Help on diff gears

[bruzza]

hi all i was lookin at getting some diff gears for the wh gen 3 but i needed some advise on them i was lookin at 3.9's but i do a fair bit of highway driving what gears would be good for performance and still keeping decent highway economy??
thanx all

[RVN 355]

hi all i was lookin at getting some diff gears for the wh gen 3 but i needed some advise on them i was lookin at 3.9's but i do a fair bit of highway driving what gears would be good for performance and still keeping decent highway economy??
thanx all

3.7.3 mate

I got quoted for my rebuild for my vn ss v8 stock 3.08 with new crammnion and pinoin and 3.7.3 ratio $1100 SA Trans & Diff

[383 hatch]

new crammnion and pinoin

That would be Crown wheel & pinion.

[OLS108]

That would be Crown wheel & pinion.

BWAHAHAHHAHAHHAHA

[AirStrike]

3.7.3 mate

I got quoted for my rebuild for my vn ss v8 stock 3.08 with new crammnion and pinoin and 3.7.3 ratio $1100 SA Trans & Diff

1.23:1 diff gears are hella tall!!!
AirStrike

[bruzza]

yea i know 3.7s would be good, but they will make the car drink even more then 3.9's am i right? how much difference is there between 3.7's and 3.9's?

[IBLOWN]

i got 3.9's in mine (i know not a gen 3) and highway driving is not so comfy. theres not much difference between 3.7's to 3.9's. i got 2 mates with vx ss's, one with a tune and zorst pulling 235 rwkw doing 13.7's with only a slight traction problem, yet the other vx with mafless tune & zorst with 206 rwkw but he has 3.45's and does 12.9 1/4's. so yeah diff is well worth it. but i would go for 3.45's as its perfect for cruising.

[bruzza]

anyone know of a good diff shop in melbourne where i can take it down?

[SLugg]

3:45's are a good in the middle range

[Jecs]

Preston Automatics And Differentials, they are very famous and i think they were on the "Grunt Files" dvd hope i helped

Jecs

[sloth1198]

I need some advice on how to change the diff oil in a vt Berlina....and what is the best oil to use

[DrZ]

I need some advice on how to change the diff oil in a vt Berlina....and what is the best oil to use

Try having a search through all the threads here.. there are even a few 'how too's' which tell you how to do the whole job urself with the appropriate oils...

and then it all depends if you have an LSD or not.. If you have LSD you need to also buy a GMH LSD additive but as for the other oils, I think even your user manual wld have it in the spec sections.

Sorry for being frank, but I cant remember the oil weights atm, at uni and cant be to bothered looking around..

but just write 'diff oil change' in the search bar on the top of the forum.. will likely fix ur probz

[eaton v8]

.................

[cpbait]

we used the castrol diff/gear oil you can get from repco, bursons, autobahn, etc for a vt, like said above just got to work out if its lsd or not. castrol oil guide book at autobahn, etc will tell you exactly which to use or on the castrol website. Also price up the oil from holden, some times you find there the same price or sometimes holden is cheaper.

[helicraze]

I have 3.7s, wish i had gone 3.9s (had them in a V6), the 4.11s are too tall IMO i had them as well. All autos

[DrZ]

I have 3.7s, wish i had gone 3.9s (had them in a V6), the 4.11s are too tall IMO i had them as well. All autos

Huh? 4.11s are to tall?? What are you running? 26" rims?? If 4.11s are to tall for you 3.7 must be rediculasly tall for you mate..

[mooseboost]

I have a VXclubsport 6 speed. Standard diff gears in my car are 3.73. Fuel economy is not and issue. Best I've seen it do before I did cam etc was 8.5ltrs/100km. This was filling up at BP and doing the Cruise for Charity last year on the drive to Bundoora. After the hole trip to Heatcote, staying in Bendigo and driving around then back home it averaged 10.2ltrs/100km. Now with cam etc it still gets 9.4ltrs/100km on a trip with highway driving. So if you won't to living that big bitch up go 3.73 or 3.9's because you fuel economy will change #### all. You will need to get your ECU speedo setting modifed to accept new gears as your speedo will be out, so remeber to keep this in mind as an extra expence.

[VX SS 340 HP]

I have a VX SS with 3.73s in it...it has been MAF less tuned made 340 HP at the wheels it sits on about 2500rpm at 110km with cruise control

[Chrisvyss]

I went 3.73 in my vy ss auto sits just under 2500 at 110 with cruise on
fuel economy around 13.5 to 14.5 i do mainly suburbs but to and from work on western highway for 25 ks each way
kicks off the line beautifully, i would recommend GM Motorsport for the diff change because they also have the Software to reprogram speedo and gearbox that the Retards at local dealer dont.
If you dont reprogram your speedo it will be anywhere between 17 and 23 ks out depending on speed.

[vuTobySS]

haha i got 6spd with the 4.11 and i sit on about 2k at 110km/h, my speedo on the other hand things im doing 130 (used a gps to work out my speeds)
I find that under 100km/h im 10km out on the spedo and over 100km is 20km+
Would love to get the spedo fixed tho :P

[immortality]

when selecting diff gears you should take into consideration the type of transmission as well as intended application.

if you have a older 4speed auto (4l60e) which has a .70 overdrive you would be doing approx 2400rpm with a 4.11 diff @ 100km/h, however if you had a T56 trans which has .50 6th gear ratio @ 100km/h you would only be pulling approx 1700rpm.

also, 1st gear on a 4.11/T56 equipped car is only slightly shorter then the factory 4l60e/3.07 combo 1st gear

[sus_calais]

Prob best to go for a ride in a few cars with different gears if ya can! The lower ratio u go the more responsive but alot of the time, the less kms per tank u wil get..depending on driving conditions but as a general rule of thumb..

[walesy]

even the 3.46 make a massive difference with the big weight of the WH over the standard 3.07's, i got 3.9's aswell but never put them in yet, IMO there would be hardly a difference between 3.9 and 3.7's, i doubt you would really be able to tell really

[Jonno]

4.11s ftw

[03 VY]

hey guys, i know this thread started years ago but seems people are still making the odd comment so thought i'd chuck up a question....i'm thinking about changing diff gears to 3.46 in my vy ss auto, will this put the speedo out? i will be getting them installed perfessionally. cheers