Cv8 diff ratio and power output

Cv8 diff ratio and power output

Author
Discussion

91964

Original Poster:

266 posts

194 months

Friday 22nd November 2019
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Hi guys, I’m shopping for another Monaro and it seems the price gap between good and bad has widened (as you would expect I guess) we’ll the good ones appear to have held values well and the tired ones are getting cheaper as the mileage rises and conditions worsen.
My previous pre facelift CV8 was great and I had no real areas I disliked other than the gearing. I’m aware the VXR stuff had resolved that issue with closer ratios but what about the Facelift CV8? Are these still on the old diff and original 333bhp ish power out?

Thanks

mfp4073

1,946 posts

174 months

Friday 22nd November 2019
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I have owned a facelift VZ Monaro for over 12 years, and the gearbox ratios were indeed the same as the 04 spec cars.
I changed mine to a 3:90 diff with a Wavetrack LSD. This is the best option for these particular Monaros.
Obviously these are not cheap options, however the only regret I do have is fitting a Truetrac LSD beforehand which was poorly made and caused me issues, overall my diff cost me a bloody fortune..
As I've said a number of times before, go for a Wavetrac and a 3:90 diff especially if you are not going to supercharge your engine.

91964

Original Poster:

266 posts

194 months

Friday 22nd November 2019
quotequote all
It’s a tough choice. I’ve seen a nice facelift CV8 but it needs cosmetics, for another £4K I’ve seen a very smart VXR which has exhaust done (one of my must haves and then for another £4K a low mile minter with every essential mod done. I’ve just got to decide where to dive in. I love my cars but I’m a bit of a tight arse! Worst combo!!

mfp4073

1,946 posts

174 months

Friday 22nd November 2019
quotequote all
Lesson number one, you might be a self confessed tight arse? but the reality is you have to pay to play.....I gave up years ago trying to save money on my car.
Don't get me wrong you shouldn't throw money at them without thinking, you just need to be honest with yourself and decided what you want out of the car and what you are prepared to pay.
My advice,..... decide what you want out of a Monaro and how long you are going to keep it. Don't buy a car and spend money fixing it up or modding it only to sell it on at a loss a year or so later.
Buy the best condition car you can, hopefully with a few desirable mods and see how you go.

JAMESHSV1

291 posts

98 months

Tuesday 26th November 2019
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mfp4073 said:
I have owned a facelift VZ Monaro for over 12 years, and the gearbox ratios were indeed the same as the 04 spec cars.
I changed mine to a 3:90 diff with a Wavetrack LSD. This is the best option for these particular Monaros.
Obviously these are not cheap options, however the only regret I do have is fitting a Truetrac LSD beforehand which was poorly made and caused me issues, overall my diff cost me a bloody fortune..
As I've said a number of times before, go for a Wavetrac and a 3:90 diff especially if you are not going to supercharge your engine.
A 3.9 diff works very well with a procharger

mfp4073

1,946 posts

174 months

Tuesday 26th November 2019
quotequote all
JAMESHSV1 said:
A 3.9 diff works very well with a procharger
Yes a good point, I didn't consider one of those smile

vxr2010

2,565 posts

159 months

Tuesday 26th November 2019
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bolting on a 3.9 is a lot more noticeable than having a remap , it really changes the car , especially on the cv8

bigwheel

1,618 posts

214 months

Tuesday 26th November 2019
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smileyes

Drihump Trolomite

5,048 posts

81 months

Friday 29th November 2019
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Don't go 3.9, the best rear ratio is 3.7 as used in the VXR. If its to be used properly, 3.7 all the way.

Drihump Trolomite

5,048 posts

81 months

Friday 29th November 2019
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91964 said:
It’s a tough choice. I’ve seen a nice facelift CV8 but it needs cosmetics, for another £4K I’ve seen a very smart VXR which has exhaust done (one of my must haves and then for another £4K a low mile minter with every essential mod done. I’ve just got to decide where to dive in. I love my cars but I’m a bit of a tight arse! Worst combo!!
Spend the 4k on the VXR. The exhaust alone is a grand, a diff the same then you have the body work to sort out and the brakes and the suspension - all of which adds to insurance. Just go for the VXR


mfp4073

1,946 posts

174 months

Friday 29th November 2019
quotequote all
Drihump Trolomite said:
Don't go 3.9, the best rear ratio is 3.7 as used in the VXR. If its to be used properly, 3.7 all the way.
I'm not sure I understand where you're coming from with that statement.
The 3.9 diff is an excellent choice in my opinion, it really wakes the car up and sixth gear is actually useable.
I'm not sure why the 3.7 ratio is better? What I did want for my money was a dramatic improvement in my cars overall ability, and that's what I got with the 3.9.

