Best diff for high horse powered L98

[Fatty8711]

Hi all, just trying to find out what people think the best diff options are for a blown ve ssv L98. I would like a 3.9 ratio that can easily handle 800+ rwhp

 

[losh1971]

You will need a Harrop or Kaaz to handle that kind of power and torque. 3.9 is normally N/A. Do you have a manual? If you go 3.9 then your best option is Motive gears. They are made in Italy whereas the others are made in Korea. If you go 3.7s you could use genuine gears, which are the best of the lot. If you use aftermarket gears they really need to go on the lapping tank to be polished. If you don't you can expect them to be noisy. I know a bloke with the lapping tank and can provide his details to have them done. Gen 3.7s don't need to be polished.

 

[losh1971]

If you go Trutrac don't be fooled into going for one of the cheap copies, as they are cheap for a reason. A Harrop is about $1500 as is a Kaaz.

 

[Fatty8711]

You will need a Harrop or Kaaz to handle that kind of power and torque. 3.9 is normally N/A. Do you have a manual? If you go 3.9 then your best option is Motive gears. They are made in Italy whereas the others are made in Korea. If you go 3.7s you could use genuine gears, which are the best of the lot. If you use aftermarket gears they really need to go on the lapping tank to be polished. If you don't you can expect them to be noisy. I know a bloke with the lapping tank and can provide his details to have them done. Gen 3.7s don't need to be polished.

Yeh it's a 6 speed manual, how much difference is there between 3.7 and 3.9? I looked at the Harrop set up for $4k but that's only rated at 700rwhp

 

[losh1971]

I can't remember who it was but a member of here had to fit taller gears as the SC was too much with the gears he had.

 

[losh1971]

I've got 3.9s for my L98 and mine is only 325rwkw. From my research this was about the happiest medium for the power and torque I have. Having regeard my old VR Buick ute, from 3.08 to 3.45 I noticed a decent improvement on a relatively stock V6. Which is another reason I chose 3.9s.
On the VE some say it's 4.11 or nothing. But those a just a few opinions and not the majority vote.

 

[Fatty8711]

If you go Trutrac don't be fooled into going for one of the cheap copies, as they are cheap for a reason. A Harrop is about $1500 as is a Kaa

I've got 3.9s for my L98 and mine is only 325rwkw. From my research this was about the happiest medium for the power and torque I have. Having regeard my old VR Buick ute, from 3.08 to 3.45 I noticed a decent improvement on a relatively stock V6. Which is another reason I chose 3.9s.
On the VE some say it's 4.11 or nothing. But those a just a few opinions and not the majority vote.

Yeh I had 4.11 in my last 6L but I found them to be a bit to aggressive for a daily. Great fun but I am looking for something a little less this time around. The car I drive now days is already quite beefy, it's running a vortec blower with a 4 inch crank so it's pushing abit over 800rwhp. I don't want to be replacing Diff's every few months though so I'm trying to find out as much info on different Diff's as possible

 

[07GTS]

u will be struggling with traction going higher diff gears with that power, even now u shouldnt be able to even use it

 

[Fatty8711]

u will be struggling with traction going higher diff gears with that power, even now u shouldnt be able to even use it

It definitely doesn't take much to break traction, but I drive it to work every day so it is obviously not un usable

 

[07GTS]

im meaning when u want the full beans it just wont get it to the ground then going a higher diff will make that slip happen even easier, im all for big power and if having to manage the power more with your right foot dosnt worry u then all good, i have the hsv 3.7 diff in mine and was even thinking bout going to a 3.45 just so its more usable