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front differential part number


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14 replies to this topic

#1 grossgary

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Posted 08 October 2007 - 12:34 PM

anyone know the part number for the EJ series front differential on an AWD automatic?

#2 svxpert

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Posted 09 October 2007 - 12:02 AM

what year?

#3 grossgary

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Posted 09 October 2007 - 12:18 AM

i thought they were all identical?
let's say a 1997 Legacy GT sedan Automatic, AWD, but i'd be curious about any EJ series as i think center diffs are interchangeable.

for the XT6 it's:
38438AA010 superceded by 38438 AA041

funny you should reply m., i'm putting the XT parts catalog to work!

#4 svxpert

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Posted 09 October 2007 - 01:36 AM

looks like its 31331AA221
from what the fast parts has

#5 grossgary

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Posted 09 October 2007 - 01:53 AM

38438AA041 is the "new" XT6 center diff part number. and here is a Subaru parts response i just received:

38438aa041
suits:
96-2000 - legacy AT
02/99-03/200 - Legacy AT
03/1996-03/2000 AT Impreza
11/1996-03/2000 AT Forester


Looks like XT6 and EJ stuff may be interchangeable?
I wonder why they gave me that and you got a different #?

#6 johnceggleston

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Posted 09 October 2007 - 07:20 PM

are you looking for the front diff part number or the "center diff" , which in an auto trans is the tranfer clutch unit??

i've never seen a part number for the front diff, but i do know that 95 - 99 2.2L autos all used a 4.11 front diff. and with the possible exception of the 99 (did they go to 8 bolts on the ej22 as well as the ej25?) they are all interchangeable.

for that matter, my guess is that you can swap the ej25 front diff with the ej22 front diff without any problems, as long as you get the matching rear diff. both differentials, the 22 and the 25 have a 9 tooth pinion coming out of the trans. the only apparent difference is the ring gear, ej22= 37teeth, ej25 = 40 teeth..

i recently did the math on the 4.11 final drive with the legacy 195/70/14 tires and the 4.44 final drive with the outback 205/70/15 tires and they are the same. the pinion gear 'revolutions per mile' are almost exactly the same. this is why there is not a huge fuel consumption change between the 2 final drives.the transmissions are turning the same number of times for each mile. the only difference is the engine displacement.

#7 grossgary

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Posted 09 October 2007 - 08:44 PM

are you looking for the front diff part number .

yep front differential. in my Subaru parts catalog it's listed as a "Case-Diff". will this part have teeth on it?

what i want to do is install an EJ style LSD front diff into my XT6 - from what i'm getting from subaru it should work, but i'm not sure why the final drive isn't an issue with the part numbers. the XT6 automatic is a 3.7 final drive, none of the EJ's are. maybe this part doesn't have the teeth on it? i've never taken a diff apart before so i do not know the intricacies of them.

#8 scoobyclimbs

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Posted 09 October 2007 - 09:56 PM

yep front differential. in my Subaru parts catalog it's listed as a "Case-Diff". will this part have teeth on it?

what i want to do is install an EJ style LSD front diff into my XT6 - from what i'm getting from subaru it should work, but i'm not sure why the final drive isn't an issue with the part numbers. the XT6 automatic is a 3.7 final drive, none of the EJ's are. maybe this part doesn't have the teeth on it? i've never taken a diff apart before so i do not know the intricacies of them.


I just rebuilt my 4eat phase II('03) front diff. As far as I know there is no front diff. LSD available.... even on the WRX's it's a open front diff.

#9 grossgary

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Posted 09 October 2007 - 10:35 PM

As far as I know there is no front diff. LSD available.... even on the WRX's it's a open front diff.

they are available. CUSCO, Phantom Grip, ebay...etc....

#10 WAWalker

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Posted 10 October 2007 - 09:09 AM

yep front differential. in my Subaru parts catalog it's listed as a "Case-Diff". will this part have teeth on it?

what i want to do is install an EJ style LSD front diff into my XT6 - from what i'm getting from subaru it should work, but i'm not sure why the final drive isn't an issue with the part numbers. the XT6 automatic is a 3.7 final drive, none of the EJ's are. maybe this part doesn't have the teeth on it? i've never taken a diff apart before so i do not know the intricacies of them.



According to what I find, the front EJ diff case is sold in two peices. No they will not have teeth on them.
Right side case PN 38438AA041
Left side case PN 38439AA040

The ring gear bolts to the out side of the diff case. The LSD parts go inside the diff case.

So if you are finding that the part #'s for your XT diff case are the same as the EJ #'s, then you should be able to install a EJ LSD in the case that you have. No need to worry about ring gear or pinion or a new case.

#11 WAWalker

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Posted 10 October 2007 - 09:16 AM

Posted Image

The LSD will replace parts numbered 11 and 12, and probably 10. These go inside 2 and 3, which are the "differentail case".

#12 grossgary

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Posted 10 October 2007 - 09:32 AM

No need to worry about ring gear or pinion or a new case.

that's what it seems like, because i don't see any mention of various final drives when looking at LSD conversions. but never taken one apart before so i'm not sure how it works.

from pictures i looked at, it seemed like the LSD units replace part #2, but maybe i was looking at it wrong or the pic's had more than just the LSD specific parts in it. i recall the installation instructions mentioning punching out part #10, that pin.

#13 johnceggleston

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Posted 10 October 2007 - 04:12 PM

that's what it seems like, because i don't see any mention of various final drives when looking at LSD conversions. but never taken one apart before so i'm not sure how it works.

from pictures i looked at, it seemed like the LSD units replace part #2, but maybe i was looking at it wrong or the pic's had more than just the LSD specific parts in it. i recall the installation instructions mentioning punching out part #10, that pin.


you all are a little over my head here, but for what it's worth, the 3.9 diff has a 10 tooth pinion and a 39 tooth ring gear. i think most if not all of the 2.2L 5 speeds had the 3.9 final drive. the 2.5L 5 speed (96-99) has a 4.11 final drive, 9 tooth pinion and 37 tooth ring gear.

but what i think you are talking about is swapping the gears , etc. inside the ring gear housing. way beyond mortal men.

#14 grossgary

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Posted 10 October 2007 - 04:14 PM

i don't think the final drive has anything to do with this - i'm not sure how it works, but the LSD units do not replace any particular part that changes the final drive. don't know how it works, but i'm guessing the ring gear bolts to the LSD unit i'm sure the companies that sell the LSD units know, i'll ask them if i get to that point.

#15 WAWalker

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Posted 10 October 2007 - 08:04 PM

Can you post a link to a web site that shows the LSD unit that you all looking at?

Technicaly, the ring gear and pinion have nothing to do with the differetial part of a differetial, or the limited slip part of a limited slip differetial. They are just the gears driving the differetial case / carrier, whatever you want to call it. It is the four little gears (spider gears) inside the case that allow the wheels to turn at different speeds. In the case of a LSD, normally two of the gears are removed, and spring loaded clutch's or some other method is used to "lock" the side gears (ones driving the axles) together, but still allow slippage so that the wheels can still turn at different speeds. So it is still a differetial, but tracktion is improved somewhat.

Now a Locker (ex. ARB's) or a spool is NOT a differetial at all, because they do not allow the wheels to turn at different speeds. There is still a ring gear and pinon, but they are not part of, or driving a differential anymore.

Sorry for all the BSing. Some LSD units may replace the differential case or part of it. I don't know what all is out there for Subarus. The one I've seen only replaces two of the spider gears inside the carrier along with the cross pin.




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