Please be gentle
Discussion
HI. Was really looking for some help on my best diff options since my diff gave up the ghost on my 06 cv8. Worst thing was it was during the five mile drive home (on the last hundred yards to be exact) from the body shop after it had pretty much a full respray and was looking great. I was grinning from ear to ear then the silly noises started lol
Reason I’m saying be gentle is because the last few times posted here it always seems like because I’m not a mechanic and don’t know the complete workings of my car I’ve had a few snide remarks. Can be a bit off putting when your only trying to sort out what the solution is to a problem on a car that isn’t well known and parts are getting scarce. Saying that I also had some very good information on here and I have been to some meets since I bought my car in 2008.
Had a few options since the diff went last month. Like buying a stock diff from a breaker. Slightly expensive which was fine but a bit worrying incase I’m only buying a part that’s going to give me the same problem a year down the line or upgrade to a wave trac which I’ve been told isn’t an ideal option because it’s isn’t just a straight swap to fit wave trac parts into this diff. I might be getting that last part wrong because like I said I’m not a mechanic. I’m not worried about spending money on this car but just don’t to make the wrong decision.
Reason I’m saying be gentle is because the last few times posted here it always seems like because I’m not a mechanic and don’t know the complete workings of my car I’ve had a few snide remarks. Can be a bit off putting when your only trying to sort out what the solution is to a problem on a car that isn’t well known and parts are getting scarce. Saying that I also had some very good information on here and I have been to some meets since I bought my car in 2008.
Had a few options since the diff went last month. Like buying a stock diff from a breaker. Slightly expensive which was fine but a bit worrying incase I’m only buying a part that’s going to give me the same problem a year down the line or upgrade to a wave trac which I’ve been told isn’t an ideal option because it’s isn’t just a straight swap to fit wave trac parts into this diff. I might be getting that last part wrong because like I said I’m not a mechanic. I’m not worried about spending money on this car but just don’t to make the wrong decision.
The fish re built my diff with 3.9 gearing , it not only works well ratio wise , the car is a lot pokier , i have had no issues with it , you can get other diffs as you mentioned , im running around 430 bhp with no issues , supercharged i may go for a heavier duty diff , the 3.9 is also the cheaper option , diffs are not that common to fail on the cv8 so i’m surprised yours failed any way
It is unusual to hear of a diff going, they tend to just wear out so that they no longer lock up and allow just one wheel to spin.
I thought the diff went on my Ute based on the noises and behaviour, turned out it was a wheel bearing that had spectacularly failed (i.e. no build up, just sudden rhythmic graunch sound and occasional random twitch to the back end.)
My understanding diff wise is that some bits needed to rebuild them are a bit hard to get hold of, bearings and such mostly. I have heard also that they're a bit of a special case in terms of setting up but I don't know why or how and for what reason any place used to dealing with diffs couldn't sort it... Would be interesting to find out why it's such a faff.
Your options are as you say, replace with a stock one from a breaker, a Wavetrac is pretty expensive but considered the best option. There is the Truetrac, although the tolerances around the driveshaft splines are apparently a little loose which causes a bit of clunk / shunt. I've abused mine for probably 30,000 miles with no issues and they seem very tough but yes, a little less sophisticated than the Wavetrac.
People have fitted Kaaz diffs too, but whether any of them are still on the forum to tell you about it I don't know!
I thought the diff went on my Ute based on the noises and behaviour, turned out it was a wheel bearing that had spectacularly failed (i.e. no build up, just sudden rhythmic graunch sound and occasional random twitch to the back end.)
My understanding diff wise is that some bits needed to rebuild them are a bit hard to get hold of, bearings and such mostly. I have heard also that they're a bit of a special case in terms of setting up but I don't know why or how and for what reason any place used to dealing with diffs couldn't sort it... Would be interesting to find out why it's such a faff.
Your options are as you say, replace with a stock one from a breaker, a Wavetrac is pretty expensive but considered the best option. There is the Truetrac, although the tolerances around the driveshaft splines are apparently a little loose which causes a bit of clunk / shunt. I've abused mine for probably 30,000 miles with no issues and they seem very tough but yes, a little less sophisticated than the Wavetrac.
People have fitted Kaaz diffs too, but whether any of them are still on the forum to tell you about it I don't know!
Hey thanks for the reply’s all good stuff to know. I’m sure after it was stripped down the mechanic said the crown or pinion had sheered a part off not sure what bit out the two but in the short drive to get it home the loose piece rattled about and caused a bit of mess inside the casing.
