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View Full Version : Question A4 Quattro Sport Rear Wheels Making Strange Noise



Adam A41.8T
18-05-2009, 04:29 PM
When I pull off at low speeds I get a strange noise coming from the rear wheels. Its the same kind of thing as if I were driving over the lines on the road approaching a round a bout or over cats eyes. It only happens at low speeds. I have a 2003 '52' plate A4 1.8T Quattro Sport. Can anyone help?

hagis
19-05-2009, 12:43 PM
Hi Adam,

This might relate to your problem:

http://www.vwaudiforum.co.uk/forum/showthread.php?t=67781

randall977
19-05-2009, 11:14 PM
That's exactly what mine does! Are you sure it's the rear? I'm pretty sure it's the front on mine but it's possible I'm wrong... It must relate to the wheels - ie from the driveshaft onwards so it can't be the transmission or anything. I don't surpose your car does a funny jumping sideways in the wet thing when on hard lock?

Adam A41.8T
20-05-2009, 08:57 AM
It is defo coming from the rear and seems to be a bit worse if there is a lot of weight in the car. We went camping recently and there were 3 people in the back and all the equipment in the boot (quite suprised how much you could get in the boot!) I hope it is not anything too serious. At first I thought it may be the wheels rubbing as it has 18" RS4 alloys on it but I dont think this is the case. I have not had the problem in the wet though. It also does something similar if you are doing say about 70 on the motorway in 5th gear and put the accelerator hard to the floor.
I am hoping it is not anything to do with the 4 wheel drive system?

randall977
20-05-2009, 11:23 AM
While I was driving it today I was trying to pin down the circumstances which cause it but it's not easy. This is how far I have got;

Happens when pulling off under load - ie up a hill or with weight in the car but not so much when you floor it.
The knocks seem to coincide with the revolution of the wheels.
So not much information but it suggests to me that it's not the transmittion otherwise the knocks would be far more regular...relating to the revs. I'm not an expert on 4WD but I did wonder about the diff between the front and rear axles - can these develop play???? If so would it cause a knocking like this? My car is an 05 with 60K miles and 6 spd btw.

Adam A41.8T
20-05-2009, 12:34 PM
Ok, this does sound like the same problem I think. Mine is defo coming from the back and only when setting off in a straight line at slow speed. Mine is a 2003 which has covered 67k miles and is only 5 speed (I do miss that extra 6th gear!)

Adam A41.8T
20-05-2009, 04:03 PM
I have done a bit of digging around and wonder if this is what the problem is?

I know its a different forum (sorry!) http:/www.audi-forums.com/b6-forum/48446-cracked-rear-anti-roll-bar.html

Can you have a look and see what you think?

Thanks,
Adam

maccamanus
20-05-2009, 04:11 PM
Just a thought but how about wheel bearings? .....

Adam A41.8T
20-05-2009, 04:14 PM
erm... I am not sure? When I have had wheel bearings go on my other car, the wheel makes a low droaning noise all the time. I guess if you leave them too long then the wheel would cease up so I cant see that this would be the problem? Not sure really though. I dont know enough about it?

randall977
21-05-2009, 10:02 AM
Well I know the collars are cracked on mine but I thought it generally didn't cause a problem until the anti roll bar comes loose (as the thread suggests). I assume your rear bushes are also cracked? It could be worth checking out, maybe it's knocking that we are experiencing due to failed bushes? Good suggestion! My only other thought is differential but I'd rather not go there! So who's going to get it checked out first then? I'll call my local dealer and get it booked in...

Adam A41.8T
21-05-2009, 10:15 AM
OK cool. I htink the more I read that thread I think it must be something to do with that.
If you are booking yours in now then I will sit and wait to find out the bad news!!

I will get mine looked at next week! Hopefully it will not be something too expensive. What are your thoughts on cost?

randall977
21-05-2009, 02:37 PM
Well I've had the car looked at by an Audi specialist (who are reputable) and they say the rear bushes are not cracked - in fact I looked as well and they're fine so I'm not sure why Audi told me they were cracked. They also had a good look at everything suspension related and found no problems. They then turned thier attention to the engine mounts and adjusted one...it made no difference! So I'm afraid the answer is not clear yet but suspension may not be the answer. I would be interested to look into the rear differential as a source of knocking but I don't know much about it...

Could still be a CV...

Cost incurred so far - £0 for inspection + mount adjustment. £130 for drive shafts (not fitted).

Adam A41.8T
21-05-2009, 02:55 PM
That is quite interesting then. Did they drive the car at all to hear the noise for themselves?

I must admit, I have looked through some previous service notes from Audi and they advise that the rear anti roll bar is corroded. It is only a advice though and when I look myself it appears to be only part of the casing so I cant see that this is causing the problem.

