1970 Nova L78 rear axle options

[JHS]

Were there any required gear ratios for the 1970 L78 Nova, ie- 3.73 or 4.10? My book indictes that the 4.10 was not available for the Nova in 70 so assume it could be ordered with a 3.55 or 3.73? My car has the TH400 which might make a difference. Thanks.

[WILMASBOYL78]

The "default" axle ratio for the L78 Nova (4spd/th400) was the 3.55....you had to order the G80 positraction as an option....3.55 was the steepest gear available on the 70 Nova except for the Deuce with the COPO options...many guys had the gears changed prior to delivery or it became the first back yard improvement...there is definately a big difference when you step up the gears with the L78...I have a 4.56 setup in the 70 TH400 car and it is a monster!!

wilma http://www.yenko.net/ubbthreads/images/graemlins/burnout.gif

[396L78canuck]

I agree with Tom.My 1970 L78 Nova ( November 69 Build date) also came with a 3.55.The documentation I received from GM of Canada only shows a 3.55 with the L78 and no optional ratios from the factory.Bob http://www.yenko.net/ubbthreads/images/graemlins/scholar.gif

[@wot]

3:55 was it, unless you made the change after delivery.

[JHS]

[ QUOTE ]
3:55 was it, unless you made the change after delivery.

[/ QUOTE ]

ust wondered. My L78 rear tube has the CBT suffix but had a 4.10 gear in it, which is what the second owner said was in the car when he got it and I knew the 4.10 was not available so guess the 1st owner changed it out.

[YENKO DEUCE REGISTRY]

What's the date on the ring gear?

[@wot]

If its CBT and belongs with that car, it was a 3:55.Does the month and day of manufacture seem right for the car, or match the POP?

[JHS]

[ QUOTE ]
What's the date on the ring gear?

[/ QUOTE ]

I will have to look but I believe my mechanic indicated it was a "richman 4.10 thick gear", not sure what that means, but assume an aftermarket gear, and will have to find out the date. The second owner who bought the car in 1977 told me the 4.10 had been installed shortly after taking delivery of the car but said it was changed under warranty so something must have broken as the car was bought to race.

[YENKO DEUCE REGISTRY]

That means that they installed a 4 series gear on a 3 series carrier. That also means that you can change it back to a 3.55 without changing the carrier http://www.yenko.net/ubbthreads/images/graemlins/biggthumpup.gif

[JHS]

You are correct and the change back to a 3.55 was made, although the 4.10 would have been nice to play around with. I got educated on that subject last night by my mechanic! One day I may learn something about rear axles.