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differential swap/ upgrade?

('03-'05) 
5K views 8 replies 4 participants last post by  Dickie 
#1 ·
so ive been talking to my friend who owns a 1998 subaru legacy outback, and we got to talking about our gear ratio on our diff's... the legacy outback comes stock with a higher gear ratio (from what he was saying). so i got to thinking about increasing my get up and go, i was wondering what the best route would be to do? (for a reasonable price). can i just drop a new diff in, or will i need to swap other stuff? im new to awd as i used to work on 4x4's
 
#6 ·
So your car should have a 4.44 final drive. I am pretty sure that is already the shortest final drive you can get in a factory subaru. That will give you the most get up and go.

Also remember that you also need to change the front differential as well and that is easier said than done. You will basically have to swap the trans and the rear diff.
 
#8 ·
Ok, lets start off by defining some terms. Lower gearing is probably what you want meaning for the same gear and speed your engine RPM will be higher. Lower gearing also means that you have a higher final drive number like 4.44 in the Forester.

Subaru uses these final drive ratios:
4.44
4.11
3.90
(I think there is one more as well but cant think of it off the top of my head)

I am pretty sure you already have the shortest or lower gearing (4.44), I know for a fact that my car does. They do this because our tire diameter is larger than other models so they balance each other out.

The only option to go lower is to change the individual gear ratios in the trans itself. You can get JDM transmissions that have shorter gearing as well as the 4.44 final drive. I actually have one of those transmissions (Ver5 RA Trans with semi straight cut 1-3) that is going to go in my car. I am going to swap over to a longer 5th gear for that trans for better highway driving as well.

Or your other option that was already pointed out .... smaller tires! LOL
 
#9 ·
smaller tires look like garbage though... its like driving a monster truck with stock size tires, just dont look right. also my car already has slightly smaller tires than stock because my speedo reads faster than i am gong by about 5mph+ which isnt a big deal other than my miles go by a lot faster than they should be...
on another note, isnt your foz your daily driver? the #1 worst thing you can do with straight cut gears is drive them like a daily driver if im not mistaken. i was thinking about doing this until i did a lil research
 
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