Speed Freaks USA: OS Giken discussion thread
 

Some time has passed since the first group buy closed and people have been able to get the new LSDs in their cars and put some miles on them. I wanted to create a review/discussion thread for anyone using an OS Giken Super Lock LSD to gather some impressions. This is aimed at the guys involved in our first group buy but is open to anyone and everyone who has experience or questions so please post up!

I just picked up my differential and will try to swap it in the car sometime this week to give my impressions. I don't have a track event scheduled until next month but I will be sure to go for some "spirited" drives on some of amazing roads we have in the mountains around the SF bay area and update along the way.

-Matt M.

Below is a review I did about two years ago on my initial impressions of the OS Giken TCD for my IS350 and the info should be relevant for the IS-F as well:

https://www.clublexus.com/forums/per...ml#post8038610

Looking back at my initial impressions and what I think of the TCD today, I still marvel at how impressive the TCD performs for both daily driving and on the track! The IS350 and IS-F are some of the lucky few models which sport the full set of 28 clutch plates inside the LSD as well as the 3rd generation TCD clutch plates which allow for an even more progressive lock-up compared to the original Super Lock LSD. This mechanical torque vectoring differential will literally pull you through every corner using the rear outer wheel and drastically changes how you would normally approach your driving line since you can get back on the throttle even before you hit the apex. As others have quoted on the internet: “The OS Giken is a cheat code. Absolutely unreal what you can do with a rear end with it”. This is easily my most favorite mod that I’ve done to my Lexus. :thumbup:

Mine has yet to be installed, but it's scheduled to in the shop fairly soon. The shop has one of my Supras, with another Supra to follow and, then, my IS-F. I saw where lobux posted that his had been installed, along with some nice FIGS pieces, so I think he'll be in here fairly soon (was on a long driving trip when he posted).

Ken.

Love the SuperLock. Hate the installation. It is not for the faint of heart, and if you are not a master level mechanic, I would not recommend attempting this yourself. Getting the diff out requires moderate skills. Buy seals. You will destroy them taking them out. Figure out a method of removing some very large and very stiff snap rings. We welded cylindrical bearings to the jaws of a pair of Vise-Grips and ground them to be parallel when closed so they would not push off when we clamped them. It was a lot cheaper than buying a one time use $100 snap ring tool. We had to grind the housing (see Figs blog for more info) to get the spool in, and it required attention to the exact clocking of the spool to minimize the amount of metal I had to remove with a burr bit and die grinder (I have hundreds of hours of porting experience with burr bits, so the grinding wasn't hard, but it was tedious because I didn't want to remove even 0.005" unnecessarily). This part took about 5 hours because it is imperative you block off the pinion gear and ensure no metal shavings get in the case where they can float around. I made a cardboard blocking plate and taped it in place, then stuffed a rag over the blocking plate, and used a vacuum cleaner to remove the chips as I ground down the surface.

Anyway. This is not a task for the guys who have difficulty distinguishing between a #1 and #2 Phillips.

Install was no big deal, just a lot of work because you have to fully disassemble (almost) at least one side of the rear suspension. I chose the right and ended up with only the top rod holding the knuckle. It's the only way to get enough room to remove the axle.

As Figs says in his blog, the axles need to be pryed out with large pry bars. Works great.

As Figs doesn't say in his blog, installing the axles will require a brass drift and BFH to make them fully seat. AMHIK.

Lots and lots of details to consider if you are doing this yourself, but if you are seriously considering this, I don't need to elaborate beyond what I have here.

This is the perfect time to install the Figs/SuperPro differential bushings. In fact, I would say if you don't do this at the same time, you are missing half the good part. They eliminate (yes, I said ELIMINATE) wheel hop under acceleration. You will be amazed at the improvement in acceleration, but if you fail to install the bushings, you'll just invoke wheel hop and you'll say, "WTF was lobux talking about, my wheels are hardly in contact with the ground now?" With the diff out, you can't have a better circumstance for installing the polyurethane diff bushings. Just be sure you have an air chisel to get them out. Or a 20+ ton press. I think the chisel was easier.

On to driving impressions.

THIS IS HOW THE CAR SHOULD HAVE COME FROM THE FACTORY!!!!

I am not kidding when I say you will not believe the difference. It is night and day. Also consider I replaced both of the bushings in the lower control arms in the front. The immediacy of response is absolutely stunning.

I can also say NVH is not noticeably different, but front end and rear end traction has made a quantum leap. Mid-corner speed is up about 4 mph on street driving, and drift control in the back is nothing short of spectacular.

The first pic is the spool straight from the freezer (it makes putting in the snap rings a breeze), second is after the RTV cured with the Figs bushings installed on the pinion ears. That is one big snap ring.

If you missed out on this buy, you made a big mistake. Anyone in ATL who wants to feel the difference, LMK....

Housing was trimmed between the red arrows:

https://cimg7.ibsrv.net/gimg/www.clu...1bb5266f44.jpg

We removed the diff by removing the rear section exhaust / unbolting the driveshaft and getting the axles out past the snap rings and then undid the bolts that hold the diff in, and lowered it down gently using a transmission jack while gently removing the axles. We did not have to undo any suspension components.

Glad you are enjoying the diff! If the 08 diff to the Torsen was like a different car, yours must feel 10x better! Enjoy that steering with the throttle!:thumbup:

Well said lobux! I have a complete is350 2way neo in my isf. I daily the car and takin it to the drags every month and drop hammer the streets. I want to get the isf is giken unit as I'm getting tired of the lower mpg. The car is a beast though and I am very pleased with the os giken company, will definetly be buying the f unit and any others for future projects

This thread makes me want to get a OS Giken right away. Thanks for sharing !

it's a whole different experience, especially if you have a non LSD car. With the weight/suspension/ size of the car and all the other variables I think I like drifting my f over my old rb powered s14. If I could get the f about 600 lbs lighter that would be sweet, so far my race weight is 3600 which it should be dropping a little more here soon.

You bought your OS Giken off of CL member mikellucci, correct? If so, your 2-way LSD was a JDM unit that was specially built and used by a Formula D team. The internals contain the original version Super Lock disks and it is tuned to be more on the aggressive side (unless you did additional modifications to the unit before you installed it). :driving:

You are correct, the thing holds power without a single hickup! Even with 275's @ 80+% tread hankook evo v12's, they keep goin well into 3rd then start gripping

That's how I put it back. Definitely a lot easier. Probably the most important thing is to be sure you have the seals. The likelihood of getting the diff out without seal damage is not in your favor.

Thank you guys for the contributions!

lobuxracer- Thank you for taking the time to explain the installation process as well. I am thrilled to hear such positive reviews. This isn't an inexpensive modification but it's one that seems to entirely change the characteristics/dynamics of the car for the better. I can't wait to get mine in!

-Matt M.

What are peoples thoughts on a core exchange program if we were to host another group buy sometime in the future? Would that make it more convenient or would you prefer to figure out the instal on your own using your existing rear end?

-Matt M.

I believe figs was going about that idea already, for some it would be good but for the mechanically inclined it would be more downtime.

man shipping a diff...

Have to looking figs diff bushings though