[Jeffn]

I now have an '06 4eat trans installed in my 04 Xt. I was told the 06 has a positraction differential and that the 2 trannys are incompatible for parts interchange? C'est vrai? Or can I pop the good 04 diff into the bad 06 trans? Apparently the software is not controlled by the ECMs, only within the trannys.

 

[phantomfozzy]

I believe in the facelift (06-08) they switched to the VTD center diff from the MPT center diff. I'm almost positive that at least one user has swapped the MPT for VDC.

EDIT:
http://www.subaruforester.org/vbulletin/f89/mpt-vtd-conversion-37441/
http://www.subaruforester.org/vbulletin/f89/mpt-vs-vtd-4eat-62799/

 

[dirteemac]

I think only the 07-08 sports and the 08 xt 4eats got the vtd trans. Also I think I read that the 04 4eat was unique and an 04 can't use an auto trans from any other years.

 

[Jeffn]

That part's disprove-I have this 06(f that's what it is) in my 04 now and no probs other than the diff is bad(could that be the problem-incompatible diff in an 04 causing the vibes and the massive torque steering?).

 

[dirteemac]

I got that info from this thread: http://www.subaruforester.org/vbulletin/f65/04-fxt-4eat-235025/ maybe he was wrong.

 

[dirteemac]

That part's disprove-I have this 06(f that's what it is) in my 04 now and no probs other than the diff is bad(could that be the problem-incompatible diff in an 04 causing the vibes and the massive torque steering?).

I think 04 4eats had a 4.44 rear diff and 06's may have had a 4.11. Not certain, but that may be your problem if your front and rear diffs have different ratios.

 

[Jeffn]

I saw that one also. Maybe this is the result as my seller swears it was working fine in his 06 when he pulled it out. the sube dealer says it's likely spider gears in the diff.

 

[Jeffn]

Ok, so the service tech at Sube DOES say that an 06 w/viscous diff could cause these symptoms...I have a good 06 trans perhaps in an o4 and cannot swap diffs...

 

[Jeffn]

I believe in the facelift (06-08) they switched to the VTD center diff from the MPT center diff. I'm almost positive that at least one user has swapped the MPT for VDC.

EDIT:
http://www.subaruforester.org/vbulletin/f89/mpt-vtd-conversion-37441/
http://www.subaruforester.org/vbulletin/f89/mpt-vs-vtd-4eat-62799/

SO you think the diffs are interchangeable? My Sube tech says no or he may be trying to sell me a $4k rebuilt...

 

[stan_t]

Final drive ratio is different in '04 4EAT vs. '06+, shouldn't be compatible.

Stan

 

[Jeffn]

Final drive ratio is different in '04 4EAT vs. '06+, shouldn't be compatible.

Stan

Wouldn't that only screw up the speedo? Whatever ratio coming out of the final splines would spin the rear at whatever rpm...no?

 

[guroove]

The '06 FXT has a different final drive ratio than the '04, so you can't use the same rear end. Also the '04 FXT has a limited-slip diff in the rear end, if that's what you mean by "posi."

 

[phantomfozzy]

SO you think the diffs are interchangeable? My Sube tech says no or he may be trying to sell me a $4k rebuilt...

The center differentials should be interchangeable if you also swap the tailhousing per that thread, but I suspect that your problems are caused by the 4.11 final drive in the 06 trans conflicting with the 4.44 rear end ratio in your rear diff.

 

[Jeffn]

Still daft re: the rear pumpkin ring/pinion ratio. Why does it matter how many revs are coming out of the driveshaft since the rear ratio is a constant at 4:11 or 4:44 and converts the driveshaft revs to it's own fixed ratio (4:11, et al)? In the old days we would stick whatever ratios we wanted into the rear diff to change the final ratio to the wheels. Thus, we wold drive around in my pal's 65 stang with 5:30 rear at 50 mph and 3200 rpm-luckily it revved to 6000 and only had one contender on Long Island, a GTO, but I digress 8 ')

 

[Flighht2k5]

As these are not made by GM. It will not have a "posi."


Sent from AutoGuide.com App

 

[Jeffn]

Although effectively the same system with clutches and sprags to the 'wheels that grip' albeit more sophisticated.

 

[nepbug]

Am I the only one that is a little lost here?

You just keep saying diff/differential. Are you talking front, center or rear? There are 3 differentials in your car.

The 04 XT 4EAT was a 4.44 front differential, 4.44 rear differential and of course a 1:1 center diff.

The 06 XT 4EAT was a 4.11 front differential, 4.11 rear differential and of course a 1:1 center diff

You have to match your front and rear ratios if you have a 1:1 center diff, they can be different if you have a different center diff (like out of a WRX).

Now, what diff is supposedly "posi"?

Is the 06 donor from an XT, or a 2.5X/2.5XS?

If you've been driving a 4.11 transmission with a 4.44 rear diff, you've likely smoked your center differential. You'll need a new center diff and a rear diff to match the new transmission.

 

[Jeffn]

Ignoring positraction for now, thanks for the simple explanation.
The center diff is inside the trans, not in the transfer box thing that's pn the tailpiece(from a quick glance in the shop), correct? And if the 04 & 06 are both 1:1 direct drive, why wold they not work with either 411/444 ratios?

I have about 30 miles on the mismatched 06/04 combo.

RE the antiquated term 'positraction,' is not a Sube awd system a sophisticated positraction; power to the wheel that's not slipping with a clutch system?

Close, I just discovered: The Differences Between Positraction & Limited Slip | eHow

 

[Flighht2k5]

Although effectively the same system with clutches and sprags to the 'wheels that grip' albeit more sophisticated.

People tend to think a posi is better than a limited slip. Like you said they are the same thing.


Sent from AutoGuide.com App

 

[Jeffn]

In the article I posted, it would seem the LSD would be a better system in that it keeps some power on both/all wheels, even the slipping one. BUT, why do 'posi' cars do equal burnouts on both wheels and not just one like a non-posi car(legal evidence in 'My Cousin Vinny')? More early morning auto-theory...