So my gearbox has started popping out of 4th gear again… this was rebuilt a few years ago (2019 I think) and has been running with the Subaru EJ25 since without problems.
But now it’s popping out again. Sometimes I can go on quite a long run just resting my hand on the lever and it’s ok, but at other times it just doesn’t want to know.
So, I am looking at the subarugears conversion that uses a Subaru gearbox and wondered if anyone here had gone this route? They are located right here in Perth so that’s a bonus at least…
I did the conversion to the Subarugears 5 speed AWD in 2016 and its been trouble free, mated to an EJ25, also helped Todd with the front gearbox mount so it may have been the first install into a Syncro, its also my daily driver. No granny gear so no real 4WD but great everywhere else.
The front diff will need a crown and pinion change to match the gearbox if you currently have 5:43, I went with the 4:86 and sourced a second hand one with help from Arnie out of Germany. It certainly has no trouble keeping up with traffic and hills.
The Subaru box has a central diff meaning a solid shaft is also needed for the front diff replacing the VC. I find my solid shaft has some play in it making the shifts a little clunky, I’ve been tempted to put the VC back in with a welded centre diff in the gearbox to see what it does. I’ve also thought about creating a planetary gearset replacing the centre diff to give a switchable 1:1 and ~3:1 reduction to get the granny back, just needs some engineering, if only I knew somebody that knows somebody .
Todd has always been very helpful and I know his has tried a half casting to get the Subaru ‘Low’ range installed but it hasn’t proceeded to date.
Great info Uwe!
Yes Todd did say the VC needed to go… I’ll need to source a replacement for my VC and get a solid shaft as well… any help / hints on this appreciated! Is Arnie still active?
I don’t do much serious 4x4 so not too worried about losing the Ground gear.
Arne is still active I believe, his forum username is
kleinersyncro, another thread on the subject is Front diff required. VanCafe sells solid shafts amongst others.
Do you know what your VC ratio was? Todd says there should be a sticker on the VC to find out its ration, but I’m unable to see/find it in situ.
He says I may need to open my VC to count the the ring & pinion number of teeth,. is that an easy thing to do or not?
Also he says he has a couple of 5.43:1 5 speed AWD ring and pinions in stock to match those vw syncro front diffs now. Would that be suitable or must it match whatever is in my VC?
Hi Gaetan, The Viscous Coupling “VC” is a silicone filled drum with lots of metal plates inside the front diff case and allows slippage between the gearbox and the front diff (just like the centre diff in the Subaru gearbox), it needs to be removed and a solid shaft put in its place (ie, straight through with no slippage).
Great news that Todd now has 5.43 ratio crown and pinion for the conversion. Most Aussie Syncro’s got the 5.43 so that is probably what you need, you could possibly confirm from the Syncro gearbox and diff codes assuming nothing has been altered.
Perhaps get the car off the ground and measure rotations, One full turn of the front wheels should turn the prop shaft almost 5 and a half times “5.43 times”
Keep in mind if you test by number of turns of the input shaft to the wheels.
Ensure both wheels turn together (both front wheels doing exactly the same turns), otherwise your count will be out.
If there is any slight difference in resistance to turn on each wheel, they will not spin exactly in time and will mess up your count.
Your diff ratio will be 5.43, it is very very unlikely that you will find another ratio here as this was the standard configuration for Aussie Syncros. Diff ratio has noting do with the VC. The VC is a just a device, not adjustable or in anyway controlled (apart of its adjustment from factory), transferring drive from the rear to the front.
Check your gearbox code on the housing and that will tell you what ratio you have (unless someone did modify it, again very unlikely).
If your engine revs at around 3400-3500rpm @ 100km/h it’s a 5.43.
The code is stamped into the bottom of the gearbox or front diff, from the file Jon listed the front diff should be a code 6N if you don’t have a front diff lock or ADM or ADN if you do
I just checked one of mine and its on the front ribs in the flat section which has 6N and another code underneath “D”, the other side also has 5 digits.
