Seems like play toward the more street oriented, or dual-purpose crowd, that don't want to use a diff cooler, which is basically everybody with these cars.

I actually am pulling my 1.5 OSG LSD to send back to them for a rebuild and setup change. Ever since going to stiffer springs and sticky tires like RE71RS, the inside wheel spins so badly in corners and curbs, it's not even worth driving anymore at the track. Not sure if it's all my car setup/power, or a combination of high wear when I first installed it and didn't have a diff cooler for a couple track days, and only had a Z1 diff cover (which are absolute garbage BTW, they actually increase oil temps because they don't adequately lubricate things inside like an OEM one does with the rounded interior). Trust me, everybody should ditch those and just use the Nismo cover, which I did switch to, in addition to a cooler.

Regardless, the LSD needs adjustment.

The idea of a Wavetrac sounds great, but the lack of lock on coast/decel still bothers me. Who knows, maybe they still work great on track. Not having to run a diff cooler certainly would be nice, and make diff oil changes a helluva lot easier.

1) The OS Giken is tuned from the factory for stock power and street use. It definitely needs to be tuned for track use, and/or higher than stock power

2) I completely agree with you on the Z1 cover. I scrapped mine for my new build and had a Nismo cover installed instead.

3) Rob Fuller from Z Car Garage runs OS Giken's on all of his race cars, including his IMSA car and doesn't run an oil cooler on any of his cars and has never had a diff failure. Take that for what it's worth but he's a reputable source.

I puked diff fluid out the vent tube of my OS Giken on the Tail of the Dragon. In my eyes, you need it. Plus, your diff fluid last longer. No need to change it after every track day.

Agreed. My car would have puked regardless of what diff cover I had on my car with the OSG LSD on track.

I think between my aggressive track setup (springs/bars/tires) etc. and making 340 WHP, along with the 3.92 final drive from the 2016+ Nismo, it just puts too much power down for the OTS setup.
I should have consulted with them first, because most of the time their OTS setups work great for track cars, but just doesn't seem to be the case for the 370.

My car was bone stock with the 3.69 OS Giken. No tune. All I had was a 2.5in. Fast Intentions exhaust. Suspension was upgraded, wheels and tires. This was before I went twin turbo.

I now have an OS Giken tuned 3.357 rear auto diff now. It was tuned for 900whp. No more one-wheel peel. I still have my diff cooler. My Essex parts AP racing brakes are excellent. No more hot spotted rotors while out having fun.

Reading these last several posts got me thinking.....I have shorter final drive (4.08) and pretty stiff suspension setup. In super tight corners I feel the inside wheel spinning through after which it locks up. The LSD is stock OS Giken. Does this mean that stock OSG setup isn't good, i.e. it's too loose and should be setup specifically for "higher power" i.e. to lock up sooner?

May be the case. The locking can be set in a couple different ways, how fast it locks and how much it locks. I like progressive lock the OTS setup has, not an on-off switch, so it works better on track, but I want the amount of lock to be increased significantly to avoid wheel spin.
OS can tune both and will set it up accordingly. It seems pretty clear the OTS setup is on the soft side for whatever reason.

Yeah, I learned my lesson on my first one. I had my new one tuned by OS Giken. I called and was talking to them. $150 bucks, Oh yeah I am getting mine tuned.

Many years ago, I caught a video from Gale Banks (Banks Power) on diff cover interior curvature and how that affects fluid temp, aeration, gear lubrications, etc etc…he had an experiment with clear diff covers to show the theory. Since then, it was an easy conclusion for me to skip the Z1 cover.

When I do diff upgrade, Nismo cover will be my choice.

He even did air flow testing behind the diff cover and came up with a pretty cool design to guide the moving air into the cooling fins. Wish we can have that.

For all,

Why does an aftermarket differential require a cooler? :eek:

Clutch type diff = more heat generated.

The Wavetrac doesn’t need a cooler because it’s a helical diff, not a clutch type diff.


Sent from my iPhone using Tapatalk

That's what I assumed and wouldn't want a clutch type for street usage anyway as I don't need track car tunability, nor do I want to get into clutch pack maintenance. Thanks for the insight! :tiphat:

The OS Giken works absolutely beautifully on the street. They come with a street tune. If you use the OS Giken fluid and change it periodically, the diff rarely needs maintenance

You will know when to change the fluid. It starts to make noise. Mine needs changed.