VZ Diff Clunk, advice needed please

[Cod]

Hey guys I did raise this in another thread before but after changing nearly every bushing I can under the car I know the thud/clunk must be coming from the transmission or differential. After reading old posts on the problem there wasn't any follow up them if the problem was resolved or how.

Anyone know more about this problem now? My car is out of warrantee and I was thinking of taking it to a diff specialist, but didn’t want to pay to have the diff pulled apart if it's a problem with the transmission.

The clunk sound comes from the rear end, out of the diff but I’m not sure what part of the drive train is at fault causing it. It'll do it when shifting gears under light acceleration and lately has gotten worse, will also clunk after taking foot off throttle after hard acceleration.
A couple of times the clunk has "shuddered", as if it was bouncing back and forth clunking both directions in the gearing.

Oh yeah it’s a exec auto v6.

[Aussie_VZ]

I had the same clunk in the diff, i tried changing diff oils made a small difference but still had the clunk, i ended up getting a rebuild.
set me back around $1250 and now its awesome.

plus i had to use synthetic oils which wasent cheap to buy.

[Cod]

Rebuild of the diff or transmission? I'm worried I'll get the diff pulled apart and rebuilt only to find the clunk is still there with the problem in the trans :-/ Because the car does always clunk shifting from 2nd to 3rd under light acceleration, but rarely 1st to 2nd. Had it thudding over and over once when i lightly tapped the throttle while the car was drifting about 10kph but it's intermittent.

If you can remember, did they tell you what parts were worn/needed replacing in the diff? That might help me if i relay that info on to the mechanic.

[Aussie_VZ]

the diff.
i had clunks coming from the back from gear changes and also slow take off.
i had the trans pulled down for a full service and clunk was still there.
also when i was adding the oils to the diff it would stop for maybe a week then came back.
which then i got the diff rebuilt.

main things that were stuffed was the diff gears and because they were stuffed other problems followed.

[Cod]

I've got the car booked in for tuesday to have the diff dropped and cover taken off, anyone else had this problem rectified from a diff rebuild?

I'm still not convinced it's the diff and not the trans as it seems to only consistantly clunk when it shifts from 2nd to 3rd. That sounds like gearbox? Or could that still be the diff even tho its only a particular gear change? I think i read an older post that had someone with the same problem once but not follow up on what happened.

Edit: I've read through these old posts -
VZ Thump from 2nd to 3rd gear
Clunk when shifting 2-3

Mine definitely has a clunk on 2-3rd shifts, maybe i should be getting the box looked at instead :-/

[Aussie_VZ]

In this case id be getting both trans and diff looked at.

[MrVZSS6L]

i have a clunking issue on light acceleration and also when slowing down to a complete stop, i mentioned this to a friends dad which they have said to me its a common problem with the lsd holden diffs also said to change the diff oil and also put a additive in which will take away the clunk havent tried it yet but will be very soon the additive isnt cheap either holden quoted me (my price) $61 so will giver this a go and hopefully it does the trick and fix it

[VzVzVz]

Mine does the same thing. I'm getting my diff replaced with a reco unit soon. I'll lower the ratio just for kicks too.

[mattyk]

it'll be most likey the diff thats clunking, the tranny isnt the best either as is well noted, but aslong as neither are whining OR shuddering, they are reletively normal noises... my SV6 non-lsd had a diff clunk on take offs if i rolled back a bit before (manual) and traction control would flash for a sec... the car used to trailer a caravan, so i assume the gears in the diff slackened for lack of a better word... the tolerances just arnt precise...

Also, my VX SS with lsd has a minor clunk as well when taking off sometimes... but the diff is perfect, the driveshafts have been changed... its just inherite with the design, its not a precise piece of kit... and i've heard many times of the ls1 piston slap issue, very minor sounds are common from an engine such as the ls1, and do not harm performance... its just how they were build... not german... lol...

[Clutchy]

It would be the backlash in the diff they should be able to shim the diff to fix it it wont need a full reco unless its gone to far but id be goin to a diff shop not holden or a machanic just a shop that does diffs as they will be ya best bet.

[bigdaddycool]

Diff oil grade can effect it definately........ Depends really how bad the clunk is, I know when I changed my diff oil on my original vz diff to the holden manuals recommended it seemed worse........... anyways I changed it to thicker stuff and it was fine......... i changed my diff to a 3.45 vt lsd diff and still use the thicker stuff with an additive and it's pretty much fine.

If it clunks only on hot days thats probably nothing really to do with the diff, more to do with the car being hot (adjusting the fueling etc)........ from my experience anyway.

[sp001in]

hey mate, I just replaced my VY diff, doing the exact same thing, under light accelearation when coasting or when decelerating. Is is backlash and is from wear of the crown and pinion in the diff.
i tried replacing the oil and even added the $65 LSD additive from holden first before replacing it. only way to fix is to replace crown and pinion.

I found a VZ SS diff on ebay for $400. and had it fitted for $260. V8 and V6 diffs are 100% interchangeable. without any modification. I even managed to find one with a similar ratio.