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Revision as of 05:57, 15 May 2016

What Diff and LSD should I use? The stock differential is very lightweight yet very reliable 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 reliably handle the torque even from an A14 engine
To obtain commonly available Limited Slip. LSD for the stock differential is now quite rare and expensive
To get rear disc brakes

Terminology

Differential: The word "diff" refers to the small gears in the rear end that control the left-to-right wheel speeds

Album 29522

38100 SET-HYPOID GEAR & PINION

open type with differential gears visible

Datsun 1200 uses H145 type differential

By popular usage "diff" is also used to refer to these parts:
Gear Carrier Assembly ("diff head" or pumpkin or "center section"), including Ring and Pinion and the carrier these bolt to
Album 25280

Or, the entire Rear Axle Assembly including the housing, gears, axles etc.
Album 21319

Axle Housing
Post 461926

Axle aka axle shaft (includes wheel bearing)
Album 3621

Gear Carrier aka "center" (not to be confused with "center section" which is the center with the gears installed)
Album 29523

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.

Album 29524

38100 SET-HYPOID GEAR & PINION

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

Album 29525

38423 SIDE GEARS
38427 PINION SHAFT
38425 PINION GEARS

LSD: Limited-slip differential. Most designs use a spring-loaded clutch to prevent one wheel from spinning by itself. Instead, the LSD resists spinning but when traction is overcome, both wheels will spin.
Album 13712

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.

Engine Swaps

When swapping engines, if the torque of the new engine exceeds 85 ft lbs, the 1200 sedan/coupe/wagon rear axle will need to be swapped for a stronger unit. For best performance and smoothest ride, use the lightest axle assembly which will reliably handle the torque of your chosen engine.

NOTE: Australia-assembled Datsun 1200s which came with Borg-Warner Rear Axles can handle more torque, as can 1200 ute rear axles.

In general, determine how much torque you new engine will output, then choose a Rear Axle that will handle that much torque. See: #Diff Strength

A14

Swap in the H150 Rear Axle from a B210, which was designed for the A14's torque and so will provide factory reliability. See #B210 Japan (Hitachi) axle.

A14 with A14 gearbox (60-series Transmission) has a high first gear, and the 1200 diff can handle it.

A14 with A12 gearbox (56-Series Transmission) has a low first gear, and so will multiply the torque beyond what the H145 can reliably handle.

A15

Swap in an H150 Rear Axle, which was designed to handle increased torque and so will provide factory reliability. See #B210 Japan (Hitachi) axle.

CA18DE

A stock CA18DE makes 117 lb ft torque. The most obvious swap is the #1200 ute axle swap, which can handle far more torque than this. You could swap an H150 diff head into the 1200's rear axle housing (the H150 will handle the torque), but the Ute axles are much stronger.

SR20DET

SR20DET makes 202 to 220 ft lbs of torque from the factory, so you'll need a Rear Axle that can handle it. The H165 can handle this. See #B120 axle swap.

SR20DET modified can easily make 400 ft lbs. For this you'll want a big Rear Axle like the #Ford 8.8 swap or one of the larger #Toyota Hilux rear axles. A popular swap in Australia is the BW78 Rear Axle Swap using the strong AUS-built R31 Skyline unit.

Stock Datsun 1200 Rear Axle

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

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

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 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 diffs 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

B120 Truck (Ute)

1200 Utes (B120) have a much bigger and stronger diff, the H165 (165mm diameter ring gear). This has stronger axles too. It has slight differences in mounting from the car axles.

H165

Good for maybe 225 lb. ft. of torque ???

Axle baffles and Oil Coolers were available from Nissan Competition

Easy Swaps

1200 Axle

B110 Axle

Coupe into Sedan into Wagon: 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.

B120 Axle

1200 ute/pickup (B120) used the H165 Rear Axle. Good for high-torque. With larger axles and axle tubes, it's also good for heavy payloads.

