Same here, Ambient temp was in the mid 90s'.Diff was acting weird on my second session on the fifth lap pushing really hard. went back to the pit and what you just explain happened to me.
Though i damaged the diff. towed the car back home from the track, and the next day towed it to the dealer. Mechanic drove the car the sound and the locking on light turning was gone! I drove the car back home and luckily i didn't damage the diff. probable the oil cold down and got back some of its velocity. changed the diff oil. Oil was lighter and the magnetic plug was full of tiny grinned metals. oil also smelled burned. I put in a new OSG oil and nothing happened after that.

Car drives like nothing happened to it. I just had to go down from 5 laps to only 2-3 flying laps. I give the OS diff 10/10. for taking that much beating. the rest of my mods is in my sig.

Ya a diff cooler is a must if your going to track your car regulary.

Turns out the diff is OK. Strangely enough, the oil seal near the front of the diff(where it connects to the driveshaft) had melted out of spec and was causing the final drive to bind up a bit. Once the seal was out, the assembly rotated freely. I did not have to swap the bearings.

I HIGHLY recommend the OS Giken fluid for their diff. It has a 250 weight rating. This is DRAMATICALLY different from the Motul 75 140. the Motul is a fantastic fluid, but it just can not match the viscosity of the OS Giken fluid. The OS unit is very reliant on the oil to lock the diff properly, so I would stick with the OS stuff for anyone using this unit.

On a side note, the guys at OS said many people have overheated the diff and they withstand the abuse. So if you have overheated it, there is a very good chance you are OK. just get the cooler on there and change the fluid asap.

Thanks guys.

John

The OS Gikens are super strong. Being going on mine for a year now with about 7 track days. But I change the fluid pretty often. Every two to three track days. I've only used the OSG fluid. It's costly but worth it.

It's only binded on me once and that's when it was brand new on my first rough outings. Not a lick since.

^ Smart thing to do is to often change the oil (if you regulary track your car). But if you install a Diff cooler you will double or even triple the life of your oil. you'll save money in the long run.

And yes AkumaMS, I had the Motul 75 140, but after what happened i only use the OS oil. You can feel the difference the diff is smother and less noise.

What is best option now? These kits seem very expensive.

Also is there an aftermarket high capacity diff cover for 370z? See them all the time for S2000 and BRZ.

Build your own part by part. A lot cheaper. A diff pump is about $180, about a 13R cooler $140, lines, fittings (this is the costly part. Fittings are costly about $250), and a inline switch to turn on at will. Forget the the temp sensor and automatic activation.

Never seen a high capacity diff cover. There not much room there. A small spacer would be neat.

Anyone done this and have part #s?

What makes all that so costly? A built oil cooler costs no where near these prices and use a bigger cooler and hoses.