bigwheel

1,618 posts

214 months

Friday 29th November 2019
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mfp4073 said:
Drihump Trolomite said:
Don't go 3.9, the best rear ratio is 3.7 as used in the VXR. If its to be used properly, 3.7 all the way.
I'm not sure I understand where you're coming from with that statement.
The 3.9 diff is an excellent choice in my opinion, it really wakes the car up and sixth gear is actually useable.
I'm not sure why the 3.7 ratio is better? What I did want for my money was a dramatic improvement in my cars overall ability, and that's what I got with the 3.9.
Don't rise to the bait.
Roger at Monkfish recommended the 3.9 for my '05 CV8.
It transformed my naturally aspirated car, very happy days.
He said if supercharging, then a higher ratio is better as it gives the supercharger resistance to work against thus bringing the supercharger into it's ideal use.

Edited by bigwheel on Friday 29th November 18:55

mfp4073

1,946 posts

174 months

Friday 29th November 2019
quotequote all
bigwheel said:
Don't rise to the bait.
Roger at Monkfish recommended the 3.9 for my '05 CV8.
It transformed my naturally aspirated car, very happy days.
He said if supercharging, then a higher ratio is better as it gives the supercharger resistance to work against thus bringing the supercharger into it's ideal use.

Edited by bigwheel on Friday 29th November 18:55
bigwheel you've just jogged my memory, Roger said somethings similar to be me when I booked my car into Monkfish for the 3.90 diff.....now there's one guy I wouldn't question when it comes to advice about Monaro's smile

John

Drihump Trolomite

5,048 posts

81 months

Friday 29th November 2019
quotequote all
The vxr was a 3.7, most sportier models go 3.7 it's the benefits of a 3.9 with lower cruising revs (around 5%)

Theres no bait

fred bloggs

1,308 posts

200 months

Saturday 30th November 2019
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The gts has a 3.7 diff and I think its quite a high ratio.

I did want to go 4.11 when I got my diff built, but spent the money in the kaaz 2way centre instead.

The best choice I think is to buy a re-built diff from one of the Australian diff shops, built to your spec, but the shipping is quite a lot.

Lincsls1

3,335 posts

140 months

Saturday 30th November 2019
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fred bloggs said:
The gts has a 3.7 diff and I think its quite a high ratio.

I did want to go 4.11 when I got my diff built, but spent the money in the kaaz 2way centre instead.

The best choice I think is to buy a re-built diff from one of the Australian diff shops, built to your spec, but the shipping is quite a lot.
Yeah I agree. My 5.7 VXR has the 3.7 as standard, I still find it all a bit tall and wouldn't mind going for a 4.11
Swapping to a 3.9 from 3.7 just doesn't seem enough of a jump, but I'm sure going from the CV8 original diff it would be.

Lincsls1

3,335 posts

140 months

Saturday 30th November 2019
quotequote all
Drihump Trolomite said:
The vxr was a 3.7, most sportier models go 3.7 it's the benefits of a 3.9 with lower cruising revs (around 5%)

Theres no bait
Only the 5.7 VXR got the 3.7 diff, not the 6.0.

vxr2010

2,565 posts

159 months

Saturday 30th November 2019
quotequote all
certainly on the cv8 , a 3.9 is a great move plus you still maintain a good mpg , i managed 35 mpg out of mine on a run to scotland , i don’t know if vxr ratios are different to a cv8 ? , i would not go with a 3.7 on a cv8 , i would consider going the other way from a 3.9 IF i wanted more performance but gear range would be shorter , but i’m more than happy with the 3.9 fitted , the gears are just standard gears in the standard diff , plus with the correct fluid no klunks and works well

Lincsls1

3,335 posts

140 months

Saturday 30th November 2019
quotequote all
vxr2010 said:
certainly on the cv8 , a 3.9 is a great move plus you still maintain a good mpg , i managed 35 mpg out of mine on a run to scotland , i don’t know if vxr ratios are different to a cv8 ? , i would not go with a 3.7 on a cv8 , i would consider going the other way from a 3.9 IF i wanted more performance but gear range would be shorter , but i’m more than happy with the 3.9 fitted , the gears are just standard gears in the standard diff , plus with the correct fluid no klunks and works well
Gearbox ratios I believe are the same on ALL 5.7 variants including the 5.7VXR. But remember the 5.7VXR gets a shorter diff.
The 6.0VXR, IIRC correctly has a slightly lower ratio gearbox, but keeps the taller diff of the CV8.

fred bloggs

1,308 posts

200 months

Sunday 1st December 2019
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Basically anything is an improvement over the cv8 . And probably any centre is better than the horrible cone type lsd, which is most likely not working as it should anyway.
Personally, I like a 1.5 way diff most, but you can only get a 2 way centre for this unit(in the positive lock types)