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 Post subject: '06=3.90 fd
PostPosted: Mon Apr 28, 2008 10:35 pm 
Fourth Gear
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Location: Oak Harbor, Washington
Jake--I did some research and the '06 STi transmissions are 3.90 FD


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 Post subject: Re: '06=3.90 fd
PostPosted: Tue Apr 29, 2008 1:17 am 
Fourth Gear
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kleinkid wrote:
Jake--I did some research and the '06 STi transmissions are 3.90 FD


yeah, but if it is for sure an 06 tranny they run a 1.1 to 1 reduction in the center diff witch makes the final drive at the rear diff a 3.545

asc_up wrote:
Ah ok. What year tranny do you have Jake?


mines an 04 tranny

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94' Impreza wagon AWD 2.2ltr rally wagon FTW!


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PostPosted: Tue Apr 29, 2008 4:01 am 
Fourth Gear
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Several different sources state that the number TY856WW7MA is for an '06. At this point I don't know if there is any problem, so I don't have any solutions. Is this an issue for my 3.90 LSD rear differential or the 6spd?


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PostPosted: Tue Apr 29, 2008 5:52 am 
Fifth Gear
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Only the '07 has the 3.545 final.

BTW, brand new '07 6mt's can be had from the dealer for about $3800 right now. For some reason Subaru is selling them cheap.

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PostPosted: Tue Apr 29, 2008 6:16 am 
Fourth Gear
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So you think it will be OK?


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PostPosted: Tue Apr 29, 2008 6:03 pm 
Fifth Gear
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If its an '06 you'll be fine with the 3.90 rear. '04-'06 was a 3.90, and the '07 is the 3.545.

'07 STi on top


Image

Image

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 Post subject: '07 and '06 not '06 and '05 ?
PostPosted: Tue Apr 29, 2008 8:34 pm 
Fourth Gear
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Dan--Those charts look good. Thanks.

To verify--you are sure that the top chart is NOT for the '06 and the lower one for an '05?

Thanks, John.


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PostPosted: Tue Apr 29, 2008 8:50 pm 
Fifth Gear
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I got those from a friend who is a tech at Morries Minnetonka Subaru. We had this same debate on MNSubaru. '04-'06 is 3.90. Mine is an '05.


Have you driven the car yet? If you have you would have noticed if it was wrong.

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PostPosted: Tue Apr 29, 2008 9:03 pm 
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It has at least 500 miles on it since the swap. Seems to drive fine. Nothing has broken yet.


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PostPosted: Tue Apr 29, 2008 9:36 pm 
Fifth Gear
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You probably would have noticed before you got out of the driveway.

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PostPosted: Tue Apr 29, 2008 9:37 pm 
Fourth Gear
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http://forums.nasioc.com/forums/showthread.php?t=1074497

i've personally taken apart an 04 tranny and an 06 tranny and the transfer case gears do not swap between them... they are different

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PostPosted: Tue Apr 29, 2008 10:47 pm 
Fourth Gear
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I have done a lot of searching on this the last few days. There is conflicting information to sift through. I believe that the reduction gear(rear) transfer reduction gear ratio for the '04- '06 is 1.0 and for the '07 is 1.1.


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PostPosted: Wed Apr 30, 2008 3:11 am 
Fifth Gear
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^ That is what the dealer info states. Again, if he had a mismatch, there would be noticeable side effects before now. They may have changed the design, but that doesn't mean its not a 3.90 rear final.

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 Post subject: Subaru Technical Information Site Adobe files I.D.?
PostPosted: Thu May 01, 2008 2:10 am 
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Dan--Sent you a PM that has more detail, but briefly, those charts are from a Subaru document. The second one, Adobe Reader MSA5T0510A, is from the '05 Service Manual. I can't see what the top one is because it is cropped off. Do you have the Adobe Reader file number from the top one?


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PostPosted: Thu May 01, 2008 6:07 pm 
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I would like to just clarify/correct something.

There is a difference between final gear reduction and overall final dive ratio.

The overall final drive ratio is the same between the 06 & 07. The 1.1:1 stepper in the rear transfer gear combined with the 3.545 rear diff provides roughly a 3.9 final drive ratio.

Obviously you can't use an 06 transmission with an 07 rear diff, but in terms of overall final drive ratios between the 06 & 07, they're the same....and that may be 100% understood by the parties posting, I just fealt it wasn't very clear, especially to someone searching for information.

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PostPosted: Thu May 01, 2008 6:51 pm 
Fourth Gear
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very good point josh.....

let me see if i can clarify a little bit. all of the STi's final drives are 3.9 but the 06-08 use a 1.1:1 reduction in the transfer case which makes the final drive at the rear differential a 3.545

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94' Impreza wagon AWD 2.2ltr rally wagon FTW!


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PostPosted: Thu May 01, 2008 6:57 pm 
Fourth Gear
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For me the issue is this, if after the transfer reduction, the final reduction is 3.90, then it is compatible with my 3.90 rear differential.

If the final reduction is 3.545 then it is not compatible with my 3.90 rear differential.

Are those two statements not correct?

Does the 06 use a 3.545 rear differential?


