Spec B diffs locking up when hot?

by **DeeviousDeeve** » Wed Sep 19, 2012 1:36 am

Hi all,

I bought a 3.0R Spec B (MY08 manual sedan) late last week. Basically, when the drivetrain heats up - seems to only take 20-30kms - and I then slow to a crawling pace, when I try to turn the car there's a clunking noise from one wheel that puts me in mind of a locked up 4x4 trying to navigate a carpark. And it's never the same wheel, sometimes it'll just be the left rear, then the right rear, front right, etc, sometimes it'll sort of "hop" back and forth between both rear wheels. I've read around this and other forums and believe it to either be a CV joint or a differential issue. There's no leakage or obvious wear around the CV boot but there's clearly repairwork done to the front left wheel where I'm guessing a previous owner has gone over a rock or curb, but then the fact the issue only presents when at certain temperature makes me think diff oil.

I took it to the Subaru dealer I purchased it from today (Tuesday), so they could check it out. I warmed it up before I arrived, then took a technician for a short drive to demonstrate the problem. His comments were something along the lines of "I've seen this a couple of times before, but not this bad." So I handed over the keys believing everything would be sorted under warranty. However, when I called up again at the end of the day they said there was nothing wrong, and that the service manager himself had taken the car out and said everything was normal. Their explanation was "the diffs in the Spec Bs are wound really tight, they do this normally". I told them I would have it independently assessed, and would have asked them to take me for a drive in another Spec B to prove it, but as you can imagine there weren't any 4gens on hand.

So, fellow Spec B owners, is this normal?

by **rooby** » Wed Sep 19, 2012 1:48 am

Nothing like that in my car. And I even have worn out CV boots.

I have driven a few other gen 4 libs (not for very long periods) that also had nothing like that.

by **alessandro132** » Wed Sep 19, 2012 9:01 am

DeeviousDeeve wrote:Hi all,

I bought a 3.0R Spec B (MY08 manual sedan) late last week. Basically, when the drivetrain heats up - seems to only take 20-30kms - and I then slow to a crawling pace, when I try to turn the car there's a clunking noise from one wheel that puts me in mind of a locked up 4x4 trying to navigate a carpark. And it's never the same wheel, sometimes it'll just be the left rear, then the right rear, front right, etc, sometimes it'll sort of "hop" back and forth between both rear wheels. I've read around this and other forums and believe it to either be a CV joint or a differential issue. There's no leakage or obvious wear around the CV boot but there's clearly repairwork done to the front left wheel where I'm guessing a previous owner has gone over a rock or curb, but then the fact the issue only presents when at certain temperature makes me think diff oil.

I took it to the Subaru dealer I purchased it from today (Tuesday), so they could check it out. I warmed it up before I arrived, then took a technician for a short drive to demonstrate the problem. His comments were something along the lines of "I've seen this a couple of times before, but not this bad." So I handed over the keys believing everything would be sorted under warranty. However, when I called up again at the end of the day they said there was nothing wrong, and that the service manager himself had taken the car out and said everything was normal. Their explanation was "the diffs in the Spec Bs are wound really tight, they do this normally". I told them I would have it independently assessed, and would have asked them to take me for a drive in another Spec B to prove it, but as you can imagine there weren't any 4gens on hand.

So, fellow Spec B owners, is this normal?

Your centre diff is worn out and needs to be replaced. The clunking you're feeling is the diff binding and is not 'normal'. I'm getting mine replaced this weekend as mine does the same thing and it's starting to get quite annoying.

Do a search and you'll find that this is quite a common problem for the 6MT. Out of interest, how many kms has your car done?

by **DeeviousDeeve** » Wed Sep 19, 2012 10:12 am

Thanks guys,

It's got 93,000kms on the clock. I suspected it was the diff; in carparks you can hear the tyres kicking up gravel and rubbish as the torque "uncoils" through its chosen tyre.