It is very similar to the B110 (coupe/sedan/wagon) rear axle and so bolts right in but has these small differences which mean it's not quite so simple to make it work:

* H165 flange requires a shorter driveshaft
  Use the B120 short wheelbase driveshaft
* Brake hydraulic line is in a different spot
* Handbrake cable attaches differently
* Shocks attach differently

You can also swap the H145 into a ute, which is lighter, thus giving it a smoother ride. Use the Coupe unit along with sedan/coupe leaf-springs.

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, so use the 1200 spring pack. 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 when swapping housing into a 1200, different offset wheels are needed 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 (needs 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

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

120Y 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.

This is the swap of choice for 1200 Sedans, as it already has the correct shock mounts. As usual, obtain the diff assembly along with its matching tailshaft. If using a sedan assembly in a coupe, wagon or ute, some modification is needed -- see 120y borgwarner into a 1200 ute.

BW - removable back cover

For more details, see main article: Borg Warner Differential

H190 320 Truck

1962-1965 320 Datsun Truck came with a very narrow H190. It needs no narrowing (it's already slight narrower than a 1200 axle).

Only needs the usual swap items: custom tailshaft, brake hooksups, leaf spring mounting. And obtain two 6-lug rims.

1200 Ute

B120 Ute, B140 Bakkie & 1200 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 these exceptions:

handbrake adapter fits in a slightly different in position
make sure you get the ute rear brake fluid splitter along with the hard lines attached it the axle housing
the driveshaft is 25mm longer (than a B110 shaft) and has a different yoke. The flange bolt pattern is the same as the H150. So get the driveshaft from the ute. It is a direct bolt-in for a sedan/coupe/wagon fitted with a ute diff.
The leaf spring mounting pads and U-bolts are different, so get those from a ute
The shock mount differs from a sedan. It is same as a 1200 wagon -- similar to a Coupe but with a larger diameter bottom pin.

ute difference

to use your h145 handbrake you'll need to make a bracket that offsets the mounting position on the 165, if you can get both together and look at the back of the diffs where the handbrake connects to you'll see it easy, or cutoff and weld the h145 mount onto the 165 housing

Toyota

Corolla KE30 or KE55 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. KE30 and KE55 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" (162mm) 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 Hitachi diff and and LSD centre will fit found here in the US on the Subaru XT models. It is an 3.70:1 Hitachi R160 and is the same as the OEM diff in the datsun 510 (1600) and also Fuji Heavy Industries' Subaru cars. See R160 Swap.

Ford 9"

Order a custom-width 9" housing and axles from Currie, with leaf spring pads in stock 1200 location. About $1400. Bolts right in after modifying the spring seat plates using 9" u-bolts.

Supply a center pumpkin of your choice and brakes from an old Ford.

Have 9" flange added to custom driveshaft.

Jeep

Postal jeeps -- leaf spring pads wider than CJ

Spring pads will need to be moved outboard to work in Datsuns.

late DJ Dana 35 7.5" 
5-on-4.5
53"?

8.75
early DJ Dana 44 5-on-5.5 wheel bolt pattern
most with LSD and 3.73 gears
axle tubes are 2.75" -get the jeep u-bolts
49" or 50.5" hub-to-hub
27.5" spring pad width (very narrow)
11" brakes

Shortened

A popular choice in Australia is the AUS-built Skyline/Pintara R31 BW78 Rear Axle Swap

Just about any rear axle assembly can be narrowed to fit a 1200 and 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
1960s Ford Falcon six-cylinder
- Falcon XK width: 1450 mm drum-to-drum
Nissan Bluebird TRX
H190 was found in most Datsuns (510, Roadster, 320,520,620, 720, Navara, also available in a lighter (but weaker) alloy version.

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 7.5" diff
Mitsubishi Scorpion 8" diff

Ford 8"

Ford 8" is common and durable.

Ford 8.8

The Ford 8.8 rear axle is a good choice -- it can handle extreme torque, nearly as much as the Ford 9" but considerably lighter. Being cheap and easy to find, along with available LSD makes this a top option.

