We posted that hub photo somewhere on Sunday morning and Dave in NJ posted an identical photo of a Cressida hub (same part) that failed on their race car. This is his photo:Awesome! What a great debut for the new tune, that is one fast race mk2!
Racing breaks the damnest things for sure, I've certainly never managed to break a hub.
I did add a cooler, pump much like yours, added the glowshift short sensor in an -AN tee (didn't have time to weld a bung directly into the diff cover) so I read temps coming out of the diff when the pump was running. I built it into a steel box with a naca duct with an inline blower for insurance. without the blower the hottest it got on a 90deg day on a shorter course was 185. with the blower it dropped below 160. The cooler and lines brought total capacity to just over 2 qts. I cooked 2 diffs in one weekend prompting it.It is a Glowshift - seemed like a good price for the entire set-up. If it fails it doesn't affect anything related to racing, we would only lose a diagnostic data point.
I'm interested in your measured diff temps. Do you have any type of cooler or added oil volume? I believe that my 2 diff failures have been heat related in long races, and installed the diff cooler to alleviate the issue. I still don't have a temp sensor.