds a possibility! I checked the bolts that hold the bumper carrier in place were tight when I cleared the boot out, but I was unaware there are weights in the bumper. Could someone give me a bit more insight into where to find the weights and check them?

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Southernboy
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Re: Annoying rattle from the rear

Post by Southernboy » Tue 18 Nov, 2014 17:15

They're on the corners inside the bumper proper...you can reach in there if you get under the car a bit... :wink:
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Hoppo1979
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Re: Annoying rattle from the rear

Post by Hoppo1979 » Wed 19 Nov, 2014 09:23

Southernboy wrote:They're on the corners inside the bumper proper...you can reach in there if you get under the car a bit... :wink:
That has to be the noise! It's like somebody tapping a hammer in the boot. I was at the point of thinking something had been dropped in a panel and was rattling around. I've googled it and the rear bumper is coming off at the weekend.

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Southernboy
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Re: Annoying rattle from the rear

Post by Southernboy » Wed 19 Nov, 2014 09:33

.... I hope it is the problem for your sake...good luck! :wink:
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Hoppo1979
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Re: Annoying rattle from the rear

Post by Hoppo1979 » Thu 20 Nov, 2014 15:10

Southernboy wrote:.... I hope it is the problem for your sake...good luck! :wink:
Thats it!! Got it on ramps on the drive and put my hand up to the bumper shocker, the heavy weight thing is all loose!!! Hopefully I can sort it without the bumper coming off but thats definately it! Thanks guys! Great help! It was driving me mad! :)

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Southernboy
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Re: Annoying rattle from the rear

Post by Southernboy » Thu 20 Nov, 2014 15:21

Another relieved Z driver..... :wave
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Hoppo1979
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Re: Annoying rattle from the rear

Post by Hoppo1979 » Sat 22 Nov, 2014 15:46

Ok guys thought an update would help. I removed the rear bumper, and the passenger side bumper weight had collapsed! It was rattling around in the bumper carrier and at over a stone (8.2kg) in weight there's no wonder I thought the rear end was collapsing!

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I purchased 2 new units from BMW at £90 each, I was not happy removing such a large amount of weight, in my opinion it's there for a reason. Anyway I can now report the rattle is cured and it's transformed the drive of the car. Thanks to everyone for the advice.

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TomH84
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Re: Annoying rattle from the rear

Post by TomH84 » Sat 22 Nov, 2014 18:34

Thanks for sharing this. I've got a similar rattle to that you describe. Thought it was the drop links, but they seem ok. Hopefully, I might now have cracked it too :squeeze:
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Gareth 161
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Re: Annoying rattle from the rear

Post by Gareth 161 » Sat 22 Nov, 2014 19:58

What exactly do these weights due as it would just seem to add extra weight?
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gookah
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Re: Annoying rattle from the rear

Post by gookah » Sat 22 Nov, 2014 22:30

along with the battery in the boot it helps the 50/50 weight balance of the car.
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Re: Annoying rattle from the rear

Post by Dino D » Sat 22 Nov, 2014 22:54

I've hot to say I'm pretty shocked to see this ridiculous idea of weights hanging out there.

If they needed more weight they should have just fitted a bigger fuel tank.
Or a proper spare.
Or a stronger rear floor and diff mounts!!
Or lightened the front.

Just hanging weights off the back just seems lazy and not what you'd expect from BMW. Seems more like an idea a backstreet garage would come up with.

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Re: Annoying rattle from the rear

Post by gookah » Sat 22 Nov, 2014 23:12

Dino D wrote:I've hot to say I'm pretty shocked to see this ridiculous idea of weights hanging out there.

If they needed more weight they should have just fitted a bigger fuel tank.
Or a proper spare.
Or a stronger rear floor and diff mounts!!
Or lightened the front.

Just hanging weights off the back just seems lazy and not what you'd expect from BMW. Seems more like an idea a backstreet garage would come up with.
I suppose the reasoning was as follows
The car is balanced around a half full tank. Bigger tank would have more imbalance between full and empty.
Proper spare would impact on the already small boot.
Stronger floor was never designed but was needed in hindsight, however it would have had to be even heavier than putting weights at the extremities
Front end is not easy to lighten without altering the shape of the car or compromising rigidity and safety.
Hanging two weights in there gives a better balance and is probably what helps make the car fun to drive.

