Unwanted rumble

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jjorj
Joined: Fri 27 Nov, 2009 21:06
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  Z1 roadster
Location: Canterbury

Unwanted rumble

Post by jjorj » Thu 07 Jun, 2018 11:47

Hi,
On the way to the tour we noticed a rumble from the rear of the car. It seemed to reduce on left hand bend but otherwise built with speed and didn't seem related to engine or gears. I put it down to the new OE exhaust I had fitted just before touching something but having got it on my ramp at the surgery it appears it doesn't touch. There is adjustment and it could be that at speed the downward pressure makes it touch on the rear bumper plastic and vibrate but when I jack the car up and run it it seems the noise is from the prop shaft area. It looks difficult to access as it runs through an enclosed space?
Questions, are there bearings inside, could it be UJs or the rubber equivalent? I this a known problem?
Any ideas welcome and anyone who can suggest someone in the UK to look and deal with it?

I may just raise the exhaust a bit and try it to rule out my initial idea first though.

Regards, George

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Southernboy
Joined: Thu 07 Oct, 2010 13:39
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  Z3 roadster 3.0i
Location: Johannesburg

Re: Unwanted rumble

Post by Southernboy » Thu 07 Jun, 2018 17:25

The propshaft has 2 universal joints which are not renewable. ie. they don't have circlips to remove the + inner piece. There is a rubber dampener at the front end between the propshaft and the gearbox output flange, and finally there is a center bearing just aft of the front end of the rear section of the propshaft. There is also a locking nut which locks the front and rear sections of the propshaft where they join via a splined shaft.
Universal joints eventually wear and if they have worn excessively they can create a vibration.
There is a company here in Johannesburg that undertakes to machine out the "sealed" OEM fitting and convert the joint to accept the conventional fitting with circlips. It is fairly effective, but they don't guarantee any durability.
The center bearing is held by two bolts which screw into the underside of the floor pan into fixed nuts. The bearing can collapse and guaranteed you will have vibration.
The rubber dampener at the gearbox end will eventually crack and deteriorate. This will also cause a vibration.
And if the lock nut between the front and rear sections of the propshaft is loose, this may also allow movement causing vibration.
That's the propshat... then you have two drive axles from the differential with rubber boots and inside those boots a re universal joints. The boots hold grease to lubricate those universals. Some years ago I had a "one sided" vibration which turned out to be a "dry" universal"
The boots are held at the ends by clips. Easily removed and a common zip tie is as good a replacement clip. You will need to pump some suitable axle grease into the boot by removing one of the boot clips to allow access for the grease to be pumped in. It is important to note that the amount of grease is surprisingly little, and there is a specification somewhere for the actual volume to be used. I think Bentleys manual has the info under rear drive shaft servicing / replacement etc etc. Anyhow, my problem of the "rumble vibration" was sorted by putting grease into both boots.
Hope this gives you some insights in where to look...
BTW... access to the propshaft is easy - remove the exhaust and sensors from the exhaust, remove the center heat shield and there she is...
"Normal is overrated"
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felix
Joined: Sat 02 Jul, 2005 17:25
Posts: 553

  Z1 roadster

Re: Unwanted rumble

Post by felix » Thu 07 Jun, 2018 19:50

Southernboy wrote:
Thu 07 Jun, 2018 17:25
The propshaft has 2 universal joints which are not renewable. ie. they don't have circlips to remove the + inner piece. There is a rubber dampener at the front end between the propshaft and the gearbox output flange, and finally there is a center bearing just aft of the front end of the rear section of the propshaft. There is also a locking nut which locks the front and rear sections of the propshaft where they join via a splined shaft.
Universal joints eventually wear and if they have worn excessively they can create a vibration.
There is a company here in Johannesburg that undertakes to machine out the "sealed" OEM fitting and convert the joint to accept the conventional fitting with circlips. It is fairly effective, but they don't guarantee any durability.
The center bearing is held by two bolts which screw into the underside of the floor pan into fixed nuts. The bearing can collapse and guaranteed you will have vibration.
The rubber dampener at the gearbox end will eventually crack and deteriorate. This will also cause a vibration.
And if the lock nut between the front and rear sections of the propshaft is loose, this may also allow movement causing vibration.
That's the propshat... then you have two drive axles from the differential with rubber boots and inside those boots a re universal joints. The boots hold grease to lubricate those universals. Some years ago I had a "one sided" vibration which turned out to be a "dry" universal"
The boots are held at the ends by clips. Easily removed and a common zip tie is as good a replacement clip. You will need to pump some suitable axle grease into the boot by removing one of the boot clips to allow access for the grease to be pumped in. It is important to note that the amount of grease is surprisingly little, and there is a specification somewhere for the actual volume to be used. I think Bentleys manual has the info under rear drive shaft servicing / replacement etc etc. Anyhow, my problem of the "rumble vibration" was sorted by putting grease into both boots.
Hope this gives you some insights in where to look...
BTW... access to the propshaft is easy - remove the exhaust and sensors from the exhaust, remove the center heat shield and there she is...
The OP is posting about a Z1...

