6MT Centre Differential Rebuild Project

[bigBADbenny]

Love it!
Have you considered offering the option of superfinishing and stealth coating select internal parts?
Could benefits ensue?

[BillyCorgi]

So, after nearly 170,000 kilometres my trsty steed gave out its first BANG-BANG-BANG-BANG from the driveline yesterday evening.

I am so excited. I am (finally) going to get a CorgiWerx Centre Diff.
I am about the last one in my family to get one!

Have not yet decided to go standard 4kg build or to make an 8kg special. (Because I can)

[fedaykin]

Always upgrade.

[cortin]

(Because I can)

good day.
6мт и 5 мт details in the photo
the same?

[BillyCorgi]

(Because I can)

good day.
6мт и 5 мт details in the photo
the same?

The 5MT and TY85 6MT pinion gearset and shaft are the same
The TY75 6MT use the same pinion gear and thrust washer but different shaft.

[BillyCorgi]

Have not yet decided to go standard 4kg build or to make an 8kg special. (Because I can)

I decided to build an 8kg special. (Because I can)

[bigBADbenny]

Is it in?
Does it skid?

[BillyCorgi]

Is it in?
Does it skid?

Uhm.....

It was fitted over Easter (last) when the centre diff was changed out.
As a daily, I cannot really decern much of a difference with the 8kg unit fitted.
Not quite sure what skids should be expected?

[bigBADbenny]

Potentially understeery type skids if not installed with torsen front diff and excessive throttle applied during cornering.

But really that’s more likely to happen with a 20kg centre

Have you done many cdiffs over 4kg?

Any feedback?

[BillyCorgi]

Have you done many cdiffs over 4kg?
Any feedback?

Sufficient.

[ronangills]

Interesting, this will be really helpful for the people who are working in that science center. I hope you will get huge amount of donation for this project.

[BillyCorgi]

120,000 km Tear Down Review

So, after 120,000kays in James' H6 6MT Outback, the centre diff was removed to upgarde to a higher viscosity unit.
This differential had been given the CorgiWerx rebuild in February 2017 and had done 120,000 kays of James abusive driving. This included only replacing 2 tyres at about 50,000 kays.

PERFECT
The centre diff measures up the same as the day it was assembled in 2017.
The differential gear clearances are still at the CorgiWerx settings.
The internal fluid is clean and without any signs of carburising nor blackening. The fluid still smells sweet.

By-The-Way.
The CorgiWerx Shifter Joint Bushes in the lower left hand corner of the last photo are still perfect!

post a pic

[bigBADbenny]

Sooo good!
And something something 50th?

[BillyCorgi]

Time for a short update.

Recently, a customer took their CorgiWerx supplied 6MT Centre Diff to a "reputable Subaru specialist mechanic" to have the centre diff installed.
After the job was complete, the customer contacted me advising of unpleasant sounds eminating from the gearbox.
Confidently I advise "Highly unlikely that it is the replacement centre diff"

Customer took the car to a second shop for a diagnosis.
Turned out to be a bad install by the original "reputable Subaru specialist mechanic".
The oil pump drive gear had not been kept in mesh when the rear cover had been reinstalled on the gearbox.
The oil pump drive gear was damaged and teh oil pump (driven) gear was bent to all fuckery.

CorgiWerx installation guides advise how to keep this gear meshed during rear cover installation and little tricks to monitor the position of the centre diff to detect if it starts to slide out.
We also recommend that the output yoke from an offcut of rear propeller shaft be used as a service toool.
With the yoke inseterted into the ooutput hole of the rear cover, the yoke will keep the Transfer Drive Gearset perpenticular to the case (where it should be) and allow the transfer driven gear and the transfer drive gear to be "rotated" to allow meshing of the splines in the centre diff and ensure meshing of the oil pump gears.

The rear cover should be able to be inserted by hand force only all the way on until the dowels touch at the gearbox face.
Only tighten the rear case bolts by hand, as you can then feel if there is a binding.
If binding is felt, take the cover off and find out why.
NEVER use a rattle gun to reassemble this area!

[BillyCorgi]

Centre Differential Viscous Coupling Failure.
CorgiWerx have rebuilt over 500 Subaru Centre Differentials and have built up a wealth of product knowledge on the viscous couplings. Apart from the occasional mechanical failure of the diferential gearset, the common failure is deterioration of the silicone viscous fluid. The viscous fluid can expand, the fluid can thicken, the fluid can separate.
Here is one of the typical fluid failure mechanisms.
Attached is a photo of the clutch plates inside the viscous coupling.There are outer clutch plates with external teeth that engage in the body of the centre diff and inner plates with internal teeth that engage with the differential gears. There are interlaced A-B-A-B=A=B etc. The plates are not designed for friction contact, the plates float between each other dragging themselves through the viscous fluid.
In the picture the outer plates are on the left and the inner plated on the right.
Here, the upper two plates are "normal" and the lower two plates show the signs of the viscous fluid failure coating the plates with a black tar like wax. This can be best seen on the plate on the lower right on the teeth from the 8 O'Clock to the 2 O'Clock position.
When the diff gets hot, the waxy coating black coating on the suface of the plates acts like a brake and casues the centre differential to bind up.

CorgiWerx - The Subaru Centre Differential Subject Matter Experts