I was really wanting to upgrade to the wave trac but like you said it’s an expensive option. The figures I got told were between £1500 and £2000 does that sound about right? At this point though I would take the quickest option to get the car back on the road again.
My next spend was going to be repair the bad stitching on the rear seats and recon the alloys and it would’ve been looking like a new car almost. I’ll get pics on once the job list is ticked off.
I was really wanting to upgrade to the wave trac but like you said it’s an expensive option. The figures I got told were between £1500 and £2000 does that sound about right? At this point though I would take the quickest option to get the car back on the road again.
My next spend was going to be repair the bad stitching on the rear seats and recon the alloys and it would’ve been looking like a new car almost. I’ll get pics on once the job list is ticked off.
Mace Performance (I think) on eBay Australia do rebuild kits for these and are happy to ship to the UK - I bought a 3.9 crown wheel & pinion set and a diff rebuild kit myself from them (still on the shelf!)
https://www.maceengineering.com.au/epages/mace.sf/...
https://www.ebay.co.uk/itm/MACE-PERFORMANCE-M80-DI...
https://www.maceengineering.com.au/epages/mace.sf/...
https://www.ebay.co.uk/itm/MACE-PERFORMANCE-M80-DI...
Edited by robbyd on Wednesday 12th January 15:10
I really did like like the thought of upgrading to a better ratio but the help I received on here has well and truly speeded the time frame of getting my ozy beast back on the road so I’m a happy camper now 
if I was going to upgrade in the future where would I notice the most difference? Is it noticeable 0-60 time or is more of a handling thing?
Thanks again
if I was going to upgrade in the future where would I notice the most difference? Is it noticeable 0-60 time or is more of a handling thing?Thanks again
mr nosiris said:
I really did like like the thought of upgrading to a better ratio but the help I received on here has well and truly speeded the time frame of getting my ozy beast back on the road so I’m a happy camper now if I was going to upgrade in the future where would I notice the most difference? Is it noticeable 0-60 time or is more of a handling thing?
Thanks again
A higher final ratio (so 3.7 or 3.9) will effectively shorten all of the gears, and increase the amount of torque at the wheels. if I was going to upgrade in the future where would I notice the most difference? Is it noticeable 0-60 time or is more of a handling thing?Thanks again
So the car will pull through the gears quicker basically, handling wise beyond making it easier to break the rear tyres loose it won't really make any difference.
A new / upgraded LSD can have an impact on the handling, but it depends somewhat on the type of LSD and whether it locks up under deceleration or just acceleration.
The more it locks up under deceleration, the more it will keep the car straight and stable whilst slowing down, which also makes the car a bit more reluctant to initially turn, i.e. understeer.
The more it locks up under acceleration the more it will want to straighten the car out under acceleration, this will mean more traction accelerating out of a corner (as opposed to spinning up an inside wheel for example) but once you're nearer the limit of traction it'll be more likely to oversteer. The resulting oversteer is more predictable and controllable though
Roughly anyway. Of the options I only have experience of the stock diff for a bit and the truetrac for a long time. The TT doesn't lock up at all under deceleration but does under acceleration. Unfortunately when I had the fish fit the TT I also had a stiffer rear antiroll bar fitted, so how much of the change on oversteeryness was the stiffer rear and how much was the diff I can't isolate. Those two together made a big difference to how much throttle was required to rotate the car though and not just the initial pointiness, so I'm assuming the diff played its part...
Janosh said:
Where are you based?
Up north I’d be speaking to MWP
Midlands there’s Top cats & Walkinshaw
Down south to Carl @ LS Performance
They’re all specialists that I’d trust to get it fixed properly…
Further North lets not forget the excellent AAS either.Up north I’d be speaking to MWP
Midlands there’s Top cats & Walkinshaw
Down south to Carl @ LS Performance
They’re all specialists that I’d trust to get it fixed properly…
They have serviced, repaired, upgraded many a Monaro/R8 along with lots of other cars too.
The 3.9 reduces the top end in each gear by a few mph as in maybe 7 or 8 miles less in 1st gear , it’s more punch in your seat , the pull through the gears is definitely stronger , 4 th 5 th and 6th become a lot more useable , mpg seems to improve as you can shift up earlier , my mpg on a long run was 36 mpg , but the whole car seems more powerful , i had a remap done on an ls1 so about 30 bhp more , the 3.9 diff was a much more noticeable mod than the remap
mr nosiris said:
HI. Was really looking for some help on my best diff options since my diff gave up the ghost on my 06 cv8. Worst thing was it was during the five mile drive home (on the last hundred yards to be exact) from the body shop after it had pretty much a full respray and was looking great. I was grinning from ear to ear then the silly noises started lol
Reason I’m saying be gentle is because the last few times posted here it always seems like because I’m not a mechanic and don’t know the complete workings of my car I’ve had a few snide remarks. Can be a bit off putting when your only trying to sort out what the solution is to a problem on a car that isn’t well known and parts are getting scarce. Saying that I also had some very good information on here and I have been to some meets since I bought my car in 2008.
