Tom MIata Posted August 2, 2019 Report Share Posted August 2, 2019 Never had this problem before. But after 10 hours at Indy the diff was extremely hot. It’s 99 a 4:30 thurston diff and the oil that came out it had a burt odor to it. We ran 10 hours on Sat and Sunday. Had the diff apart this winter with no sign of wear. Ran 3 days at WGI no issues and the oil that came out then was ok, no smell. Run Red line 75/90 the only thing that was different was the wheel size change from 15 x 7 to 15 x 9. Looking for any ideas on what may have caused it to overheat. Tom M 91 Miata Sweetwater racing Quote Link to comment Share on other sites More sharing options...
Team Infiniti Posted August 2, 2019 Report Share Posted August 2, 2019 Thanks for reminding me, it was hot out there, our diff briefly got hot, time to check/change fluid. 1 Quote Link to comment Share on other sites More sharing options...
JDChristianson Posted August 3, 2019 Report Share Posted August 3, 2019 11 hours ago, Tom MIata said: Never had this problem before. But after 10 hours at Indy the diff was extremely hot. It’s 99 a 4:30 thurston diff and the oil that came out it had a burt odor to it. We ran 10 hours on Sat and Sunday. Had the diff apart this winter with no sign of wear. Ran 3 days at WGI no issues and the oil that came out then was ok, no smell. Run Red line 75/90 the only thing that was different was the wheel size change from 15 x 7 to 15 x 9. Looking for any ideas on what may have caused it to overheat. Tom M 91 Miata Sweetwater racing Check your exhaust close. Any leaks can put extra heat on the diff. Have you added any front aero that’s limiting air under the car? We’ve been through some diff failures, all heat related. They need air. 1 Quote Link to comment Share on other sites More sharing options...
Tom MIata Posted August 3, 2019 Author Report Share Posted August 3, 2019 No aero changes. The exhaust is an inch or so away as it has been. At this point I am going to change the oil and run it. Does anyone run a diff temp gauge? If so any recommendations? Quote Link to comment Share on other sites More sharing options...
Team Infiniti Posted August 3, 2019 Report Share Posted August 3, 2019 We run a diff temp gauge of dubious calibration, it’s more an indicator when it’s getting hot, rather than exactly how hot is it, if I were to believe the numbers... ( track dependent) 250 to 280 sustained, without lubricant break down, 310 peak. Indy briefly saw considerably more than our previous peak. I will report back if the fluid is burnt this time. Redline has been in there as well as Mobile one & Castrol Syntech , no functional difference between any. Quote Link to comment Share on other sites More sharing options...
55mini Posted August 3, 2019 Report Share Posted August 3, 2019 I would consider your exhaust as the cause, we worked on pit row for Indy and yes it was really hot. In years past with our Miata and the exhaust underneath we could cook the oil on any very hot race of 8 hours or more. If your pipe is not heat wrapped I would suggest that to be done asap. We have also cooked the inner cv joint and boot. Might consider a heat shield attached to the pipe and off by say 1/2" and if you can make it out of stainless steel as it has better cooling properties. Last option I can think of would be a vent and duct like for the brakes and bring cooler air in to blow by the diff, this would take some effort but could be done. 2 Quote Link to comment Share on other sites More sharing options...
Mazmarc Posted August 5, 2019 Report Share Posted August 5, 2019 ^^^^ Exactly this^^^^ Keep the exhaust heat off the diff and CV boot. 1 Quote Link to comment Share on other sites More sharing options...
Gkuhn41 Posted August 8, 2019 Report Share Posted August 8, 2019 We pulled off @ the 8 hour mark day one. I slid under the car and bumped our rear diff and burnt my arm. Ours has never gotten hot like that and it was very hot at Indy. Our exhaust is the same, we are adding heat wrap to that area to cut down on the transfer. Quote Link to comment Share on other sites More sharing options...
67Mustang Posted August 10, 2019 Report Share Posted August 10, 2019 Be weary of you bearing life if that has happened multiple times. Quote Link to comment Share on other sites More sharing options...
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