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Diff Centre

hey guys,

i have a few questions, please bare with..

my id plate on the front of my car suggests that i have a GV7 rear axle. i have 1975 holden hj with a 202 and a 3spd manual is the GV7 common in this type of car??

also i have read that the GV7's ratio is 3:55:1 is that correct?

plus i know its a banjo diff of some sort however it doesnt have ne id numbers on it and is definately an open wheeler... is this also possible.. im going to replace the diff centre and i need to be sure.

Cheers, Nick



"is the GV7 common in this type of car??"

Yes, correct.

After all this time the Diff Ratio might be anything.

If it were me I'd measure the Diff Ratio this way.

Secure both Front Wheels so the Car can't roll.

Jack up one rear wheel and with the Handbrake off and the car in Neutral count the number of turns of the raised roadwheel to 3.55 turns of the prop shaft.

It will come out as 2 roadwheel turns if you truly have a 3.55.

The Diff ratio will be halved because the diff spider gears will be forced to rotate by the stationary rear wheel (the one still on the ground).


Holdenpaedia, they're the brakes Mate.


My Shed

Holdenpaedia, they're the brakes Mate.

A better way to check diff ratio is , 1 full turn of your rear wheel while counting tail shaft revolutions, if your tail shaft does 3.55 turns to one wheel revolution thatโ€™s what it is.

GV7 is the 3.55:1 ratio diff yes it is the most common diff ratio holden made from 1966 to 1978 , and the yes that is right for your car , the next common would be the 3.36:1 ratio diff , if your going to replace it get 3.36 ratio one , you will get better fuel economy and better for cruising with ..


cheers for the tips.

with the 3.36 wat would that do in regards to the top end??? and with the rest of the gears?