Clonking diff

Author
Discussion

FENTY

Original Poster:

47 posts

177 months

Wednesday 10th January 2018
quotequote all
Hi everybody just bought my second cv8 and it has a clonking diff drivechafts have already been replaced so I am going to go for a diff rebuild . I was thinking £500 should cover it. Where's best to buy parts

91964

266 posts

193 months

Wednesday 10th January 2018
quotequote all
How many miles has your monaro done? Have you considered changing the ratio? I would like to go for a better ratio in mine but don’t really know where to start.
Sorry I realise this is no help to you whatsoever but possibly another option if standard parts are hard to find

stevieturbo

17,229 posts

246 months

Wednesday 10th January 2018
quotequote all
you sure it needs rebuilt ?

Many clonks have been sorted with friction modifier in the diff.

91964

266 posts

193 months

Wednesday 10th January 2018
quotequote all
stevieturbo said:
you sure it needs rebuilt ?

Many clonks have been sorted with friction modifier in the diff.
Is this a liquid additive? Like slick 50

monkfish1

10,874 posts

223 months

fred bloggs

1,300 posts

199 months

Thursday 11th January 2018
quotequote all
Bet one or both cones are broken.

Yes friction modifier will shut it up, but then youll be spinning one tyre everywhere.

I fixed my diff with a kaaz. works properly now.

maccavvy

660 posts

163 months

Thursday 11th January 2018
quotequote all
mine used to clonk a little on low speeds on lock.

drained all fluid over night..new Castrol syntrax fluid.. quiet as a mouse now

selym

9,539 posts

170 months

Thursday 11th January 2018
quotequote all
maccavvy said:
mine used to clonk a little on low speeds on lock.

drained all fluid over night..new Castrol syntrax fluid.. quiet as a mouse now
This has got to be your first port of call, and may save you £470.

FENTY

Original Poster:

47 posts

177 months

Thursday 11th January 2018
quotequote all
Thanks for all your replies. The P.O. has tried replacing oil and the shafts but it still clonks and gets worse as it gets hot.
It has had the 3.9:1 mod done to it already which I am pleased about as my previous car had this and it was excellent.
My intentions are to replace the lsd unit with an aftermarket one i think. True trac or Kaaz who supplies in the UK and what are the prices anyone know

FENTY

Original Poster:

47 posts

177 months

Thursday 11th January 2018
quotequote all
Thanks for all your replies. The P.O. has tried replacing oil and the shafts but it still clonks and gets worse as it gets hot.
It has had the 3.9:1 mod done to it already which I am pleased about as my previous car had this and it was excellent.
My intentions are to replace the lsd unit with an aftermarket one i think. True trac or Kaaz who supplies in the UK and what are the prices anyone know

mfp4073

1,940 posts

173 months

Tuesday 16th January 2018
quotequote all
If you are going to replace the LSD, I would pay the extra and buy a Wavetrac as they seem to work without the dreaded clunk. Some people run Truetracs without any issues, but mine clunks like you would not believe. I'm going for a Wavetrac in a few months time. I would suggest that you replace all the bearings while you have it all apart.

stevieturbo

17,229 posts

246 months

Tuesday 16th January 2018
quotequote all
There is nothing in any Torsen diff ( which includes the trutracs ) that should clunk....so if it is the actual diff unit itself making the noise it has to be well and truly fked....which would be surprising if it still drove at all, or at least without some major symptoms.

monkfish1

10,874 posts

223 months

Tuesday 16th January 2018
quotequote all
stevieturbo said:
There is nothing in any Torsen diff ( which includes the trutracs ) that should clunk....so if it is the actual diff unit itself making the noise it has to be well and truly fked....which would be surprising if it still drove at all, or at least without some major symptoms.
As i think ive said elsewhere on the forum before, the issue with the truetracs in this application is the chronic slack in the splines on LSD where the stub shafts go in. Because, basically they have made it wrong. Its much more slack than the OE.

