Forged Performance/ OS Giken LSD Review (pics)

A.J@CarbonSignal

Very good and detailed review.

You can't go wrong with OS Giken products.

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SPOHN

Yea I have a base model Z so I didn't have a VLSD in my car. Even if I did, I still would of purchased this. It really is worth it by leaps and bounds if you plan to push or defiantly track you car.


Thanks. It's defiantly worth it. I wouldn't pass this mod up if you didn't have to.

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John@Z1

Very nice, I bet it feels like a dream come true.

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SPOHN

Oh it does. As I told Spencer earlier next best mod to a TT. Lol.

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Sharif@Forged

Just to clarify with respect to the installation issues. We're very familiar with Nissan's habit of using different length and shaped stub axles in the various trims of 350Z. With the 370Z, the base model includes traction control but still an open differential. In the process they also elected to use a revised set of stub axles as well. So with 6 different stub axle choices even OS Giken wasn't entirely sure what ones to use. We ordered one short and one long axle in preparation for the installation. Upon inspection of the OEM parts we discovered that we need two SHORT stub axles NON TAPER with snap ring grooves/snap rings. Instead of sending Chris home and ordering a second short stub axle we machined and modified his existing axle to precisely the same measurements and tolerances of the OEM part which including machining a new snap ring groove. This is a substantial amount of extra time, but we didn't charge the customer of any of this and our objective was to complete the job as promised and get him on the road safely. Under normal circumstances no modifications are needed during install. Mission accomplished.

Shifting gears to the performance aspects, the OS Giken is the highest performing and smoothest engaging clutch-style LSD we've used in every car we've put them in. Prior to using them on the 350Z/370Z, we had used them on the GT-R, Subaru, and Porsche GT3. It's the best kept secret in performance handling and laptime reduction, bar none.

The OS Giken is a 1.5 way clutch style LSD, with a perfectly machined outer case and ring gear shelf. No shims have ever been needed in our installs and that says a lot about their machining processes. The LSD locks 100% under acceleration, and 50% under deceleration and has an undetectable ramp that is seamless in it's engagement.

The best way to test and describe an LSD's action is on track, but the benefits as Chris alluded to are also immediately apparent during street use as well. A full locking differential allows the driver to roll into full throttle much sooner in the corner, without causing speed robbing wheel spin. On the OEM diff this is very noticeable on tight and slow mountain roads such as those that have visited the Tail of the Dragon. In contrast, with a "locked" arrangement you are providing equal thrust to both engines back there (your tires). Although it seems contradictory, you do not want an overload of power to the tire that is gripping, as it quickly causes you to light up BOTH tires and you cannot control the back of the car with the throttle as readily as a locking diff.

Hope that adds some additional color, to an already awesome product. Now lets talk about the OSG Twin Plate Clutches....haha...ok next time. Thanks for reading.

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ChipsWithDips

So if I have a base model, I can order 2 short stub shafts from OS Giken and they will fit without modification?

SPOHN

You have to order them from Nissan.

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Sharif@Forged

The stub axles are a Nissan oem part. You can order them from Ryan or myself and we will make sure you have what you need. It goes without saying you also need two new side bearings.

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Sharif@Forgedperformance.com
General Manager/Certified Tuner/NASA-PCA-BMWCAA Instructor
JRZ RS1's Available NOW...PM me
Cobb ProTuner, Uprev ECU Flash, FCON Vpro, Haltech, Motec Certified

Belsavis

Did you replace the side bearings? If so, do you have the part number?
Thanks

Sharif@Forged

Chris is mistaken. We replaced the side bearings as it's not possible to remove them from the old diff without likely damage. We did NOT replace the side seals because they looked perfectly new and had very low miles on them. No reason to change them out.

__________________
Sharif@Forgedperformance.com
General Manager/Certified Tuner/NASA-PCA-BMWCAA Instructor
JRZ RS1's Available NOW...PM me
Cobb ProTuner, Uprev ECU Flash, FCON Vpro, Haltech, Motec Certified

SPOHN

Thanks for clarifying all this Sharif. This is truly a great performance piece. I'm having so much fun in this car now. It's amazing the traction this baby gives. I actually finally experience the lock under declaration leaving you shop Monday. I wasn't really expecting it but that was amazing also. It almost seemed to oversteer some but very controllable and predictable just waiting for you to accelerate out of turn. I was smiling all the home.

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Ryan@Forged

Very nice review! The OS Giken differential's really do make a huge difference. We couldn't believe the difference it made on track when we tested them at Road Atlanta. For you track guys this really is a MUST. Enjoy the new diff!

flashburn

Sounds pretty awesome.

Can I get a PM with a install quote for this? I'll be heading up to Georgia to go to AMP in the fall.

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Ryan@Forged

sent you a PM

Red__Zed

Sharif--

So the issue was just getting the wrong stub axles, which presumably won't happen now that they know which ones to send?