O.S. Giken "DualCore" LSD
 

Haven't seen this discussed here; seems like discussion has centered on the 1.5 Way (plus cooling)

Apparently OS Giken makes version called "DualCore" which is a Torsen combined with a clutch-type diff. With wheels on the ground, it acts like a Torsen; if a wheel lifts, it locks and becomes a clutch type:

https://www.osgiken.co.jp/DualCoreLSD/

It is listed as available for Z34 (if i'm reading this correctly)
https://www.osgiken.co.jp/pro_lsd/nissan.php

Almost new reviews available in English

Thoughts on this?

It may simply come down to whether it locks hard enough on power, but in theory this seems good for cars that see track/street duty.

This is news to me. Sounds like a good idea.

Sounds like someone is shopping for a lsd.
https://media.tenor.com/XYMCSWgDsJkAAAAM/do-it.gif

How often does a wheel lift?

If you push it, basically on every tight hairpin.

So this is suggesting the normal OSG will have less than 100% lock if a wheel is lifted. It hasn't bothered me, but seems like it'd add just a tad more consistency.

The only time I've noticed wheel slip under wheel lift is low load lift like angling up a driveway. At the track, I think the lift has been short enough that I can't tell I'm spinning the inside slightly, because I'm still getting power to the outer wheel.

If i'm reading you correctly, you're saying the normal OSG 1.5 way clutch type won't lock at low speed situations?

but this Dualcore version will, due to its gear type engagement on acceleration?

No, it locks all the time. That's what I saw at the Tail of the Dragon. Now, If you have 900whp you can have the 1.5way tuned by OS Giken in the states. I had my last diff tuned by them for 900whp. It is only $150 to have it done. It is tuned in California. Why did I have it tuned? Because my old 3.69 OS Giken diff would one wheel peal on me in the right conditions. The only downside is the OS Giken diff fluid won't help the LSD shuffle under tight turns. You got to give to get sometimes.

As a 1.5 OSG owner let me chime in.

At super slow speeds, doing a parking lot turn, the inner wheel sometimes locks up and chirps. Not often, but sometimes.

If it's a normal corner, drifting is easy, controllable, both wheels lock up as they should, all good.

BUT. There is a situation where the OSG is not acting well.....namely, uphill hairpins. Whenever I was driving an uphill hairpin, and if I approach it normally, slightly too quickly and want to just powerslide through it, the inner wheel WILL SPIN for a brief second, after which it locks up, and spins the outside wheel, acting normally. But this will happen. And I tried and tested it over and over. It's just how it acts.

My preload is factory:

338kg of negative preload (Pressure preventing lockup)
25/38 degrees ramps (coast/accelerate) Angle of 10 active clutch plate sets.

Good to know, I'll have to keep my eye out for some pics!
It actually happened to me this weekend in a parking garage with a large ramp elevation change and the OE LSD pulled the Z up on the LHS side wheel without issue haha.

At 102k miles on the OE LSD i'm figuring on it needing replacement in the near future but the subject OS Giken unit seems like overkill for spirited mountain corner carving.

Filtering through Japanese sites and advertisements, here is the best description I could find. Unfortunately, it is from 2014, and it's from OS Giken USA's Corvette build:

https://www.corvetteforum.com/forums...ln-2015-a.html

What is the benefit of Dual Core?

Improved Turn-in
. When converted to a one-way configuration turn-in ability improves due to the decrease in static decel lock from the pressure ring. The benefit of the variable deceleration lock provides the stability under trail braking and corner entry.

Variable Deceleration lock
. Decel lock is now determined through the difference in
wheel speed. This compensates for the lack of initial decel ramp angle by going to a one-way configuration and allowing the helical side gears to engage the differential lock during cornering. The greater the wheel speed difference, the more the differential will provide locking. This lock can start at 0% utilizing our new zero preload option for Dual Core use.

Smoother Acceleration Lock
. The transition from deceleration locking to
acceleration lock is seamless. This is due to the helical side gears being active during cornering. As there is difference in wheel speed; the clutch plates are locking mid-corner at about 30% total lock. As you pick up throttle there is no abrupt action caused by differential locking. On some Super Lock applications slight wheel spin may occur during curb hopping maneuvers or when one wheel is off the racing surface. The Dual Core cures that and stays locked even when the vehicle is temporarily airborne.

***Our LSD's are fully tune-able; however, I must disclose that all tuning is done in house here at OS Giken USA. This is similar to how one would submit their shock absorbers (Penske, Moton, etc) in for service. Tuning parts are not sold to the general public. The reason for this is for the customer's ease of mind. We have the experience and data to be able to achieve the characteristics you want from your differential. Also the complexity of reassembly is much more than your typical clutch type differential. There are many little details that need to be followed in order to have a proper working diff. We have seen many units come back to us due to improper tuning that we would like to protect our customers by providing a service linked to the us directly. We want our customers to be fully satisfied with their unit and tuning is a daunting task especially for our units.***

MSRP for LSD Tune when purchasing a new differential is $150. MSRP for LSD upgrade will be $150 plus cost of parts. Please note that Dual Core will be available for the C5/C6 sometime late in the year transitioning to 2016 once full development and extensive testing (Track and Autocross) has been performed.

We are still in the process of firming up applications with Japan. At this time we do not have a set cost on upgrading LSD units to Dual Core at this time as we are still in testing phase. You will see release of various applications towards the end of the year and enter 2016.

Good info. but seems like overkill for a canyon carver. In which case what would the member base recommend for streetability but proper lockup when mountain driving?

Wavetrac.

I enjoyed my OS Giken on the Tail of the Dragon. It's worth it in my opinion. Paying them $150 to tune my new one was money well spent. No more one wheel peels at 764whp and up. If my car spins now it goes straight. I have no more issues with it stepping out.

The OS Giken needs a cooler, though, which is another $1,000

I believe the Wavetrac doesn't need one. That's a big advantage


Speak of which

Since the "Dual Core" is a mix of helical and clutch . . . . do we think it will need a cooler?

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.

I just have mine done with every oil change

After this weekend's track day, I gotta say, it's not biting fast enough. I have to get my retuned for more aggressive use. And....just knowing that means dropping the diff AGAIN.... :shakes head:

Fortunately, for me, OS Giken is about 10 minutes away from me ;)

Getting my retuned diff back today. Looking forward to testing it.

Just reading through some diff threads for other platforms

BMW M3 crowd has a guy that is a diff expert, tests off the shelf and builds custom setups.

consensus from track crowd was that OS Giken did not lock hard enough out the box and needed to be upgraded to more aggressive specs

interesting because I had not heard that from z34 track guys - who, to be fair, may not be putting out the same power

Mine needs redone.

I went that route. Tuned by OS Giken themselves.

so it really is a bit too "soft" out of the box?

According to the OS Giken techs when I sent mine in for tuning. It's tuned for stock power and aggressive street driving

Yeah, I sent them my dyno graph and all associated info for my setup, so I expect the new "tune" to be much, much better.

I'm actually surprised by their soft initial setting. Most of their other OTS setups for many other car makes are great for track use. Oh well, live and learn.