Different final gear ratio problems?

[Danny]

Hi, I have an automatic transmission and I've bought a manual gearbox from Outlander 2003. It is a W5M51-2-X4B with final gear ratio 4.529. Our cars have a final gear ratio 4.111 which should be the rear diff too.

Will there be a problem if front diff final gear ratio doesn’t match the rear diff final gear ratio?

 

[6A13TT TYPE S]

The final drive has nothing to do with the diff ratio or transfer case ratio.
In our cars the final drive (which is inside the gearbox) is turned by the gearbox output shaft which then turns the front diff and transfer gear at the same speed.
All the transfer gears do it gear the driveshaft up to spin at a faster speed to reduce the torque load. Which is then undone at the rear diff to make the rear axle turn at the same speed as the front axle.

The transfer ratio is the same as that of the rear diff which 3.303

In a rear wheel drive car the output shaft drives the driveshaft directly which means the rear diff ratio is the final drive.
The VR4 is more like a front wheel drive car where the transfer case "piggy backs" off the transaxle to steal power to send to the rear axle.

Subarus are a bit different again because they are longitudinal engine the gearbox and rear diff setup operates like a regualar RWD setup, but the front diff is inside the gearbox so you have to make sure the ratio of the front diff matches the rear as the gearbox output spins both the front diff and rear diff at the same speed without an external transfer case.