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Revision as of 05:19, 5 November 2012

What Diff and LSD should I use? The stock differential is a very lightweight yet hardy unit behind the small-bore 1200cc engine. However, there are three big reasons people swap differentials into their 1200:

To handle increase torque of a larger engine. The stock unit won't handle well the torque even from an A14 engine.
To gain access to available Limited Slip units. LSD for the stock differential is now quite rare and expensive.
To get rear disc brakes.

Definitions

Differential: The word "differential" refers to:

The small gears in the rear end that control the left-to-right wheel speeds
By popular usage it also refers to either:
- the center gear assembly (pumpkin), including Ring and Pinion and the carrier these bolt to, or
- the entire axle assembly including the housing, gears, axles etc.

Ring and Pinion (R&P) are the large final-drive gears e.g. the "ratio" gears. Known as "Crown Wheel and Pinion" (CWP) in British English.

Spider gears: The other smaller side gears are known as the "spider gears". These are the ones that actually allow a differential speed.

LSD: Limited-slip differential. Most designs use a spring-loaded clutch to prevent one wheel from spinning by itself. Instead, both will spin.

Strength of Differential -- Torque Rating

diff	inches	max. torque capacity
H145	5.71	~100 lb. ft.
H150	5.91	~125 lb. ft.
H165	6.50	~225 lb. ft.
H190	7.49	~285 lb. ft.
R200	7.88	~300 lb. ft.
Ford 8	8.00	~325 lb. ft.
Ford 8.8	8.80	~500 lb. ft.
Ford 9	9.00	~600 lb. ft.

Horsepower is irrelevent for the differential. What matters is the torque:

Engine Torque x gearbox multiplication = twisting force applied to differential

For example:

A 400HP engine with 275 lb ft torque could get by with a much smaller diff than a blown 400HP engine with 500 lb ft torque. Yet both are 400 horsepower. Why does the second engine need a differential that's twice as strong? Because torque matters, HP is not directly related to the strength needed.
A 'built' 125 hp A12 will versus a stock 125 hp 3-liter V6. You need a bigger diff for the latter since it has more torque.
Lower first-gears in the transmission mean more torque gets to the differential. For example, the stock B110 4-speed first gear (3.757) will multiply torque more than the B310 5-speed first gear (3.513 in the 60a transmission).

The Datsun 1200's H145 differential is only safe for as much torque as an A12 puts out, or maybe as much as 100 lb. ft. of torque.

Datsun used the larger H150 for all A14-powered cars, this was good for maybe 125 lb. ft. of torque. The much larger H165 was good for maybe 225 lb. ft. of torque. Finally, the H190 was the big gun (approx. 7 1/2 inch ring gear) and good for maybe 285 lb. ft. of torque.

Stock Datsun 1200 Rear Axle

Coupes, Wagons and Sedan use the small H145 differential. 1975 and up Datsun 1200 Trucks use the stronger H165 differential.

Car Rear Axle

The stock rear-end assembly works great for the A12 or the A14 engine. This is the H145 (145mm diameter ring gear). The diff is open (non-limited-slip) and the diff assembly unbolts from the front of the axle assembly (like Ford 9", but much smaller). All 1200's (except newer utes) had the H145. Sedan coupe and Wagon had a 3.900 as standard and the Wagons optionally had a 4.11 ratio. The 4.11 ratio diff, when used in Wagons and [as standard] in vans have alloy center.

Datsun Competition (later Nismo) used to sell various ratios: 3.9, 4.111, 4.375, 4.625

LSD (Limited-Slip Differential) units were also available from Datsun Competition. Axle baffles and Oil Coolers were available from Nissan Competition Good for maybe 100 lb. ft. of torque

Datsun 1200 rear axle assembly width is 1305 mm drum to drum.

A15 Diffs If you have swapped an A15 into your 1200, the stock H145 differential isn't strong enough except maybe for use with an automatic transmission. Instead, use an H150 (as fitted to B210s and B310s) or larger differential.

B120 Early Truck

1971-1973 1200 trucks used the same H145 design as the sedan/coupe/wagon. Slight differences between all models.

