Choice of diff gears for starters?

[.Holdon.]

hey,
i have a VT SS 5L. what would be a good choice of diff gears to start with - 3.7's or 3.9's? have heard 3.55's dont really make too much of a difference. 3.7's seam to be the way to go but would 3.9's to too short for starters?

what have you guys with some knowledge on this found is the best set up? or advantages of each set of gears?

cheers

 

[fabz]

Depends what your aim is. Drags - 4.11 hiway - 3.46 (i think). happy medium would be 3.7's but all depends what your looking for. SS should have 3:46 i think already.

 

[Immortality]

VT 5Ltr should have 3.08 ratio diff, VT s2 was the change over model with 5.7 LS1 got 3.46 (man) and 3.07(auto) a. diff gears are also influenced by the trans. 3.9's make 1st gear on a 5speed manual very short. but aren't bad with a auto trans. if you do a lot of highway driving and gas mileage is important then 3.45 are ideal

 

[.Holdon.]

i have an auto with 3.08 gears. dont do alot of highway driving. living in darwin atm so its mainly just driving around there. not over 100 much of the time. after the new gears to wake the car up a bit.

you said it would go thru first quickly on a manual, how would the 3.9s go in an auto?

 

[walesy]

the auto will be fine... im looking for a set of 3.9s for mine too...

 

[.Holdon.]

anyone know what rpms the 3.9's sit at when crusing at around 60, 80 or 100km/h?

 

[crazybiker]

It all depends on the rolling circumference of your tyres though.

 

[Morton]

3.89s should sit you up around 2400rpm.

My 3.73s had me on 2300rpm at 100.

 

[crazybiker]

On my tyres, which have a rolling circumference of 201cm, I'd be sitting on JUST over 2,200RPM to keep 100km/h, that's in 5th gear.

With the original 3.08 diff though, to sit on the same speed, in the same gear, I'd be running at around 1,850RPM.

 

[LAPD-VN]

a nice set of 3:45's is the way to go, mayve 3:7's but you dont want to much more unless your made of money and love to pay expensive petrol bills.