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PostPosted: Thu May 01, 2008 7:06 pm 
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jake15 wrote:
very good point josh.....

let me see if i can clarify a little bit. all of the STi's final drives are 3.9 but the 06-08 use a 1.1:1 reduction in the transfer case which makes the final drive at the rear differential a 3.545


That's incorrect terminology. The final gear reduction at the rear differential is 3.545, NOT the final drive.

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1990 Legacy (AWD, 6MT, & EJ22T Swap)
1997 Impreza OBS

If you need to get a hold of me please email me rather then pm


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PostPosted: Thu May 01, 2008 7:07 pm 
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kleinkid wrote:
For me the issue is this, if after the transfer reduction, the final reduction is 3.90, then it is compatible with my 3.90 rear differential.

If the final reduction is 3.545 then it is not compatible with my 3.90 rear differential.

Are those two statements not correct?

Does the 06 use a 3.545 rear differential?


Those statements are correct.

From the info posted above, the 06 does not use a 3.545 rear differential.

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1990 Legacy (AWD, 6MT, & EJ22T Swap)
1997 Impreza OBS

If you need to get a hold of me please email me rather then pm


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PostPosted: Thu May 01, 2008 7:21 pm 
Fourth Gear
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Where I am having a mental problem understanding this is the lower chart above. The number of the Adobe reader file, MSA5T0510A, is taken from the '05 Service Manual. I got that info from the Subaru Technical Information Site. Dan says it is the '06 tranny. You can't see the number on the upper chart, but he says it is for the '07 tranny. What if it is actually the chart for the '06 tranny? That is the big question for me right now. I am going to the local Subaru dealer in a while and the lead mechanic is going to show me what their service manuals say.

Update--went to the dealer and got a sheet printed for the '06 STi tranny specs. The transfer gear ratio is 1.1 and the final is 3.545. I verified the data was for the '06.

On the charts above the upper one is for the '07 and the lower one is for the '05.

My fix now is to get a WRX R160 3.545 rear diff and the axles. Hope driving the car with the 3.90 rear diff did not break anything in the '06 tranny.


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PostPosted: Thu May 01, 2008 10:07 pm 
Fourth Gear
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Legacy777 wrote:
That's incorrect terminology. The final gear reduction at the rear differential is 3.545, NOT the final drive.


My bad... i'll try better next time :lol:

i just called my friend in the parts department at the stealership and guess what? the 06 STi rear diffs are 3.545

i might have a WRX rear diff at the shop john.... but i dont have any rear axles. or i'm pretty sure you can just swap the ring an pinion... that way you wouldnt have to change your axles




















told ya so
:lol:

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94' Impreza wagon AWD 2.2ltr rally wagon FTW!


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PostPosted: Thu May 01, 2008 10:35 pm 
Fourth Gear
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There is a NASIOC guy in Mukilteo that has an '02 WRX rear end and axles for sale. How hard is it to swap ring and pinion gears? Do you need to press anything out/off? Jake, pm me your phone #, please.



Jake or Dan or Josh or anyone else--I would never doubt anything you say or post! Except, that there were diffrent opinions and even printed data on this. I had to make sure.


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PostPosted: Fri May 02, 2008 12:43 am 
Fifth Gear
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I've torn down a couple rear diffs. Its not that hard, and you don't need a press. The key is making sure your backlash is correct. The side covers with the races in it are labeled as to which side they should be on. As long as you don't take the shims off and get them mixed up, that part is no worry.

The pinion is the other critical area. The big nut on the end that also hold the companion flange in must be torqued properly. Otherwise it will make noises and prematurely wear out gears and bearings. My buddy who does that stuff all the time did it by feel, but there are torque specs out there, probably in Josh's collection manuals.


You can check the tooth engagement by putting chalk on the teeth and turning the diff through a whole rotation.



New seals are in your best interest when you do through it.



I'm not always right though, as we all found out in this thread :lol:

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PostPosted: Fri May 02, 2008 2:11 am 
Fourth Gear
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It looks like I am going to replace the differential and the axles. Good idea on the new seals, I'll do that.

The mix up on the year of the charts was a clerical/administrative error. Glad we figured it out. Now I know what the fix is.


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PostPosted: Fri May 02, 2008 2:12 pm 
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kleinkid wrote:
Update--went to the dealer and got a sheet printed for the '06 STi tranny specs. The transfer gear ratio is 1.1 and the final is 3.545. I verified the data was for the '06.

On the charts above the upper one is for the '07 and the lower one is for the '05.

My fix now is to get a WRX R160 3.545 rear diff and the axles. Hope driving the car with the 3.90 rear diff did not break anything in the '06 tranny.


John,

If the transfer gear ratio is 1.1:1, and the rear diff is 3.545, then the final drive is 3.90, NOT 3.545.

If the final drive is 3.545, which I'm 99% positive it's not, the rear diff would be aprox 3.222.

I know I am making a big stink out of this, but this is a terminology issue that can be extremely confusing and misleading, as can be seen here. We may be saying the same thing....but it's how it's being said.


Also, did you notice any noise or other types of problems with the transmission? How long did you drive it?

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1990 Legacy (AWD, 6MT, & EJ22T Swap)
1997 Impreza OBS

If you need to get a hold of me please email me rather then pm


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