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01 Caprice

WHCapriceHBD

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I hope it will be worth it... It should be less lazy than the current 3.08:1 anyways.
I think this diff would have come out of something like a manual VZ Clubsport. The guy I bought it from said it was removed at 140,000km for a 3.90:1 diff, not because there was anything wrong with it.

Irregardless, I sent the diff to a diff specialist in town for a rebuild and a clean up as soon as it arrived. I got the diff back from the diff specialist a few days ago. Its now got 4 pinion gears instead of 2, and the cone LSD has been checked over and tightened. New bearings in the sides and in the front input. Its cost a bit for the rebuild and the initial cost of the diff, but I think it will be worth it, versus just throwing it in unchecked.

While it was apart, some parts went off to the powder coaters. Let me explain what I wanted:

I didn't have it powder coated or painted plain black, as I wanted to be able to look underneath and see and oil leaks it might develop in future. Oil leaks on a black diff would be hard to spot, so I had it done in a lighter gunmetal type of colour, which I'm happy with.
They also coated the fill and drain plugs in wrinkle red for me, so they are easy for idiots to see underneath a dark car and not slip out of oily fingers.
And they did the little axle retaining clamp plates on each side of the diff in wrinkle black which looked good too.
Replaced all the screws on the diff cover with polished stainless steel button head allen screws.

So its basically ready to go in on Tuesday. Probably the prettiest looking Commodore LSD I've ever seen :rofl2: Almost too nice to throw under there and get covered in dirt and road grime...





 

Husky

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Looks good. I bought a 3.46 and had some issues when I first got it. it got better after some LSD additive was put in, and now just has a slight judder when reversing on an angle. I'll be aiming to get a rebuild on it next year.

Doing it all in one hit was wise.
 

WHCapriceHBD

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Its in there and its a massive improvement in terms of no more screaming pinion hell noise at all speeds. The car is just... quiet... now. It's almost disconcerting how quiet it is inside. Your brain has the expectancy of the screaming whine every time you drive the car, and its not there anymore.

Best way to describe it is the 'phantom limb' syndrome. Once a leg or arm is gone, you still look over and expect it to be there, and at times you think you hear/feel it, but its your brain playing the noise back instead. Its bizarre.

As far as how the new ratio effects the car performance wise, I haven't had the chance to really drive it other than around the city. I'll try it out in the coming days. I'm just so happy its finally quiet.

I have noticed something odd that there is no mention of, anywhere online about the VX VY VZ VU WH WK WL diffs though... So I'll be the first to point this out maybe...?

In the below picture, look at the rear cover of the new diff. Notice the shape of the rear cover and how it forms into the goose neck that sits in the rubber cradle. Notice the smoothness of the rear cover and how it angles into segments, and the goose neck is smooth:




Now look at the old worn out diff that came out of my 2001 WH. The rear cover is a completely different shape. And the goose neck that sits in the rubber hanger has ribs on each side of it:



Strangely it seems there were two different rear diff cover designs and I didn't notice this until I sat the two together on the ground and saw the difference. Maybe one rear cover is stronger. Maybe they revised it for some sort of reason. I looked online and I see photos of both types but nobody ever makes mention of this difference, or why it is.

The only telling clue I have found is that VT uses the old round pinion flange to the driveshaft. We all know that. And all the round pinion flange VT diffs have the rear cover with the ribs.

VX2 and VY VZ have the 3 bolt triangle pinion yoke flange. We know that. And these diffs got the smoother rear cover with no ribs.

Therefore my theory is that the diff cover was upgraded and strengthened somewhere after VT. And stayed that way until VZ. And the upgraded rear cover is the smooth one with no ribs (as I just unwittingly put in my car).
 

WHCapriceHBD

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And just further to that, I've had a good look and VR VS Holdens also have the ribbed rear cover. So it must have been phased out in favor of the smooth cover.
 

Skydrol

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I was under the impression the ribs are there for 2 reasons... Heat Disipation and Added Strength.

Perhaps the upgraded version is a weight and cost saving measure (less material and easier to manufacture); are they both made out of the same alloy?
 

WHCapriceHBD

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I've had both rear covers off now (just had the ribbed cover off out in the shed... Its like 2C out there..... And the ribbed cover is actually substantially thinner in most places and definitely doesn't look stronger from the inside.

The smooth cover is a thicker casting and the goose neck is thicker and tapers out more gradually for what I assume is more strength over the ribbed version, combined with the thicker casting.
My verdict is, if you want the strongest factory rear cover for some application, go for the smooth cover. It seems to just be noticeably beefier.
 

WHCapriceHBD

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Update. Wheelspin is quite apparent. Traction control seems to be coming on with too much delay.

In the wet with very little provocation it wants to spin the rears. With the shifting firmed up, its not impressed by things like roundabouts. Sudden throttle inputs during turning tend to lead to loss of traction and then the traction control wakes up and bangs the accelerator pedal up against your foot.

I thought that having this type of fresh LSD centre, things would hook up in the dry and it would move off the line in a pretty brisk way. Instead, the back jerks to the passengers side and the revs increase without the proportional forward movement. I think the tires must be letting it down either by not being sticky enough or being too low profile with no sidewall flex.
 

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I think is a tire issue.
 

uniacidz

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What tyres you have?
 

MEANL67

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mine had no problems with 17s,but as soon as I upgraded to the 20s it did make a slight clunk from the diff.
 
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