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I have been having difficulties finding a replacement Auto transmission for my 1990 Liberty. A nice low km wrecked 2001 Forester has presented itself to me with the opportunity to purchase to Auto, TCU and rear diff.

This sounds appealing as the 4.11 final drive ratio on the Liberty struggles with the big 27" tyres. The 3.9 forester ratio would be much better and I understand the transmission is generally tougher all round than the older Liberty unit.

So I want to ask the forum community is this conversion possible and what should I look out for?

The transmission will fit mechanically, but electrically they are quite different. The sensors and valvebody are quite different and the TCU and ECU talk to each other in post 1998 models (identified by a round oil filter on the passenger side of the transmission).

More hassle than its worth really. If you found a transmission from a pre 1998 liberty/outback or even impreza (as long as it doesnt have an external oil filter) you should be sweet.

Gannon wrote: If you found a transmission from a pre 1998 liberty/outback or even impreza (as long as it doesnt have an external oil filter) you should be sweet.

Great info thanks. So the models you mentioned all have 3.9 final drive ratio and are essentially 'plug-and-play' with respect to TCU?

Hang on, I have stuffed up here haven't I?
I should be looking for a 4.44 final drive to compensate for the big tyres, shouldn't I ???

Yepif you want to lower the ratio to make it rev higher for the same speed youneed a higher numericalk diff - so yes 4.44.

I think Gen2 Outback (94-98 ) have a 4.11 final drive and should be compatible with your car.

im not sure its that simple though. is a 4.44 auto necessarily geared lower than a 4.11 auto? Depends what the gear ratios are internally.

My solution was to put a 4.44 diff on the front of a 4.11 box. Made 27" tyres feel normal.

PM subaman (Grant) i know he has a good GX auto he wants to sell.

Gannon wrote: If you found a transmission from a pre 1998 liberty/outback or even impreza (as long as it doesnt have an external oil filter) you should be sweet.

Hi Gannon,

I have been offered a 95 Outback auto transmission but the drive shafts look different to the Liberty where they enter the transmission. (ie. push in rather than slide on to the splines)

Would it be simple enough to also use the Outback driveshafts in my Liberty?

Also, would I need to run the Transmission Computer from the Outback?


Thanks, Scott

Being an outback it could possibly be a different ratio so the rear diff will have to be changed too. And because outbacks had taller tyres, so the speedo will be slightly out. You might get away without needing to change the tcu. I think you could just change the inner cups to change from female to male joints

vincentvega wrote:im not sure its that simple though. is a 4.44 auto necessarily geared lower than a 4.11 auto? Depends what the gear ratios are internally.

My solution was to put a 4.44 diff on the front of a 4.11 box. Made 27" tyres feel normal.

PM subaman (Grant) i know he has a good GX auto he wants to sell.

AFAIK all the 4spd autos have the same internal ratios.

Gannon wrote:Being an outback it could possibly be a different ratio so the rear diff will have to be changed too. And because outbacks had taller tyres, so the speedo will be slightly out. You might get away without needing to change the tcu. I think you could just change the inner cups to change from female to male joints

Also AFAIK all Outbacks have 4.44 diffs.

So you will have to change rear diff to 4.44

I have since come to the same realisation about the internal ratios. I went to a lot of trouble to build my box. I should have just fitted outback speedo gears to a gen2 TT legacy box.

Yeah and if you are going to the trouble of fitting a different box you should try andf get a WRX or Gen 2 Twin Turbo box - they have VTD centre diff which is 1000 times better than standard

This is all too hard. One bloke swears a 95 Outback Auto will slip straight into my Liberty but then the crowd claims that I will also need to change drive shafts, rear diff and TCU.

Honestly I just want the car driveable, I do 90 kilometers per day on the highway and occasionally drive it on the beach. If I could just find a straight replacement transmission I would have it in the car tomorrow.

Mate,
I think you need to take a teaspoon of cement and HTFU.
or
Maybe you should give up offroading, buy a Hyundai and play Golf.

Did you try my original suggestion and pm subaman?

Alternatively i reckon the outnack box will be ok with your original tcu as it isnt vtd. You will need a 4.44 rear diff to go with it. Doesnt havd to be the one from the outback. A gen1 turbo auto rear diff will drop straight in and is a viscous lsd.

Best thing i ever did was switch to 4.44 it made a huge improvent in all areas.

I could not agree more. Everyone worries about big tyres and lift kits, more power, loud exhuasts and flashing lights.

Getting the correct Final drive gearing is one of the best mods you can do, it makes all the other mods you do work as they should, but unfortunelty you cannot see it or hear it, so not many do it.

vincentvega wrote:Did you try my original suggestion and pm subaman?

Yes thanks, the PM didn’t work but I found his number and called him this morning. I will be picking up a stock standand transmission this weekend.

ktm300 wrote:Mate,
I think you need to take a teaspoon of cement and HTFU.
or
Maybe you should give up offroading, buy a Hyundai and play Golf.

Good wan. Now FOB.

that wasnt so hard then was it

subaman owes me a beer..

Yes not too hard at all but ktm300 is still unhappy that I haven't corrected my gear ratios to compensate for bigger tyres. I guess there comes a point where I'd rather spend Weekends at the beach with my family in a nearly great Subaru then spending weekends in the garage working under a perfect subaru.