felix
Joined: Sat 02 Jul, 2005 17:25
Posts: 553

  Z1 roadster

Re: Unwanted rumble

Post by felix » Thu 07 Jun, 2018 19:55

If it changes in volume/tone as you load up the suspension going left or right I would have guessed a CV joint (in the driveshafts) or a wheel bearing as opposed to the propshaft?

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Southernboy
Joined: Thu 07 Oct, 2010 13:39
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  Z3 roadster 3.0i
Location: Johannesburg

Re: Unwanted rumble

Post by Southernboy » Thu 07 Jun, 2018 20:14

Thanks Felix... :oops:
"Normal is overrated"
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jjorj
Joined: Fri 27 Nov, 2009 21:06
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  Z1 roadster
Location: Canterbury

Re: Unwanted rumble

Post by jjorj » Sat 09 Jun, 2018 02:10

Thanks guys, its still on the ramp so will take a look but did check for movement at both wheels incase it was a wheel bearing and both sides seemed to be fine.

George

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Jet
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Re: Unwanted rumble

Post by Jet » Tue 12 Jun, 2018 17:25

While your under there, check the exhaust hangars also .....

jjorj
Joined: Fri 27 Nov, 2009 21:06
Posts: 21

  Z1 roadster
Location: Canterbury

Re: Unwanted rumble

Post by jjorj » Tue 12 Jun, 2018 17:44

They look fine Jet and I have shaken it very hard to make sure it doesn't contact any other structures, but I did notice some oil or grease on one of the output shafts from the diff so will explore that next.

George
Last edited by jjorj on Thu 14 Jun, 2018 03:24, edited 1 time in total.

a1z1
Joined: Tue 04 Sep, 2007 21:43
Posts: 139

  Z1 roadster
Location: Newark

Re: Unwanted rumble

Post by a1z1 » Tue 12 Jun, 2018 18:35

Hi George,

Is the oil or grease on the output shaft around the Bellows on the CV joints. The rubber on these is beginning to get old and I’ve noticed on some cars although they are not split they have small holes that allow the grease to leak when they rotate.
Molybdenum Has to be the dirtiest grease on earth :(
A tell tale sign is a line of oil/grease on the underside of the floor/ petrol tank directly above the joint.
If you have a suspect wheel bearing, now would be the time to replace these as the Output shaft has to be removed to fit new wheel bearings.

Best wishes
Ivor
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jjorj
Joined: Fri 27 Nov, 2009 21:06
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  Z1 roadster
Location: Canterbury

Re: Unwanted rumble

Post by jjorj » Tue 12 Jun, 2018 18:57

Thanks Ivor. I know what you mean about the line of grease have seen it from old propshafts on some of the older cars but haven't noticed it on the ZETTIE. We are off touring in Brittany for about 10 days so will be looking further on my return.
Regards, George

jjorj
Joined: Fri 27 Nov, 2009 21:06
Posts: 21

  Z1 roadster
Location: Canterbury

Re: Unwanted rumble

Post by jjorj » Thu 14 Jun, 2018 03:22

Right, my mistake, so no escaping grease just someone's hand has been on the shaft and the dust has gone.And there is no splattered grease anywhere.
Will probably just realign exhaust to rule that out and then look for someone more skilled than I to tackle the noise if it remains.Not keen on removing shafts and other bits as need to keep hands mainly clean to go into gobs. Such is life. :cry: :cry:

George

jjorj
Joined: Fri 27 Nov, 2009 21:06
Posts: 21

  Z1 roadster
Location: Canterbury

Re: Unwanted rumble

Post by jjorj » Tue 03 Jul, 2018 22:30

Well, original equipment BMW exhaust rehung in slightly better position and noise is as loud as ever. There is no escaped grease as I though just where hands have made the drive shaft shiny and all seals seem intact. Tried to check diff oil levels but don't have the correct size of hex and don't want to round it off. Is there anyone in the south east that Z1 owners would recommend to take a look and try to keep car as original as possible. I have garages I use but originality is not necessarily their forte.
Rene is too far this time in Holland but am prepared to trailer it to someone with the hands on knowledge to fix it and make it nice again, any takers?

