Phase 9 - Trial ReassemblyTook the 5MT Centre Differential unit and attempted a trail reassembly.
The used orings and seals were reused to avoid damaging new seals (which are yet to be manufactured).
http://imgur.com/a/WVoqoThe reassembly was first trialled "wet" with water inside the unit while the plates and discs were restacked back in.
The first image is the C-D housing.
The second image is with the side plate and differential side gear installed.
The third image is with all the plates stacked in. You may probably be able to see the water which came up through the plates as they were stacked in.
They were stacked in sequence - Outer plate then spacer ring then inner plate; Outer plate then spacer ring then inner plate; Outer plate then spacer ring then inner plate; etc, unit the last outer plate was placed in.
The fourth image is with the bronze thrust washer placed on top, ready for the end cap.
At this stage a failure was experienced.
While the end cap would go back on, the end cap would bot go on sufficiently to allow the retaining ring to be inserted to secure the end cap. It was about 0.4mm short (using feeler gauges)
The unit was disassembled cleaned, dried and then reassembled dry.
This time the side plate and differential side gear (mentioned above) were reassembled in a different sequence and tapped securely "home" before proceeding to stack in the plates.
This time the end cap went on sufficiently far and the retaining ring was able to be inserted easily. See the fifth image.
So, the internal flooded volume has still not yet been determined.
However, the ability to reassemble the C-D unit has been proven.
My thoughts from here is to seek out someone in Sydney area who has access to a 10kilogram by 1-Gram electronic scale and do a unflooded and flooded weight.
Can anyone help out, please?Edit UpdateSearching on key word strings "viscous + coupling + fill"; "viscous + coupling + hump"; "viscous + coupling + rebuild"; has turned up various fluid fill volume ratios.
Someone quotes the GKN coupling as 70%
Someone quotes 84%
Someone quotes (about) 90%
Someone quotes 7% to 12% air.
(The links to these figures have been stored in my research files)
To further complicate matters, this links claims that the units are flooded, with no airspace?
https://www.youtube.com/watch?v=feD4D1quS0kWhat is apparent is that the fill percentage will affect the onset of "hump" mode.
In hump mode the silicone fluid expands and causes the coupling to "lock-up".
Less fill, a delayed "hump mode", more fill, less time to achieve "hump mode".
"Hump mode" is a desirable characteristic in a all-wheel drive centre differential as it will provide the momentary "kick" to get an AWD out of a bogged situation.
"Hump mode" is not desirable for a front wheel drive car as the sudden onset of hump mode and coupling lock-up causes undesirable handling characteristics in a front-wheel drive car.
Excessive time operating in "hump mode" leads to silicone fluid degradation and viscous coupling failure.