[Fot] IRS diff overheating

[Chip Collingwood]

Don't overfill the diff, it is designed to run in a shallow amount of fluid, not in a bath. Definitely use synthetic as it will run cooler

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> On Jun 3, 2015, at 9:30 AM, Greg And Alison Blake <ablake2 at austin.rr.com> wrote:
> 
> 
> Got some great feedback on this one. Such a great list. Just wish I knew before last weekend about this failure mode.  We could have turned another 200+ laps. 
> 
> One follow up. Is there a down side to overfilling an IRS diff unit?  I am thinking I'll install a metal catch can in the trunk and plumb to the bottom of the can. Would putting in another 1/2 quart into the diff aid in cooling or just  get puked out earlier?  If that's not an option, I'll investigate adding a bit of capacity to the cover along with a few fins. 
> 
> Thanks. 
> 
> 
>> On Jun 2, 2015, at 12:40 PM, Greg And Alison Blake <ablake2 at austin.rr.com> wrote:
>> 
>> Some of yall may have followed the social Media posts provided by our teammates through the weekend. We were racing the Beanitos TR6 this past weekend at what was to be TWS's last ever race. It was a split 16 hour endurance race (Sat&Sun). 
>> 
>> We had a strange failure on Saturday. About 6 hours in, the truck was full of gear oil. I had routed a diff vent line to the trunk. Upon returning to the garage, we discovered melted poly diff mounts. Pic below. 
>> 
>> I've been scratching my head on this one. Prior to boiling the diff fluid, we had zero leaks in the freshly serviced diff. I had replaced all seals and filled with STALUBE 90WT GL4. 
>> 
>> I've been racing my TR3 using this same diff fluid for 6 years (replaced every two weekends). Never a problem with my vintage race car. Of course, I've never run the 3 for 6 hours straight. 
>> 
>> Some of the more seasoned endurance racers asked what fluid I had in the diff. All suggested that mineral based fluid is not a good choice for endurance events. 
>> 
>> I'd love to hear opinions as to the route cause of our failure and more importantly, suggested remedies. 
>> 
>> As to the results, the car was running consistently 2:1x laps with a fast lap of 2:10. We ended up taking the workers choice award. Had we run w/o diff failure and a subsequent battery failure, we could have been in the hunt for a podium finish. Fastest lap in our group was 2:09.9
>> 
>> Great weekend
>> 
>> <image1.jpeg>
>> 
>> 
>> Thanks 
>> Greg
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