Subaru Forester Owners Forum banner

1 - 3 of 3 Posts

·
Registered
2014 FXT CVT
Joined
·
359 Posts
Discussion Starter #1
So 4EAT's in 06 and newer had their final drive downgraded to taller 4.111 from shorter 4.444. I'm noticing the car laboring more to get the car up to speed, compared to my 06 STi with much shorter gears, especially in 2nd/3rd. Here is short list of what I'm talking about

Car........06 STI.........06+ FXT auto....04/05 FXT auto
Redline...7100............6500................6500
FD.........3.90............4.111...............4.444
Tire.......225/45/17.....225/50/17.........225/50/17
1st........37 mph.........44 mph.............40 mph
2nd.......57 mph.........79 mph..............73 mph
3rd........77 mph.........122 mph............113 mph
4th........100 mph.......175 mph............162 mph
5th........139 mph
6th........179 mph

If you look at it, with 4EAT I am shifting from 1st straight to 3rd speaking in terms of STi 6MT gear ratios. With 4.444 FD, 2nd and 3rd gear would be more responsive, although the car would rev about 200 rpm higher at 70 mph - but I didn't get this car for economy. So then taller final drive is useless, since I will be drag limited to 150 mph anyway even on a track. Something like 4.666 would be even sweeter but Subaru doesn't make that.

The other day...I had Cobb stg 2 on 08 FXT and I was dead level with stock 04/05 4EAT to 60 mph. That taller gearing loses so much in acceleration. I can tell that in the 6MT as well, where USDM STi's got taller ratio's for 5th and 6th (where JDM STi gets all 6 gears evenly spaced with short gears) as a result, shifting 1-2-3-4 @ 3~3.5k will still leave you in the power band after shifting, but 5-6 will drop you below power band.


So with that out of the way, my question is, how hard is it to swap final drive back to 04/05 4EAT of 4.444 for quicker acceleration? As far as I know rear diff and gear ratios are the same between 04-05 and 06+.
 

·
Registered
none none
Joined
·
8,844 Posts
You would have to swap in a 4.44 rear diff (could even get a jdm R180!). Then you'll have to pull the trans, pull the front diff casing, swap the 4.44 R&P from an earlier model. You'll likely also have to shim it etc.

If you've never regeared a diff or opened up a trans, I'd probably have a shop do it.
 
1 - 3 of 3 Posts
Top