Knocking sound from back

[tony_anon]

A4 B6 2003 1.9 TDI.
First time in ages turned off the cd player. Apart from silence, a strange knocking sound was coming from the rear passenger side while driving. Especially noticeable over bumpy roads/small potholes. Looked in the boot for anything loose, all seems ok including spare tyre and the locking nut for the wheels. Had a look in the back seat for any interior trim funnies/seatbelt etc. All seems fine. Even went to local kwik-fit (gud idea?!) to check underside of car. Said all seemed fine i.e. bushes/exhaust/etc.

Sound still there. Anybody got any ideas? Might take to local ******* and get a roadtest with one of their 'technicians' along for the ride.

Cheers.

[tony_anon]

Just got back from *******. Anti-roll bar needs replacing at back. Plastic sleeve around bushes gone. Teccie knew what it was right away during test drive. Reckons £200 to replace!! Parts prob £50 for bar and £20 odd for bushes, rest I guess is labour. I'm sure it can be done cheaper via independent. Rang a few places, need to take in for quotes. Any guesses for the job?

[Niall76]

On a 2003 car I seriously doubt the ARB needs replacing.

Bushes are cheap as chips, find a local indipendant to fit them. Have a look in the 'dealers' bit and see if there's anyone close to you.

[tony_anon]

Thanks. Will try local independents. Would you expect bushes to wear out for a 2003 car so soon if not the ARB? The ******* guy said its probably the ARB. He seemed to think that if the plastic sleeve had gone around the bush for that side, the whole of the ARB had to be replaced as the part is all in one. I'll find a 2nd opinion somewhere else.

[s0niX]

you say he seems to think??

I would get it checked else where first dont go paying for something u dont need... i mean 03 is a bit new for that too happen.

[Niall76]

How many miles has the car covered?

Proflex will make a bush to fit, although I'd say that you'll also get an pattern part from Euro car parts. Also, I don't believe it's all one part, that's crazy if it is. Where are you?

[tony_anon]

Hi Niall,

Sorry for the late reply. Had car checked by another garage, This one says its not the anit-roll bar (although it was a bit rusty but nothing serious). The bushes seem fine also. However, he said that one of the back coil springs has broken and that's what's causing the noise. Its only done 42K after 3.5 years so I'm a bit surprised its the coil spring. How and where do these things break? Are they attached to the ARB? Shock abosrbers?

Cheers.

[Niall76]

No probs. Usually if a coil spring breaks it the pig tail at one of it's ends which snaps off. The ARB is attached to both the suspension wishbones - similar to the path of the rear axles. It's purpose simply is to stop the car rolling about like a small boat out at sea in a storm when you go around corners. The shocks are attached to the wishbones and the coil spring goes either around the shock (coilover) or next to it depending on design. (There are other designs but I'll not go into it). Springs do break and at 42k it's really just down to luck. I've had one break at 120k and my Audi broke both the front springs at under 60k. I didn't even notice until I was prepping it for MOT! No noise, didn't look lower (it's prety low anyway). It's not uncommon. For a rear spring I'd expect to pay £40 - £60 plus fitting. Take it to your local friendly mechaninc - he'll do a fine job at a fraction of the cost.

Hope that helps.

[tony_anon]

Thanks for the info, very useful. Got a price for the part - £55+VAT. Will take to local independent. Reckons about 1.5 hrs to do.

Cheers.

[Dave Avant]

It does seem more common nowadays for springs to snap, especially on the middle to large cars as they are getting heavier. I've seen some snap at low mileages.

But a small note; When replacing suspension parts or brakes, you should replace the item in a pair, ie both sides of the same axle. Its not critical, but the new parts will have a slightly different 'rate' of damping, spring tension, friction than the parts that have done the miles, so it can make the balance or handling 'off'. But you don't always notice, so its up to you on the expenditure. It will be fine replacing just 1 spring, just making you aware.