Steering rattle on breaking.

[gcgregory]

Hi,

I have a 2011 Q5 3L diesel. It has now done 145k miles. I am the second owner and have owned it since 30k miles, over 7 years.
The car has been faultless (except one problem with the air intake that was solved), but over the past 10k miles it has developed and odd rattle on breaking which the garage has not been able to diagnose.

This rattle makes the steering wheel shudder and I can feel it through my foot on the brake pedal. It occurs on breaking but only at a very specific breaking point: if I break with slowly increasing intensity, it will shudder only at a certain compression of the breaks, not before and not after. This range is very small. It is worse at higher speeds and when it is warm. When it is cold (under 10oC/50oF) or I am slow it is barely perceptable.

Even more strange is that each time the dealer replaces a part it solves it for a few weeks and then it comes back. So far this includes:

One set of front suspension arms.
....the rattle went and then came back.
A different set of suspension arms.
...the rattle went then came back.
The front brake disks and pads.
...the rattle stayed off for two months and has now come back worse.

(There was another part replaced first that I cannot remember.)

The mechanics have no idea what to try next, and this trial and error is very costly.

Any ideas?

Thanks

Gordon 

[Steve Q]

Is it going to Audi or an independent garage? If it's the latter it might be worth taking it to Audi. 

[gcgregory]

Thanks for the reply. It has been to both, Audi first, then an independent garage when Audi didn’t solve it. I could try a different Audi I suppose.

[Magnet]

Hello Gordon,

I think valuable clues lye in the fact that this can be felt through the brake pedal, and that it seems to have disappeared for 2 months ( the longest symptom free period) when the brake discs and pads were renewed. 
What make discs and pads were used?

I ask the question since your description smacks of symptoms of warped brake discs. 
If this were mine, I would be wanting to check the run-out on the discs as they are now, in their installed state, and if found to be warped, I would be extremely fussy to ensure the mating surface of the hub - where the disc fits - is scrupulously clean and sound. If genuine VAG discs haven’t/aren’t going to be used, then I would opt for Brembo, and not be very keen to use anything else. When fitting new pads, I would be again be very fussy to check that the caliper sliding pins were clean, suitably lubricated, and we’re moving freely. 
All of this would be my starting point, unless anyone else sees anything untoward on inspection. 
Kind regards,

Gareth. 

[Steve Q]

11 minutes ago, Magnet said:

Hello Gordon,

I think valuable clues lye in the fact that this can be felt through the brake pedal, and that it seems to have disappeared for 2 months ( the longest symptom free period) when the brake discs and pads were renewed. 
What make discs and pads were used?

I ask the question since your description smacks of symptoms of warped brake discs. 
If this were mine, I would be wanting to check the run-out on the discs as they are now, in their installed state, and if found to be warped, I would be extremely fussy to ensure the mating surface of the hub - where the disc fits - is scrupulously clean and sound. If genuine VAG discs haven’t/aren’t going to be used, then I would opt for Brembo, and not be very keen to use anything else. When fitting new pads, I would be again be very fussy to check that the caliper sliding pins were clean, suitably lubricated, and we’re moving freely. 
All of this would be my starting point, unless anyone else sees anything untoward on inspection. 
Kind regards,

Gareth. 

I felt the same about warped discs but dismissed it as they'd recently been changed. But I guess it will depend on the quality of the discs and also I guess the way the car is driven will depend on the brake wear also. 

Not that I'm saying your braking like a racing driver, I'm just wondering do you do a lot of towing? As that would put extra strain on the car in general. But I could be totally off 

[gcgregory]

Magnet, thanks for the advice, I'll take it is for a full assessment.

Steve Q, 

Quote

Not that I'm saying your braking like a racing driver, I'm just wondering do you do a lot of towing? As that would put extra strain on the car in general. But I could be totally off 

No I'm a doctor, I do lots of miles driving on call and in-between hospitals, hence why I've racked up 125k miles in 7 years, most of which is motorways and dual carriageways, and I've never towed anything.

Thanks again.

[Steve Q]

3 hours ago, gcgregory said:

Magnet, thanks for the advice, I'll take it is for a full assessment.

Steve Q, 

No I'm a doctor, I do lots of miles driving on call and in-between hospitals, hence why I've racked up 125k miles in 7 years, most of which is motorways and dual carriageways, and I've never towed anything.

Thanks again.

No probs. All respect to you, my mum and sister are both doctors so I can appreciate the intensity of the job. Last thing you need is car that is eluding being fixed. 

[Magnet]

Hello Gordon, 

Thanks for coming back on this. I’m sure you more than anyone, will appreciate the difficulties/impossibilities?  of trying to diagnose the cause/s of such issues without examining the patient! All you going to end up on here with ( with all due respect) is a list of could be this/I had that with my car etc.

The fact is that the car is trying to tell you something, and it now needs to be examined by a recommended  ‘specialist consultant’. 

If this were mine, I would be concentrating my efforts on researching recommended garages in your area - not necessarily Audi specialists - but an establishment where you can talk to the principals, in person, and go through everything with them. 
Perhaps you could let us know how you get on Gordon.

Kind regards,

Gareth.