Jump to content


Welcome to Ultimate Subaru Message Board, my lurker friend!

Welcome to Ultimate Subaru Message Board, an unparalleled Subaru community full of the greatest Subaru gurus and modders on the planet! We offer technical information and discussion about all things Subaru, the best and most popular all wheel drive vehicles ever created.

We offer all this information for free to everyone, even lurkers like you! All we ask in return is that you sign up and give back some of what you get out - without our awesome registered users none of this would be possible! Plus, you get way more great stuff as a member! Lurk to lose, participate to WIN*!
  • Say hello and join the conversation
  • Subscribe to topics and forums to get automatic updates
  • Get your own profile and make new friends
  • Classifieds with all sorts of Subaru goodies
  • Photo hosting in our gallery
  • Meet other cool people with cool cars
Seriously, what are you waiting for? Make your life more fulfilling and join today! You and your Subaru won't regret it, we guarantee** it.

* The joy of participation and being generally awesome constitutes winning
** Not an actual guarantee, but seriously, you probably won't regret it!

Serving the Subaru Community since May 18th, 1998!

Guest Message by DevFuse
 

Photo
- - - - -

Downside to 3.9 ratio


  • Please log in to reply
43 replies to this topic

#26 edrach

edrach

    Charter member OFRT

  • Members
  • 12,324 posts
  • Bothell, WA

Posted 14 October 2012 - 09:39 AM

That truly is a mystery. Sadly FHI never marked the outside of the rear diff with the ratio. Only way to reallly tell is to count teeth on the ring and pinion gear. Impractical for the front, but relatively easy for the rear. Wait until you plan to change the gear oil in the rear, drain out the old, get a new gasket and pull the rear cover off. Count teeth in the ring gear and divide that number by the number of teeth in the pinion gear to determine the true ratio.

Obviously, in your case the front and rear ratios are matched.

#27 Gloyale

Gloyale

    It's a sickness

  • Members
  • 8,538 posts
  • Corvallis, OR PNW

Posted 14 October 2012 - 12:44 PM

i believe it really had 3.90, especially since the replacement transmission is supposed to have 3.90, and i didn't change/replace the rear diff.


You could be just cooking your center diff. It could be gone and be completely open now.

But the chart has been wrong. there are 2 of the same trans #s listed for diffrent models with different ratios.

Best thing to do is to count teeth on the ring gear. it can be done through the drain plug hole.

#28 Gloyale

Gloyale

    It's a sickness

  • Members
  • 8,538 posts
  • Corvallis, OR PNW

Posted 14 October 2012 - 12:50 PM

From the chart at gearhack. Same # for both trans.


US Impreza EJ22E (AWD) MY96 TY752VABBA 3.9 ratio


US Legacy Outback MY95-96 TY752VABBA 4.11 ratio

#29 edrach

edrach

    Charter member OFRT

  • Members
  • 12,324 posts
  • Bothell, WA

Posted 14 October 2012 - 03:42 PM

From the chart at gearhack. Same # for both trans.


US Impreza EJ22E (AWD) MY96 TY752VABBA 3.9 ratio


US Legacy Outback MY95-96 TY752VABBA 4.11 ratio

That's interesting. Quite a find.

#30 wally

wally

    USMB Regular

  • Members
  • PipPipPip
  • 88 posts
  • new england

Posted 15 October 2012 - 05:31 AM

You could be just cooking your center diff. It could be gone and be completely open now.


it could be, but after 2 years, it's still functional, so i'm going to say it's the same ratio. i know it's functional, because of some of the client properties where i drive the car (very steep hill, loose gravel). when i took out the rear driveshaft prior to replacing the transmission, i couldn't even get one-third of the way up the hill. last month, i was able to ascend it slowly, in very dry, loose conditions. no way the car goes up without functional awd.

#31 GeneralDisorder

GeneralDisorder

    Elite Master of the Subaru

  • Members
  • 20,279 posts
  • Portland

Posted 15 October 2012 - 12:30 PM

The charts are notoriously wrong. It's bit me before.

Count gear teeth - that's the best way to know. You can do it from the drain plug's.

As for what happens when they don't match:

MT: The whole car will shake like it's falling apart when the center diff heats up and starts to lock - this will take about a mile or two to happen. The tires are skipping going in a straight line - just like if you were turning tight circles in a locked 4WD. At freeway speeds this is REALLY disconcerting - it feels like gnomes are banging on the bottom of the car with sledghammers.

AT: The rear diff will get really, really freakin hot and especially if there's oily residue all over it they will start smoking.

