Xantia- knocking noise

[lazza]

HI

Well having fixed the rack and pinion problem and the airbag slipring... looks like all my work has created another one!

Now at slow speeds on small acceleration or light braking I can hear a knocking sound which appears to come from the left hand front wheel getting towards the maximum turn to the left. The same noise is replicated when going slowly over small bumps.

If you've followed my work, you'll know i took off the front subframe to examine the steering system... the wishbones I swung towards the front out of the way (to save undoing the ball joints) so that I could work on the steering. I wonder if I damaged the drive shafts or something like that??

I know it's difficult to diagnose this kind of thing, but any suggestions very grateful.

Cheers
Larry

[CitroJim]

Larry, as you’ve had all that lot in bits recently it's well worth checking that all nuts and bolts you disturbed are still nice and tight.

That the noise happens on light acceleration and braking points to the wishbone moving, possibly, if all is tight, to a failed front wishbone bush or a failed lower swivel joint. Perhaps having the weight of the wishbone on it at a funny angle upset it?

The other possibly is that it's the brake caliper making this noise...

It's similar to the noise I had on my Activa recently and we diagnosed that by carefully looking for play and movement in the suspension as the car was rocked back and forth... We could then see the whole wishbone moving sideways and creaking.

[lazza]

HI

Yes, I thought it may be something along those lines. However, I've checked all my nuts and bolts and they were all nice and tight (i'm a bit obsessive about tightening) so that was as expected. The wishbone bushes are not great, but also not terrible, so I doubt it would be those on a simple visual inspection (i could be wrong).

In my examination however, I did notice a strange anomaly. Whilst lifting the right hand side (with an spanner on the lower suspension ball joint- well the one on the wishbone) I noticed that the hub raises nicely up to this point and is quite spongey:



However on the left-hand side (the side I believe the knocking to be coming from) I could only lift it a certain way up and the piston seems to be very hard:



So i guess this is something to do with the suspension arm- or the lower ball joint??

[CitroJim]

It's an interesting anomaly Larry but unlikely to be the cause of the knock.. More likely one strut has a little more internal leakage then the other. Nothing more than that.

Tell me, does the car sink at the front if left for any length f time?

[lazza]

HI Jim

Yes it has tended to recently.

Ok, so if it's not that... err i'm perplexed as to what it can be.. could it be the lower ball joint?

[CitroJim]

could it be the lower ball joint?

Yes it could Larry and it could also be play in the front wishbone bush too..

Try levering the wishbone from side to side...

[lazza]

Err, how exactly can I do that- i cant quite work it out what parts to put the bar between?

[CitroJim]

A spanner on the balljoint nut will do it Larry... If the wear is bad enough you'll see movement...

Else do as I we did. Put the handbrake on hard and have someone rock the car back and forth. Any movement will be visible and will be felt (and possibly heard).

Also, jack up so the wheel is clear of the ground and grasp the wheel and try rocking it up-down and side to side...

[lazza]

Nope, cant see any real slack in the lower ball-joint. When I move it forward and backwards there's a slight movement in the wishbone bush.. is this normal, or should it not move at all?

[CitroJim]

Nope, cant see any real slack in the lower ball-joint. When I move it forward and backwards there's a slight movement in the wishbone bush.. is this normal, or should it not move at all?

You might see just a little tiny bit of movement in the rear rubber P bush as the rubber flexes but you should see no movement at all in the front bush...

The lower swivel is a bit hard to check and if any doubt exists it needs to be separated from the wishbone for testing. Just moving it around disconnected from the wishbone will soon show up any wear there.

[lazza]

Ok thanks. Well, it looks like i'll be replacing the front bushes as a first step. The protective cover on the right-hand side lower ball joint has gone, so I guess I might go the whole hog and change the ball joints aswell.

Then if it still makes the noise.. it's something else !

[CitroJim]

The protective cover on the right-hand side lower ball joint has gone, so I guess I might go the whole hog and change the ball joints as well.

It's likely to be worn then Larry..

A missing rubber boot on a balljoint is now an MOT failure in the UK...

[Hell Razor5543]

As well as a damaged cover on the drop link joins.

[lazza]

I was looking at the Haynes manual, and it said something about refitting the wishbone that before tightening the bolts "the lower edge of the outboard end of the lower arm should be positioned approximately 8mm below the lower surface of the suspension subframe".

When I refitted the two wishbones, i simply tightened the bolts in what seemed the natural position.. ie with the suspension strut at its lowest (depressurized, front wheels off ground) ... should I have done something different? their instructions are hard to follow

[lazza]

Hi guys

A funny thing has happened. Having resolved to have to change the lower ball joints and the front wishbone bushes, I put the car back together to wait until an opportune time to do the jobs.

Magically, the noise has disappeared! Not a dicky bird.

The only thing that occurs to me. I did manage to tighten the front wishbone bushes bolts/nuts very slightly as much as I could. Maybe they are worn, and needed a bit more pressure.... I guess the noise will return again therefore when they wear a bit more, but for now I'm inclined to go with the maxim "if it aint broke, dont fix it".

So thanks as ever to Jim and others... i'm a happy guy ... until the next time

Larry