Jump to content
Please check your junk folder for registration emails ×

Center diff gone in your BH? heres a VERY cheap option


Recommended Posts

Ok, the Bh center diffs are crap right, you know when they are crook when you drive about 20mins @ 100kph then you do a sharp turn and it binds up like a b1tch, sounds and feels like all yr CVs are f#ked.

I thought i would start this thread as i have bits n bobs on this subject all over the show. This 'how to' thread is based on the fact you can swing a spanner better than average. If you have a dropped a subaru G/box before you will have a better idea than most.

I had been putting off buying a new center diff because of the cost.. around $1200 and $300 odd bucks for some one to install it.

The GO is... from 99 on (or there abouts) the center diffs on Legacy BH wagons are shyte.. prone to this problem, pre 99 CDs never crap out right, this is well known...

(FYI - my car is a 2001 BH5 GT-B)

SO.. get your self an STI gear box from a 97-98 GC8 or GF8, i scored one with a stuffed 1st & 2nd gear off TM for $50.

What you do is use the STI transfer case (center housing), the rear housing and the C/diff. Basically you are going to fit the 97-98 center housing, rear housing & C/diff into your later g/box.. and yes they interchange very easily.

Now, you can do all this on axle stands, you will need good lighting and a creeper. Failing that, the money you save from not spending $1500 on a brand new one you could put towards paying a mechanic to do ot, it will still be waay cheapr than the $1500. But the savings really come into play if you DIY.

the main part of the G/box stays in place, you just remove the center and rear housings.

Now this is the thread that helped me get going, have a good read of it first: http://www.subaruforester.org/vbulletin/f89/center-diffs-how-replace-them-46979/

FYI - i did my diff bushes at the same time, thats another kettle of fish & a time in my life i would rather forget ::)

Here are some pics




This is the sealant i used instead of gaskets... no leaks thus far :D.


You will need G/box oil too unless you want to reuse your old oil. Get GL5 multitrax from subaru $58.00


Costs for me were:

- STI G/box = $50

- Oil = $58

- sealant = $18


TOTAL = $126

Thats it really, if there is anything you think i have gotten wrong, have forgotten or should add in, just let me know.

Its great to have the car running normal again, and the missus thinks i am a legend for saving all the $$$, OHH YEA, ganna get me some LOL

  • Like 1
Link to comment
Share on other sites

 pl0x said:

Did you need to drop the whole box to get off the rear transfer housing?

(assuming those pics aren't your gbox haha)

Yea, that G-box in the pic is the stuffed STI one, and no I didnt hv to drop the main g/box just the transfer case and rear housing. the G/box cross member had to come off, used a sissor jack to take the weight, didnt have to take off the siamese DP off but did drop the rest of the zaust down.

Link to comment
Share on other sites

 pl0x said:

nope, the top left corner of the middle bit in this:

i didnt have to remove any of those, thats a locater pin/dowell and there is two of them.

I am not sure why you would have to remove them? Once all the bolts are out a good wack with a soft hammer should crack it open.

The housings should just drop off with ease.

Link to comment
Share on other sites

 pl0x said:

mine where stuck on like buggery, thought we were going to have to remove the whole gbox, but ended up just doing it the easy away (swap the center diff by itself) thanks to some advice from boostin

sh1t aye, i wudnt have thought they wud have hung on so tight, but maybe i struck an easy one, dunno... i have only done one :D boostin prolly done hundreds so he'd know

Link to comment
Share on other sites

  • 4 weeks later...

[quote name='gazzy2000 said:


have driven car to Ch-ch and back (from timaru) plus Ashvegas & back twice and C/diff is sweet as


Do we get another update once you've driven it around corners? :D

haha yea na, its mint, i drove the car for long enough with the old crook one in it so i know full well the characteristics of the problem and what conditions brought it on etc, i.e. long 100kph driving then tight turns etc

So yea, i have fully put it through its paces and its no worries :)

Link to comment
Share on other sites

  • 1 year later...

are there any early signs of the centre diff going? mine ova the last few weeks has started a bit of a knock (sounds like exaust hitting the floor) when taking off at intersections ect then noticed today a slight whine well kinda sounds like a drive shift rubbing hard on a driveshaft loop and can feel a bit of a vibration if i leave my foot on the floor next to the clutch. I havent been launching it hard or anything but do you reckon the centre diff is the problem.