Had a few options since the diff went last month. Like buying a stock diff from a breaker. Slightly expensive which was fine but a bit worrying incase I’m only buying a part that’s going to give me the same problem a year down the line or upgrade to a wave trac which I’ve been told isn’t an ideal option because it’s isn’t just a straight swap to fit wave trac parts into this diff. I might be getting that last part wrong because like I said I’m not a mechanic. I’m not worried about spending money on this car but just don’t to make the wrong decision.
The big problem with these diffs is getting them apart. The aluminium side carriers swell up with the salt and seize in the diff housing. Its not uncommon that they are destroyed in the dismantling process. Reason I’m saying be gentle is because the last few times posted here it always seems like because I’m not a mechanic and don’t know the complete workings of my car I’ve had a few snide remarks. Can be a bit off putting when your only trying to sort out what the solution is to a problem on a car that isn’t well known and parts are getting scarce. Saying that I also had some very good information on here and I have been to some meets since I bought my car in 2008.
Had a few options since the diff went last month. Like buying a stock diff from a breaker. Slightly expensive which was fine but a bit worrying incase I’m only buying a part that’s going to give me the same problem a year down the line or upgrade to a wave trac which I’ve been told isn’t an ideal option because it’s isn’t just a straight swap to fit wave trac parts into this diff. I might be getting that last part wrong because like I said I’m not a mechanic. I’m not worried about spending money on this car but just don’t to make the wrong decision.
Hey sorry I haven’t been back on to reply to some of the comments. The monkfish comment on and extra 50 bhp was something I always remembered. That would be cool. Although I am very happy that my car should be ready by the end of the week after help I got on here 
I also (think I) remember years ago on the monkfish website they were doing a swap for your old diff BUT you got a Harrop diff for like £400! Was that any good? Or was that a dream lol.
The mechanic bought some new tuning tech so he’s hoping he can give my car a little tune while it’s in and maybe skim my ap discs aswell. I’m sure I’ve heard before there isn’t a lot of play on these discs for skimming but maybe worth a try.
After that I’m looking at Refurbinshing my alloys and get the back seats (which have been out for months) restitched and I think I could be doing with some new clips to reseat them in them back. Don’t know if this is cool or not but I got a Vxr interior in a cv8. It made sense at the time because I got a job lot of a class b scrapper.
I also (think I) remember years ago on the monkfish website they were doing a swap for your old diff BUT you got a Harrop diff for like £400! Was that any good? Or was that a dream lol.
The mechanic bought some new tuning tech so he’s hoping he can give my car a little tune while it’s in and maybe skim my ap discs aswell. I’m sure I’ve heard before there isn’t a lot of play on these discs for skimming but maybe worth a try.
After that I’m looking at Refurbinshing my alloys and get the back seats (which have been out for months) restitched and I think I could be doing with some new clips to reseat them in them back. Don’t know if this is cool or not but I got a Vxr interior in a cv8. It made sense at the time because I got a job lot of a class b scrapper.
I do have a real good diff guy and transmission guy close to home in Blantyre. He done my clutch and a few other things a couple of year back. I asked him for some advice and it wasn’t to good after he tried to sort the very same problem a year or two ago. He said the worst part was he couldn’t get the seals anywhere and something else that I never understood.
I’m a roofer and I like too help people understand problems not confuse them ( I’m probably the only one tbh) . And I had to let him know how I got on with the problem I had.
I hope maccavvey has good stock. TOP MAN
I’m a roofer and I like too help people understand problems not confuse them ( I’m probably the only one tbh) . And I had to let him know how I got on with the problem I had.
I hope maccavvey has good stock.
TOP MANHi guys. Just wondering if the gods of the monaro can offer any tips or advice here. The mechanic is in the middle of taking out the old diff but is struggling because its bolted from the top and the bolts are pretty bad with corrosion.
Thinks he may have to drop the rear subframe which isn’t too great. Was just hoping someone here has dealt with this in the past and can offer a bit of advice. CHEERS
Thinks he may have to drop the rear subframe which isn’t too great. Was just hoping someone here has dealt with this in the past and can offer a bit of advice. CHEERS
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