Questions about the diff in my monaro

[bigfatnick]

Hi all.

Had my LS2 Monaro VXR for a few months now and I quite like it. I'm still not sure I shouldn't have bought a E46 M3, as I feel when I'm really driving it, I have to be gentle with it, as if I could break it being too rough with it. (though i'm sure i'll feel better once i get rid of this awful standard clutch).

My main question is about the diff, how much noise should it make? I know the previous owner changed the diff oil, but I don't think he put any friction modifier in it. It clonks and knocks a bit, makes grindy noises when making tight left turns at car park speeds and and seems to have a bit of a driveline shunt/clunkage which seems to manifest itself as a knock from the N/S at the rear. Is this normal? Mine is the only Monaro I've ever driven so I don't really have anything to reference.

I'm reluctant to put friction modifier in it as i think it reduces the locking effect of the diff. (though would love to be proven wrong). If it's supposed to make the noises it does, then i'm happy, if not, i'll fix them.


Any advice would be really appreciated!

[EmmaJ]

bigfatnick said:

Hi all.

Had my LS2 Monaro VXR for a few months now and I quite like it. I'm still not sure I shouldn't have bought a E46 M3, as I feel when I'm really driving it, I have to be gentle with it, as if I could break it being too rough with it. (though i'm sure i'll feel better once i get rid of this awful standard clutch).

My main question is about the diff, how much noise should it make? I know the previous owner changed the diff oil, but I don't think he put any friction modifier in it. It clonks and knocks a bit, makes grindy noises when making tight left turns at car park speeds and and seems to have a bit of a driveline shunt/clunkage which seems to manifest itself as a knock from the N/S at the rear. Is this normal? Mine is the only Monaro I've ever driven so I don't really have anything to reference.

I'm reluctant to put friction modifier in it as i think it reduces the locking effect of the diff. (though would love to be proven wrong). If it's supposed to make the noises it does, then i'm happy, if not, i'll fix them.


Any advice would be really appreciated!

They all clonk on pull away. Not all the time but it's a foible of Monaros. You'll get use to it

I'm running a standard diff but an uploaded drive shaft (single), modified prop, upgraded gearbox and an ACT twin plate clutch and the diff is still going strong........

[Mr C v8]

I had some knocking from my diff, well more like a tightness at very low speed.
MF added some modifier which sorted it straight away, needless to say I had to check the diff still worked.

[Codswallop]

Funny you mention the M3 - I bought my Monaro precisely because I was worried by how fragile (and potentially expensive to repair) M3s were. My diff makes the occasional clunk and noise too, but I have no worries over durability in a standard car.

[r8black]

Mr C v8 said:

I had some knocking from my diff, well more like a tightness at very low speed.
MF added some modifier which sorted it straight away, needless to say I had to check the diff still worked.

Think these 11s Win

[EmmaJ]

Mr C v8 said:

I had some knocking from my diff, well more like a tightness at very low speed.
MF added some modifier which sorted it straight away, needless to say I had to check the diff still worked.

Line locker, or left foot braking?

[ARAF]

Mr C v8 said:

I had some knocking from my diff, well more like a tightness at very low speed.
MF added some modifier which sorted it straight away, needless to say I had to check the diff still worked.

You hooligan!

[Mr C v8]

Left foot Emma point is the standard diff locks up just fine with the modifier in it, so won't do any harm.
May even be a cheap fix.

[fletch78]

This thread has more skid marks than the laundry room at an Old folks home

I don't give it full beans like some of the usual suspects, but the clunking seems perfectly normal, never worried it might pop....whereas with complicated German engineering I'd always be worried about a huge bill....

[EmmaJ]

Mr C v8 said:

Left foot Emma point is the standard diff locks up just fine with the modifier in it, so won't do any harm.
May even be a cheap fix.

Knew it had to be

Both of mine were the maximum run out in 1st gear from a stationary start to bouncing off the limiter so I knew something trick had been done

[Mr C v8]

EmmaJ said:

Mr C v8 said:

Left foot Emma point is the standard diff locks up just fine with the modifier in it, so won't do any harm.
May even be a cheap fix.

Knew it had to be

Both of mine were the maximum run out in 1st gear from a stationary start to bouncing off the limiter so I knew something trick had been done

Some of us aren't running quite as much power as others
So we have to use all the tricks we can.

[ARAF]

Mr C v8 said:

Some of us aren't running quite as much power as others
So we have to use all the tricks we can.

I think your front brakes are helping.

[EmmaJ]

Once my line locker is fitted I'm worried if Michelin will be able to keep up with demand.....

[Mr C v8]

ARAF said:

Mr C v8 said:

Some of us aren't running quite as much power as others
So we have to use all the tricks we can.

I think your front brakes are helping.

Sorry OP, it looks like we've gone off topic. Again

[stigmundfreud]

MF did my diff and it was the single biggest major improvement. The mix was just spot on, transformed the car better than any of the other mods done to it.

[bigfatnick]

Thanks guys.

Further question, how loud should the slack takeup clunk be and is it normal to do it whenever you set off in first/reverse? And is it normal for it only to appear to manifest itself in the left rear? I think i need to check the driveshaft when i get a moment.

Thanks

[luminass]

My lumina which is very similar to cv8 but with 3.07 ratio being auto has creaked and clonked for last couple of years, I've changed oil trying different brands and with a little modifier and almost all modifier, but it's still don't and got really bad when parking now and driving after 5-10 miles , so im changing it as we speak , I've just had a tool made up to remove the sude adjusters , just hope this makes it better with replacement one in it

[stigmundfreud]

bigfatnick said:

Thanks guys.

Further question, how loud should the slack takeup clunk be and is it normal to do it whenever you set off in first/reverse? And is it normal for it only to appear to manifest itself in the left rear? I think i need to check the driveshaft when i get a moment.

Thanks

its quite a clunk, along the lines of engaging diff lock ups on an old discovery. The diff is somewhat agricultural and slack. Due to the type of diff (which does its job well) and the noises, I imagine that is why VX sold them without the FM applied so they never actually worked properly.. you'll get graunching noises on slow speed turning. The Monkfish treatment really did improve things, get down there for a service and get it done at the same time

[SturdyHSV]

EmmaJ said:

Once my line locker is fitted I'm worried if Michelin will be able to keep up with demand.....

I'm hoping after an initial price peak through your increased demand, they'll ramp up supply to keep up, and bring about better prices for the rest of us

[mfp4073]

I have just had my Monaro dif rebuilt, with a 3.90 gear set and a True Trac LSD...it still clunks all the time,hot or cold.
I wonder if there is some slack from inside the gear box?