Centre Diff Binding

Posts specific to the 3.0 litre NA H6 engine

Centre Diff Binding

Postby Robbks » Wed Mar 09, 2011 3:47 pm

OK, i'm after a show of hands from 6 speed owners who have experienced a binding centre diff (failure of internal seals, causing the diffs to bind up when turning sharply)

My car has done it and is about to be replaced but just seeing if it's a common issue with the 6speed
the Gearbox builder believes it's a know issue in 5 speeds, but people usually break the gearset/ synchros first and bin the whole box
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Re: Centre Diff Binding

Postby smythie » Thu Mar 10, 2011 9:51 am

Mine went at a bit over 3 years old. Fortunately it was still within the 3 month used car warranty for me. I think the diff was about a grand. Didn't do any noticeable damage to the gearbox

I have heard of one or two others as well
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Re: Centre Diff Binding

Postby Robbks » Thu Mar 10, 2011 10:51 am

spoken with foreman at Subaru Docklands last night and it appears to be a very common issue
they just replace with another stock one that will crap itself in another 100,000km
rrp of the VCD is $1439.68

mine is also covered under statutory warranty, and it will be replaced with a non-viscous centre on the advice of my gearbox builder, and it WONT happen again :D
blessing in disguise as my clutch needs replacing too! (free labour!)
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Re: Centre Diff Binding

Postby sooobi » Thu Mar 10, 2011 11:32 am

Robbks wrote:OK, i'm after a show of hands from 6 speed owners who have experienced a binding centre diff (failure of internal seals, causing the diffs to bind up when turning sharply)

My car has done it and is about to be replaced but just seeing if it's a common issue with the 6speed
the Gearbox builder believes it's a know issue in 5 speeds, but people usually break the gearset/ synchros first and bin the whole box


What does this feel like? (so I can describe it to the wife?)

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Re: Centre Diff Binding

Postby Robbks » Thu Mar 10, 2011 12:51 pm

try and do a full lock turn you will hear/ feel the inside wheels skipping and the box/ diffs clunking and the car hard to actually move
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Re: Centre Diff Binding

Postby smythie » Thu Mar 10, 2011 4:37 pm

early signs for me was when the gearbox was hot. It wouldn't clunk and such if it hadn't been running at speed (over 80) for half an hour straight.
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Re: Centre Diff Binding

Postby zoidberg99 » Sat Mar 12, 2011 11:27 pm

Hey all,

Ive had this problem for quite a while, tried a few things that didn't work and will be replacing the Center diff end of march if i cant find another solution.

I noticed that the binding only occurred when the oil was hot, so i tried a thicker oil for the diff to no avail. Took it to a few gearbox guys and they all said the same thing, The viscous Coupling had gone and needed to be replaced.

Sadly, as it is only sold as a whole unit (diff with VC inside) its a costly exercise at around $1400 to get a new center diff.

As for a cause, i have heard a few people say that it is caused by running different sets of tires (different size, different make, even different wear rate) which labors the VC until POOF! it goes.

when i bought the car 20 months ago, it had stock potenzas on one side and Yokies on the other.

The gearbox guy also mentioned it was common amongst the 5 speeds, but mine was the first he'd seen it go in a 6.

BTW the $1400 mentioned above is just for the part, ill be putting it in myself (with the help of a subie nut mechanic cousin,) saving me heaps of doh, as it will be a SH*t of a job. I helped him pull the gearbox out of another 3rb 6 months ago, which was a monster job, this wont be too bad.
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Re: Centre Diff Binding

Postby zoidberg99 » Mon Mar 14, 2011 10:06 am

Robbks wrote:mine is also covered under statutory warranty, and it will be replaced with a non-viscous centre on the advice of my gearbox builder, and it WONT happen again :D
blessing in disguise as my clutch needs replacing too! (free labour!)


What is the trade of (if any) of having a non viscous Diff as opposed to a standard one? and what is the cost difference?
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Re: Centre Diff Binding

Postby kiks » Mon Mar 14, 2011 10:59 am

So in countless 6 speed viscous centres since 2001, suddenly a bunch of australian liberty 6sp owners are having issues? Please.....
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Re: Centre Diff Binding

Postby zoidberg99 » Mon Mar 14, 2011 3:44 pm

THE SKY IS FALLING, THE SKY IS FALLING!!!
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Re: Centre Diff Binding

Postby Robbks » Tue Mar 15, 2011 9:52 am

zoidberg99 wrote:
Robbks wrote:mine is also covered under statutory warranty, and it will be replaced with a non-viscous centre on the advice of my gearbox builder, and it WONT happen again :D
blessing in disguise as my clutch needs replacing too! (free labour!)


What is the trade of (if any) of having a non viscous Diff as opposed to a standard one? and what is the cost difference?


I've been told it won't drive any different under normal circumstances. when pushed hard on the track it may lead to slightly more spinning of the most unladen tyre as compared with the stock viscous centre. but nothing i'm going to be worried about
from what i can ascertain it's a mechanical (Sun-geared) "Torsen" style centre diff, as opposed to a fully open diff
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Re: Centre Diff Binding

Postby zoidberg99 » Wed Mar 16, 2011 6:22 pm

Does the solid diff have any impact at full lock. with the strong torque, will it do damage to the gearbox?

What does it cost and where from (make). Sorry for the bombardmentm just want to cover all of the bases before i throw $1500 at it.
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Re: Centre Diff Binding

Postby Robbks » Thu Mar 17, 2011 7:59 am

try this
http://www.torsen.com/files/Traction_Co ... rticle.pdf

I don't know the make or where from. being supplied by the box specialist.
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Re: Centre Diff Binding

Postby zoidberg99 » Sun May 15, 2011 2:30 pm

Hey,

just an update. I finnaly got around to replacing the VCD yesterday, works a treat now. the job was easier than anticipated, and only look us around 4 hours to do (at a leiserly pace)

Ill pull apart the old one soon, just for the fun of it.
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Re: Centre Diff Binding

Postby Brad88 » Mon May 16, 2011 6:37 pm

being all wheel drive you need all 4 tyres the same, so you cant just replace the rears or the fronts etc..


anything with a diff needs tyres/wheels to be the same on either side.

the spier gears and side gears in the diff are only supposed to rotate at different speeds when turning, when you drive straight the spider and side gears are supposed to be rotating as one unit with the "diff carrier".

but if you have different sized tyres or wheels either side of the diff the spider and side gears are constantly turning at different speeds which wears them out extremely quick.

if you have one size on front and rear left and another size on front and rear right, this means your front and rear diff spiders and side gears are doing different speeds constantly.

if you have one size on rears and one on the front, this means the centre diffs doing different speeds constantly (usually not enough to engage the viscous coupling).

and the viscous centre diffs are filled as the name suggests with a viscous fluid. which when under no force is a liquid, but when too much force is applied it turns solid (allot like corn flour and water when mixed right if you ever did this at school) so when there is too much difference in speed (the rear wheels start to spin) the viscous diff's are supposed to turn into a sort of limited slip or lock diff.
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