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My Lexus TRD IS350 w/ OS Giken Super Lock Traction Control Differential (TCD) LSD
“The OS Giken is a cheat code. Absolutely unreal what you can do with a rear end with it.”
When I began my research on other performance vehicles equipped with an OS Giken Super Lock LSD, I would constantly read quotes such as the above on how much of a significant difference in handling and reduced lap times the OS Giken LSD made when compared to OEM LSDs or other aftermarket LSDs.
My goal with the IS350 was to make it a Lexus version of the BMW E46 M3. While on paper, the skidpad and slalom numbers of an IS equipped with the TRD-tuned F-Sport accessories package (shocks/springs/sway-bars/chassis brace) was similar to the e46 M3 but one significant component that the IS lacked was a mechanical LSD. This became very apparent to me when I took the IS350 to an autocross and noticed how easily the inside wheel would spin around each tight corner thanks to the open differential. This was the catalyst that made me research for months in early 2013 on what options I had regarding limited slip differentials and whether or not it was worth the cost. At the end of my research, I decided to take the plunge and go for it.
If you’re not familiar with the different types of LSDs available and how the OS Giken clutch differential compares to the competition, the diagram below provides a good synopsis (and the general consensus of opinions I’ve read from competitive racers):
The particular OS Giken unit I purchased was the next-generation Super Lock LSD known as the Super Lock TCD (Traction Control Differential). There are special grooves on the clutch disks that allow the TCD to progressively lock even smoother than the original Super Lock LSD which results in even better performance and quieter/cooler operation (The IS350 version comes with the maximum of 28 clutch disks).
I had my OS Giken Super Lock TCD LSD installed in May at Titan Motorsports. They did a phenomenal job at making sure everything was installed carefully as I wanted to ensure long-term reliability. They did recommend that I get the differential case modified with a pair of solid diff ear mounts to prevent potential wheel hop as the TCD would likely cause a lot of stress to the drivetrain with its potential grip.
I’ve had the TCD for almost 3 months now and the amount of grip the rear tires now have is unbelievable! I’ve yet to break traction on hard corners that I used to when the IS was with the open differential. The outside rear tire would pivot the IS seamlessly around every corner and there are no understeering issues during low-speed maneuvering. I plan on keeping my IS350 for a very long time so while the overall initial cost of the unit and install was pricey, I feel it is the best and most fun mod I’ve ever done, even more so than going APU with a larger turbo on my old MKIV Toyota Supra! Overall, I believe I’ve surpassed my initial goal on building a Lexus version of the BMW e46 M3 and with the OS Giken Super Lock TCD, I believe I’ve built a car that can handle as well as most cars under $100k (IMHO). Hopefully I’ll have a chance to participate in another autocross event this year and truly put the TCD to its limits as I don’t want to risk it on the streets. Every minute of seat time in the car is bliss and you truly can’t put a price on that.
Below are some pics of my OS Giken equipped IS350:
Great info! Although I still have to come to my conclusion if doing this will be right for me (as I have contemplated this from time to time) I think this is a great addition to the forum for other members to have a first-hand experience on this product. Thanks!
Great info! Although I still have to come to my conclusion if doing this will be right for me (as I have contemplated this from time to time) I think this is a great addition to the forum for other members to have a first-hand experience on this product. Thanks!
I too had contemplated this mod for quite a while and I wasn't truly serious about it until earlier this year when I thought about how much longer do I plan on keeping this car. My rational for investing in this mod was more of a "what if Lexus had built a track-tuned special edition TRD IS350" scenario. With the 3rd Generation IS already on the roads and Lexus focusing more on the "fun-to-drive" aspect, I thought to myself, "I can do better" and decided to one up Lexus' efforts, lol. I figure that if I plan on keeping the car for quite a while, the cost of the LSD mod would simply blend in with the rest of the Total Ownership Cost depending if I keep it for another 5-10+ years. I think of it as a check-in-the-box option like paying for the Navigation/Mark Levinson or luxury package. Plus, you get a really cool spooling sound coming from the differential every time you press on the gas.
Originally Posted by Gville350
Thanks bro for posting this up! It'll help someone down the road.
