Front end knock/rattle

[RedSwede]

Hi - first post here!. 3.0 TDI 272, 70000 mi.

In the last 10000mi it has had every arm replaced on the front end, either Audi genuine or Lemforder. 2x upper arms, 2x lower arms, sway/arb link, the additional lower ball joint, inner track rod, outer track rod end.

This has cured the heavier knocking and vagueness. Feels great.

But over very specific types of rough road - series of small bumps, like a bad patch job or flaking top skim - there is a “rattle” from the front end. I’ve checked and secured all loose undertrays etc. Checked top mount nuts and brace bolts.

The only only things original are the arb/sway bushings, the shocks, and the top mount.

The arb bushings look perfect and don’t have any play. Plus it’s a “hard” rattle, not a soft knock.

On most bumps it is silent.

Could dampers or top mounts rattle like this?

 

[spartacus68]

Lemforder is OE, and suspect they probably make the Audi ones anyway. I also rate Meyle HD (heavy duty). That seems a little premature at 70k miles, but the A6 isn't exactly lightweight, so it could just be wear and tear.

In my experience the top mounts rarely fail at that mileage, but they can deform. It's a relatively inexpensive part compared to arms, but if you're stripping out, then you'd be as well have them on hand to replace. Again, if you have swapped out the ARB links, then the ARB bushings don't tend to go until higher mileage. Again, the ARB clamps that hold them in situ will be rusted solid, so you'll probably need an air impact gun to remove, and you will need both sides jacked up for access.

Are the shocks weeping? I think there are foam bump stops, these can deteriorate and come out of the housing which could be the cuplrit.

 

[RedSwede]

OK, so probably rules out top mounts and arb bushes. Thinking about it, not being a mcpherson strut, top mounts are pretty simple I guess.

The shocks all look dry as far as I can tell. However… there is an advisory on the MOT from about 4 yrs/45k mi ago, noting a leak on that shock. Then nothing else. Could it leak and stop?

 

[19ryanh93]

Probably not the case but I have had it in the past if the arms are replaced but not set to “driving level” when tightening up it can damage the bushes as they are put under pressure when the car is put back on the floor.

Might be worth just checking the bushes in the arms.


Sent from my iPhone using Tapatalk

 

[RedSwede]

As far as I can tell, it’s all OK in that regard. Work was half done at Audi, half at a Porsche specialist that I know well and are meticulous. I’m sure they will have torqued it up correctly/under load.

 

[19ryanh93]

Fair enough. Was just something I’ve come across before.

Did you check ARB without any weight on it?


Sent from my iPhone using Tapatalk

 

[RedSwede]

Fair enough. Was just something I’ve come across before.

Did you check ARB without any weight on it?

Actually I only looked at it while I had the wheel off. The Porsche place told me it was in perfect condition when I asked them to change it together with the top arms.

It seems like the only real help possible through words only is to know whether a failed shock on these is known to rattle? Or should I look for something else loose?

(Strangely it is getting even more minor as of late. I wonder if colder weather -> thicker oil in shocks -> less rattling???)

If I just replace all 4 shocks anyway - are Koni Special Actives highly rated?

 

[Reginka]

Actually I only looked at it while I had the wheel off. The Porsche place told me it was in perfect condition when I asked them to change it together with the top arms.

It seems like the only real help possible through words only is to know whether a failed shock on these is known to rattle? Or should I look for something else loose?

(Strangely it is getting even more minor as of late. I wonder if colder weather -> thicker oil in shocks -> less rattling???)

If I just replace all 4 shocks anyway - are Koni Special Actives highly rated?

I used Koni Special. There were no problems.