knocking sound from the front, confused!

[Dony-Jam]

Hi everyone.

Hopefully, someone can help me with this one, it is a 56 Passat b6 2.0 TDI saloon.

Just trying to get her ready for the next MOT, I noticed the driver's side CV boot was torn a little around the inner boot clip (wheel side) so I've removed everything as normal to change the CV boot, packed it with grease and put everything back together with no issues (new cv boot)
When I've come to test the car, there's a persistent knocking coming from the front end, mostly over smaller sharper bumps and dips on the road, it doesn't seem to happen over speed humps which to me rules out any problem with the suspension if I'd upset anything having it up in the air.
Over the smooth sections of the road, there's no knocking at all.
It's quite difficult to pinpoint where the knocking is coming from, sometimes it sounds like the front left but other times it sounds central or on the right.

I've had the car back in the air and checked all over, springs, ball joints, everything I can think of and made sure everything is tightened back up as it should be and still it's there so yesterday I completely removed the driveshaft and split the wheel side CV joint again to make sure nothing had gone wrong in there but its all fine and as it should be but what I did notice is the transmission side CV joint feels dry and lumpy when you rotate it by hand?? there's nothing wrong with the CV boot at that end though, could it be that knocking the drive shaft about a bit to split the CV joint and then again to rebuilt could have caused the dry bearing to start knocking? or is there more chance I've upset a hub bearing?

I'm stumped, I just can't figure out what's gone wrong, has anyone got any ideas? I'm praying someone just knows what mistake I'm likely to have made.

Any help would be greatly appreciated,

Cheers, Jamie...

[Roverfan]

Sounds like anti roll bar links

Knocking over smaller road irregularities but not over speed bumps etc has always proved to be anti roll bar links for me.

Confirm this by feeling for looseness before changing any parts. Tug it for front to back and side to side looseness

[Crasher]

We had an 8P A3 in yesterday (same basic PQ35 platform as the PQ46 under the 3C) with a seemingly catastrophic rattle and in the air I could see nothing even after bending and levering everything with a big bar. With someone in the car rocking the wheel I could see the new (not us) drivers lower ARB drop link nut was loose.

[DMitch16]

Car is old enough to have worn inner tie rod ball joints or steering gear, as likely to be Gen 2 rack, both of which often only make noise over smaller sharper road undulations. Sound transmission with everything else now tighter and no CV joint noise may make it seem like suspension perhaps? It is the shaking that emphasises such noise rather than fuller suspension travel (e.g. over speed bumps) or no travel (e.g. smoother roads).

With the engine off and gently rocking the steering left to right very slightly is there a noticeable knocking? You will hear it clearly if there is wear in either pinion gear or inner tie rod end ball joints.

Also, check your REAR shocks as often with older springs, a top coil piece breaks off and ends up inside the remaining spring and wishbone cup. Mine did!

[Dony-Jam]

On the wheel side of things the roll bar drop links are the only thing I didn't actually check so could be those. I watched some YouTube clips of drop link related noise and it sounds very similar. Will be checking those later, weather permitted. If that fails it will be a deeper look at the parts you mentioned Dmitch16. Fingers crossed for drop links though, cheap and easy fix 🤞🏼

[Dony-Jam]

Got the car in the air again. Just had a loot at the drop links and apart from being rusty the rubbers in them look OK and they aren't loose but the other bell shaped bushes further down the anti roll bar don't look in great condition.

How tricky are these to change?

[DMitch16]

Got the car in the air again. Just had a loot at the drop links and apart from being rusty the rubbers in them look OK and they aren't loose but the other bell shaped bushes further down the anti roll bar don't look in great condition.

How tricky are these to change?

If you mean the actual Anti Roll Bar mounting bushes then pretty easy, they are split so just wrap around the bar and are bolted down with retaining brackets. From memory I don't even think you need to undo the droplinks nor remove the ARB and can just do it on the car. Perhaps a chance to fit polys as they'd be a better (but a bit more expensive) shout?

[Dony-Jam]

Cheers for that Dmitch, mine don't actually look like they're split. If that's the case is it just a case of taking the droplink then sliding it off the bar or has the bar got to be clamped in place while the job is done if you have to take the droplink off?
Hopefully I'm making sense and talking about the same part, if you imagined looking at a bell from the side, it's a similar shape to that with 2 bolts and a rubber bush with the roll bar going through the center?

Cheers, Jamie

[Crasher]

If you mean the actual Anti Roll Bar mounting bushes then pretty easy, they are split so just wrap around the bar and are bolted down with retaining brackets

Sorry to disagree but they are evil to do. You have to drop the entire subframe (so you need the four alignment pins and ALL new fasteners which there are a lot of) and that means disconnecting the rack (VW say inside) and following the VAG way, disconnect the ball joints and track rod ends and then lower the subframe down on a jack or gearbox lift if the car is on a 2 post. I tend to also diverge from the VAG way by leaving the assembly dangling from the ball joints and release the rack from the subframe leaving it dangling so you don't have to disconnect the track rod ends.

The bushes themselves are not available standard, only as a full roll bar which can be bought aftermarket from Febi or Meyle in some cases and to fit poly bushes the clamp, which is a two piece part peened over, has to be drilled to get it apart and it's a fiddle to reassemble the clamp.

[DMitch16]

As usual you are correct Mr C and I have the front and rears in a mucking fuddle. Rears are a P.O.P. as I have just done a rear ARB on a 2010 and fronts are a royal P.I.T.A. due to subframe removal which adds 30 to 45 minutes each way to the job. Apologies to the OP for getting his hopes up, it's a sod of a job. I've had my subframe off in 25 minutes when in a hurry, but 6 new subframe bolts are needed and cost depends on how well you get on with the VW parts department. I get a great discount from my local dealer.

VW Special Tool T10096 subframe alignment pins required as mentioned (torque no more than 20Nm), with perfectly acceptable imitations on a well known auction site for around £8 to £15.

Set a full day out for this minimum if a DIY on the drive and it's the first time.