Jepor

Would the unmatched at the back not make the humming also ?

I was hoping video would give an idea of what it was , you can really hear it at 31 seconds in .

I would apart from the fact that they are getting close to end of life thread getting low and would rather the deeper thread on the front.

Hankook the other wheels , like I said I had a blowout and that tyre was the only one available at that time .

My initial thoughts on the noise was that it had something to do with the outer cv joint that was changed as it started within 2 weeks of the job being done , but I have never heard of a bearing or humming noise from a cv joint . It was too much of a coincidence in my mind , but I suppose coincidences do happen after all . Thanks for all yer replies gang , as always ye were very helpful.

I'm going to leave it run for a while as there is no play in any of the wheels and if it is a bearing it will only get louder and will know for sure then, it's going for a service in 3 weeks so it would surly be worse by then if its a bearing. And if its only an tire issue I can live with that until new tyres are called for , by the way the tyre i got was a Roadx brand and thats the only one they had in my size 255/35/ r20 at the time . Don't know what they are like for road noise . Thanks

Hi I actually have got 2 new front tyres in the last month , and unfortunately they are 2 different makes in front (had a blowout and had to get a different tyre in emergency) , could be onto something as the noise is worse on smoother surfaces and not so noticeable on other surfaces . If thats only the case i can live with a slight humming. But to me if definitely sounds like a rubbing noise or bearing noise , is that possible with tyres?

Hi I have jacked the car up and spun the wheels and checked for play , nothing . But it is mild at the moment and might not be gone far enough to cause movement on the hub at 12 and 6 o clock , sounds stupid but I cant seem to spin the front wheels fast enough by hand to hear anything , back wheels no problem, and don't have access to a full car lift . I suppose my main worry is can the gearbox or something more serious cause this wheel bearing type humming? it doesn't seem to change pitch when I coast as in taking my foot off the gas , so that would lead me to wheel bearing. Should a wheel bearing be changed at the same time as the outer cv joint , is it common for a bad cv joint to damage a wheel bearing ? And how long can I drive this way if its slight and no play in the wheels ? Thanks

Hi All A weird humming noise has started in my a6 , now it's not very loud but just looking for ideas , it seems to be there when I accelerate and when coasting , it's the same level all the time once started , im wondering wheel bearing, it doesn't seem to change in pitch when turning left or right . I recently had a new outer cv joint fitted and this humming noise has started within 2 weeks . I am uploading a short video , you can hear it as I coast to a stop . Just wondering do ye think wheel bearing , tire noise or something else ?? Ive read about transmission noise can be humming , but don't think it's that as car is driving perfect and absolutely no issue with gear changes or slipping . 20250614_033652.mp4 Thanks

I think this stage im just paranoid about my A6 , I've waited for years to get one as I could never afford one before in my life and I have now finally got the one I wanted " my dream machine " ( a 10 year old a6 I suppose some would say it's not much of a dream ) , but not that I have it im listening out for every knock and click and i find myself actually to nervous to enjoy it , with the fear of a major bill . And the thought of major gearbox damage has me actually sick to my stomach. I think it's time I just drive it and enjoy it , because it is a joy to drive . Thanks

To be honest at this stage I don't think it's a crack , it's showing no sign of oil coming through it , and like I said there is absolutely no sign of oil anywhere i park . Also surly if it was leaking out oil there would be traces of it the whole way along the bottom side of the car , of which there's none . And also the car is driving extremely well surly a crack gearbox would show alot of symptoms. Thanks

Looking at it closely I think it's just staining and not actually a deep crack , it's like the edges of wet staining. The car is driving to well for me to believe that the gearbox is cracked, When I look there is no sign of oil leaking down from the marks . That surly would suggest that it's not leaving oil out .

Also the car is driving perfect, no skipping gears , smooth gear changes , everything seems normal .

Did a bit of further investigation and something the scares the s**t outta me , what looks like a small hairline crack along the metal over the plastic sump , it doesn't look like oil is leaking out of it looks dry around it , can these cases get small hairline cracks that don't go the whole way through , so they actually don't leak ? Surely the would be fluid marks running down from the crack , and there is also never oil on ground underneath the sump

Ya will do thanks . I'd imagine if it was leaking for a long time I'd have some alarm by now.

Never get an alarm in the car for low level gearbox oil , and no trace of any oil on the ground where i park , think it might just be a case of a sloppy mechanic when last serviced , which was 45000 km ago . And haven't had to top it up since .

Hey all I was just having a look at my inner cv joint earlier and I could see passed it to a sump , not sure if these is the main oil sump or the transmission sump , but I noticed it looked a bit damp around it , just wondering is this a bit of sweating , the car is driving well and have no oil lights coming on , it's been 45000km since last auto transmission service . The car is a 2015 audi a6 c7 s tronic . Thanks

Oh ok thanks , I took it to him with a clicking when turning left , got it back and the clicking was gone , but now have the single knock when initial acceleration in drive and reverse . So hopefully the 2nd new outer cv joint will fix this .

I suppose my mechanic who's working at it 40 years knows more , also he's covering the cost of the replacement cv joint so not going elsewhere , I can just try the outer and if still knocking i have lost nothing, then move onto inner . My question is can the outer cause this knock noise ? I thought it would just be a clicking while turning .

He also doesn't want to change the whole driveshaft he says there's no need. His logic is the only thing that was changed before the knock came was outer cv joint , so it's obviously the outer thats the problem . Has he a point or am I being paranoid?

Just another enquire , my mechanic is convinced it's the outer cv joint making the knocking noise when accelerating, but everything iv read on the web suggests that this knocking is the inner joint not the outer , can anybody tell me can an outer joint cause this singal knock when accelerating? Don't want to have to go back again if it was the inner after all this.

UPDATE : took the car back to garage , they took everything apart and retightened all the bolts on the inner cv joint and also the cv hub nut , Absolutely no movement on inner joint . Unfortunately the noise still there , on the plus side it's definitely coming from the wheel area not the gearbox , it's there when put the car into drive or reverse and accelerate hard . So at least he was able repeat the sound . He reckons it must be a faulty part out of box , he reckons theres movement on the spline when accelerating, he has ordered a new part and will fit next week when it comes under warranty , he says it's perfectly safe to drive until then . Hoping the new part will solve the problem , he's says that's all it can be as that's all that was changed on the car . It's an SFK cv joint not sure how good they are but he says they are very good parts .

Thanks for replies , going back to garage today , think it's just the way the drive shaft was reassembled after changing the cv joint . It's only happening on initial movement back and forward . No sound actually going into gear .

Luckily it's going into gear ok so don't think it's the gearbox , it's seems to be when I start to move while in drive or reverse, so it feels to me like something lose and knocking, im starting to think about lose driveshaft bolt .

Hey all I have an 2015 audi a6 c7 auto s tronic 7 speed , yesterday I got the passenger side outer cv joint replaced, it sorted out the usual cv joint symptom of clicking when turning. Today I noticed something strange , when I put the car and reverse and accelerate the is a clunk noise only once , it then does it when I stop and go into drive , again one singal clunk . The car is driving perfect it's just the signal clunk on initial take off either in drive or reverse. Have to wait to go back to garage . Could it be backlash. It's only come since the cv joint was replaced . Sounds harmless but nervous that it's doing damage . Has anybody experienced this before ? it's like a singal metallic clunk in drive and reverse , nothing while driving after initial acceleration . Thanks