VN conversion to LSD

[savage1987]

Can you get 3.08 gearsets in an LSD? Was this combination OEM gear on any of the Commodores? I have a single-spinner standard VN-spec differential at the moment, but it's starting to develop a bit of backlash so I think it could be on its way out . . .
An LSD is the obvious choice for replacement - what are my options? How much money are we talking about? I don't want to lose highway fuel economy either - my starts are fast enough, I have no need for a lower gearset.

[greenfoam]

Pretty much all of the ones you will find are 3.08 and yep it was a factory option on just about everything, how much? depends what kinda deal you can find could be anywhere from almost nothing to quite a few hundred

[VN_Luke]

^^

yup, 3.08 LSD = most common gearset you will find...


firstly, to answer the original question:

your options:
1) buy a nicely built LSD diff to suit your car with choice of ratio ($1,000+)
2) buy a 2nd hand LSD from a vn-vs solid axle car ($100-$400) (add $300 for basic rebuild if faulty when bought)
3) buy a replacement single spinner from any given thousands of vn-vs's ($0 -$200)
4) get the lash adjusted in your diff so it's nice again ($50 - $200)

also you have a choice of many gearsets, but if you're happy with 3.08, keeping the speedo and computer right, then it's the mooooooost common ratio in vn-vs commodores.


Now for just crapping on for the sake of future searches:

for a bit of information on commodore diffs: (i only know a limited extent), there are a few good forums that cover this information *ultimately*


Basics:

vn-vs (non irs) commodore v8/v6 diff = same diff, (borgwarner) BW78 center.

the BW78 diff CENTER is shared with:
- newer falcons (EA-EL)??? (apparently XR6 had 3.45 gear ratio, the rest of the falcons had something cruisy as... 2.78's or something??)
- early skilines/pintaras (85-92)???? (pintara runs 4.11 gears, skyline manual runs 3.7's, and auto runs 3.9's)
- Commodore VL V8, VL turbo, VN, VP, VR, VS (without IRS) (Vl turbo runs 3.45 gears)


The BW78 center in question is a four pinion, 28 spline axle center,

it is also worth mentioning that vb-vs (non irs) diff mounts have the same (control arms, shocks, etc)... (refer to note below)
**note below**
VN-VS WAGONS+UTES = same same for shock mounts (and all the rest)
and then.....
VB-VS SEDANS/SEDANS = same same for shock mounts (but be weary of the track width)
**note above**

So what about the track width?
(vb-vk) commodores ran a shorter track width than the vl, and the vl still had a shorter track width than the vn-vs....


My thoughts/beliefs:

from personal experience (and mates experiences) the BW78 LSD center cannot cope with too much thrashing! (a few donuts and you're single wheeling). Depending on use, if you're going to thrash it (a fair few bangers here and there) I would recomment a KAAZ LSD center, which sell for about $1,800, but you won't need a rebuild every few months, and there's always the locked diff, but I'll leave everyone's choices about that to them.


Random Information:
There is a company in brisbane that do detroit locker style kits for the BW78 center, they were called 'Lokkas' or 'Lokas' At the time of writing this, the company had stopped manufacturoing for a few months.




Keywords for future searches:
diff, ratio, LSD, center, bw, 78, bw78, borg, warner, 3.08, 3.45, 3.7, 3.9, 3.89, differential, apples, gear, set, gear-set, gearset, lash

[savage1987]

Thanks for that, VP_Luke. A lot of info there. I think I'll go with a factory one, as I plan to make these tyres last a bit longer than my last ones did :P

[immortality]

VP_LUKE pretty much covered it all above. any LSD you pick up from a wrecker will probaly need some work if you want it to survive for any period of time however