Link to comment
Share on other sites

  • 2 weeks later...
 Evokillaz said:

Ok so tried this today and now the car is stuck in gear. Any ideas?

yea, i did this first off too, if i recall its the selector fork not in right, hate to say it but it all has to come off and be set properly.

when its all off have a good look at the internal workings of gear selection and it will make sence what has to be done i.e. smooth operation and selection of gears. pays to test it all before you do all the finishing.

When you think you have it all in right do a couple of bolts up on teh housings (dont bump any of the workings) then jump in the cabin and test the gear stick/gear selection.

this job is not really for the faint hearted.. pays to know a bit about g/boxs + pay good attention to detail with the mechanical aspect :-\ sucks i know!

Link to comment
Share on other sites

Pull it apart again, when you fitted the centre housing, you have miss aligned the geat shift rod to the shift forks

and have the shift fork in one "gate" with another gate engaged

Sorry no other options but to pull it apart

Link to comment
Share on other sites

no need to change shift rails

Have a good look at the shift mechanism and see why its stuck in gear, and where you accidentally went wrong

Get an understanding for how it works

Just make sure when the centre housing goes back on that, the selector rod in the centre housing is in the neutral position

Once the centre housing os back on, use a #2 philips screwdriver thru the gearshift linkage roll pin hole and check that you can select gears

Link to comment
Share on other sites

So boys thanks to your help and a helluva lot of perseverance the transmission is all back together! I have a 2002 V7 wagon. Used a V3/V4 rear housing, transfer case and centre diff cost me 60$ from readosnr. Used CRC Gasket cement at the cost of $15ish dollars and 4L of Multitrax at about $50. So a total of $125ish.

To be honest went in pretty confident of getting it all off and back together fairly problem free. The initial drop down of the gearbox crossmember and the removal of the driveshaft was fairly standard. The teardown of the box itself was pretty time consuming as some of the bolts were in awfully hard places but after a bit of sweat and manpower (and time) was able to remove the back of the tranny. The old diff had a bit of colour to it which I think shows that it is either out or on its way out. Tried to put the V3/4 parts in as one whole unit. Didn't work, found this out the hard way as when I went to try and change gear it was stuck after putting it all back together >:(!! Make sure if you are doing this you have an understanding of how the shift system works when you have all the parts off. Make sure the fork is in the right gate, and that you are able to change gear with a screwdriver in the shift linkage. So after tearing it apart, again, I was able to get the transfer case on (I put it on, and removed a little 10mm nut/screw inside that stops the shift fork from turning too much and from moving too far up and down, and was able to put it into the gate that way and then put the nut/screw back in). Then the centre diff and shaft went in, make sure these seat properly, give them a tap in with a rubber mallot or similar. Next put on the rear casing making sure the gears mesh perfectly. Then screw it all back together. Now some of the bolts are an absolute mish to get to but there is always a way! From then on it was smooth sailing, reinstall shift knuckle by pounding the roll pin in with a punch hook your gear shift all back up (check gear lever that it changes), reinstall driveshaft and everything else you have taken off!

I found that I did not need to take down any of the exhaust however after a few cuts from hitting it I can understand how it would have made the process a bit less pain free. I filled it up with oil (about 3.6-3.7L) and ran it for the first time off the ground. Left it for a little bit and then dropped her down and took her for a very slow yet rewarding drive! Checked the underneath of the car this morning and can report one tiny spec of oil (which is probably from when I spilt the oil trying to fill it).

This job is definately not for the faint hearted and to be honest if you are not willing to be extremely patient at times I wouldn't bother starting it. On the other side of the coin it was extremely rewarding to turn into car parks without the bind that I have had for a while now.

There are heaps of guys on here that have been extremely helpful during the process gazzy2000 and Ichiban to name a couple. So if you do have any questions, don't forget to just ask!

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Create New...