Front-end Knock [Resolved]

[Paynewright]

I've always had an occasional knock from the front when hitting a speed bump or pothole, from either side, which has got more frequent of late. Occasionally, the knock is a fair bit louder and can be felt through the floor via my feet.

I recently put the winter wheels and tyres on and there was a very slight bit of feathering on one edge of one tyre after a year of use. For this reason and the knocking I booked the van in for a geo check and mentioned to the guy.

He had a quick drive and picked up lots of movement of the front wheels under sudden braking (I watched a couple of inches of movement on the front wheel when he braked) He put up on the ramps and could detect a bit of movement in the rear bushes on the front control arms. So I swapped the control arms out for Meyle HD arms with solid bushes rather than OE ones with voids. The old rear bushes were starting to split, surprisingly at only 11K miles but not unheard of. I was confident this would sort it, however, it still knocks. I also fitted new bottom ball joints.

So, I've done a nut and bolt tightness test of everything at the wheel end, put a bar under the wheel and levered up and down to check strut top mount tightness, wheel bearing check, hub nut check and nothing untoward found. I disconnected the ARB last week and went for a drive and slight knocking still there but no big bangs (It was only a drive around the village over the usual speed bumps so possibly not enough to induce a big knock).

On smooth(ish) road it drives perfectly, corners nicely and no vices. The tyre wear suggests there isn’t much out geometry wise.


The van is on H&R -40 springs and Koni dampers, fitted at about 1000 miles.



Next steps:-

• New drop links and ARB bushes (albeit disconnecting the ARB suggests its not this). Can anyone suggest an equivalent 40mm longer drop link from the VW parts bin that is suitable (I’d rather not have adjustable ones)? I wonder if the big knock is the ARB hitting the chassis rails?
• Fit new top mounts / bearings like these… MEYLE HD 2 Top Shock Strut Mounts Bearings VW T6 Transporter T5 Upgrade Kit NEW! | eBay
• Anything to do with the subframe?

I'm running out of ideas what it could be – any other suggestions / things to check?

Cheers
Ian

 

[Dogs Dung]

I’d put money that’s it’s a sub frame mount

is it mostly on camber when you hear the knock

had my prev T6 done with same symptoms

Our local dealer had tried everything including front end parts from a stock vehicle, and eventually narrowed it down by process of elimination

 

[Ed Webb]

@CRS Performance

 

[Paynewright]

I'd already been in touch with Steve.

 

[Minimucks]

Sounds a bit drop linky to me.
Annoyingly it might end up being one of those jobs which only gets found by the process of elimination.

 

[Paynewright]

Sounds a bit drop linky to me.
Annoyingly it might end up being one of those jobs which only gets found by the process of elimination.

That's what Steve @CRS Performance said - May do the bushes too. One thing I dont like is that the OE ones don't use a rod anymore, but a folded bit of flat steel in a U shape.

I'd like them a bit longer though!

 

[Minimucks]

I know what you mean. Had a similar issue with an AMG c class merc previously.

I was very surprised to see that the originals were made of plastic.

 

[Paynewright]

Bit of googling, with an inkling of Vauxhall Insignia from a thread on here, looks like it has a 300mm drop links with M12 fixings and 180 degree rotation on the fixings (Vs 260mm T6 OE size).

The Meyle part number is 616 060 0003/HD. I’ll do some more checks tomorrow before ordering!

 

[ei-aprilia]

I'd say it was drop links too, been there and got this t-shirt.

 

[Dave Lawson]

Keep us posted @Paynewright mine is the same, drives and corners great (CRS) but knocks on bumps/potholes?

 

[BognorMotors]

Are you local to us, to bring it in for a look?

 

[Paynewright]

I’m south Leicester so a bit of a trek! Thanks for the offer

 

[matt_r]

Keep us posted @Paynewright mine is the same, drives and corners great (CRS) but knocks on bumps/potholes?

Same here..

 

[JasonW]

I thought this was a common issue if the vans been lowered as the lowering spring has less compression.. so occasionally if you hit a pothole or vicious speed bump too fast the spring coils will touch, leaving no compression resulting in a 'knock' sound...

That was just my thoughts and you would need stronger springs which compress less under load.. but then would probably compromise the fantastic ride achieved by the konis on 90% of road surfaces...

Yes, keep us posted @Paynewright as it will be interesting to see if you can find a fix..

 

[Dogs Dung]

The knock I had was t over potholes or speed bumps, it was always while turning at slow speed and particularly so when on a camber , I had H&R springs , knock was there with both standard and H&R Springs, 20” wheels and 16” standard wheels ,

Gents the knock I was feeling was as per the OP and could feel it thro my feet/pedals, we may be talking about differing concerns

 

[mtm77]

Following also

I have a sharp knock if the brakes are applied quickly - almost like the callipers are moving or the brakes need bleeding.

Have had it in with the dealers and apparently it is a characteristic!

Dec 2019 t6 kombi edition 150 dsg, 7000miles

 

[Paynewright]

New 300mm drop links ordered. I’ll report back once fitted!

 

[CarpyT6]

I have something similar, can you disconnect the drop link and take for a drive to see if that is the issue??

 

[Grim Reaper]

I had a similar knock that felt like it was coming from the floor under my seat, it was the drop links (newly installed uprated adjustable ones from VMaxx) that had worn through the powder coat on the new uprated H&R anti roll bar and were moving ever so slightly in the holes, after retightening them the knocking went away.

 

[Paynewright]

So today I’ve done two things and the squeaky / creaky noise over speed bumps has gone away:

1) I was going to fit the 40mm longer drop links however, on full droop (jacked up & on stands) the ARB is touching the wishbone which didnt feel right so I refitted the old drop links and did the nuts up really tight.

2) whilst doing this, I noticed the bump stops were appearing out of the bottom of the dust shields on the front shocks. These are usually an interference fit in the spring seat at the top of the assembly. I could push them up to the top but they just fell down again. I then disconnected the dust cover and dropped it down to see better, hoping I’d be able to re-attach it. Bump stop would go into seat but instantly fell out again. I took a couple of pics and went inside to google. It would appear the bump stops have been cut down, shortened on the end that fits into the ally spring seat, so they are no longer retained. It is simply loose (literally) on the piston rod. A couple of wraps of trim tape and a bit of insulation tape was enough to jam the bump stop back in as a temporary measure. With patience I refitted the dust covers.

I think I understand the logic in shortening the bump stops - less suspension travel so likely to contact more often. But why not shorten the free end rather than the section that is designed to attach to the strut top?

Anyway, after driving a local very bumpy B road and several speed bumps in the village, all is quiet. I still think there is further work needed to resolve the occasional hard bang (I still think this is ARB touching the chassis rail on full compression).

I’ll drive it and report back in a couple of weeks if anything changes.

Ian