Difficult to describe...

Philip Chidlow · Post by **Philip Chidlow** » Thu May 24, 2007 9:41 am

...but the TXD estate is making some noise from the front end. I'll try to describe: At low speed along slightly uneven (normal) town road there is a muffled clonk (irregular) that seems to be transmitted a bit through the steering. My instincts tell me it's coming from the driver's side of centre. But not sure. At cruising speed there seems to me a dull thunking but also at higher speeds I notice some (and this is difficult to describe) lack of 'smoothness'. I don't instantly suspect wheel balance but I'm having new wheels and rubber soon anyway. It is certainly something not quite right.

I also thought 'struts' but they don't creak or groan when rising or falling...

What are the probable (possible) causes? I want to make a 'checklist' and go through it.

Post by **mat_fenwick** » Thu May 24, 2007 10:16 am

Anti roll bar drop links perhaps?

Philip Chidlow · Post by **Philip Chidlow** » Thu May 24, 2007 10:26 am

That's one for the list...

cheers

jeremy · Post by **jeremy** » Thu May 24, 2007 10:46 am

As the drop links are part of the roll bar system they are not under load when both front wheels move - as when traversing a joint in a concrete road surface or a speed hump that goes right across the road and is met square on. In fact its only under these circumstances that you have pure hydropneumatic suspension - for a single wheel bump the anti-roll bar is part of the system so some steel spring is involved.

This means that you may be able to distinguish which circumstances produce the noise.

However the drop links are not going to cause a roughness - which could be caused by an engine mounting which might even allow something to touch the bodywork.

Another possibility is the front wishbone inner rubbers (lever between bush housing and chassis) or the bottom ball joint between the hub and the wishbone (Support chassis, raise wishbone a bit and lever between it and the hub)

AlanS · Post by **AlanS** » Thu May 24, 2007 12:19 pm

Common one used to be ball joints on the drop links partially seized. When they try to move, they clunk and do affect the ride to a degree.
I have removed them, lifted the dust cover, tapped the back of them with a small hammer, regreased and reassembled and they've lasted for years. I have also seen the rack end worn and giving a strange knock, but my money would go on the drop links being almost stuck solid. The half shaft bearing on the driveshaft can also cause it if it's worn.

Alan S

Philip Chidlow · Post by **Philip Chidlow** » Thu May 24, 2007 1:14 pm

Thanks for the advice. I'll report back.

DLM · Post by **DLM** » Thu May 24, 2007 1:16 pm

I started on de-clunking and de-rattling the front end on my most recent purchase last weekend by replacing the droplinks (without greatly reducing the clunks). As a BX owner of 15-years standing, I was both ashamed and amazed to realise it that it was the first time I'd done this myself, as the drop-links are classic front-end rattlers on a BX.

They are hardly rocket science to replace, but awkward buggers all the same. I found it both reassuring and worrying to be following the "hacksaw cutaways" present in the wheelarch protectors, once I finally realised this was the only way I'd free the roll-bar ends of the old droplinks. The lower-arm-end nuts undid with a minimum of fuss but the insert required a lot of "persuasion" before they could be withdrawn. The old links were totally grease-free under the boots, and hence had a lot of play in all directions. Maybe this can have a bearing on lazy height correction at the front end, given the increasingly indirect connection to the rollbar in those circumstances?

Jeremy is spot-on on the other points to look at, and these are the next ones I'm checking, but I'm advised that balljoint replacement is not to be undertaken lightly, though it's tempting because the balljoints themselves are very cheap. I have a gut feling that strut wear could also be a factor in front-end noise, but can't quantify it.

I'll point anything useful I discover in this ongoing exercise, but I'll be very interested to see what happens once I replace the oil-soaked lower engine mount, as this is a classic cause of big drivetrain clunks, among other things. In the worst cases, the engine swings back and contacts the subframe with a pronounced thud on taking up gear.As my new BX was found to have a completely fractured top engine mount when collected (now replaced), this task is a priority.

Oscar · Post by **Oscar** » Thu May 24, 2007 1:51 pm

It may be worth checking that the steering wheel column is still firmly bolted to its bracket underneath the binnacle. I thought my front end was going to drop off on one occasion - turned out that 3 of 4 nuts were loose on the bracket

Philip Chidlow · Post by **Philip Chidlow** » Thu May 24, 2007 2:00 pm

That's interesting, Oscar. Thinking about it I do get knocks transmitted through the steering wheel.

Oscar · Post by **Oscar** » Thu May 24, 2007 3:59 pm

Another possibility is that the steering column sometimes drops out of its lower bearing, and you get looseness and knocks that way. A sharp tug upwards on the steering wheel does the trick.

I'm not suggesting that these are responsible for all the knocks or vibes, but it's worth eliminating.

O

Kitch · Post by **Kitch** » Thu May 24, 2007 6:44 pm

I think I have exactly the same noise! But I've never been able to put my finger on it.

However the other day, I jacked the front of the car up (one side only) and lifted the strut with the suspension on normal setting. I had some play, and then that noise. I wondered if my struts were cained?

RichardW · Post by **RichardW** » Thu May 24, 2007 9:19 pm

I've had similar troubles with a Xantia. Knocking away, but when on high suspension and jacked up no play evident. Took me a long time to figure out it was a track rod end, and it went tight when on high

Try rocking the wheel 3 o'clock to 9 o'clock at normal height with it on the ground...

Barnsley BXer · Post by **Barnsley BXer** » Thu May 24, 2007 9:36 pm

I had a knock a while back,replaced the usual drop links and still had the same noise.After a seized caliper repair(plenty of bashing to free it) the noise was worse.Upon investigation,it turned out that one of the caliper bolts was a bit loose.Tightened it up(very tight).Bingo.No noise

Philip Chidlow · Post by **Philip Chidlow** » Fri May 25, 2007 3:12 pm

Narrowed it down to a noisy o/s strut. Not a lot I can do about that (with any lasting benefit) so unless I can get my mits on a VGC replacement (as I don't want to fork out for one at a breakers with no idea whether it'll be an improvement) I'll have to live with it.

Also some droplink wear in the very early stages and I will check again at the next service.

mountainmanUK · Post by **mountainmanUK** » Fri May 25, 2007 3:38 pm

Sometimes, the simple act of disconnecting bits, then putting them back together with a bit of grease to taste, can actually 'quieten down' some of those irritating little creaks and groans!
Obviously it won't fix the long-term cause, but it can make things a bit more bearable until a suitable time can be arranged for fitting replacement bits!