Small Update.
As of close of business 31st December 2022 CorgiWerx has rebuilt and shipped 1,205 Subaru Centre Differentials
BillyCorgi wrote:Centre Differential Analysis.....
So a young gentleman on club.liberty.asn.au Facebook page posed this question.....
"Brand new tires on the rear axle & completely worn tires that need replacing on the front axle.
Does driving with this arrangement damage the viscous coupling & gearbox?"
Here is my response.....
"Hi, This is Peter from CorgiWerx, the Subaru Viscous Centre Differential Expert
For those playing along at home lets do some analysis....
Let's take a Gen4 Liberty 2.5NA running 215/45R17 tyres and a 3.9to1 final drive.
The rear tyres are new and the front tyres are worn out.
The vehicle in question is doing a steady 60kph.
Th rolling diameter of the front tyres in 625.3mm, the tread depth for these tyres is 8mm so the rolling diameter of the worn front tyres is 609.3mm.
At a speed of 60kph, the front tyres are rotating at 509.05 rpm and the front tyres are rotating at 522.42 rpm.
The rotational speed difference is 13.37 rpm.
With a final drive ratio of 3.9to1 the speed difference across the centre differential is 52.13rpm.
For a standard OEM centre diff with a 40N.m @100 rpm rating the centre diff torque will be 20.85N.m.
The 52.13rpm equates to 5.46 radians per second.
Power = Torque x Rotation Velocity or in other words, the heat generated within the centre diff will be 114 watts.
Now, I do not know when it is the last time you grabbed hold of a 100watt incandescent light bulb, but they get fecking hot!
It can quickly overheat the viscous fluid.
Analysis: Not good for the centre diff"
BillyCorgi wrote:The Rear Tyres were new.
nvmylh wrote:But if that light bulb was in 60km/h airflow, it wouldn't get that hot?? haha
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