Traveling along a bad dirt road in my 2006 Subaru Forester XT when suddenlly there were a couple of huge bangs from the left rear suspension - it sounded like the suspension was forcing its way into the car. Stopped immediately and checked but couldn't find anything wrong so carried on a lot slower only to have it repeat several times whenever the car went through a dip in the road.

Strange thing was that there was no banging when travelling at speed on corrugations and car handled absolutely normally with no skittishness so went back to travelling at my normal speed on the better dirt roads only slowing to around 70kph when the going got rough. I did about 100 km's on dirt roads after it started banging and it seemed to take a hollow in the road where the suspension was rapidly unloaded then loaded then unloaded again for it to happen.

Took the car to a suspension shop as soon as I got to civilisation and they put it on the hoist but neither I nor the technician could see or feel anything wrong. Checked the top strut mount but it seemed fine visually - I could see that the technician thought I was BSing so took him for a drive and when he heard it his eyes went wide and he told me to stop immediately as something was seriously wrong as he had seldom heard anything so bad - checked the car again on the hoist and still couldn't find anything so he said it must be a shock absorber problem although in every way the shock seems fine.

Just done a 200km trip at 120 kph on tar and not a single sound.

Any thoughts before going to the expense of replacing shocks maybe needlessly.

Have a 1000 km trip on Saturday to get back home and to the nearest Subi agent so some thoughts & advice might help set my mind at rest.

Broken coil springs can be very hard to spot and might explain the symptoms?

maybe the bump stops are missing at the back

[Edited on 18/5/11 by Mr Whippy]

Does your Subaru have active suspension? My Disco 2 did exactly the same thing. It was a software fault in the ACE unit making the hydraulics thumping away at random. If you have Active Suspension disable it by removing ther fuse/relay and see if the symptoms go away.

Are you sure that policeman was sleeping?

Sounds like a broken spring to me, probably at the top or bottom end. More common than you would think.

spring can make one hell of a bang.

I had exactly the same when the spring broke on my honda - was right at the top where it seats intot he top mount and not at all obvious.
Regards
Hugh

Thanks for the replies guys - never thought of a broken spring - will check that out first.

And no - it doesn't have active suspension - Subaru's just arent that sophisticated.

Just to complete the thread:

Got home safely - the suspension behaved itself till Cape Town although I took it easy on right hand bends but in Fish Hoek the handling started to deteriorate noticeably and rattles and bangs increased - turns out it was definitely the shock that failed - replaced it today. The Technician at Subaru mentioned that it is normally the left rear shock that fails on Foresters - no one knows why.

that's good to know I have the same symptoms on the WRX at the moment, and so will get it done in the next few weeks

thanks again