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A little about LSD's

by Adrian Teo (2/25/99)
There are LSD's and there are LSD's.

The are primaritly a few types.

1. Helical gear type torque biasing LSD

This LSD uses the nature of worm/helical gears to transfer torque in
one direction and not in the other. This includes all the Honda and
Quaife LSD's. These LSD's are sufficient for light duty racing and are
known to have a tendency to break, due to the nature of the design.
This usually occurs when one wheel is unloaded (like in the air) and
then loaded very suddenly.

The amount of torque bias is set by the cutting angle of the helical

2. Clutch Type/Plate Type LSD

These LSD's use friction plates which compress against each other to
lock the differential. Clutch type LSD's are VERY beefy and stand to a
massive amount of torture. Also, these are adjustable in the sense
that they can be shimmed to give different torque bias
characteristics. These, however have to be rebuilt once the plates
lose their frictional properties.

Popular brands for this category are: KAAZ/Spoon/ATR, Cusco, Mugen.

3. Viscous type LSD's

These are similar to the viscous LSD's used in some AWD vehicles. The
way these work is that a special fluid is used in the differential
which THICKENS when excessive slip is induced. Stators and impellors
in the diff make this even more efficient. Although there is a slight
delay in locking of the differential, they work very well and last a
long time.

Honda has optional factory viscous LSD's available in some of their
earlier cars (EF8/9).

4. Ratchet type LSD's

These are the most extreme of the LSD. These come on and off, with no
in between settings. These include the detroit locker types which are
used in RWD race cars (NASCAR) and the AP-Lockheed Suretrac ($2000+)
used on FIA homologated Touring cars.

My personal choice will be the clutch type LSD due to the nature of
racing I do...

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