Knocking from rear of van

[Fox McIntyre]

I have a knocking kind of rattle noise from the rear of the van, it seems to be N/S/R.
I've checked the CV joints and the driveshafts, so its not that. Its a going 'over bumps rattle', dosn't do it above 45 MPH and worse on rougher roads (obviously)
Its lowered on BMW cabriolet springs which bring it down 2 inches.
It has some interesting top and bottom wheel bearing play, but not side to side, but I'm still ruling this out at the moment as it dosn't do it with the handbrake on and the van on jacks yet it can knock when I'm braking and on the road.
I'm going to take the shocks off tomorrow and potter/bounce along my road tomorrow slowly, to see if lowering it has done in one of the 20Y/O shocks, but if its not that, I'm stumped- All the bushes on the wishbone seem fine with no play, wheel bolts are tight..
I'm doing my nut! Its loud and annoying, and It won't defeat me!

Rich

[CovKid]

Rich - sounds like you've got what I've got. All my CV joints in A1 condition, nothing noticeable in terms of wheel play and yet I get this sound centre to rear of vehicle (I think) that sounds like the gear shift rods banging about underneath - mostly when I'm slowing. Still not found cause yet but will be jacking her right up and doing a thorough inspection tomorrow. If I find the culprit I'll let you know!

[Fox McIntyre]

Rich - sounds like you've got what I've got. All my CV joints in A1 condition, nothing noticeable in terms of wheel play and yet I get this sound centre to rear of vehicle (I think) that sounds like the gear shift rods banging about underneath - mostly when I'm slowing. Still not found cause yet but will be jacking her right up and doing a thorough inspection tomorrow. If I find the culprit I'll let you know!

I'll have a nose at the shift rod as well.. I did think about that but it does it whatever position the lever is in and if I wiggle it, ect. Will check it out though. If I find anything, I'll let you know.

Rich

[CovKid]

Pretty sure its not the shift rod - just sounds like it - kinda metallic. About to jack it up and have a real nose around. Definately worse when I slow down, disappears (I think) under load.

[Fox McIntyre]

Any luck?
I found that when I jacked my van allll the way up, the rear N/S spring made a funny noise, and when I undid the shock lower bolt to get the spring out it was tight but loose..
So, I found that the BMW spring had a little burr on it that was making a metalic scraping noise so I filed that off, refitted the shock with some thread-lok and its all good.
Might be worth spannering your shock bolts, it would be worse I guess if your slowing down as the vans wieght would be thrown forward, leaving the shock to do less but the same, if that makes sense..

Rich

[CovKid]

Thanks Rich, jacked up all four corners in turn. Only thing I could find that might be causing the din is the remains of a former brake pipe that I was never able to fully remove which clattered if i shook one end. Cut that back a bit. Hysterically, MOT failed my van one year for that pipe, despite the fact it wasn't connected at either end. Slight play in one wheel bearing (which I'll do next week) but while laying underneath, I heard a whistling noise like air escaping. Crawled out and unbelievably the tyre valve on one of the front tyres had inflated like a balloon (I kid you not) and was slowly going down! - ANOTHER job to deal with.

However, after all that, I'll bet that bloomin noise hasn't gone so will follow your shock tip. If nothing there, only other thing I can think of doing is removing brake hubs and nosing in there. This noise is driving me nuts.

[CovKid]

Grateful to Merc Doctor today for taking my bus around the block to identify the noise. He jacked each rear corner and ran it in gear to isolate the noise along the drive train and unbelievably its a brand new CV joint with more play than you'd find in a knackered one! Thanks Marcus.

[DubSyncro]

Hi Lads,
Just came across this old thread by chance.

I went to look at a 2002 T4 syncro yesterday with exactly the same symptoms.
When ever I slowed down there was a strange knocking noise from the rear of the van and it dissapeared when I accelerated again.

Would there be any other posibilities for this for this apart from a worn CV joint.Maybe a knackered drive shaft or viscous coupling?

Any ideas??

[CovKid]

Well, I do know mine stopped when I put more weight on so I'd look at shocks, springs. Can only presume in my case that noise was attributable to a part of the shock movement that isn't up to par, causing a clanking noise. Never did actually find the cause.