Original 9 inch ,swap or keep it?

[70CougarXr7]

Hi all ,

2 questions :

1= How do i know which gears i have in my diff ? ( no identification tag )
i know its a 9 inch but that's it.
(diff is coming out one of these days for some customistation of the rear axle ( coil over suspension).

2= Adding a new engine soon , around 450hp and same amount +- of torque,
is this original 9 inch gonna hold out ?

Idea's and suggestions,
always welcome !!

Greets!

[1985olds]

To figure out what gear ratio it is, Jack up both rear wheels and with the car in neutral spin the wheels. Count how many revolutions the driveshaft makes in order to spin the wheel once. That is your gear ratio.

Whether or not it will last depends on other variables. Tire size/compound, driving aggression, car usage, auto or manual etc.

[70CougarXr7]

Sounds easy enough, will give it a go tomorrow,
axle has been removed from the vehicle but will make it work.

Will most likely go for a manual transmission and i am aiming for a car which can be driven normal but offcourse aggressive aswell...

Thanks !

[1985olds]

Are you are pulling the center out? If so, you can count the ring gear teeth and pinion teeth. Divide the ring by the pinion and that will give you the ratio as well. Also it could be stamped on the ring gear too

[andrewb70]

If the diff is out, the ring gear will have two numbers stamped into the edge. Divide the bigger number by the smaller number to get the ratio.

Andrew

[70CougarXr7]

Thanks guys ,will look into it!
So by tomorrow i will know my gear ratio ,

what's your thoughts on using the original differential for the engine and manual transmission i have in mind ?

Differential is a bit chinese for me so i'm just curious about your thoughts

[andrewb70]

I think for what you have in mind, it will be fine.

[70CougarXr7]

I think for what you have in mind, it will be fine.

Thanks Andrew ,

Found the identification tag, 2.75 gears in it...
For my usage ( normal roads and fast acceleration) and not really worried about top speed that much
i think i should swap gears to something around 3.50/3.73....

So even though this original diff is strong enough, dont think this gear ratio is for my build....

Cheers

[andrewb70]

Might as well get a new whole center section with the diff of your choice and gear and upgrade to 31 spline axles.

Andrew

[70CougarXr7]

Yeah probably will (was thinking it needed to happen but hoped i could save money there) (but hey,no shortcuts!)
I just was not sure on how to identify my current gears.

Thanks for the advice ,
will start looking at options.