Shifting thud movement below car

[Cod]

I tried asking this before in another post but it disappeared for some reason O_o

I'll try explaining this best I can and hopefully someone can offer me advice. My 2006 VZ auto has a clunking/shifting movement below the car, it seems towards the rear.

After braking then accelerating I’ll feel something move and give a light thud sound, I notice it more so if I’m accelerating out from an intersection turning at the same time. I've found that I can get it to lightly "thud" over and over if I gently tap the throttle when the car is coasting very slowly (about 20kph). The car will also do it when shifting gears from 1st to 2nd or 3rd (only after I've been on the brakes which I assume shifts the loose moving part forwards).

I've had the car up on a hoist with the mechanics pushing and pulling at the transmission, rear diff etc. but not luck in finding what it is.

I'm thinking some worn bushes or mount somewhere could be doing it? Car has done 97,000kms, the problem was there when I bought it a couple weeks ago.

[Not_An_Abba_Fan]

I have a Senator that is doing the same thing. I think it is the diff mount bush. Or it is the diff itself.

[Cod]

I have a Senator that is doing the same thing. I think it is the diff mount bush. Or it is the diff itself.

Yeah I think it's something around there, there's no "clang" or metal on metal sound, it is more of a deep thud so i'm thinking rubber or plastic bush sliding around(with weight behind it) somewhere.

[bigdaddycool]

change diff oil, see if it helps over a week......... if not, get ur diff and or universal joint checked.

[Exidor]

Mine has a thump too when changing to third
under a light throttle.
There is also a dull muffled "let me out" coming
from the boot region. Gotta check it out one day.

[vb sle 253]

center bearing?

[az_sv6]

yeah i get the same thing. i can go weeks without it happining but some days it will happen over and over again.
the hole car jolts when it happends

[Kal123]

I get this all the time.. Will get it 100% of the time in a drive through, when driving really slowly, will thud a few times.

Will also thud when im reversing while turning. It's bloody annoying. I'm getting my diff oil changed soon, and the nolathane diff bush, will let you know how that goes.

I've also heard it's just the A5 gearbox.. But if people are getting it in the 4sp, then I guess not..

[JBDrifter]

I'm glad mine doesn't do this! When I was looking for my new car I was considering a BA/BF XR6 and they ALL had the diff thud problem, which turned me right off them! I had heard that some VZ's also suffer from it, but none of the ones I drove had it. I'll consider myself very lucky as it seems to be quite common... or I'll probably jinx myself here by posting this lol.

[Cod]

After seeing others also getting the same issue it seems to be a common fault with the VZ's, surely a mechanic somewhere has seen a lot of this and would know what needs to be fixed/replaced.

[boofis]

My Auto VZ does this too. Not very often, as a previous poster said, usually when crawling really slowly, i.e. stop/start of a traffic jam.

I've never been too worried about it..... clunky diffs + commodore = normal! LOL!

[JBDrifter]

After seeing others also getting the same issue it seems to be a common fault with the VZ's, surely a mechanic somewhere has seen a lot of this and would know what needs to be fixed/replaced.

If they're anything like the Ford BA/BF then no, nobody has a cure for the problem. My dad owns a BA MKII XR6... had his diff replaced 3 times under warranty but still no fix. He's been a Ford man all his life but says he'll never buy another one in his life (I don't believe him lol... we'll see).

[Cod]

Kal123 I just had a look at those nolathane bushes, i think it might be the way to go and sounds like from their description they correct the problems we're having. Can't paste the description from the PDF catelogue because they've "secured" it for some reason.

http://www.nolathane.com.au/catalogu...ogue_Ed9.0.pdf

Anyone who's interested open that up and search for "differential" until you get to the Commodore Differential Mount Inserts section.

I was going to get one of those but it suggest in the description to get the Rear Cross Member Mounts as well with the diff bush, didn't want to waste money getting the other mounts but at the same time i dont want to have to place 2 orders and making 2 visits to the mechanic for installation.

[Cod]

I'm a bit impulsive so i've just bought the nolathane bush i was just talking about, getting it put in this afternoon, i'll let everyone know how it goes.

[Fully]

I was just about to post this very same topic!

Well I just picked up a vz sv6 2 weeks ago and have since noticed the same thud sound coming from the rear when mainly reversing and turning.

When i bought the car I had it inspected by State roads which did not even mention the issue, now i am hoping to get it fixed with their warranty they provide

Let us know how the replacement mount goes and the total cost please

[andyman]

ahh the old umm,,,, im trying to think of the term here.......... cyclic knock they call it,

caused by the outer splines of the cv shaft being undersized and slightly twisting causing the knock,

there was a fix kit for it, unsure if you can buy it, but you need to swap a couple of parts on the cv shafts i believe to an uprated spec spline, and apply loctitie to the splines, let the car sit overnight to set and off you go again

[Exidor]

Diff noise " cyclic knock " a Holden Service Issues

[Fully]

ahh the old umm,,,, im trying to think of the term here.......... cyclic knock they call it,

Diff noise " cyclic knock " a Holden Service Issues

The link above applies to non lsd differentials as i have an may 05 vz sv6 wouldnt i have a lsd? does it affect lsd aswell? what would the cost be on this fix?

Cheers

Jezza

[Exidor]

LSD optional on SV6.
Check compliance plate or stick your head
under your ride to find out.

[Cod]

The nolathane bush didn't fix the problem, still clunks from 2nd to 3rd. Costs $49 for the part and half an hour labour to install but is done in about 15 minutes.
I'm going to check out that cyclic knock link.

[Adlikada]

ahh the old umm,,,, im trying to think of the term here.......... cyclic knock they call it,

caused by the outer splines of the cv shaft being undersized and slightly twisting causing the knock,

there was a fix kit for it, unsure if you can buy it, but you need to swap a couple of parts on the cv shafts i believe to an uprated spec spline, and apply loctitie to the splines, let the car sit overnight to set and off you go again

I had a mechanic look at mine nearly two years ago when I had the same noise. Worried the hell out of me, as I use my car for work. The mechanic said it was the UV Joints (only mine was only the drivers side). I still haven't had them replaced or repaired, and I hardly hear the noise now, it comes back sometimes, I'll get it fixed eventually. The whole car needs a good service, and a few other things done to it first (like, fix the oil leak!).

[impulsive]

Extreme Thread revival...

[fyfee]

Extreme Thread revival...

Good thing too. My car is doing the same thing. Haven't been too worried about it, it's more annoying than anything. Has anyone found a fix for it? By the way mine is an LSD and 4 speed auto, if that matters