What Diff Ratio to get?

[GIMPEESS]

Hi All im just wondering if anyone could recommend what diff ratio i should put in my 5L VP irs commodore. It needs a better take off as its a little sluggish off the line. But i dont want it to be revving its tits off on the Highway. Any help would be greatley appreciated!!!!!

[AirStrike]

Is it an auto or manual? There isn't any way really to get the best of both worlds, I have 4.11's and its an animal off the line but sits abit above 2,500rpm @ 100km/h.
Us the program I have included to work out what it will rev at for a given speed.
Use the following ratios:

1st 3.06
2nd 1.63
3rd 1.00
4th 0.70

1st 3.25
2nd 1.99
3rd 1.29
4th 1.00
5th 0.72

[IBLOWN]

3.45:1 to 3.7:1 is fine and will make a big difference.

[V85000i]

i'm gonna get 3.7's. and i do a lot of open road driving, but i worked out that the fuel usage won't be that much worse.

[10000_fists]

I have a V6 AUTO with 3.7 diff gears and at 100k's(123 on speedo) it revs at 2300rpm. I didn't notice a great change in fuel consuption, and it made a big difference in take off, i'd recomend 3.7 gears...
i never worked it out but i reckon my average fuel consuption probably only changed 10-20k's per tank, i can still easily get 380+ out of about 50 litres, thats with the supercharger on to, with 30-30k's everyday on the highway, rest is flogging round town.

Just note that changing your diff gears will effect you speedo reading, when my gauge says 123 i'm really doing 100km/h

[pumba]

i have 3.9 geas in my VP SS (irs) and i sit on about 2600 rpm at 100km/h

as 10000_fists said, it will affect your speedo abit aswell. mine sits on about 130km/h when doin 100km/h... so yea, u quickly learn to read it differently lol.

and i probably get about 350kms per tank with about 50% highway and 50% city driving

[vq~gangsta]

There have been lots of threads on this subject, just search for 'diff ratio'

I would recomment 3.45 if you're on a budget, that's what i've got. You can get the gear second hand from VL turbos, but they are a little hard to come by.

Otherwise for an extra couple of hundred dollars you can get a 3.7 ratio. It's a wider cog, so it's stronger, and it will give you a little more accelleration than the 3.45

If you want to do the car up for the drags i'd use a 4.11 if you had up to about 250 Kw, and 3.9 if you had over 250 Kw. Beware though, these ratios will completely kill your fuel economy on the open road.

[JD]

3.45 are a nice ratio, mate just got them on his vn and it made a hell of a difference

[AirStrike]

3.45 are a nice ratio, mate just got them on his vn and it made a hell of a difference

You would **** a brick jumping in mine with 4.11's then

[immortality]

i changed my VH (V8 trimatic) from a 2.6:1 to 3.08:1 and didn't notice a thing, except that i couldn't break every speed limit in the country in first gear any more

[pumba]

^^^ hahaha yea a mate of mine had a old V8 mercades benz and it had like 2.5 or something like that and 1st gear wound out to about 130km/h

if u want an eas way put of it, go hunt thru some wreckers for a R31 skyline or pintara diff... between the R31 skyline and pintara seies, they had 3.7:1, 3.9:1 and 4.11:1 diff gears... and there a borg warner 28 spline diff so they are a straight swap with a commodore diff...

BUT sus that out 1st seeing as u have IRS... im pretty sure there a hydra-trac diff which might be different... not sure though

[AirStrike]

^^^ hahaha yea a mate of mine had a old V8 mercades benz and it had like 2.5 or something like that and 1st gear wound out to about 130km/h

if u want an eas way put of it, go hunt thru some wreckers for a R31 skyline or pintara diff... between the R31 skyline and pintara seies, they had 3.7:1, 3.9:1 and 4.11:1 diff gears... and there a borg warner 28 spline diff so they are a straight swap with a commodore diff...

BUT sus that out 1st seeing as u have IRS... im pretty sure there a hydra-trac diff which might be different... not sure though

No hydratrack in a VP SS mate.

[GIMPEESS]

Thanks for the suggestions. Ive heard the 3.45 diff gears out of a vl turbo diff will fit and would be a bit better than the 3.08. is this so?

[GIMPEESS]

I have not had a lot to do with diffs . So is this all that i would be needing to do the job?????


http://cgi.ebay.com.au/3-45-1-DIFF-G...QQcmdZViewItem

[m62vpute]

Yes the diff gears will fit , just a word of warning when you get the diff gears make sure you get a matching set as this is most important.


Not sure what you mean is better but 3.45's is in my view a very good ratio as you can still get some fuel econ but also still get a bit more sting of the line and around town

Hope that helps

[JD]

You would **** a brick jumping in mine with 4.11's then

i already did that when my old boss took me for a fang in a VY Clubbie!

[vq~gangsta]

If you want your car to be a good cruiser, have good fuel economy, and a riduculously high top speed then 3.08 is the best option.

If you want something that is more responsive, with more accelleration and better pick up then 3.45 would be a better choice.

[flyen]

i got 3:45 gears from a VL TURBO in mine
soooo much better than the 3:08 but my diff was fair rooted from 270xxxk's of hard driving.

spedo is 10k's out now at 60k's

[jNINE]

Thanks for the suggestions. Ive heard the 3.45 diff gears out of a vl turbo diff will fit and would be a bit better than the 3.08. is this so?

ALL VL's 6cyls are 3.45 ratio - just go and get one from the hundreds at a wrecker, that's what I did for my VR and got a Jaycar corrector kit to fix the speedo

[pumba]

as i said to u somewhere else, r u sure abou tthat? ive always known them to be 3.08's in the standard VL's and ive had 4 of them lol

[jNINE]

as i said to u somewhere else, r u sure abou tthat? ive always known them to be 3.08's in the standard VL's and ive had 4 of them lol

VL V8's run 3.08 and 6's are 3.45

[pumba]

hhmm... so it seems your right... i just had a look on the net at a few sites and they all sem to say the same thing...

i guess u learn something new every day lol

[1991_Vn2nV]

Yeah as said ALL VL 6's are 3.45 ratio, only the 5L VL's had a 3.08 ratio.

The VL Turbo's had a 4 pinion, 28 spline diff though while the N/A 6's had a 2 pinion 25 spline.

But the gears are the same, 3.45 ratio.

[V85000i]

well now i know how easy it is to get 3.45's i might go them instead of 3.7's, what difference is there between 3.45's and 3.7's in terms of acceleration 3.08-3.45 is another .37 and 3.45-3.73 is another .28 and 3.08-3.73 is another .65

[1991_Vn2nV]

3.7's are readily available in skylines anyway. If you choose to go the second hand route that is.