That was definitely the intent of this thread. I'm not sure how many IS350 owners have a mechanical LSD, let alone an OS Giken clutch-type. From talking to IS-F owners on their sub-forum, I believe only 1 or 2 IS-F owners have a Super Lock LSD on their car. If someone else decides to take the plunge, this thread will always be here for future questions.
Originally Posted by viprtwo
I'm assuming this means u drive your car with TC and VDM off?
Yes and no. Back when I was on open differential, I pretty much had both TC and VSC off whenever the road conditions were optimal. VDIM on the 2IS has always been a bane to getting the most out of the vehicle. The 4GS and the 3IS should have a much more lenient VDIM setting (Sport +) but we're stuck with a fairly aggressive VDIM.
Surprisingly,since installing the Super Lock TCD, I've noticed that the VDIM actually complements the differential as both rear tires are rotating at the same speed almost all the time. When I'm feeling adventurous and there is no traffic anywhere, I'll test out the rear wheel grip with the TC and VSC off. As mentioned before, I've yet to fully reach the grip limit on the streets and I plan on keeping it that way as recovery from a slide will very likely be more abrupt and dangerous. So I'm pretty much 50/50 on when I leave VDIM on as it lets me have fun on the road while keeping me in check. When I get back on the track, I definitely plan on turning off TC and VSC.
Originally Posted by badx33
can you tell us how much was the unit and install?
Total cost for the unit and labor will fall between $4k to $4.5k. The OS Giken Super Lock TCD goes for about $2800. If you look online, you'll sometimes see the lower priced NEO version for sale (which is the 2nd generation of the Super Lock LSD family) but OS Giken no longer will supply them due to issues with progressive locking consistency on the track. The feedback received from race teams regarding the Neo model is what lead to the development of the TCD version which brings back the progressive lock predictability that the Neo model lacked.
Labor is about 8 hours and if you decide to get the solid differential ear mounts to eliminate potential wheel hop, that's another hour or two of labor plus the part.
After installation, you need to change the initial differential fluid between 500-1000 miles to get rid of any gunk but after the first fluid change is done, you can change the differential fluids every 30,000-50,000.
Thanks for the write up. I'm on the fence as well.... 5k is a lot to spend, but same as you I plan on being here for a while, so the sooner the better I guess. I too have the F-Sport accessories you list (and a couple more). I wanted to get teh wheels next, but you have me re-thinking that choice.
I'm not sure how many IS350 owners have a mechanical LSD, let alone an OS Giken clutch-type. From talking to IS-F owners on their sub-forum, I believe only 1 or 2 IS-F owners have a Super Lock LSD on their car. If someone else decides to take the plunge, this thread will always be here for future questions.
There is one IS350 Quaife owner on here I've spoken with AND one member with a '12 IS-F Torsen in his 350. Both love the results.
Do you think I would benefit from the OS Giken upgrade? I have a manual transmission IS250....thanks
You'd definitely benefit with the OS Giken upgrade but I'd probably recommend installing an IS300 Torsen LSD on your IS250 instead (as they can be found for $700-800 bucks). Here's the install thread from Jeff Lange for your reference:
You'd definitely benefit with the OS Giken upgrade but I'd probably recommend installing an IS300 Torsen LSD on your IS250 instead (as they can be found for $700-800 bucks). Here's the install thread from Jeff Lange for your reference:
I've yet to take my car to the drag strip as I'm more of a corner carver type driver.
Looking at the start date of this thread, it made me realize that I've had the OS Giken TCD on my IS350 for close to 3 years. Impressively enough, the comment that I made in 2013 "Every minute of seat time in the car is bliss and you truly can’t put a price on that" still applies to this day.
I've put in nearly 30,000 miles on the differential since it was installed and it has been chatter-free and there has been no degradation in performance on both the track or the streets.
Hard cornering is extremely predictable with the torque smoothly being transferred to the outside rear wheel and my exit speeds are noticeably faster as I can apply the throttle at any point of the turn to pivot the car through a corner. It's a very unique experience!
07-14-13, 07:38 PM
My Lexus TRD IS350 w/ OS Giken Super Lock Traction Control Differential (TCD) LSD