B120 Late Truck Rear Axle

Newer Ute Differential Newer 1200 Utes (1974 and up) have a much bigger and stronger diff, the H165 (165mm diameter ring gear). This has stronger axles too.

H165

Good for maybe 225 lb. ft. of torque ??? Axle baffles and Oil Coolers were available from Nissan Competition There is one LSD for Type I, and another for Type II

Easy Swaps

B110/B120 axle

Coupe into Sedan into Wagon into Ute: All B110/B120 H145 rear-axle assemblies (housing, etc) generally interchange but may be small difference in the brake line routing, handbrake cable location etc. Also use the shock-mounting plates from the right vehicle:

1200 Shock Absorbers

TIP: Wagons had a alloy carrier.

B10

Use a B10 alloy diff to save a few pounds.

Size of B10 axle:

1240 mm drum to drum +- 2mm
910 mm distance between the leaf mounts, centre to centre
65 mm wide leaf mount plates

banjo housing (no backing plates,axles or drums)

B10: 1120 mm
B120: 1185 mm (H165, same as H145 B120/B110 - 65 mm wider than B10)

B210 Japan (Hitachi) axle

The easiest swap is to get the entire rear-axle assembly from a 1975 or newer B210 with A14 (140Y) -- this is the H150 (150mm diameter ring gear). The main spring is 55mm longer, but the others can be used on the 1200. See Bolts right in!

Japan diff

NOTE: The 1974 B210 uses an H145, although the housing is the new stronger design. H145 can be distinguished by studs, whereas H150 uses bolts to fasten the diff to the case.

B210s have a strong axle housing (axles tubes are larger, to 2.2 inch up from 2.0 inch, so U-bolts are different). The B210s use an isolation clamp (the axle tube is rubber mounted), and so the mounting pad is wider. You will need the clamps, u-bolts and shock mounts to do a swap. The housing also user larger ball 72x32x19 bearings (up from 62x32x16) with both inside and outside seals. The B110 only had one seal.

Because the H150 is longer, the driveshaft is shortened by 7mm. The housing face is 2mm toward front of car (diff gear is 5mm larger)

Datsun Competition (later Nismo) used to sell various ratios: 3.545, 3.7, 3.9, 4.111 for the H150.

Whilst NISMO produced H150 LSDs (Limited-Slip Differential), Axles baffles and Oil Coolers were not available from Nissan for the H150.

Good for maybe 125 lb. ft. of torque

You can also just put the H150 gear assembly in the stock H145 axle housing. You just need a 2mm spacer:

Pitroad Spacer
Use a B310 propeller shaft with H150 diff in B110.

B310 Rear Axle

The axle assembly from a B310 (Datsun 210/Sunny) uses the H150 differential. Although the H150 is stronger than the H145, you can just put the H150 into the Datsun 1200 rear axle assembly.

All B310 axles are about 2" wider. So different offset wheels are need OR overfender flares.

Driveshaft length for H145 will be different due to the longer nose of the H150

VB310 square-back wagon (van) uses leaf springs and so can be easily fitted.

Most B310 uses coil springs so it's not a good choice (need modifications). It's also 4 link, so you have to do some significant mods to mount it to the chassis. This involves grinding off the existing multiple brackets and welding on a leaf spring perch. Note that the B110 perches are for a smaller-diameter axle tube and so will not fit.

H145 leaf-spring axle vs B310 H150 coil-spring axle

A10 Wagon

1978-1981 Datsun A10 (Violet/510/Stanza) is same width and flange as B310 but is an H165 unit with 9" drum brakes.

Leaf spring pads are 1000 mm center to center
between outer edge of leaf and backing plate: 100 mm
Backing plate to outer face of drum: 65 mm
overall width drum to drum: 1000 + 65 + 65 + 60 leaf width = 1190 cm

B210 Borg Warner Axle

Australian 120Y 4-dr Sedans from July 1976 were locally assembled and used a Borg Warner rear axle assembly. (BW model 68). All were 3.889 ratio. The BW rear ends are pretty strong - meant to be stronger than H165. The BW68 is the same width as a 1200 H145 diff, but have a different input flange, so you will also need the matching 120Y-BW tailshaft. This is the same type of differential in the early Corollas.

