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Revision as of 23:09, 5 November 2012

A Limited Slip Differential (LSD) prevents one of the rear wheels slipping. A differential is inside the final drive (ring & pinion) gears and allows the left and right wheels to turn at different speeds. This is important of course for going around corners. The downside is that if one wheel is on slippery ground (ice, gravel, mud, etc) the car doesn't go at all, as one wheel is turning but slipping and the other not turning at all. Hence the usefulness of LSD or locking diffentials, which are typically used on high-performance cars. Locking is typically used on off-road vehicles, LSD for road vehicles, including racecars. Most productions cars did not and still do not come equipped with LSD. Less expensive cars (like the 1200) did not even have it as an option, however Datsun Competition sold an LSD that fit Datsun 1200.

Overview

Limited Slip Differentials come in many different types, but the main thing is they limit wheelspin. This is useful in racing and in low-traction surfaces (rain, snow, etc). Or for maximum accleration at full throttle. Different types of LSD are cone-clutch, spring-loaded, clutch-pack, hydrodynamic (viscous), etc. Some trademarks are "Posi-Traction" (GM), "Traction-Lok" (Ford), Torsen (Bosch).

A differential is inside the "final drive" (ring & pinion) gears and allows the left and right wheels to turn at different speeds. This is important of course for going around corners. The downside is that if one wheel is on slippery ground (ice, gravel, mud, etc) the car doesn't go at all, as one wheel is turning but slipping and the other not turning at all. Hence the usefulness of LSD or locking diffentials, which are typically used on high-performance cars. Locking is typically used on off-road vehicles, LSD for road vehicles, including racecars.

LSD

Nissan Performance racing parts used to sell a clutch-pack type LSD for the H145, H150 and H165. These parts are NLA, however may be found occasionally in specialty shops or on eBay.

H145

Nissan Performance racing parts used to sell an LSD for the 1200.
H145 LSD (NLA)

Nissan Part Number: 38420-H1020 L/S ASSY H145 (TO 8/74)

Parts

From the 1984 Nissan Competition Catalog:

H145A LIMITED-SLIP ASSY (TO 8/74)

38420-H1020 L/S ASSY
38423-H0120 SIDE GEAR (2)
38424-H0120 THRUST WASHER (1.0MM) (2)
38424-H0120 THRUST WASHER (1.25MM) (2)
38425-H0120 PINION (4)
38427-H0120 PINION MATE SHAFT
38429-H0120 PINION SHAFT
38430-H0120 DISTANCE PIECE
38431-H0120 PRESSURE RING (2)
38437-H0120 CENTER RING
38432-H0120 FRICTION PLATE (1.5MM) (2)
38432-H0121 FRICTION PLATE (1.45MM) (2)
38432-H0121 FRICTION PLATE (1.55MM) (2)
38433-H0120 FRICTION DISC (1.5MM) (2)
38434-H0120 SPRING DISC (1.5MM) (2)
38435-H0120 SPRING PLATE (1.5MM) (2)
08320-61000 SCREW (4)

H150

Nissan Performance racing parts used to sell an LSD for the B210, part number 38420-RS210.

Aftermarket H150 LSD

H165

AE86 Swap

Re-drill H165 housing for AE86 centre section

Use driveshaft adapter ring & machine AE86 companion to match. That's it.

propeller shaft pitch adapter
Datsun 38mm center hole on one side
AE86 46mm(?) spigot on the other
use B120 driveshaft
12cm(?) thick 
45 x 54 mm H165 pattern (drill AE86 flange to match)

Use early T-series diff

AE86 DX & SR-5 
6.38 ring gear
S292: 4.10 2-pinion (Automatic) USA
S314: 3.91 4-pinion (5-speed) USA

AE86 GT-S
6.7" ring gear
T282: Open 
T283: optional LSD (USA Only) 4.30 2-pinion
T234: optional LSD

tap 10 new holes

Non-threaded Adapter

Modified Flange Type

Drill 2nd pattern on AE86 flange.

AE86 flange is 78mm pcd (~55mm square). Drilled for smaller H165 pattern:

Bolt-Through Type

Requires more complicated spacer machining

Threaded Adapter

AE86 side, 78mm PCD, spigot hole ~46mm

Sunny Truck tailshaft side, 45 x 54 mm pattern, spigot ~38mm O.D.