It was obvious when they gave me my car back the dealership knows there is an issue and just doesn't want to do the job under warranty. Getting them to admit it and make good on their obligations shall be fun.

by **Robbks** » Wed Sep 19, 2012 10:57 am

same issue with mine when i got it.
centre diff is about $1400 from Subaru Aus
ask Michael (PHAT GT) how much he can get them from Japan parts for, i think around $500
can be swapped with the box in the car

I had my stock one modified to remove the Viscous Coupling all together
The parts are replaced with a big metal shim and some thrust washers to provide some pre-load action.
woks fine, will never fail and lock up again. about a $500 fix

by **HoFF** » Wed Sep 19, 2012 12:13 pm

Robbks wrote:same issue with mine when i got it.
centre diff is about $1400 from Subaru Aus
ask Michael (PHAT GT) how much he can get them from Japan parts for, i think around $500
can be swapped with the box in the car

I had my stock one modified to remove the Viscous Coupling all together
The parts are replaced with a big metal shim and some thrust washers to provide some pre-load action.
woks fine, will never fail and lock up again. about a $500 fix

What's the trade off with removing the viscous coupling?

by **DeeviousDeeve** » Wed Sep 19, 2012 12:27 pm

Robbks wrote:same issue with mine when i got it.
centre diff is about $1400 from Subaru Aus

It should be covered under statutory warranty so cost is no issue to me, it's getting the dealership to accept their liability without having to take them to court. They're telling me it's a non-issue and normal behaviour for a Spec B, when it clearly isn't.

by **Robbks** » Wed Sep 19, 2012 1:16 pm

HoFF wrote:What's the trade off with removing the viscous coupling?

theoretically you may have more chance of getting in a situation where you are spinning one wheel and the car goes nowhere
the VCD works by one side of it spinning faster than the other, when the goop inside gets warm, it starts to lock up and provide LSD action.

BUT, the stock VCD is NOT tough enough to transmit enough power to move a 1500kg Subaru that is stationary with one wheel in the air.

so in a road car, it makes 4/5th's of fk all difference
i've had no issues with only spinning one wheel and not moving on gravel, muddy grass, wet bitumen, etc.
it allows handbrake turns BETTER because it doesn't have that locking force to act against
IF i installed a front LSD it would be even better again. the Cusco Tarmak Centre Diff is an Open diff designed for bitumen rallying.

mine was covered under statutory warranty also.
but i put the extra $1000 that they paid my mechanic to put in a Jim Berry Clutch as i knew that was stuffed before i bought the car
I also know that i won;t have to replace the VCD again when it fails in 60k km's

by **HoFF** » Wed Sep 19, 2012 2:30 pm

Interesting Rob.

Mine is starting to show symptoms of it binding, but it's not concerning me yet.

It is good to know I have some options when the time comes.

Cheers

by **Robbks** » Wed Sep 19, 2012 4:37 pm

what i noticed was how much better it feels mid-corner in reasonably tight turns (signposted 60km/h so you try to take them at 120

)

by **DeeviousDeeve** » Fri Sep 21, 2012 4:45 pm

I've been experimenting with tyre pressure to make sure it's not some error on my end, but nothing so far.

I swear at crawl speed there's a bumpiness to the driveshaft, I'm guessing this is an indication of severity?

The dealership who sold me the car still won't own up. I told them I'm driving down south this Sunday to Wednesday and they're on record having said everything was fine. I wonder if it'll last another 800kms before the viscous couple gives up and jettisons itself up through the shift column?

by **GTB Liberty** » Sun Sep 30, 2012 2:03 pm

62K Km and no issues at all.

by **Robbks** » Mon Oct 01, 2012 9:13 am

DeeviousDeeve wrote:I've been experimenting with tyre pressure to make sure it's not some error on my end, but nothing so far.

I swear at crawl speed there's a bumpiness to the driveshaft, I'm guessing this is an indication of severity?

The dealership who sold me the car still won't own up. I told them I'm driving down south this Sunday to Wednesday and they're on record having said everything was fine. I wonder if it'll last another 800kms before the viscous couple gives up and jettisons itself up through the shift column?

It's the diff.

The dealership HAVE to sort it.
take it to a reputable Subaru specialist mechanic and have them formally inspect and diagnose the problem and quote to fix it with factory parts including all fluids, etc that will be needed.
take the report to the dealership and inform them in writing aswell.

They have no choice but to have it repaired and cough up for it.
They have insurance for this stuff. otherwise call the ACCC/ Fair Trading in your state and ask for more advice.