WATCH: $1500 for a LSD?!?! Why the OS Giken Super Lock Limited Slip Differential is worth it!


We recently installed an OS Giken Super Lock limited slip differential on our Project DC2 Integra! Watch as Mike Kojima explains everything you ever wanted to know about LSD but were afraid to ask! The OS Giken Super Lock 1-way differential completely transformed our Integra, and even at a price point around $1500, it's one of the biggest bang for the buck performance modifications you can do on a front wheel drive car- especially if you take it to the track!


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Tuesday, February 20, 2018 5:01 PM
I really want one of these for my NC but all the adjustable makes me nervous... I mean thats a crap ton of work if my first guess is wrong and I need to pull it out and change stuff... can't decide between this and a Quaife unit
Wednesday, February 21, 2018 8:41 AM
@warmmilk, As mike states in the video, OS diffs typically have a really good setup right out of the box. Unless you make a lot of horsepower or are a really serious autoX or Track car you will most likely not need to make a change. Having the adjustability is really nice to have if you want to make a change.

The difference between a Salisbury diff and a Helical like in the Quaife is quite significant. An open diff will send torque to the wheel with the least amount of traction, a Helical will send torque to the wheel with the most traction and, a Salisbury will send torque to both wheels regardless of where traction is.

Helical diffs are more versatile for most road conditions. Having the front wheels locked with a Salisbury in the rain can be very tricky. However, with a Helical you will still be able to have a fair amount of control.

Helicals typically do not much to any adjustability. A chassis engineer looking to use the diff for chassis setup other than just putting the power down will not have much luck with a Helical. Another thing to take into consideration with a Helical is Hunting. Since a Helical is not able to lock up, it will always be searching for traction. In the event you have full traction on both driven wheels you may feel the diff Hunt(sending power back and forth to each driven wheel). This is felt more in FWD applications.

In racing it is really common to see Salisbury diffs due to their adjustability, ability to lock both wheels together(no torque hunting) and how they can help weight transfer/chassis dynamics.
Mike Kojima
Mike Kojimalink
Wednesday, February 21, 2018 12:30 PM
Helical diffs do not send all the torque to the wheel with the most traction, they have a torque bias which depends a lot on the angle of the teeth in the helix. They act more like an open diff and lose the abilty to distribute torque when one wheel runs away like if a wheel gets airborn or if the chassis setup is weird and a wheel lifts. They also can get weird in the back of high powered cars and cause a difficult to control oscillation. For the most part, I dislike Helical and relegate their use to the front of AWD cars and for FWD cars if you can't get anything else. It's just my preference as a chassis guy, others may have opposing viewpoints.
Wednesday, February 21, 2018 2:30 PM
does OS Giken do any consulting with their sales? recommendations on how to setup the diff for my setup? cause my car has significantly more grip than a stock miata does, and will have 70-100whp more when I'm gonna be upgrading the diff
Thursday, February 22, 2018 9:51 AM
So, I said a "Helical will send torque to the wheel with the most traction". I didn't say "all of the torque". Depending on the torque bias ratio when uneven traction is had the Helical can send more torque to the wheel with the most traction up to some 80-90% in very high biased ratio diffs(TBR@5:1+). We are just agreeing that in motorsports Helical have their place however Salisbury diffs are more desirable due to the adjustability and for how they work over a Helical.

@warmmilk, Yes, They will provide some type of support at the time of sale. Typically they will give you a general direction you will want to go. A lot of things need to be taken into consideration when making diff adjustments. I think you will find that what they recommend will not be too far off from what the diff comes with.
Friday, February 23, 2018 10:05 AM
Warmmilk, yes I believe they do. Send them an email and whatever you need and they'll be able to tune your diff in house.
Tuesday, February 27, 2018 1:48 PM
do you guys still recommend WPCing the clutch disks?
Mike Kojima
Mike Kojimalink
Thursday, March 01, 2018 6:42 PM
it actually works pretty well. I don't think this diff needs it, it is pretty smooth to begin with.
Friday, March 16, 2018 10:17 PM
@warmmilk: I began running an OS Giken in my 2009 NC Miata setup for STR competition in autox in 2012. It was clearly better in putting down power on corner exit and there was no understeer on corner entry. I opted to keep the factory settings after talking with Ken Motonishi about the Bjoin team's tuning of their OS Giken for autox. Ken said that they had changed things many times trying different settings out and ultimately went back to the factory settings as they were the best they had found. I may be selling my OS Giken if the car doesn't sell at the price I want in the next few weeks. Email me if you're interested.
Wednesday, April 11, 2018 9:31 AM
OS Giken diff failed on us, causing major accident

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