Tacho vs Speedo

[Gelf VXR]

Does anyone know what the gearbox ratio's are?

Whats should the Speedo be reading at 6000rpm in 5th gear?

[mackie1]

158mph on an 05 VXR assuming a 3.46 final drive and a T56-M12 with a 5th gear ratio of 0.840 or 180mph if it's got the 0.74 5th (I'm not sure which).

This got me a little confused as it seems my car has the shorter ratio box when it shouldn't have - I think. I thought only the VZ CV8 got the shorter ratio T56-M12 but my calculations show that my revs tally with the shorter ratio box. Weird.

Edited by mackie1 on Thursday 22 March 14:49

[greens vauxhall]

6.0 VXR got M12 5.7 only got MM6

[mackie1]

greens vauxhall said:

6.0 VXR got M12 5.7 only got MM6

Can you clarify what the ratios are for each? I think mine has had a new gearbox at some point so maybe it was swapped for a slightly different version. I'm pretty certain that 6th on mine is 0.57 and not 0.5.

[Gelf VXR]

mackie1 said:

158mph on an 05 VXR assuming a 3.46 final drive

Close enough, I read 157mph @ 6000 rpm

Edited by Gelf VXR on Thursday 22 March 16:38

Edited by Gelf VXR on Thursday 22 March 16:38

[splatspeed]

i have calibrated my monaro with the sat nav

and it is scarily accurate

so if it says you are doing 70 i was doing 70

so not hard to work out the figures as the tachos are electronic as well and just as accurate