Axle bolt pattern is 5-on-4.5" (same as Nissan S14 5-bolt or RX-7), and usually comes with 10" drum brakes.

Do the same as mounting any coil spring-fitted rear axle assembly: Cut & grind the 4-link brackets off, then weld leaf-spring perches on. Get the perch to pinion angle exactly same as original 1200 unit.

Narrowing: The axle tubes are held in with a pressed-in plug. Drill the plug out, press the ends off the tube, cut tube to length using cut-off saw for perfect 90-degree straight cut. Align the axle end straight on tube, weld the plug hole, then weld the tube to the end.

Canada or USA Ford Ranger 8.8 can be narrowed at home to fit a Datsun. Housing on one side only needs narrowing, and stock axles can be used, so no need to buy custom axles or shorten any axles. Obtain an additional short-side axle and cut only one side of the axle housing to narrow it. Mazda B4000 and Ford Ranger 4.0 1990-1992 have the shortest 8.8 with 28-spline axles (1993-up are 1.5" wider). 28-spline is used by Mustang V8, so they are strong. Look for door tag AX R6, and confirm with axle tag 3L73 (limited slip). 4x4s have 4.10. It will be 53" after converting to two short axles. Same Diff Widths as 510 or S110. Will fit a 1200 using high-offset wheels.

Toyota Hilux

Hilux trucks & Hiace vans used beefy rear axles assemblies. In general, Hiace rear axles are wider than Hilux. They use either 7.5" or 8.0" diffs. The 8.0 varies in strength, with 4-cylinder getting smaller axles, but V6 models getting tougher 8" diffs and 31-spline axles.

 Wheel PCD
 5-lug: 4.5" (114.3mm), same as Nissan S14
 6-lug: 4.5" same as Nissan Ford, Chevy

See: hilux diff convertion to 1200
     hilux diff
* $800 for the diff cut down and both axle re spline (narrowing)

Rear Axle assembly Widths:
* factory  1200: 1305mm drum-to-drum (1295 flange to flange)
Hilux
* 1972-1978 N20: 1370mm, 5-bolt wheels
* 1978-1983 N30: 1410-1430 mm
* 1983-1988 N50:
* 1988-1997 N80: 1450 mm
Hiace: 1470 mm some years

For ID, check the build plate, located in the engine compartment (Hilux) or by the front seat (Hiace).

ID code example:
G082
G = 8.0" ring gear
 08 = ratio 4.11
   2 = 2-pinion open diff
   3 = 2-pinion LSD
   4 = 4-pinion open diff
   5 = 4-pinion LSD

F 7.5" (185mm)
G 8" (200mm) ratios from 3.1 to 7.6
A 8" North America-built
? 8" heavy-duty with larger bearings (requires HD case)
     12 ring gear bolts instead of 10 on "normal" 8"
  * 2000-2006 Tundra
  * T100 pickup
  * Tacoma 4x4 (except electric locker)
B 9" (220mm) 
  * Supra Twin-Turbo (TT)
  * Chaser with JZ engine
D 10.5"
  * 2007- Tundra with 5.7 liter V8

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 the big gun used in most of the Datsuns from the early 1960s into the 1990s. 1960's Datsun Roadsters, 1600 wagons, 320/520/620/720/D21 pickups and other Datsuns.

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 - 9-bolt

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:

Driveshaft fitting
* Auto vs. Manual input slip yokes
* Japan diff vs Borg Warner diff
* H145 vs H150 vs H165 (ute) flanges

Coupe, Wagon and Sedan shafts are the same. Truck shaft is shorter as it fits the larger H165 diff.

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 lines 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.

Converting to 4-lug

You can convert 5-lug or 6-lug axles to standard Datsun 4-lug

Re: 620 diff

Or just use different wheels on the back.

Miscellaneous

See also: Brake Swaps

race car mounting
album

4-link

album

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Rear Axle Swaps