BW - removable back cover

Japan - welded back cover

For more details, see main article: Borg Warner Differential

Truck

B120 Ute, B140 & B122 Sunny Truck: The next best swap (at least in countries that got 1200 utes) is to get a 1200 ute H165 assembly, although it may cost a bit if you can find one.

In North America, Nissan Motorsports used to sell the empty axle housing, axles and other parts. rear disc brakes are available for this axle housing.

The 1200 ute uses the H165 differential, which is strong enough for a stock CA18DET engine. It bolts right into a coupe or sedan, with this exception

handbrake adapter fits in a slightly different in position
make sure you get the ute rear brake fluid splitter
the driveshaft is 25mm longer (than a B110 shaft) and has a different yoke

discussion: ute difference and ute history

Toyota

Corolla KE25 or KE30 will increase the track about 3", but is reportedly a bolt in.

An option for the Aussies out there is the Australian Toyota Corolla diff. KE25 and KE30 models used the same Borg Warner diff as the 120Y, but with longer axles & tubes. Approx 3" wider in total. this is useful if you have Stanza or similar front brakes, as those struts increase track by about the same amount. So you can use the same offset (fwd) wheels front and rear without looking kinda silly and undertyred at the back if you know what I mean. Using rwd offsets will require a little gaurd work depending on the width and tyre size used. The biggest reason for using the Corolla Borg Warner is the available ratios - 3.89 (manual), 4.1 or 4.3 (auto). A tag on the rear cover has the ratio stamped on it. The Corolla diffs have a different input flange, so you need a 120Y BorgWarner flange which is interchangeable with the Corolla's. You also need a 120Y Borg Warner tailshaft (for the matching flange)
[Thanks L18_B110 for this info]

Toyota Axle Codes
S series 6.38" (126mm) ring gear, Corolla, Starlet
T series 6.7" (170mm) ring gear, Corolla, Cressida, Corolla
F series 7.5" (190mm) ring gear, Supra, Cressida, Truck, Celica

Look on underbonnet ID plate

S292: 4.10
S314: 3.91

T282 = 4.10
T283 = 4.30 LSD
T284 = LSD

F462 = 2.92
F392 = 3.15
F012 = 3.30
F382 = 3.41
F372 = 3.58
F302 = 3.73
F312 or F072 = 3.90/3.91
F082 = 4.11
F282 = 4.30

Other Strong Diffs and Choices

Rear-axle assemblies from many different cars be be swapped in the 1200 with minor or major modifications. Advantages are strength, LSD and gear ratio choices. Oh, and if you do the work yourself, swapping in a unit could be cheaper than buying just a new ring & pinion.

Near Bolt-Ins

Non-narrowed rears (with possibly the assembly a little wider) will probably require moving/changing the leaf pads and minor fabrication of brake line connections and driveline flange.

Some reported units suitable for Datsun 1200 are:

1967 411 with alloy carrier (1160 mm)
Ford Falcon ute complete rear which gave you LSD, a live rear, and discs
- Which Falcon model?
Datsun 620 (pickup) front axle assembly with LSD
510, 610,710 station wagon (Davo_1200's 1200 used this diff).

Note that 510 sedans use IRS, a very long-snouted Subaru diff and LSD centre will fit found here in the US on the XT models. It is an 3.70:1 R160 by Fuji Heavy Industries (Subaru) and is the same as the OEM diff in the datsun 510 (1600) also made by Fuji. See R160 Swap.

