2003 H6 VDC replace 4spd auto with 5spd

[martium]

Morning all,
When the 4spd auto in my 03 H6 VDC eventually dies I'd love to replace it with a 5spd auto - there have been a few times for me when it feels like 5 gears would be better than 4.
Has anyone done it? Is it easy? What's it likely to cost?
Cheers

[Braap]

The 4 speed auto matches the engine so much better. A 5 speed auto around town it would just hang between gears the whole time. One reason why Subaru still makes a 4 speed instead of a 6 or even 8 speed like some car manufactures.

[jp1203]

Originally Posted by Braap

The 4 speed auto matches the engine so much better. A 5 speed auto around town it would just hang between gears the whole time. One reason why Subaru still makes a 4 speed instead of a 6 or even 8 speed like some car manufactures.

I respectfully disagree. There's a reason that every 2005 and later H6 is a 5-speed.

To me, it's really obvious that my 2004 H6 would benefit from another gear. Because it's a four-speed, it goes up to 45 or so in 1st if memory serves correctly...that takes a huge bite out of off-the-line performance.

It would also benefit in climbing situations where 3rd is just a bit too high to maintain speed in, but in 2nd you're racing the engine quite a bit.

I really don't know what would be involved in swapping the transmission to a 5-speed, but something tells me it wouldn't be easy.

[Braap]

For me, a 4 speed auto matched with the H6 is great. I believe a 5 speed would shift to much imo.

[Shiv]

Originally Posted by jp1203

I respectfully disagree. There's a reason that every 2005 and later H6 is a 5-speed.

To me, it's really obvious that my 2004 H6 would benefit from another gear. Because it's a four-speed, it goes up to 45 or so in 1st if memory serves correctly...that takes a huge bite out of off-the-line performance.

It would also benefit in climbing situations where 3rd is just a bit too high to maintain speed in, but in 2nd you're racing the engine quite a bit.

I really don't know what would be involved in swapping the transmission to a 5-speed, but something tells me it wouldn't be easy.

Yup, I agree.

When you're accelerating hard, you get all that wonderful torque at the top end, the gearbox changes up a gear and you gotta start all over again down the bottom of the rev range.

Also, I hate it when I have the cruise control on and I go up a slight incline and it changes down a gear, revs the nuts out of the engine and scares the crap out of everyone.

[grossgary]

Originally Posted by martium

Has anyone done it? Is it easy? What's it likely to cost?Cheers

i haven't seen on any boards anyone trying this yet, will likely be a few more years before someone does. so i don't think anyone knows yet how similar or not they are.

most folks are going to want a simple swap - meaning plug and play, simply buy the transmission and that's it.

it would surely be possible if you swapped "everything" needed TCU, transmission, possibly even engine and ECU and full wiring harness, but doubtful you're looking for that level. if you can find someone to do it that would probably run close to $10,000 depending on how you source used or new parts and who is doing the work.

if you were interested here is how you would start:

1. find the FSM for the TCU's (usually available online or forums or ask for them and someone will share). Compare the TCU and transmission connectors and see if they're the same. If they are the same then that is a good sign though doesn't mean anything by itself either way though. I've seen connectors be the same but the parts still aren't interchangeable and I've seen trans connectors be different but you can swap the connectors.

Then compare the pinouts to each TCU and see how close they are - you might get lucky. If the pinouts are identical and the plugs are the same then chances are really good.

it wouldn't surprise me if it worked and wouldn't surprise me if it didn't.

i put a FWD Auto trans in one of my current daily drivers that was originally AWD....plug and play, nothing needed.

[Kolenka]

Originally Posted by jp1203

To me, it's really obvious that my 2004 H6 would benefit from another gear. Because it's a four-speed, it goes up to 45 or so in 1st if memory serves correctly...that takes a huge bite out of off-the-line performance.

45mph in 1st seems a bit high for the 4EAT. The numbers I've seen say that it can go up into the mid-30s though. Either way, it isn't exactly geared for off-the-line performance.

Honestly, I find the 3rd->4th gear shift in drive more annoying. Nothing says "fun" like the transmission dropping into 4th while you are accelerating to meet traffic, and suddenly you aren't accelerating anymore. Sure I can put it into '3' and then drop into 'D' when I'm done accelerating (which I do), but it just feels like a giant gap is there in terms of gearing.

[Dodik]

5eat use CAN BUS system or something like that, swaping it in physically is easy but figuring out electronics will be a nightmare. iirc the 5th in 5eat is the same as 4th in 4eat so its not a taller gear just an extra gear in between. Basically no point.

[Kolenka]

Originally Posted by Dodik

5eat use CAN BUS system or something like that, swaping it in physically is easy but figuring out electronics will be a nightmare. iirc the 5th in 5eat is the same as 4th in 4eat so its not a taller gear just an extra gear in between. Basically no point.

An extra gear in between is exactly what the 4EAT is missing, IMO.

The electronics may still make it infeasible though.

[Normy]

An extremely complex swap of this nature is NEVER a good idea.

If you want a faster or more fuel efficient car, then buy one.

The engineers at Fuji have spent thousands of hours calibrating these transmissions. While I think the 4 speed tranny SUCKS [the guts are an industry standard transmission designed by Nissan for Ford that has been used in everything from the Mercury Sable to the Nissan Pathfinder]. I think you are going to gain nothing but gray hair by trying to perform this modification.

The 4 speed in my '01 Outback hunts back and forth from 3rd to 4th gear on the rolling hills in western Tennessee, the torque converter locking and unlocking constantly, it is annoying. And if you floor it, it drops one gear, then another....and then finally drops into the gear you want and the 220 hp H6 shoots the car forward. But by now, that hole in traffic you wanted to exploit has closed up and you wind up frustrated and cut off!

Oh well, you don't buy an Outback if you want nimble quickness, now do you?

Transmission reference: http://en.wikipedia.org/wiki/List_of..._transmissions