WRX tranny swap.

[logan9691]

I know this has been covered a couple of times on here but i need straight forward answers. When swapping the WRX transmission you need all 4 axels, but what about drive shaft, how do you get the speedo cable to work, and what about being able to keep the 3.9 legacy rear end?.

Thanks,
Logan

[skid542]

You do not need all four axels. The fronts should work just fine (mine did).

You need new rear axles because you need to swap the rear diff out for a WRX diff due to a difference in the transfer gear ratio. The WRX rear diff is a 3.54:1 (or close to).

The drive shaft length is different between AT and MT. So depending on what you're doing to swap will depend on if you need a new drive shaft. However, you may have to swap pinnion flanges on the rear diff as there are some variances and not all drive shafts mate to all rear diffs.

The speedo cable works just fine. You just have to 'stretch' it a little more to get it plugged in. If the WRX tranny has an electrical sending unit threaded into the tranny - just unthread it and put in the sending unit from your tranny (5mt and 4eat are the same).

Hopefully that helps a bit and I have not mis-informed you.

[logan9691]

Alright I have a MT already. Is there anyway to make the 3.9 rear diff from the legy work with the wrx tranny? What about pressure plate and fly wheel?

[skid542]

Sure you can make the rear diff from the Legacy work - just pull apart both transmissions and swap the transfer gears and then put them back together.


The pressure plate and flywheel will work just fine.