CV joint is a possibility then? I could do with finding out because it is starting to annoy me. Does yours make any difference if you pull away really slowly as opposed to at a normal speed?

randall977
21-05-2009, 03:52 PM
Of course when they drove the car they couldn't hear it! I've found that if I pull off at a slight angle in either direction the knocking is louder... This could mean it's putting more pressure on a suspension joint or a CV joint. If I accelerate very hard I don't think it does it. If I roll down a hill with no acceleration it doesn't do it. Starting on an incline will make it happen. I can't be sure it's the front... CV or diff is what I'm going to look at - see if you can find any threads of 4WD differential problems.

randall977
21-05-2009, 04:16 PM
Check out these - they'll give you a horrible feeling inside!

http://www.vwaudiforum.co.uk/forum/showthread.php?t=34577&highlight=differential

http://www.vwaudiforum.co.uk/forum/showthread.php?t=29990&highlight=differential

http://www.vwaudiforum.co.uk/forum/showthread.php?t=68751&highlight=diff

http://www.vwaudiforum.co.uk/forum/showthread.php?t=35156&highlight=diff

http://www.phonecallsfromthedead.net/thesleeper/audimain/A4reardiff.jpg

Adam A41.8T
21-05-2009, 04:33 PM
Dont like the sound of those!! I think we are looking a bit more into than we should be though. After reading those they report a clanging noise and stuff which isnt the case with mine! I am going to go out into the car park at work and try my car now just to see what happens. I will report back shortly!

randall977
21-05-2009, 05:49 PM
Actually the engine mount adjustment has cured the problem by 95%. It still does it a bit when pulling off up a hill but not as bad. This is just after one 30 minute journey mind you but it's my regular journey home. Are you sure it's rear?

Adam A41.8T
21-05-2009, 07:13 PM
OK I give up. I cant for the life of me get it to make the noise!! I wonder if it was because it was stood for a couple of months before I bought it?

randall977
24-05-2009, 11:25 PM
No still does it! Today I got the car to make the knocking noise really badly - I found that driving the car slowly (in first gear or second) up a fairly steep hill makes it knock badly. I'm thinking again that it could be a diff problem as I think it relates to the 4WD system kicking in (under load) and the drive shaft does rotate with the revolution of the wheels. It sounds like the front to me but there is a front and rear diff so your could be rear...

Dave Gee
25-05-2009, 01:01 PM
I have a similar problem with my Avant Quattro 2.4TDI, when slowly pulling away the car starts 'thumping', and can be heard / felt more in the rear. Above say 10 mph it seems to clear and run normally.
At last MOT it had a badly shredded tyre on the inside tread down to the canvas, but cannot remember which wheel the tyre was on, could this be significant?
Tyres changed/balanced but the 'thumping ' sensation has returned, like driving over rumble strips !
Any further ideas?
Dave

Adam A41.8T
26-05-2009, 09:18 AM
This sounds like the same problem to me. I have no idea what it is and if it is casuing any damage?

I think I need to get it looked at. Any ideas anyone and also any ideas on the cost?

randall977
26-05-2009, 04:42 PM
I was chatting to my father-in-law who's pretty good on 4WD and he's sure that a differential problem would have more catastrophic results...which is good as ours are fine apart from the clunking. I does sound like something slipping doesn't you think...or jumping out?

Adam A41.8T
26-05-2009, 05:21 PM
I agree.

It does sound like something slipping. I am setting myself up for something quite cheap but I am sure that whatever it is will come back to bite me!!

Mine has started doing it again. Also I have noticed that if you let the clutch out quite slowly it doesnt seem to be as bad?

Give it a try and see what you think?

randall977
26-05-2009, 10:10 PM
I was going to say that I think there is a connection between the clutch and the knocking... I was having a go today and riding it on the clutch up a hill and it was noticable. If yours is rear and mine is front and they are the same problem then it has to be something in common which is front and rear on the quattro - CV, differential...otherwise one of us has mis-located the noise. What about temperature? I wondered if it did it as much when the engine is hot or cold but not sure?

Adam A41.8T
27-05-2009, 09:42 AM
I havent noticed the change in temp. It seems to knock regardless of temperature. I do think it is linked to the clutch though. My car is at home this week as I work away from home so I cant check anything on it. If you let it free wheel down a hill it doesnt make that noise so it has to be connected to the clutch

randall977
27-05-2009, 12:31 PM
I which case that rules out the CV's and driveshafts as they still turn even when the car is not in gear... How do you know the knocking is from the rear - I mean is it 100% obvious? Sounds in cars can be hard to locate. It kind of indicates a gearbox / differential issue. Thinking about it, a clutch plates spins way too fast to cause the kind of knocking we are getting. Once in gear the whole system is locked....apart from the limited slip which I believe allows the wheels to slip upto 25 / 40mph, hmmmm...I wonder if that has anything to do with it - I think it is front and rear? Do you know anything about the limited slip differential system?

Adam A41.8T
27-05-2009, 12:57 PM
I am 100% sure that it is coming from the rear only.
My knowledge on things like that is non existent I am afraid.

