Ratio difference CV8 - VXR
Discussion
Yes, this is a good point and something that i have also showed a personal inetrest on the Monkfish website, so as per usual, i will be interested in the replies.
My two penneth, is that, its all well having a car thats capable of 170 mph+, but in real terms, how often can we do that on our roads?!!?, so, if the gear ratio was altered to give , even, more acceleration, shorely that would be a better thing?????
Paul
My two penneth, is that, its all well having a car thats capable of 170 mph+, but in real terms, how often can we do that on our roads?!!?, so, if the gear ratio was altered to give , even, more acceleration, shorely that would be a better thing?????
Paul
the 2004 vxr has much shorter gearing than a cv8.
I believe the 2005 vxr has the same gearing as a 2004 or 2005 CV8.
My VXR certainly feels much more accelerative through the gears, and i can only assume is is due to the final drive ratio as my CV8 had been remapped to a similarish bhp
bennno
I believe the 2005 vxr has the same gearing as a 2004 or 2005 CV8.
My VXR certainly feels much more accelerative through the gears, and i can only assume is is due to the final drive ratio as my CV8 had been remapped to a similarish bhp
bennno
I went for 3.91 diff on my o4 CV8 which had other mods.
I totally agree about the 170+ bit. Did a track day at Bedford and the lower geared diff meant I was puling away from M3's, standard 911's, STI's etc etc.
It lowers the change up point but the pull away is noticably different especially at the crucial hold and go point in any gear. When I had it I likened it to having another 30 - 50hp it made that much difference. In reality it gives almost instant go and provides a real thump in the back bit like turbo cars. For realworld driving I reckon its a great mod compared to standard. Remeber that 04 VXR drivers have a 3.73 already so the change is not so great.
I believe the 05 cars have the same diff but the VXR has different gear ratios and so the 3.91 works well in both - based on what I have heard from drivers.
Best I can recomend is to find someone with same engine/exgaust set up with and with out and have a go.
I totally agree about the 170+ bit. Did a track day at Bedford and the lower geared diff meant I was puling away from M3's, standard 911's, STI's etc etc.
It lowers the change up point but the pull away is noticably different especially at the crucial hold and go point in any gear. When I had it I likened it to having another 30 - 50hp it made that much difference. In reality it gives almost instant go and provides a real thump in the back bit like turbo cars. For realworld driving I reckon its a great mod compared to standard. Remeber that 04 VXR drivers have a 3.73 already so the change is not so great.
I believe the 05 cars have the same diff but the VXR has different gear ratios and so the 3.91 works well in both - based on what I have heard from drivers.
Best I can recomend is to find someone with same engine/exgaust set up with and with out and have a go.
V6 - I had other mods done first and then the new diff added by itself so I could appreciate the difference it made as a single mod.
It might be hard to 'feel' the difference if you try a car that has had other mods that yours has not so you will not be able to identify what mod is responsibel for what improvement.
All I can say from my experience is that it was a damn good one!
It might be hard to 'feel' the difference if you try a car that has had other mods that yours has not so you will not be able to identify what mod is responsibel for what improvement.
All I can say from my experience is that it was a damn good one!
Ive driven my own with 3.73 gears and a freinds with 3.91 gears and Id definately recommend the 3.9 gears. Means 6th is more useful on the motorway at ~70mph and even around town in 40 and 50mph areas. Stock 6th is almost useless.
Definately a good mod. Plus drifting and burnouts are much enhanced!
Definately a good mod. Plus drifting and burnouts are much enhanced!
Le Sarthe said:
V6 - I had other mods done first and then the new diff added by itself so I could appreciate the difference it made as a single mod.
It might be hard to 'feel' the difference if you try a car that has had other mods that yours has not so you will not be able to identify what mod is responsibel for what improvement.
All I can say from my experience is that it was a damn good one!
It might be hard to 'feel' the difference if you try a car that has had other mods that yours has not so you will not be able to identify what mod is responsibel for what improvement.
All I can say from my experience is that it was a damn good one!
Thanks for this. Next question then, how much £££'s?
All uk monaros have 3.45: diffs with the exception of the 04 VXR. This has 3.7:1 gears. As stated by others the change to 3.9:1 gears certainly has a noticable effect!
Full details of our diff upgrades can be found under diff section here, www.monkfishperformance.co.uk/2004monaroframeset.html
There is also a link to a page detailing engine speeds at 70 mph for the different gears.
Full details of our diff upgrades can be found under diff section here, www.monkfishperformance.co.uk/2004monaroframeset.html
There is also a link to a page detailing engine speeds at 70 mph for the different gears.
monkfish1 said:
All uk monaros have 3.45: diffs with the exception of the 04 VXR. This has 3.7:1 gears. As stated by others the change to 3.9:1 gears certainly has a noticable effect!
