Welcome to Just Commodores, a site specifically designed for all people who share the same passion as yourself.

New Posts Contact us

Just Commodores Forum Community

It takes just a moment to join our fantastic community

Register

RPM diff ratio

RATBOX

New Member
Joined
Feb 23, 2018
Messages
13
Reaction score
7
Points
3
Age
59
Location
coffs harbour
Members Ride
VX SS
just a general question i've just bought a VY berlina wagon 5.7 auto i'm curious about the diff ratio, having owned other 5.7 commodores utes and SSs this seems to be revving a little harder @115kmh revs are around 2200RPM from memory others i've had at this speed are around 1800RPM what do others say is normal just wondering if mine might have had a lower diff ratio fitted, speedo seems spot on based on a GPS speed app on my phone

thanks
 

markalan1two

Smile and wave boys !!!!
Joined
May 23, 2014
Messages
666
Reaction score
399
Points
63
Age
50
Location
NSW
Members Ride
X5 BMW, GenF2 GTS, HSV Y R8, Audi S3, AMG C43
probably 3.46 manual rear gears
 

EYY

Well-Known Member
Joined
Mar 6, 2011
Messages
5,416
Reaction score
1,466
Points
113
Location
Vic
Members Ride
VS Statesman
2150 rpm is normal with 3.07 gears for that speed. Small variations in tyre size, tacho accuracy etc though.
 

RATBOX

New Member
Joined
Feb 23, 2018
Messages
13
Reaction score
7
Points
3
Age
59
Location
coffs harbour
Members Ride
VX SS
thanks for the replies, maybe just seems to be revving a bit harder being a wagon can hear the exhaust more
 

markalan1two

Smile and wave boys !!!!
Joined
May 23, 2014
Messages
666
Reaction score
399
Points
63
Age
50
Location
NSW
Members Ride
X5 BMW, GenF2 GTS, HSV Y R8, Audi S3, AMG C43
http://www.apexgarage.com/tech/gear_ratios.shtml
here the link to work it out.
if you have 235/45/17 you Tyre diameter is 25.31
VY auto ratio's are
1=3.059-1
2=1.625-1
3=1-1
4=0.696-1
you can change your final drive and see the differences
 

RATBOX

New Member
Joined
Feb 23, 2018
Messages
13
Reaction score
7
Points
3
Age
59
Location
coffs harbour
Members Ride
VX SS
thanks, used the link dunno if i'm doing something wrong but get no results from it, when i hit calculate all i get in all the boxes is NaN
 

EYY

Well-Known Member
Joined
Mar 6, 2011
Messages
5,416
Reaction score
1,466
Points
113
Location
Vic
Members Ride
VS Statesman
That link figures out max rpm in each gear. You can’t do reverse calculations. All you need to know is that 1850 rpm at 100kmph is approximately correct for 3.07 geared commodores with tyres close to original rolling diameter (of course commercial variants are different due to larger tyres).

Base your comparison off this.

Eg.
In the case of 3.73 gears:
1850/3.07=602

602*[email protected]
 
Top