To ShawnW - why not just replace the input shaft bearings on the 4.11?

GD

Edited by GeneralDisorder, 16 October 2012 - 11:49 AM.


#32 edrach

edrach

    Charter member OFRT

  • Members
  • 12,324 posts
  • Bothell, WA

Posted 15 October 2012 - 07:31 PM

The charts are notoriously wrong. It's bit me before.

Count gear teeth - that's the best way to know.
GD

Well, you've certainly replaced more transmissions than I have, so obviously I've been lucky in finding the correct gearboxes. Agreed, counting the teeth is the best way to be sure.

The symptom information is useful since I've never encountered it although one would have to be pretty dense after replacing a transmission (or rear diff) and not realize that the part that went in is not the right one.

#33 hankosolder2

hankosolder2

    Subaru Nut

  • Members
  • 687 posts
  • Chicago

Posted 15 October 2012 - 10:06 PM

At freeway speeds this is REALLY disconcerting - it feels like gnomes are banging on the bottom of the car with sledghammers.
GD


Hmm. It's either the wrong ratio, or there is a SERIOUS gnome infestation on this freeway, definitely one of the two.

#34 GeneralDisorder

GeneralDisorder

    Elite Master of the Subaru

  • Members
  • 20,279 posts
  • Portland

Posted 15 October 2012 - 11:29 PM

I went by the chart a while back on an '02 Legacy. Put in an '03 Legacy 5MT and the claim in the charts was that it should be a 4.11 vs the '02s 3.9 so of course I sourced a diff to match and swapped them both.

Happy with my forethought to check the charts and feeling good about a job well done I took it on a test drive and within about a mile it began violently popping and feeling like the tranny was about to jump out of the car - needless to say I counted gear teeth and found I had to swap back in the original diff because the chart was wrong. I double and triple checked the transmission numbers and the chart. It's just not correct which means its useless to me. I now go off what I know from experience, and I count teeth.

GD

#35 edrach

edrach

    Charter member OFRT

  • Members
  • 12,324 posts
  • Bothell, WA

Posted 16 October 2012 - 09:33 AM

I went by the chart a while back on an '02 Legacy. Put in an '03 Legacy 5MT and the claim in the charts was that it should be a 4.11 vs the '02s 3.9 so of course I sourced a diff to match and swapped them both.

Happy with my forethought to check the charts and feeling good about a job well done I took it on a test drive and within about a mile it began violently popping and feeling like the tranny was about to jump out of the car - needless to say I counted gear teeth and found I had to swap back in the original diff because the chart was wrong. I double and triple checked the transmission numbers and the chart. It's just not correct which means its useless to me. I now go off what I know from experience, and I count teeth.

GD

Once burned, and I'd be counting teeth also.

#36 wally

wally

    USMB Regular

  • Members
  • PipPipPip
  • 88 posts
  • new england

Posted 16 October 2012 - 07:21 PM

i haven't been burned, but i have no use for the chart. the fact that it does have errors makes it absolutely useless for swaps.

#37 edrach

edrach

    Charter member OFRT

  • Members
  • 12,324 posts
  • Bothell, WA

Posted 16 October 2012 - 07:40 PM

i haven't been burned, but i have no use for the chart. the fact that it does have errors makes it absolutely useless for swaps.

You're entitled to that. But until someone shows me that there are more than 10% errors, I'll continue to use it to narrow down the transmissions I'm looking for. However, I will start to count teeth when I think I've found a suitable replacement.

#38 johnceggleston

johnceggleston

    Lite Master of the Subaru

  • Gold Subscribers
  • 6,080 posts
  • Virginia

Posted 17 October 2012 - 08:21 AM

some times subaru makes changes that defy logic, but usually once they make the change they stick to it for that model year and more.

for the auto trans cars they were pretty consistent. i assume the same is true for the manual trans. having said that, there are odd situations for some models in some years.

before this thread i would have sworn that the 95 outback auto was a 4.11 like all the other 95s leagacys and imprezas. and that the 95 outback manual trans was 3.9 like all the other 95s. i have been checking and learning final drive ratios since i needed a trans in my 95 lego in 05. and i have never come across a 95 trans that did not match the above info. but i could still be wrong. 95 outbacks are not very common in my opinion. and i have never seen a one in real life. so how could i be sure.

and i do know that subaru swapped the ratios between the auto and the manual with the 95 MY. auto went from 3.9 to 4.11 and manual went the other way. go figure.

but if someone at subaru spec-ed the 94 trans in the 95 outback so be it.

anyway, i follow the the patterns and then double check on opposed forces. the problem with that in, this particular case, is that they do not list the ''outback'' as a model in the 2.2L engine manual trans section for 1995. so it is hard to double check. for most years and models you can search for the ring and pinion gears in the drive ''TRAIN'' section and it will list the ratio.