OverSteery

3,586 posts

230 months

Wednesday 17th January 2018
quotequote all
monkfish1 said:
stevieturbo said:
There is nothing in any Torsen diff ( which includes the trutracs ) that should clunk....so if it is the actual diff unit itself making the noise it has to be well and truly fked....which would be surprising if it still drove at all, or at least without some major symptoms.
As i think ive said elsewhere on the forum before, the issue with the truetracs in this application is the chronic slack in the splines on LSD where the stub shafts go in. Because, basically they have made it wrong. Its much more slack than the OE.
Is the kaaz a good choice?

monkfish1

10,874 posts

223 months

Wednesday 17th January 2018
quotequote all
OverSteery said:
Is the kaaz a good choice?
They always seemed OK. However, they recommend a mineral oil. Which you cant use in the Monaro diff as you will destroy the crownwheel in short order as it utlilizes a high angle pinion..

So you have to use the right diff oil, which Kaaz claim will make the LSD more "grabby".

Personally id use the wavetrac which is foilble free.

OverSteery

3,586 posts

230 months

Wednesday 17th January 2018
quotequote all
monkfish1 said:
OverSteery said:
Is the kaaz a good choice?
They always seemed OK. However, they recommend a mineral oil. Which you cant use in the Monaro diff as you will destroy the crownwheel in short order as it utlilizes a high angle pinion..

So you have to use the right diff oil, which Kaaz claim will make the LSD more "grabby".

Personally id use the wavetrac which is foilble free.
Thanks - as is so often the way, the best choice isn't the cheapest!

Does a 2000 GTS vt2 have the same diff as a monaro of the same age?

stevieturbo

17,229 posts

246 months

Wednesday 17th January 2018
quotequote all
Any Torsen style will be fine, and the Wavetracs are a nice unit.

PeteTheFree

78 posts

126 months

Wednesday 17th January 2018
quotequote all
Put a Detroit Trutrac in mine to solve this.

WillHSV

16 posts

85 months

Monday 22nd January 2018
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possibly too late for the original poster but I have had issues with my diff clonking and I am 99% certain its oil / fm related.

when I bought the car, the diff was clonk free but no idea what oil / fm was in the diff or how long it had been in there.

changed the oil for Royal Purple at a service and it clunked and juddered like something was very wrong at the rear

added redline FM (one bottle) and clunking went away for a while

few 1000 miles later back comes clunking. put more fm in (half a bottle) and it went away pretty much

car was in for some other work (AP's and clutch) and we changed the oil for something completely different as by now the clunking had started to re-appear

can't remember what oil it was but it was blue this time

3000 - or so miles it was fine then clunkety clunk back again. argggggghhh

bit more redline FM in and it went away again

In mean time I had bought the Harrop Rear Diff cover and done a lot of reading on the Pontiac GTO forums about clunky diffs

they seemed to rate Torco RGO Gear Oil 85w140 and for some reason the FORD FM of the same brand.

so with the old oil all out as part of Harrop install in went the Torco and half the 4oz bottle of FM and once again, silence from the rear end !

I thought that was it sorted - no clunking on turning, much less drivetrain shunt when pulling away (which in my case has to be down to the diff locking / releasing not quite as it should)

then I drove a bit longer and faster than I had up until that point (all short journeys up to then) and suddenly it was back with a vengeance. sounded horrendous - made worse by the now very solid diff mounting transmitting sound into rear of cabin.

back to my now expert local tyre / friction modifier adding place (closest place with ramp) and the other 2oz of fm went in. that's a tiny 2oz in 2.5 - 3 litres litres of diff oil !

BUT very quickly the sound has gone and normal service has resumed even after some hard and fast driving. I am not holding breath though but all I would say from my experiences is that the cone type diff is VERY sensitive to temperature, oil type, oil condition AND the amount of FM that's in it.

if I knew where I could get the diff rebuilt reliably on an exchange basis (I quickly as I use my car every day) I would get it rebuilt and get a less fussy LSD put in but now Monkfish are no longer offering their diff rebuild service I think I will stick with the cones for now which, at present are behaving themselves.

fred bloggs

1,300 posts

199 months

Wednesday 31st January 2018
quotequote all
willhsv your diff will have a broken cone.

Kaaz do an oil specific to their diffs. Demon tweeks sell it.

When new they are very juddery and noisy. It took a trackday to bed mine in properly.
You set the amount of lock on the unit before fitting in the housing.
You can set the diif to100% lock ,65% lock or 35% I run 100% but that's perhaps too much for some on the road.

I'm glad I didn't do a torsen.