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Discussion Starter #1
I just bought my 840 a week ago and it has been great to drive. However about 3 days ago I started hearing a knocking sound when pressing the accelerator. It sounds like it is coming from the rear and I am thinking it is drive shaft related. Now I am also getting vibration coming through the car even at 30mph. Am I right in thinking it is drive shaft related and how easy is it to get parts if it is an issue with the drive shaft?
 

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Prop shaft bearings can cause what you are describing.
 

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.....in particular the rear CV joint which often fails on a car that has not been used for a while. The distinctive behaviour for driveshaft problems is that the noise gets louder the harder you press the throttle and the noise goes away once you reach 40 MPH. Driveshaft complaints also encompass the centre-bearing housing - this routine below shows the usual suspects:

http://www.meeknet.co.uk/e38/e38_remove_propshaft.pdf
 

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Discussion Starter #4
The noise typically goes away when I am about 40mph but I did experience some vibration at 60mph. The car has done about 300 miles in the last 3 years and it was not in use for a long time. The knocking gets louder and faster as I accelerate and then stops when I either reach about 40mph or take my foot off the accelerator.
 

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That sounds like the rear CV joint, but as the exhaust has to be removed to do the job then guibo and the centre bearing and bearing housing might as well be replaced at the same time as the parts are reasonably cheap.

RealOEM.com - Online BMW Parts Catalog

Centre bearing and housing = part 6
Rear CV joint = 13
Guibo = 2
 

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Discussion Starter #6
So I had the car up on a lift and the mechanic reckons it's the CV joint as expected. While the car was up on the lift I had a look at the guibo and half shafts and everything looks and feels ok. The knocking noise is now gone and now I am getting a constant vibration at any speed with the throttle pressed, so I guess it's getting worse. Can anyone recommend where I can buy a CV joint online?

Thanks
 

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That's what CV joints do - sometimes they mend themselves for ages - the one on my 740i mended itself for absolutely months - the one on my 840ci nearly shook the car to bits trying to get it to the garage.

Try James Aston at Cotswold BMW:

[email protected]

Email him with the part number and he will give you a quote - and delivered to your door
 

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Discussion Starter #8
That's what CV joints do - sometimes they mend themselves for ages - the one on my 740i mended itself for absolutely months - the one on my 840ci nearly shook the car to bits trying to get it to the garage.

Try James Aston at Cotswold BMW:

[email protected]

Email him with the part number and he will give you a quote - and delivered to your door
I ordered the CV joint from Cotswold BMW and it was delivered in just a couple of days.Hopefully Iwill get it fitted next week.

Thanks for the info Timm.
 

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I ordered the CV joint from Cotswold BMW and it was delivered in just a couple of days.Hopefully Iwill get it fitted next week.

Thanks for the info Timm.

Hi Amo,

Having the same issue as you described (4 years ago), did changing this CV Joint fix this?

Thanks
 

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Discussion Starter #10
Hi Amo,

Having the same issue as you described (4 years ago), did changing this CV Joint fix this?

Thanks
Hi,
Yes, it was the CV joint on the prop shaft. The bearings were rusted and completely dry. My mechanic showed it to me after removing it. It was in poor condition. I haven't had any problem since.
 

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Hi,
Yes, it was the CV joint on the prop shaft. The bearings were rusted and completely dry. My mechanic showed it to me after removing it. It was in poor condition. I haven't had any problem since.
Thanks for replying.

Going to get mine done ASAP. Vibration whilst driving makes me go insane!
 

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Discussion Starter #12
Thanks for replying.

Going to get mine done ASAP. Vibration whilst driving makes me go insane!
It is annoying. Mine got to the point that the rear view mirror was a blur and it felt like the floor was going to fall out due to the vibration.
 

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It is annoying. Mine got to the point that the rear view mirror was a blur and it felt like the floor was going to fall out due to the vibration.
Annoying is an understatement!

Steering issues (tracking and alignment) and vibration are literally hell for me.

Both of which my car has. Still love the thing to bits though!
 
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