Have you tried setting off with the door open (obviuosly in a large space where you cant hit anything) to see if you can hear anything from the outside?

randall977
27-05-2009, 02:04 PM
So you're not really familair with differential etc etc? I'm not a mechanic btw but I'm quite into mechanics. I got this from Wiki (it's about the A4 quattro) - 'The manually locking rear differential from the earlier generations was replaced with a conventional open differential, with "Electronic Differential Lock" (EDL) (which detects wheelspin via ABS road wheel speed sensors, and applies brakes to the one spinning wheel, thus transferring torque via open differential to the opposite wheel which has more traction). EDL works at speeds up to 80 km/h (50 mph) on all quattro models.' Do you roughly understand what this is saying? I'm no expert but could it be that this system which both our cars has is causing braking in one wheel (pulsed) - so front on mine and rear on yours? I'm not sure how you could find this out except by plugging the car into VAGcom (a laptop with software to anylise problems) - do you have any friends with it?

Adam A41.8T
27-05-2009, 02:15 PM
Ok I understand that. I am not convinced though why it would only do it up to about 10 mph even if it was faulty? It could be this I suppose though? I dont have VAGcom. Is it easy to get hold of etc? Have you got it/tried it?

randall977
27-05-2009, 02:57 PM
It is clutching at straws. I don't have VAGcom as it's £250 - though I'm told it's well worth it. I have a £90 fault code reader but it doesn't tell me about the kind of thing we're looking for - I selected AWD (all wheel drive) and it said 'lost link'! So no joy there. I'm not sure where to go with this one without paying someone - only problem is that it on;y does it under certain circumstances. It is annoying but the car is great apart from that. Is it possible to live with it until the problem becomes more apparent?

Adam A41.8T
27-05-2009, 03:18 PM
Is it possible to get a free download of VAGcom from anywhere? I think it looks like a worthwhile purchase.

I can live with it but I just dont wnat to risk it getting worse and costing more

Dave Gee
28-05-2009, 01:52 AM
The tyre I had replaced was shredded down to the canvas on the inside with flats on it similar to a 50p piece. This seems to indicate the tyre had been 'snatching' as it was revolving. Could this have something to do with the ABS braking system snatching?
On my car there seems to be a fair amount of back-lash in the transmission and I can imagine that there must be some torsional conflict between the front and rear tyres when the drive is initially taken up, could this be a contributing factor in the 'thumping' phenomena?
I am told that you should have similar types of tyres with similar wear on 4WD cars and they should be exactly to the correct pressures so that the rolling radius is exactly the same for all tyres. Also ensure that if they are asymmetric tyres that they are fitted on the correct axles for the correct rotational direction.
I was chatting to a Volvo 4WD owner who said that 'they' had a lot of trouble with tyres and pressures causing differentials to give up the ghost prematurely.
I will be more than pleased to get to the bottom of this problem as I am sure it could lead to an expensive solution.

randall977
28-05-2009, 08:51 AM
In theory the differential should remove any play between the wheels. Having recently looked into this the difference between a car such as a Land Rover and a Quattro is that the wheels are not locked together thus enabling better handling, cornering etc. The limited slip allows the wheels to lock when one starts spinning (on mud for example) but only over a certain speed. But I do think the ABS could be a cause of the knocking if something was triggering....surely that would show up as a fault code though?

Dave Gee
29-05-2009, 12:35 PM
On a previous Audi 90 Quattro the rear trans-axle locked up solid and it became a real pig to drive in anything other than a straight line.
All the wheels were at conflict with each other when cornering.
I had to have a second hand replacement trans-axle fitted at some considerable cost (but much lower than the £2000+ that a main dealer quoted me).
But to get back to the present problem; although the trans-axle /differential allows the outer wheels to travel a greater distance than the inner wheels on a curve, if there is torsional slack in the drive between the front and the rear axles there will be conflict between the front and rear wheels.
As I see it, initially as the front wheels start to grip and start to move the rear wheels have yet to start turning due to the 'lost' motion in the transmission tending to drag the rear wheels. Then when the rear wheels eventually start to turn they will be travelling a smaller distance initially and therefore may be causing the wheels to 'hop' or bump until all the wheels are under drive and synchronised and thus rolling at the same speed. This seems to be why this 'bumping' only occurs at 'slow' speeds when starting off.
Do we have any 4WD specialists on this forum ?

randall977
01-06-2009, 06:07 PM
I put some new tyres on the front (they were unevenly worn) and so far no knocking...

Adam A41.8T
02-06-2009, 08:43 AM
Really? Nothing at all? If that is the cure then we are laughing!! I will check my tyres out at lunch time to see what they look like.

randall977
02-06-2009, 10:46 PM
They did need replacing anyhow - worn right through on the outer edges. I havn't really driven it enough to give a definative answer yet but by the w/e I will have. If that's done it then yes an easy answer (though not cheap) to a wierd problem!

Adam A41.8T
03-06-2009, 08:51 AM
I kind of hope that os what it is. I looked at my tyres this morning. I have 18" RS4 alloys on mine and the tread does look a bit un even on the back. The back tyres are also different to the front ones. Do you think that would make a difference?

randall977
04-06-2009, 11:07 PM
I can confirm - no knocking at all - tested! I don't think it is the make of tyre (as mine were the same) but the wear - don't know why it cause the knocking though!

Adam A41.8T
05-06-2009, 08:55 AM
That is great news! At least now I know it is nothing serious!