Clonking noise from rear of car

[iburnell]

Greetings - new to this forum

A3 Sportback 1.8T brought new 1/9/2007 - warrantly about to run out

Yesterday all perfect - today I've noticed noise from rear of the car. Difficult to describe but I would liken it to a loose exhaust i.e. if you go over some rutted road or humps it will "bump" the underside multiple times - that's what it sounds like.

I don't believe it to be just a rattle - it appears to be underneath somewhere like the left rear suspension or cat/exhaust area of rear. Looking underneath car all looks fine. Its going in for service but wanted a heads up to see if anyone else has experienced anything similar

Thanks

[phil miller]

hello mate welcome to the site, your noise could well be a rear anti-roll bar link

[iburnell]

Thanks Phil - is this a known problem with the A3 ?

[djgilson]

This thread is a year old, but I thought it might be worth resurrecting, as my wife's A3 has developed a similar problem.

It's a 2004/54 2.0TDi 3dr S line with 95,000 miles, and the noise is a rattle from the right rear suspension when going over rough bits of road. Crawling underneath doesn't reveal anything loose as far as I can tell (which is not very far). The anti-roll bar seems solid.

There are lots of rubber bushes in the suspension and I imagine one of these may have worn through with the high mileage. Next move is to get my local garage to put it on the ramp and have a proper look, but before I do that, can anyone offer any ideas on the most likely culprit?

[iburnell]

Wow - this is old. It was a known problem with Audi A3. I can't remember exactly but I think they are metal stoneguards behing the rear wheels. They simply replace them with plastic ones and that fixes the problem

[VEEDUBYA]

Check your shock absorbers aren't leaking (appear damp on outside) and if u can jack it up have a look at bottom of Coil Spring. My Passat estate had a heavy twang noise and then suspension developed a clonking noise until finally handling was awful. Turns out twang was spring snapping in bottom section and then the Shocks got worse before giving up the ghost!

[djgilson]

OK, found the problem. The bottom coil of the coil spring had broken off and was rattling around in the recess in the suspension arm. Interestingly, we hadn't noticed any untoward effects on the handling - the car still runs on rails as usual. The shortened spring is still seated securely in place. But looking carefully you can see the car is sitting down slightly on that side, but only by a cm or so - thanks to the stiffness of the S-line suspension presumably.

Next question is whether to replace just the one spring or both. Think I'll go for just the one. If a broken spring is not detectable, then any unbalance due to one new and one old should be of no consequence at all. The actual replacement is a simple job (according to Haynes, with a suitable spring compressor you can remove the spring without disturbing anything else) so the spring itself is probably the major cost. If the other one breaks next week, it’s no big deal.

Iburnell, I was baffled at first by your mention of a stone guard, but then I looked up vagcat.com and there it was! It attaches to the lower suspension arm and is evidently meant to protect the coil spring. My car (2004) doesn’t have them, and I presume it was introduced on later models like yours (2007) following incidences of spring failure................

VEEDUBYA, your comment was spot on, but on my car the shock absorbers seem OK. As I say, the broken spring had no apparent effect on handling and if it hadn’t been for the rattle of the broken off piece, we wouldn’t have known anything was wrong. Maybe it would be picked up at MoT, maybe not. Actually, the most obvious clue is the changed spacing of the coils - I could put my fingers between the coils of the broken spring but not the unbroken one - a useful diagnostic check?

[djgilson]

Just an update.

My local garage replaced the coil spring for a total of £95, including £49 for the spring from gsf carparts. (Audi had quoted me £73 for the spring alone). They did have to release the lower arm to install the new spring, so I thought that was pretty reasonable.

You need to be careful about getting the right spring - vagcat.com lists 42 different rear springs for the A3! Anyway, the new spring has not only removed the 1 cm drop on that side, but has also raised the rear of the car as a whole by at least another cm. The stance had been looking extra sporty!

Re the stone guards, I thought it would be worth fitting them to protect the new spring, as they’re only £13 the pair from Audi, complete with fixing clips. It turns out that they attach to the trailing arm (which runs fore and aft), not to the track control arm (which runs across the car). However, there are no mounting holes in the trailing arm to fix them to. Trying to drill holes in the trailing arms while scrabbling about under the car is not the sort of activity which appeals much these days, so I’ll probably not bother and the springs will have to continue to take their chance with the elements.

Just for the record, for anyone who’s interested, I attach some photos which include a guard loosely in place.
http://i264.photobucket.com/albums/ii187/djjgilson/Headlamp%20Aim%20and%20Stoneguard%20A3/Stoneguard004.jpg
http://i264.photobucket.com/albums/ii187/djjgilson/Headlamp%20Aim%20and%20Stoneguard%20A3/Stoneguard001.jpg
http://i264.photobucket.com/albums/ii187/djjgilson/Headlamp%20Aim%20and%20Stoneguard%20A3/Stoneguard008.jpg
http://i264.photobucket.com/albums/ii187/djjgilson/Headlamp%20Aim%20and%20Stoneguard%20A3/Stoneguard006.jpg

[djgilson]

The saga continues............

Eventually, got my local garage to drill the holes in the trailing arms and fit the stone guards. But not very keen on the security of the plastic riv-nut fixings so I’ll probably replace them with proper bolts and lock-nuts.

BUT blow me down, my A4 has just failed it’s MoT on, you’ve guessed it, a broken rear coil spring. This seems to be catching. Same as on the A3, I hadn’t detected it on the handling or the stance of the car. But no rattle of broken pieces to give a clue this time.

The A4 is an Avant S Line quattro, 5 years old, with 91,000 miles. Perhaps S Line springs are more susceptible to breakages - anyone got experience of this?

I’ve always been sceptical of claims that speed humps are responsible for spring breakages. I meet a few, but I always try to treat them with respect. Now, I wonder....... Garage reckons 10% of MoTs reveal a broken spring.

Anyway, garage fitted the new A4 spring for total bill of £140 or so - they had to disconnect the brake hose. And the spring (£80) had to come from Audi this time.

Here’s a photo of the bits - not just the bottom coil broken this time.

http://i264.photobucket.com/albums/ii187/djjgilson/Headlamp%20Aim%20and%20Stoneguard%20A3/Stoneguard014.jpg

[timfear]

Hi all

I've been having problems with the dreaded stone guard and had a real battle with Audit to get them replaced under warranty. However, I managed to get over this first hurdle and had them replaced this morning. After checking to make sure they had replaced them I noticed the original part hadn't been replaced as pictured in this threat and as was previously fitted. I stormed back in to the Audit dealership thinking they were trying to hoodwink me and that all they'd done was removed them. However, the technician drew my attention to a new part fitted on both sides which looks totally different. They claim that the design fault has now been corrected and that this is the replacement part despite all the brand new A3's in the showroom still having the original.

The part no. on my invoice is as follows:

A1K0 511 533 D 0 013971/STONEGUARD

Can anyone shed any light on this - the new part is much rounder and appears to cover less of the underside of the car hence why I couldn't see it at the front of the rear wheels?

After my previous experiences with the dealership I'm still not sure I completely trust them!!

[djgilson]

That’s the part no of the first generation stone guard! (533D left, 534D right). These were mounted to the lower suspension arm, which runs across the car.

The later stone guard shown in my photos is mounted to the trailing arm, which runs fore and aft.

Maybe Audi have decided the later guard is no improvement, so they are re-introducing the original. Or maybe the dealer is getting rid of old stock. Either way, at least you have new stone guards installed! The guy you spoke to may not even be aware of the history.