Full details of our diff upgrades can be found under diff section here, www.monkfishperformance.co.uk/2004monaroframeset.html
There is also a link to a page detailing engine speeds at 70 mph for the different gears.
Full details of our diff upgrades can be found under diff section here, www.monkfishperformance.co.uk/2004monaroframeset.html
There is also a link to a page detailing engine speeds at 70 mph for the different gears.
What is the cost of this mod?
Paul
Suitable adjustments being carried out to correct this! hmm around 200 rpm difference at 70mph so guess that means a little poorer fuel economy but not enough to worry about - looks like a good mod to carry out. Have seen a couple of the American GTO owners fitting Harrop cases to their diffs which are meant to improve performance/reliability - standard cases are supposedly pretty crap - any comments anyone that knows about these things?
"Ratios available are as follows: 3.7:1 and 3.9:1. These are rebuilt diffs incorporating new gearset and bearings and are rebuilt to a high standard. This will allow the serious enthusiast to improve the acceleration of their car."
From the Monkfish website - I guess that means they are technically "refurbs".
From the Monkfish website - I guess that means they are technically "refurbs".
Well_Fans said:
hmm around 200 rpm difference at 70mph so guess that means a little poorer fuel economy but not enough to worry about - looks like a good mod to carry out. Have seen a couple of the American GTO owners fitting Harrop cases to their diffs which are meant to improve performance/reliability - standard cases are supposedly pretty crap - any comments anyone that knows about these things?
I have a 3.9 rear diff, and have actually seen better mpg figures, I found that I tend to use a gear higher than i used to in most cases. Especially 6th, its a real gear with the set up I have got. Have been using a car with the std diff over the last week and it is using more fuel, with my driving style anyway.
Over the last 200 miles, driving the same roads as usual etc I have seen a 2mpg decrease with std diff!!
caspy said:
Well_Fans said:
hmm around 200 rpm difference at 70mph so guess that means a little poorer fuel economy but not enough to worry about - looks like a good mod to carry out. Have seen a couple of the American GTO owners fitting Harrop cases to their diffs which are meant to improve performance/reliability - standard cases are supposedly pretty crap - any comments anyone that knows about these things?
I have a 3.9 rear diff, and have actually seen better mpg figures, I found that I tend to use a gear higher than i used to in most cases. Especially 6th, its a real gear with the set up I have got. Have been using a car with the std diff over the last week and it is using more fuel, with my driving style anyway.
Over the last 200 miles, driving the same roads as usual etc I have seen a 2mpg decrease with std diff!!
How well do they work with the CV8? I would guess that it would be the same then in terms of fuel economy? Just trying to get my story right to tell the wife
V6 - On a CV8 it does not really affect the fuel consumption too much. I would agree with Caspy re 6th gear and not having to drop down and push on.
BUT because of the extra wallop it gives you (think of it as a more positive launch system) you will want to use it more thus hammering on and using lots of fuel. The best part is if you are waiting to overtake and holding at a certain speed say 40 in second or 50/60 in third and then nail it that is where you really notice a huge 'diff'erence as you get a real thump.
I reckon if you put a stock Cv8 next to one with a 3.9 diff it would give 2 -3 car lengths advantage very quickly indeed - hence my initail comments about thsi being a great mod for real world driving.
So in short don't worry about the fuel and on motorways it will probably save you soem and make cruising easier - I only ever use 5th or 4th now if I really want to blast away.
In fact I use 6th from 40mph.
BUT because of the extra wallop it gives you (think of it as a more positive launch system) you will want to use it more thus hammering on and using lots of fuel. The best part is if you are waiting to overtake and holding at a certain speed say 40 in second or 50/60 in third and then nail it that is where you really notice a huge 'diff'erence as you get a real thump.
I reckon if you put a stock Cv8 next to one with a 3.9 diff it would give 2 -3 car lengths advantage very quickly indeed - hence my initail comments about thsi being a great mod for real world driving.
So in short don't worry about the fuel and on motorways it will probably save you soem and make cruising easier - I only ever use 5th or 4th now if I really want to blast away.
In fact I use 6th from 40mph.
Well_Fans said:
hmm around 200 rpm difference at 70mph so guess that means a little poorer fuel economy but not enough to worry about - looks like a good mod to carry out. Have seen a couple of the American GTO owners fitting Harrop cases to their diffs which are meant to improve performance/reliability - standard cases are supposedly pretty crap - any comments anyone that knows about these things?
I think they offer increased oil capacity for cooling, I have had a Harrop enduro case on on the car for a year now, no diff issues.
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