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      02-22-2013, 08:09 PM   #80
Evo Junkie

Drives: E91 325D M-Sport, Evo 6
Join Date: Dec 2009
Location: Bedford, UK

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Originally Posted by Killerfish2012 View Post
OS Giken is mainly used in FWD cars in Japan. Take a look at their website. Lock up is ok for FWD cars, but for RWD cars, you don't want lock up while you are in mid corner.
I donít need to look at a video or website to understand how a plated differential works.

I strip, setup and rebuild plated diffs every week, for all sorts of cars and applications, tailoring ramp angle, preload and plate configuration depending on car and application.

OS Giken, Cusco, Kazz etc, it doesnít matter, they all work with the same principle and are used in front wheel drive, 4 wheel drive and rear wheel drive for the same reason, obtaining maximum traction and characteristics dependant on setup.

I really donít think you fully understand how they work and what they do, if you make a statement ĎLock up is ok for FWD cars, but for RWD cars, you don't want lock up while you are in mid cornerí

With a 1.5 way differential (which is what you want for a normal track/racecar) when accelerating through a corner you want and need maximum lock-up for the best traction available. Maximum lock-up doesnít mean 100% lock-up, it means the maximum available depending on ramp angle, plate number and configuration. This is setup by the installer depending on application and driver preference. Mid-corner on trailing throttle, you will not have lock-up, unless preload is very high, and for a tarmac car this should be set to a low figure. Basically you want lock-up under acceleration and a small amount of lock-up under decal to help stabilise the rear end.

I think you are confusing a 4WD off road vehicle which has 'locking diffs' which gives you 100% lock-up across the axle. A plated LSD such as the OS, does not give 100% lock-up!! You could have 40% lock-up if configured in a certain way.

Originally Posted by Killerfish2012 View Post
I stand partially corrected, as should you. For a 1, 1.5, or 2 way diff, the issue is behavior on Load, No load, and overrun situations. I confused overrun with zero, or no load. on overrun, such as suddenly lifting off throttle during corner entry a 1.5 way does have more limiting torque, but when you power out of the corner the 2 way has more limiting torque. As much limiting torque in reverse as it does in the forward direction. % lock up has nothing to do with this.
What are you talking about??

Lock-up has everything to do with it, that is exactly how a plated LSD works.

Friction discs and plates are pressed together (locking them together) which basically transfers torque away from the spinning wheel to the wheel with more traction. Itís a totally mechanical process, very simple in design and application and physically locks the left and right wheels together, up to a maximum percentage lock-up depending on the amount of alternating plates (ie total friction surface area) and ramp angle (effective leverage pressing the plates together)

A 1.5 way is designated as such because it has maximum lock-up under acceleration, depending on ramp angle, number of plates and plate configuration, i.e. 65% and partial lock-up on decel i.e. 20%

A 2 way will have exactly the same maximum lock-up under accel as a 1.5 way if the set-up is the same, i.e. 65%, but will also then have 65% lock-up on decel.

Originally Posted by Killerfish2012 View Post
Functionally the OS is the most complicated. % lock up has to be determined and set up before manufacture. In units where % lock up is adjustable post manufacturing, the process of changing lock up percentage is too complicated, and time consuming. Then again, there is the issue of lock up being undesirable in RWD cars, during cornering
Changing a plated diffís maximum lock-up is very easy to do, itís not complicated, it is time consuming though, but once setup in the sweet spot, the benefits of improved traction out way a helical diff. The problem is, 99.9% of people donít know how to set them up for maximum performance depending on driver preference. All plated LSDís can be adjusted in regards to maximum lock-up by adjusting plate configuration.

If lock-up was undesirable in a RWD car, as you have mentioned twice now, then running an open diff would be faster!!

Originally Posted by Killerfish2012 View Post
My summation is: Quaife for the streets, OS Giken for street/some track, Wavetrac for ALL driving situations.
Quaife for the street, Wavetrac for street/track, OS Giken for hardcore street/track (best traction/adjustablility)