I dare say designers are not altogether daft.... :D
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Re: Annoying rattle from the rear

Post by Del » Sat 22 Nov, 2014 23:16

Realoem just refers to them as left and right "vibration absorbers" part numbers 5112839319 & 320 :shrug

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Southernboy
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Re: Annoying rattle from the rear

Post by Southernboy » Sun 23 Nov, 2014 06:52

It is more to keep the rear wheels on the road...M cars used to have the rear axle carrier filled with "steel gravel" for the same reason... :wink:
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Re: Annoying rattle from the rear

Post by Hoppo1979 » Sun 23 Nov, 2014 10:20

Since southern boy alerted me to the presence of these weights I did a lot of research, they are apparently there to try and counter "scuttle shake" that convertibles can suffer from. The Z3 Coupes don't have these weights, and if they were simply there for weight distribution they wouldn't have gone to the trouble of mounting them on rubber mounts that move.

My rattle sounded like I'd not shut a door properly (but coming from the back end) it was very loud and prominent over shuddery services and not over speed bumps.

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Brian H
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Re: Annoying rattle from the rear

Post by Brian H » Sun 23 Nov, 2014 10:26

^^ good info Hoppo :)

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Re: Annoying rattle from the rear

Post by Dino D » Sat 06 Dec, 2014 08:41

Thanks for that info Hoppo.
Make sense that they act as counters when you feel how they move. Ingenious way to disguise vibrations rather than get rid of it...

I was hoping this might be the source my annoying rattle.

I got one side of the bumper partially off (the t50 bolt by the exhaust side is corroded tight and getting it at properly means moving the exhaust off the hangers).
I could see and move the weight around with my hand - whilst if moved if did not make any rattles just a dull thump if I moved it enough to hit the stops. Not anything like the metallic rattle sound so I think I can rule these out. A shame as it's an easy fix...

Suspension and bushes all been checked so off to look again at the 'rear end rattle thread' for more exotic ideas...

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Southernboy
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Re: Annoying rattle from the rear

Post by Southernboy » Sat 06 Dec, 2014 08:50

Have you removed the rear wheel and drum then look at the 2 mounting bolts inside the rear drum at the very bottom (No10's - I think) They secure the small plate into which the bottom end of the shoes and cable lodge. I had the rattle and traced it to the bolts there on the passenger side. One was very loose and the other was just loose......item 4 in the diagram in the link.
http://www.realoem.com/bmw/diagrams/p/q/38.png
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Hoppo1979
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Re: Annoying rattle from the rear

Post by Hoppo1979 » Sat 06 Dec, 2014 09:22

Dino D wrote:Thanks for that info Hoppo.
Make sense that they act as counters when you feel how they move. Ingenious way to disguise vibrations rather than get rid of it...

I was hoping this might be the source my annoying rattle.

I got one side of the bumper partially off (the t50 bolt by the exhaust side is corroded tight and getting it at properly means moving the exhaust off the hangers).
I could see and move the weight around with my hand - whilst if moved if did not make any rattles just a dull thump if I moved it enough to hit the stops. Not anything like the metallic rattle sound so I think I can rule these out. A shame as it's an easy fix...

Suspension and bushes all been checked so off to look again at the 'rear end rattle thread' for more exotic ideas...

Depends how much you can move the weight, yes they swing side to side but try shaking them up and down. They should hardly move up and down. That's when they clank against the bumper carrier.

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Re: Annoying rattle from the rear

Post by Alan W » Sat 06 Dec, 2014 09:25

As Barry says above, not sure if you've eliminated this but I found it to be the culprit of the rear end rattle on my car

Tell tale sign is if you drive along and pull up the handbrake slightly the noise disappears

Video clip of noise: https://www.youtube.com/watch?v=9KaEQWn6vOo

Other common rear end rattle causes are rear drop links, shock absorber mounts and fuel tank straps

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johnz3
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Re: Annoying rattle from the rear

Post by johnz3 » Sat 06 Dec, 2014 10:26

Just a suggestion but what about the adjustment of the two 'nuts' at the handbreak.

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Re: Annoying rattle from the rear

Post by Dino D » Sat 06 Dec, 2014 14:00

@hoppo, Yes I'm not getting any UK down movement just side to side as meant to be.
I shook the around a lot really hoping it would rattle but just a dull this if they go fully side to side.

So off to the next jobs (well telling my mechanic anyway!) as listed above here and on the other threads. Plenty to look for but now my suspension has been checked it is narrowed to handbrake or fuel tank straps I think.

Thanks for all the info guys.

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Re: Annoying rattle from the rear

Post by Dino D » Sun 15 Mar, 2015 22:57

Just to update that my rattle was the diff mount bush, totally worn out so the bolt was rattling around.

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