club.liberty.asn.au

Ok, sounds good . Thanks again for your efforts.

I just ran my car on a hoist in 4th gear and heard a lot of noise coming from my gearbox/centre diff/transfer box.
I was wondering, is it normal for there to be a bit of chattering noise since there is no load on the drive train?

By your description it sounds like you were "free-wheeling" without any load on the car?
In this condition there is no load to keep the gears loaded into one-sided mesh, so expect funny noises for the gearsets.
Run the car back on the road under load, it should be "normal".

Another Diff has Arrived

Brunsy's diff arrived in the post today. (Thank you Daniel)
Here it is.
http://imgur.com/a/l25qx.

After a little cleaning and wiping off of extra lurking oil the official weight is about 4,585.6 to 4,585.7 grams.
The last image shows the scales taring back to ZERO once the diff is removed, showing the scales have warmed up sufficiently.

BillyCorgi wrote:By your description it sounds like you were "free-wheeling" without any load on the car?
In this condition there is no load to keep the gears loaded into one-sided mesh, so expect funny noises for the gearsets.
Run the car back on the road under load, it should be "normal".

Ok Cool,
I was running it on the hoist with no load on the wheels/car (besides the weight of the wheels). I was trying to find a whining noise which my car has been making when you turn left at speed (80km plus) and all of a sudden I heard this noise from the transfer box/centre diff.
I don't think that noise and the whine are connected since there is such as speed difference.
What do you think?

Brunsy's Centre Diff

So we have now got Brunsy's centre diff and I have been spending a few days thinking about the next steps.
One thing that was needed was some tools to "test" the diff.
So rather than make the error made before and proceed too quickly time could go slowly while the barin was engaging.

The things on the interweb suggest that the standard diff is rated at 4-kg.f
http://home.gci.net/~cowdookey/818/Tran ... Public.pdf
Further searches suggested that this is at 1 metre, so 40-Newton.metres is the units rated toruque.
Other information suggested that this is at 100rpm.
So 40-N.m @ 100 rpm is the present guide specification.

To test this a rotating machine is required (check - have lathe) and a splined tool to engage the side gears in the viscous coupling.
The splines in a standard drive shaft are the wrong size.
We do not have a spare 6MT gearbox to cannibalise (and I would not if I did!)
So, I had to make a tool.

http://imgur.com/a/ZA13X
First image - drive shafts with wrong spline.

Second Image - Special Tool with 1/2 socket welded to it.
(This is why I NEVER throw out broken tools as they come in handy for a special tool in the future)

The back gears were set on the lathe and using a stopwatch a speed selected as close to 100rpm as possible
Third Image - the set up in the lathe using a torque wrench to find the breaking torque of Brunsy's centre diff.
The breaking torque was found to be about 75-N.m (cold) or roughly twice the 40N.m or 4kg.f specification.

Maybe now is the right time to disassemble the diff, clean it and determine the mass of silicone fluid.

Very interesting read

Silicone Fluid Mass

Well, the Centre Differential was disassembled, pulled apart, cleaned, washed, dried, cleaned polished, cleaned and all the silicone fluid removed.
It was thick and not flowing at all. No wonder the diff was replaced by Brunsy3.0

We now have an official mass estimate for the silicone fluid. 50.0 grams or close to 50cc as the fluid has a specific gravity of rho = 0.977
http://imgur.com/9j5cSLO

Sounds like a nice round number.

It was only just starting to clunk but had been binding for some time. Good to see it go to a good cause. Hope you get it all sorted, seems like you're all over it

We Have a "GO" Project(?)

I feel like the kid who has just come from the Dentist and been told that he has no cavities and everything is fine!

Okay, since the last update where the mass estimate of silicone fluid was determined Brunsy's Differential has been rebuilt.
The old seals were used in this trial as I have been looking for a key success point before laying out the money to tool up for new, custom made seals.
During the rebuild activity the QA processes have been trialled and refined and I now know what to do and how to do it.

Here are the key images.
http://imgur.com/a/l2cmE
The first image is of the three total masses taken over a few consecutive days while I became familiar with the electronic scales. 1st; 2nd; 3rd, etc.
The third reading was the final accepted reading taken for the diff.
There is also the Empty&Clean reading from which the mass of silicone fluid was calculated.

The second image is the shot of the weigh scales of the Empty&Clean unit, with all the original parts.

The third image is the diff totally reassembled with new fluid.
You can see that the weight is the same as the original, so the correct mass of fluid has been filled into the viscous coupling to bring it back to original weight.

So, this morning I toddled off to a Subaru Gearbox specialist and asked them to test the differential.
They came back smiles and gave it the okay. (they did not know it what it was).
So, We have "GO" project(?).

My next step is to revert back to Ludowici and commission the new seals.

So please contact me if you need a replacement Viscous Coupling Centre Differential for the 6MT or 5MT gearbox and we will sort out what can be done to support you.
Cheers!

Brilliant!
Everyone of the many people who have CD building issues should jump onto this.

The man. Good to hear of a positive outcome. As these are such a common failure for the gearbox its fantastic to have a cosy effective fix rather than forking out for a brand new item as a lot of us have.
Top job Peter in approx 150,000km i will more than likely be on need of this haha

This is some excellent work - With some spare units you should also be able to do changeovers.

HardwareBoB wrote:This is some excellent work - With some spare units you should also be able to do changeovers.

Correct, that is the idea.

Hodman's and Brunsy's diffs are both 38913AA112 units.
I am yet to see the later model 38913AA200 unit to check it out? These were in the late model Spec-B and GT-Bs.

With a "changeover" system we will need to engineer the correct selection of the TRANSFER DRIVE GEAR THRUST (ref 6MT-49 from FSM).
I suppose that we have got this far, so this step should not be unachievable?

Brilliant work Peter!