US Postal Service Jeep (8 3/4" Chevy rear end with 4.11 gears)

Shortened

Just about any rear axle assembly can be narrowed to fit a 1200, with the right spring perches welded on. For example:

Custom-built Ford 9" (kits are about $500-$700 USD from Currie Enterprises or Moser Engineering - includes housing and two axles, you add brakes and center section from any old Ford sedan)
Toyota Hilux Pickup (6-bolt wheels on 4wd)(5 bolt wheels on 2wd, 4 1/2"pcd same as ford)
1960s Ford Falcon six-cylinder
- Falcon XK width: 1450 mm drum-to-drum
Nissan Bluebird TRX
Skyline Borg Warner LSD
Datsun 520 pickup/ute with H190 diff
H190 from Series 1 & 2 Bluebird wagons that came with the 4 speed trans

H190 info and discussion

Width unknown, but these solid axles have the H165 center:
S110 Sylvia (1980-1984 200SX) 82s and 83s had optional disk brakes
S10 Sylvia (200SX, note 85-up S12 uses H190, R190 or R200 diff).
reference: site
For more information on vehicles with H190, see H190

Mitsubishi Scorpion diff

Differential Gear Ratios

See main articles:

H145 from 3.70 to 4.375
H150 from 3.545 to 4.11, LSD not available
H165 from 3.545 to 4.875
H190 from 3.364 to 5.874

How to Identify Datsun Diffs

Here are some features to note to tell the difference:

does center section bolt in?
count bolt holes
Measure distance across

H145 vs H165 size comparison

Does center bolt in, or fit onto studs with nuts?

No back cover

Round or rectangular flange?

To check a Vanette diff,count the bolts holding the housing to the centre. if it's got 8, it's a H165, & the motor will be a a12. If however it's got 10, it's a H190 & the motor should be an a15. discussion: Vanette diff

H145 or H165?

H190 versus H165

H190
Axle comparison: H190 versus H165

H190 was used in most of the Datsun pickups, the 1960's Datsun Roadsters and other Datsuns.

To install a 4.375, 4.625 or 5.125 ring and pinion into a third member equipped with a 3.700, 3.889 or 4.111 ring and pinion a 4.0mm/.157" ring gear spacer must be fabricated. Due to a smaller pinion shaft, the 4.875 and 5.874 ring an [sic] and pinion sets are interchangeable, but cannot be installed into third members equipped with other ratios. Nissan Competition part catalog, 1984 edition pg 58

Datsun Competition used to sell various ratios: 3.36, 3.545, 3.7, 3.9, 4.111, 4.375, 4.625, 4.875, 5.143, 5.429.
There is one LSD for ratios up to 4.111, and another for the larger ratios
Axle baffles and Oil Coolers were available from Nissan Competition

Alloy Carrier

3486 3487

H190 vs H165

R160, R180 and R190 These were IRS (Independent Rear Suspension) differentials with long snouts. Used in the Datsun 510, 610 and other IRS Datsuns as well as most Subarus. The R180 was used in the front axle of Datsun 4x4 trucks (720, etc).

R31 Skyline Diff

Propeller Shafts

When swapping rear axle assemblies, the rule of thumb is:

get the matching shaft with the diff

In general, all B110, B210 and B310 driveshafts are the same (or close to same) overall length, but the ends differ:

Auto vs. Manual
Japan diff vs Borg Warner diff
H145 vs H150 vs H165 diff
Late ute vs Early ute

Coupe, Truck, Wagon and Sedan diffs are the same.

For more details on swapping and interchange of shafts, see Propeller Shaft Swaps.

Limited-Slip and Locking Differentials

A Limited Slip Differential (LSD) prevents one of the rear wheels slipping, as normally occurs with a regular diff.

See main article: LSD

Swap Consideration

The first rule is: There are no bolt-in swaps.

Considerations include:

Propeller Shaft (tailshaft/Driveshaft)
Strength vs Weight
Width
Mounting brackets
Brake hoses & lines
Emergency (hand) brake cables
Wheel bolt pattern
Brake type & size

All the swaps proclaimed "bolt-in" require at the very least a change in the brake line and/or cables.

The only true bolt-ins are replacements. For example, replacing a broken 1200 sedan rear axle assembly with a good sedan rear axle assembly. Even going from coupe to sedan require some changes.

Miscellaneous

race car mounting

4-link

See also:

Brakes: for information on brakes, see tech section article Suspension & Brakes

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Rear Axle Swaps