EJ driveline conversion - changing rear diff ratio

[AndrewT]

I'm installing a 4.11 AWD driveline into my L series Touring wagon.
The car currently has the standard L series 3.7 open centre rear diff.

I have a 1999 Outback rear diff, which is a 4.11 ratio open centre. It has splined sockets instead of protuding stubs.

I'm guessing I need to take the 4.11 gearset out of the Outback housing and put them into my standard L series housing (discarding the 3.7 gears) leaving me with a 4.11 open centre rear diff which will just bolt straight into my L series.
Is this the correct method?
Are there any problems going from splined sockets to stubs?
Any particular points to pay attention to?

Cheers,

a.

[SuBaRiNo]

I belive (someone stop me if im wrong)

You must use the housing of the diff ratio u wish to use... so that the gears line up.

So im guessing u need to dismantle the 4.11 diff and try and only swap the axle stud parts from the 3.7 into it... should be possible.

Dave

[tim_81coupe]

Yes Dave you are right.

You need to keep the pinion & crown wheels together as they wear evenly. The most trouble-free way of doing this is retaining the housing in which they both came. Not having done this exact swap I'll put forth a suggestion / educated guess:

Use the 4.11 housing, the 3.7 open centre (or take the opportunity to go LSD) the 3.7 side plates, the 3.7 stubs and the 4.11 crown wheel. Remember to put new gaskets or goo on the side plates and rear cover. Renew the side seals while you're at it too, I might have a couple lying around here somewhere with the proper flared ridge bit (name of which evades me right now).

[Ben]

Each diff is shimmed to suit its particular crown/pinion, centre and side plates. If you put the 4.11 crown and pinion into the 3.7 housing, on the 3.7 centre then all you'll need to do is shim the gearset to get it running right again - gregory's type manuals explain how to do this.

[steve_rising_sun]

Last time I did it I just have a groove cut for slip rings in a pair of L stubs. I sealed up the bolt hole and popped them in.
Steve

[chriSTIan]

Just bought the 3 seals 2"0" rings and metal gasket from subaru,just on
$80 the set retail.
Might b easier to find a whole 4.11 diff out of a gen 1 auto.

[Ben]

Last time I did it I just have a groove cut for slip rings in a pair of L stubs. I sealed up the bolt hole and popped them in.
Steve

So now they're mounted the same as the stubs in the front diff?

[steve_rising_sun]

Yes if you look at the late drive shaft it has the staft on the cv with a groove cut in it. Measure how far down it is and have the groove cut on a lathe. CV places sell the clips, seal up the hole through the shaft and your in.
Steve

[seagull]

I am a machinest ! & in Perth sor

[AndrewT]

Just noticed another slight problem...

The bit at the front-of-the-car end of the diff, where the tailshaft bolts onto it is different. The bolt holes are spaced wider apart on the 4.111 diff compaired to my L series 3.7.

If i'm going to be using the 4.111 housing I guess this part needs to be swaped out with the 3.7 then.

[tim_81coupe]

Could it be possible you're looking at one 90 degrees to the other? The tailshaft bolt pattern is a rectangular shape, the bolts are not evenly spaced.

[AndrewT]

Yeah I thought of that, its definitely different.

[steve_rising_sun]

Yes you must swap the flanges. Centre punch the nut and pinion shaft first so you can rattle gun the nut to hopefully the same point.
Steve

[AndrewT]

Thanks for all the advice.....luckily I have found an easy way around this. A mate happened to have an open centre 4.111 which was recently removed from his L series, bolted straight into mine. Thanks Aspro!!