Edited by johnceggleston, 17 October 2012 - 08:26 AM.


#39 jboymechanic

jboymechanic

    Subaru Fanatic!

  • Members
  • 417 posts
  • Waterford, WI

Posted 17 October 2012 - 09:08 PM

Shawn, to get back to your original question, I'm currently driving exactly what you're thinking of building.

1996 Legacy with 3.9 ratio 5MT, swapped in 2.5 with 2.2 heads. Runs great on mid grade or premium only, runs like crap on regular unleaded (87 octane). I have Outback struts with 27" tires and car is still zippier than the 2.2 with the small (stock tires were about 24.5"). My typical all around mileage is 25 mpg and I get 30 mpg on highway trips when I cruise at 75 mpg. I have a little over 10,000 miles on this setup and have been very happy with it.

#40 Crazyeights

Crazyeights

    Subaru Nut

  • Members
  • 790 posts
  • PNW

Posted 17 October 2012 - 10:54 PM

Shawn, to get back to your original question, I'm currently driving exactly what you're thinking of building.

1996 Legacy with 3.9 ratio 5MT, swapped in 2.5 with 2.2 heads. Runs great on mid grade or premium only, runs like crap on regular unleaded (87 octane). I


Are your heads and cams stock? Hydro or solid, roller or not? Also what engine management are you running, stock 2.2? Glad you are happy with the build.

#41 jboymechanic

jboymechanic

    Subaru Fanatic!

  • Members
  • 417 posts
  • Waterford, WI

Posted 18 October 2012 - 08:00 PM

Are your heads and cams stock? Hydro or solid, roller or not? Also what engine management are you running, stock 2.2? Glad you are happy with the build.


The heads are the stock 1996 2.2 heads with 200,700 miles on them. I forget what type of lifters and rockers it had, whatever the car would have come with in 1996. Thought it had roller rockers. The computer is the stock 2.2 that was in the car. The only modifications needed were a few extra water passage holes in the head gaskets and I had to cut off one little mounting tab for the timing cover of the 2.5 block as it interfered with the timing belt. I am not running a timing belt cover as that is my preference.

#42 ShawnW

ShawnW

    Subaru Master Technician

  • Administrator
  • 12,891 posts
  • Denver, Colorado

Posted 18 October 2012 - 11:04 PM

Above I was asked why I wouldn't just change the trans bearings. The shop is pretty busy at the moment and it would be a lot quicker to just test out the trans from a car I parted out than to take the one out, tear it down, order all the stuff, and put it back in. I can have the other one installed in a couple easy hours and not tie up the lift long.

I also don't like doing the input shaft bearing on a trans that I don't know how long its been bad. Many times I have seen the metal distorted on the case and that basically means the trans case is going to be scrap.

I really appreciate the comments and advice. I think I will try the Impreza trans now. Might even be able to get my bore scope in the dipstick hole and read the numbering off the ring gear.

#43 ShawnW

ShawnW

    Subaru Master Technician

  • Administrator
  • 12,891 posts
  • Denver, Colorado

Posted 12 June 2013 - 01:39 AM

Just an update.  I have long since sold the car but I did put the Impreza 3.9 trans in it.  And I didn't switch rear ends.  And as indicated above-no problems.  

 

Today I disassembled the original trans.  Now scrap metal.  I was right-the case was trashed from the bearing slopping around and the throwout bearing kit that was installed would not come off.  

I counted teeth.  39 ring, 10 pinion or 3.90 ratio.  Chart is, as indicated...wrong.

 

Thanks everyone!  Was able to help a guy out with a cheap used VIscous unit out of the box, save some parts for later, make a clutch alignment tool and a few bucks on aluminum recycling.



#44 Gloyale

Gloyale

    It's a sickness

  • Members
  • 8,538 posts
  • Corvallis, OR PNW

Posted 12 June 2013 - 11:42 AM

TY752VABBA  Is listed twice.

 

Once for 96 impreza, at 3.9

 

And again for 96 Legacy Outback as 4.11

 

I'm inclined to believe the later is correct, as that's the trans I have in my 86 GL......it's definatley 4.11 (I had it apart and counted ring and pinion teeth)

 

But indeed, Legacy Outback 5spds from 96-99 are 4.11

 

Not sure about 95, as those were still basically regular legacies with a trim package (no lift, no larger tires) I could see them being 3.9






0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users