Pitroad/TRD

Pitroad sells a brand new LSD for the H165B axle (1985-up Sunny Truck) for about $1200 USD. It is from TRD (Toyota Racing Development) and is a bolt in when using the AE86 ring gear bolts. Pitroad H165 LSD or TRD

You can also buy the AE86 LSD (PN 41301-TA005) direct from TRD, be aware however that this is untested, and probably won't fit most H165 carriers. About $850 USD

TRD Sales NZ

CA200

Nissan CA200 axle, salisbury type, is an R200 gearset in live axle form.

AC brand for 29 Spline C200 Axle
$580 USD

Will R200 LSD and VLSD fit into CA200?

Phantom Grip

Phantom Grip is an inexpensive LSD, which is spring-loaded LSD instead of the conventional clutch-pack LSD.

See main article: Phantom Grip

Depending on how you drive a phantom can last for a long time, to my memory mic had it in a rally car for 2 years then I had it in a road car for bout the same and at the end it started slipping but just needed to be re shimmed. supafatto

Torsen Diff

Torsen differential works on a gearing principal and has no friction plates:

Superior limited slip action, unless one wheel loses 100% traction
Superb for street suspension or soft racing suspension, where there is little chance of a wheel coming off the ground
If a wheel comes off the ground it stops working

For more information, see [1]LSD vs Quaife ATB]

1.5-way vs 2-way

Nismo sold both 1.5 way and 2 way LSDs. For street use, a 1.5 way is the best way to go.

The 1.5 way is a common LSD for racing as it does not give understeer on de-acceleration through cornering but gives a hard clamping force under hard acceleration, when normally you would break traction.

2-way generally causes understeer and is somewhat like a locked spool. It struggles to turn around in the street, quite similar to a welded diff, with tyres chirping and wheel spin required to get it to turn around.

Factory

Japan

38420-N9000 4-pinion
* 720 8004-8303 4-pinion 
* S110 8204- HE41.FJ20

38420-41W00 2-pinion
* 720 8004-8303 2-pinion
* 720 8303-

North America

D21 C200.Z24I.OP
D21 H233B.(VG30I+VG30E).OP
D21U
R50
S13 R200 VLSD 4WS 1990-
S14 R200 VLSD OP.
WD21
WD22
Z31 R200 VLSD, LSD

Labels:
* 'LSD'
* 'USE ONLY LSD OIL'
* 'VISCOUS LSD'

38303-10V00 LABEL-DIFFERENTIAL 'VISCOUS LSD'
* S13 1991- R200.4WS

38303-10V01 LABEL-DIFFERENTIAL 'LSD'
* D21 
* WD21 0889-0292 VG30E.OP

38303-10V02 LABEL-DIFFERENTIAL 'USE ONLY LSD OIL'
* D21
* D21U
* R50
* WD21 H233B+C200
* WD22 VG33E.SE+VG33ER+VG33E.OP

D21U
38420N DIFFERENTIAL ASSY-MECHANICAL LSD
38420-G7020 
38420-S9200
38420-T6070 <> 38420-T6073 [C200]

Z31 [R200]
38421S CASE SET-DIFFERENTIAL
38410-40F70 0188 VG30T.SS.MT.F5 $558 USD
* VISCOUS LSD 4-pinion RC37
38421-71S26 0487-0887 VG30T $915 USD
            0887-     VG30T.(GL+GLL)
* LSD 4-pinion RC37

Locking Diffs

A "locking" differential is another animal. When locked there is no slip -- not just limited slip, but none at all. When unlocked, it's the same as an open differential. These are used for racing or for seriously slow off-road work.

Locked diffs are also useful for circuit racing. Many race cars from all sorts of categories use locked diffs. The understeer that is apparent on street/drag cars with locked diffs can easily be eliminated with proper (race) suspension geometry. These settings (camber, castor, and toe) will not be practical for street use though.
L18_B110

There are different types of locking diffs.

Air Locker

The ARB air-locker is popular with Jeeps and other off-roaders. When the dash-mounted switch is flipped, air pressure locks the diff gears together

Detroit Lockr

The "Detroit Locker" was used by some high-performance Ford vehicles in the 60s and 70s. The Locker may be the only modern road-going locking differential, as it can automatically lock and unlock. It is sort of a hybrid between an LSD and a Locker.

Spools

For drag racing, the spider gears can be replaced with a sold unit so that both axles are always locked together. This is called a "spool"

spool (right center)

Welded Diff

The "poor man's" locking diff is to have the spider gears welded together so that it works like a spool, but is obviously cheaper. The danger is of a bad weld and having it explode on the race track.

Using a spool or welded diff gears on the street is illegal in most countries, and can be dangerous, especially in the wet. The danger is of spinning out as the wheels do not turn independently, but the inside wheel is forced along the same as the outer.

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LSD