Drone from rear on Superb saloon at 2500 rpm

[Wizzzzz]

Any help appreciated.

2012 Superb 170 4x4 and the rear has a drone at 2 - 2500 revs. Almost rocks the car. Disappears if I drop from 6th to 5th but really annoying that that is motorway speeds and I’ll kill the mpg. Seems to be coming from the hatch/boot

anyone else had this and any suggestions that I can look at?

TIA

[skomaz]

i had that on our Octavia...   it'll be the propshatf coupling doughnut thats worn out.

 

A febi bilstein replacement is about £100 plus fitting as an aftermarket part but skoda will want to sell you a full propshaft at about £800 plus fitting, so you'd be best to find a vw specialist to do the work.

[TasMan]

10 hours ago, Wizzzzz said:

Any help appreciated.

2012 Superb 170 4x4 and the rear has a drone at 2 - 2500 revs. Almost rocks the car. Disappears if I drop from 6th to 5th but really annoying that that is motorway speeds and I’ll kill the mpg. Seems to be coming from the hatch/boot

anyone else had this and any suggestions that I can look at?

TIA

Check your rear tyres for saw toothing on the inner edges.  More common on the estates but wouldn't rule it out as a simple fix on any Superb.  Check tyre wear all round and tyre pressures.  Any uneven wear would suggest a 4 wheel alignment is needed.

However if it is that severe, sounds like skomaz has a more viable suggestion...

How many miles has your car done out of interest ?

 

 

[DrCorbyLee]

8 hours ago, TasMan said:

Check your rear tyres for saw toothing on the inner edges.  More common on the estates but wouldn't rule it out as a simple fix on any Superb.  Check tyre wear all round and tyre pressures.  Any uneven wear would suggest a 4 wheel alignment is needed.

However if it is that severe, sounds like skomaz has a more viable suggestion...

How many miles has your car done out of interest ?

 

 

I'd agree with TasMan that it could be an issue with rear tyres.  Couple of years ago had really bad drone at motorway cruising speeds in my 63 plate FL 4x4 estate.  Was also causing such vibration that you could actually see the backrest of the unoccupied front passenger seat vibrating.  I feared the worst that it was a transmission issue but as the rear tyres were down to 3mm I decided to change them first.  They weren't badly saw-toothed (certainly not like some of the horror story photos I've seen) but sure enough with new tyres fitted the drone and vibration disappeared so possible that they were out of balance and / or saw-toothed enough to cause my problem.

 

However, what is strange with the OP's reported issue is that changing down and hence increasing revs stops the drone. Surely if the problem was down to propshaft coupling or rear tyres that would make no difference as if car is at the same road speed, propshaft, rear diff and rear wheels are all turning at exactly the same speed irrespective of engine speed / what gear you're in?.  With my issue, dropping from my usual indicated 75 cruising speed to 60 or so made it go away as the wheels were then rotating maybe 20% slower.  So if the issue here is definitely correlated to engine speed / gear selection rather than road speed then I fear the problem could possibly be gearbox related.  

[skomaz]

If it was tyres changing gear at the same speed would make no difference.

 

The age is spot on for rear propshaft doughnut coupling failure and having 🐝 there would be my first port of call...   What is the mileage...   75k ish.

Edited 12 January, 2022 by skomaz

[DrCorbyLee]

2 hours ago, skomaz said:

If it was tyres changing gear at the same speed would make no difference.

 

The age is spot on for rear propshaft doughnut coupling failure and having 🐝 there would be my first port of call...   What is the mileage...   75k ish.

100% agree that change in gear wouldn't have any effect on tyre related noise as they are turning at same rate at a given road speed irrespective of gear selected/engine rpm .  Similarly not doubting your experience with failed prop' doughnut but unless I've misunderstood how the haldex 4x4 is configured, the noise from prop' doughnut wouldn't be impacted by change in gear/engine rpm as it spins at same speed at a given road speed.  So to my simplistic thinking, it's only a change in road speed which would alter prop's speed of rotation and hence it propensity for vibration from a knackered doughnut.  Or have I missed something here and the problematic prop' doughnut isn't linking output from the gearbox to the rear diff?