Cheers, George

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Green Genie
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Re: Unwanted rumble

Post by Green Genie » Thu 05 Jul, 2018 10:08

Is there anyone in the south east that Z1 owners would recommend to take a look and try to keep car as original as possible. I have garages I use but originality is not necessarily their forte.
George
These people have looked after my car for the past ten years, and they see a lot of older BMW's.

http://www.munichlegends.co.uk/
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jjorj
Joined: Fri 27 Nov, 2009 21:06
Posts: 21

  Z1 roadster
Location: Canterbury

Re: Unwanted rumble

Post by jjorj » Thu 05 Jul, 2018 16:31

Thanks GG,
Was really wondering if there were any hands on Z1 enthusiasts ready to jump to the challenge but I can give them a ring or may even drop round if in the area.I take it, its your Z1 they have been looking after?

Regards, George

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Green Genie
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Re: Unwanted rumble

Post by Green Genie » Thu 05 Jul, 2018 22:19

jjorj wrote:
Thu 05 Jul, 2018 16:31
I take it, its your Z1 they have been looking after?

Yes it was my Z1 I was referring to.
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Jet
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Re: Unwanted rumble

Post by Jet » Tue 10 Jul, 2018 13:07

George,

He is far too modest to say so himself, but I recommend speaking to Ivor. The man responsible for restoring a few member's cars like this one.

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He is also the man responsible for overseeing positioning of the panels in the recreation of this iconic image, and got it all wonky. :D :D

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jjorj
Joined: Fri 27 Nov, 2009 21:06
Posts: 21

  Z1 roadster
Location: Canterbury

Re: Unwanted rumble

Post by jjorj » Tue 10 Jul, 2018 18:41

Thanks for that Jamal, didn't know if it was only his local friends he did work for. Will get onto it

Regards, George

Howard Adams
Joined: Mon 10 Oct, 2016 16:39
Posts: 52

  Z3 roadster 3.0i

Re: Unwanted rumble

Post by Howard Adams » Thu 12 Jul, 2018 06:37

Hi, this rumble/noise only happens when cornering? Is so the most probable cause will be a wheel bearing. When checking wheel bearings obviously if there is movement that’s an easy diagnosis, normally there isn’t any, the best way is to jack the car up, axle stands under it, get someone to drive or spin the wheel and put a long screwdriver to the hub and listen, compare it to the other side. Also on the front if you touch the spring you will feel any vibration as it amplifies it.
Basic easy diagnosis, to rule them out.
Good luck
H

jjorj
Joined: Fri 27 Nov, 2009 21:06
Posts: 21

  Z1 roadster
Location: Canterbury

Re: Unwanted rumble

Post by jjorj » Thu 12 Jul, 2018 09:52

No noise is there all the time and worse with speed and reduces when turning in one direction only. G

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SCORPION
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Joined: Tue 18 Nov, 2003 18:24
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Location: Greasby

Re: Unwanted rumble

Post by SCORPION » Tue 17 Jul, 2018 17:47

I had a rumble that sounded exactly a wheel bearing. It took the garage a lot of time to find it. It was the tyre(Dunlop!) that had delaminated. I suggest you check your tyres especially if they are old.

felix
Joined: Sat 02 Jul, 2005 17:25
Posts: 553

  Z1 roadster

Re: Unwanted rumble

Post by felix » Tue 17 Jul, 2018 18:31

That is a very good thought. Had a trailer tyre blow out years ago because I ignored a slight vibration. When I checked the other 3 tyres 2 of them had waves in the tread as the tyres were starting to come apart. In my case it was a function of cheap tyres being run near their load limit.

Running your hands over the tread and checking for any cupping or the like is easy enough.

jjorj
Joined: Fri 27 Nov, 2009 21:06
Posts: 21

  Z1 roadster
Location: Canterbury

Re: Unwanted rumble

Post by jjorj » Thu 09 Aug, 2018 19:37

Well just shelled out for 4 new tyres and the noise is the same as before, not a problem really as they were all dated 1995 and hardening so should have a better ride and some more compliance anyway. Was worth the shot though, and better not to have one delaminate on me at speed.

George

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