Suspension: Suspension knock NSF?

[hennabm]

Hi all

I have a knock from the NSF somewhere and can't seem to find the source. It knocks mostly when going over small undulations but not when I hit a big bump.

It was MOT'd at the beginning of the month and nothing was found during the test even suggesting any play or wear.

I have levered the bottom arm bushes and can't see any play.

What is the most likely cause?

Is it the strut bottom ball joint? A forum member already suggested the securing bolts to the arm being loose but mine are tight.

Is it the ARB vertical link?

Is it one of the bushes for the bottom arm that I haven't yet found the play in?

If it is the bottom ball joint has it ever been known for these to break apart?

Any help will be much appreciated.

TIA

[Bugjam1999]

Wheel bearing? Rock the top of the wheel backwards and forwards as you stand next to the car looking at it (ie left and right from the vehicles standpoint) and see if you can hear or feel any knocking.

S.

[hennabm]

Hi bugjam

Yes I thought that and when I took out the bearing to check for wear it was rather discoloured.

So, I changed both w/brg sets the other week so I know they are fine.

Thanks anyway.

[Bugjam1999]

Might they have bedded in over the week and now require tightening again? Just a thought, someone else might be able to agree/disagree with the theory...?

Actually, were they sealed bearings or were they the cup and cone with a tightening nut type? Don't think ive ever changed the wheel bearings on my 240.

S.

[hennabm]

Hi bugjam

They are the "cup and cone" type. Definitely not the bearings as I have checked this morning since the first post.

Cheers

[Suterman]

could be the large shock retaining nut on the suspension leg, jack the wheels off the ground and see if you can tighten it up (large adjustable pipe wrench)

[BrianH]

My guess would be the large 18/19mm nut at the back of the swing arm.

You will need a new Volvo nut which is squished and can only be used once.

Really you need an H lift to get enough room beneath the car to be able to get enough swing on the breaker to get it really tight.

Remember Volvo say you must have the full weight on the suspension and roll it back and fore before you finally tighten.

Good luck with all that. It took me years to figure this out.

BrianH

[Triple-S]

Just wondered: years ago on my 245 I had what sounded similar and didn't want to risk anything breaking so let my friendly freelance mechanic fix it whilst I was at work.
He said something about the top restraint of the suspension strut - he said there was lots of play there, but I never did get to find out exactly where.
Does yours clonk horribly when going over depressions like sunken drains, as my current 240 estate has the beginnings of similar knocks?

P

[hennabm]

Hi all
Thanks for all the suggestions.

I have tried to tighten the strut upper nut - That was tight and a fiddle to get to.

I'll have a look at the large nut at the back of the swing arm.

By using a different lever I have found a knock on the ARB vertical link, lower mount. By levering it against the way I would normally, I got a noise. So my next step will be to purchase a couple of those and try that.

@triple-S - the noise is when there is a small bump in the road rather than a depression like a sunken drain. It doesn't knock with those.

I'll keep you posted when I've changed the ARB links to see if that cures it.

[Clifford Pope]

Possibilities in my experience:

Suspension turret top bearing worn

Shock absorber worn

Rear big-bush on the wishbone. There is no need for the nut to be superhuman-tight. It only holds the inner steel tube 5tight onto the threaded extension - any play will be bacause the bush has broken down and the inner tube come un-bonded. Thightening the nut makes no difference to that.
The only difficulty is simply getting a socket or spanner in to tighten the nut, but a combination of sockets and ring spanner usually works, a bit at a time. Just jack the car up and lower the wheel onto something higher so you can crawl underneath.
These bushes are a pain. They are only a press fit in the housing, but take enormous torque, so sometimes won't stay tight.

Something completely different coming from somewhere else. Noise travels. My nearside suspension clonk once turned out to be the driver's sun visor not clipped home.