 

 

 

[skomaz]

2 hours ago, DrCorbyLee said:

100% agree that change in gear wouldn't have any effect on tyre related noise as they are turning at same rate at a given road speed irrespective of gear selected/engine rpm .  Similarly not doubting your experience with failed prop' doughnut but unless I've misunderstood how the haldex 4x4 is configured, the noise from prop' doughnut wouldn't be impacted by change in gear/engine rpm as it spins at same speed at a given road speed.  So to my simplistic thinking, it's only a change in road speed which would alter prop's speed of rotation and hence it propensity for vibration from a knackered doughnut.  Or have I missed something here and the problematic prop' doughnut isn't linking output from the gearbox to the rear diff?

 

 

 

 

Yes the prop doughnut links the prop to the haldex so does spin at a speed relative to the wheels butthe difference in gear affects the torque that the doughnut is transmitting and therefore how it reacts.

 

On the octavia i could cruise at around 2300 rpm in 6th and the noise was horrendous underload but tailed off on the over-run.  If it was dropped into 5th at exactly the same speed the noise pretty much went away under both load and over-run, but drop the speed to 2300 rpm and it would start again but much quieter.

 

Put it back in 6th and accelerate to about 85 and the noise stopped.

 

There are two doughnuts one at the front and one at the rear and on mine both were perished but the noise started when the rear one failed.  It took me a while to decipher what the issue was and I did wonder about tyres and DMF but eventually narrowed it down and had a local specialist check the drivetrain.  They confirmed the doughnuts were shot and also that they had experience of occasional similar issues on Audis.

[DrCorbyLee]

10 hours ago, skomaz said:

 

Yes the prop doughnut links the prop to the haldex so does spin at a speed relative to the wheels butthe difference in gear affects the torque that the doughnut is transmitting and therefore how it reacts.

 

On the octavia i could cruise at around 2300 rpm in 6th and the noise was horrendous underload but tailed off on the over-run.  If it was dropped into 5th at exactly the same speed the noise pretty much went away under both load and over-run, but drop the speed to 2300 rpm and it would start again but much quieter.

 

Put it back in 6th and accelerate to about 85 and the noise stopped.

 

There are two doughnuts one at the front and one at the rear and on mine both were perished but the noise started when the rear one failed.  It took me a while to decipher what the issue was and I did wonder about tyres and DMF but eventually narrowed it down and had a local specialist check the drivetrain.  They confirmed the doughnuts were shot and also that they had experience of occasional similar issues on Audis.

Thanks for that, can now see the logic of how varying engine speed and, more importantly, load could impact on prop' vibration. 

 

The commonality of parts in VAG is certainly a double edged sword - keeps prices down but then when there is a design "shortcoming" like this it impacts on an awful lot of different cars.  Seems very common in Audi's equipped with Haldex (rather than Torsen) diffs and is also a problem with Superb IIIs e.g. 

 

My biggest concern when I bought my car just under 8 years and 109K miles ago when it was 3 months old was the risk of a huge bill somewhere down the line thanks to complexity of the DSG + Haldex drive train.  Had been taking out Skoda extended warranty each year to cover such an eventuality.  Never had any of the feared drive train problems although each year had at least one claim (water pump, DSG+Main thermostats, 2xs window regulators, head lamp level sensor and aircon compressor) which nearly always fully offset cost of each year's warranty.  Unfortunately with mileage now past 100K wasn't able to renew the warranty at the start of December.  Never thought a disc of rubber and steel would potentially be of such concern.  One more thing for me to now worry about! 

[Wizzzzz]

I think I should clarify the issue and many thanks for the replies.

it is more of a body drone at these revs and I think it’s metal on metal maybe. I’m looking s

at adding some sound deadening to the twin hatch connections to see if  I can reduce it.

BUT what a fantastic car 👍👍👍

[Wizzzzz]

Any help appreciated 🤞I think I should clarify the issue and many thanks for the replies.

it is more of a body drone at these revs and I think it’s metal on metal maybe. I’m looking s

at adding some sound deadening to the twin hatch connections to see if  I can reduce it.

BUT what a fantastic car 👍👍👍