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[Datsun 1200 encyclopedia]

Transmission Overview

From Datsun 1200 Club

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Category: Transmission

All Datsun 1200s were fitted with a 56-Series_Transmission. Most Datsun 1200s come with a 4-speed floor shift manual transmission (FS4W56). Some Standard models had a 3-speed column shift (R3W56). In Japan, the special GX-5 model came with a direct-fifth (non-overdrive) 5-speed (F5W56). All utes came with the stronger 56A 4-speed, which was also fitted to the last of the coupes & sedans.

Contents

Overview

Main article: 56-Series Transmission
Also see: 
* Automatic Transmission
* 5-speeds
* Transmission Identification
* Transmission Diagnoses

56-series Transmission, small and light
16778.jpgAlbum click to view

In the United States, Canada & Australia, all manual shift 1200s had the 4-speed transmission. The two competition four speeds & the five speed was also sold by Datsun Competition in close-ratio and wide-ratio versions. In the five speed version, only the close ratio Option 1 gearbox was offered by Datsunsport Australia, not the standard five speed when I enquired in 1981.

Note that the 4-speed transmission was redesigned in April 1973. Gearsets are not interchangable between early and late transmissions.

The standard 4-speed was well suited to the A12 Engine's torque curve. With a steep 3.757 first gear and a medium-steep 3.90 rear Differential pushing small-diameter 12" Tires, it gave the little 1200 engine enough torque multiplication to take off easily, even with no throttle input. Yet top (4th) gear was good for 90mph. The 5-speed improved upon this by adding an extra gear between 1st and Top.

56A

Stronger gearbox is marked with '56A' on the right side. Without this mark, the gearbox is only strong enough for torque of a 1200cc engine.

1680.jpg

Powerflow Diagram

F4W56 gearset uses constant-mesh gears. Reverse is the only gear that slides

13278.jpgAlbum click to view

The countershaft always rotates with the input shaft. The output shaft (mainshaft) does not move when in neutral -- the main gears just spin freely. When the shifter is moved, it pushes one of the synchro collars against a gear, locking one gear to the mainshaft. Reverse is a special case, it pushes an idler gear between the counter and main gears, reversing rotation of the mainshaft.

Counter Gear (countershaft)
25446.jpgAlbum click to view

Maintenance Specifications

3-speed, 4-speed

  • Synchromesh type: Warner type. Synchromesh on all forward gears in both 3 & 4 speed models.
  • Oil capacity: 1.2 liter (2.5 US pint, 2.125 Imperial pint)
  • Oil type:
  • Oil Drain plug & Filler plug torque: 4.0 - 6.0 kg-m (29-43 ft-lb)
  • Speedometer gear ratio:

Gear Lube Replacement

1972 USA Owners manual (Page 33 ... ):

th_00_cover.jpg   th_33.jpg
Replace every 30 months or 30,000 miles

Undo the fill hole on side of gearbox, undo the bottom drain plug, and let the oil run into a bucket.

Tighten up the drain hole first, and then get regular gear oil (GL-4) and using a container with a pump and hose, fill the gearbox with oil until the oil just starts to come out the fill hole on the side of the gearbox. Finally, put plug back on side and tighten up.

Lubricants

Use GL-4 80W-90 or 85W-140 multiweight, same as the differential lube.

Nissan recommendation
* API GL-4 
* MIL-L-2105 
Such as:
* Chevron Multiservice Gear Lub. 75,80,90,140
* Esso Gear Oil GP 80,90,140
* Mobil Mobilube EP or GX 80-90,90,140
* Shell Spirax 75EP,80EP,90EP,140EP
* Sunoco Multipurpose Gear Lub. GL-4 80,90,140
* Texaco Universal Gear Lub. EP 80,90,140

1972 USA Owners manual (Page 23 ... ):

th_00_cover.jpg   th_23.jpg
Recommended Lubricants

NOTE: Do not use GL-5 spec differential oil. Many people have reported problems with GL-5 gear lube in their older cars. The problem won't be immediately evident but over time the synchros will wear down. GL-5 is not automatically compatible with GL-4. Reportedly there are a few brands of GL-5 that do not use sulfur additives so if the container says GL-5 AND GL-4 then it is "yellow metal" safe and won't corrode brass. However, GL-5 in any form is not a correct formulation for brass synchros, and should not be used with A-series gearboxes.

L18_B110: Don't use any GL-5 in the gearbox. GL-5 is designed for use with steel gears only.

Capacity

  • F4W56L: 1.2 liter
  • F4W56A: 1.2 liter
  • F4W60L (A14/A15): 1.3 liter
  • FS5W60L (A14/A15): 1.2 liter
  • FS5W60A (A14/A15): 1.2 liter

Lube

The filler plug is located halfway up the side of the case. Park the car on the level.

Use an oil hand pump to fill the gearbox. Alternatively, pop the shifter seal out and fish a tube down from inside the car, then go underneath and fit the hose into the filler hole.

Fill until oil drips out the hole.

14mm male square plug
Left side of gearbox
26354.jpgAlbum click to view

Ratios

  • 3-speed R3W56L steering column shift
    1st - 3.380
    2nd - 1.734
    3rd - 1.000
    Rev - 3.640
  • 4-speed F4W56L floor shift
    1st - 3.757
    2nd - 2.169
    3rd - 1.404
    4th - 1.000
    Rev - 3.640
  • 4-speed Option 1. floor shift [competition close ratio gearbox]
    1st - 2.862
    2nd - 1.908
    3rd - 1.350
    4th - 1.000
    Rev - Not listed
    Source. Datsun B110 Competition Tune Up Manual 1974
  • 4-speed Option 2. floor shift [competition ultra close ratio gearbox]
    1st - 2.169 [Note that first gear is the same ratio as the standard models second gear]
    2nd - 1.593
    3rd - 1.233
    4th - 1.000
    Rev - Not listed
    Source. Datsun B110 Competition Tune Up Manual 1974
  • 5-speed F5W56A floor shift
    Warner Synchromesh brass
    1st - 3.757
    2nd - 2.374
    3rd - 1.659
    4th - 1.291
    5th - 1.000
    Rev - 4.040
  • 5-speed F5C56A floor shift [Option 1 competition gearbox. Supersedes Option 1 & 2 four speed gearboxes]
    Servo-type Syncromesh (steel)
    1st - 2.676
    2nd - 1.691
    3rd - 1.398
    4th - 1.182
    5th - 1.000
    Rev - Not listed
    Source. Datsun B110 Competition Tune Up Manual 1974

Bellhousing Pattern

See main article: Bellhousing

Weight Comparison

  • 17.8kg (39.2 lbs): 56-series 4-speed (B110 edition)
  • 24.8kg (54.6 lbs): 60A 5-speed (KPB310 edition)
  • 31 kg: 63a gearbox complete with clutch set up (with no gearbox mount)
  • 36.5kg: T50 with bellhousing and clutch set up
  • 43.5kg: CA18DET 5-speed (rwd edition)

Rear Seal

Extension housing (driveshaft yoke) seal.

See main article: Output Shaft Seal

32136-G1001seal.jpg

Part Numbers

See:
* 56-Series Transmission Parts
* Release Lever
* Transmission Gear Control 

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This page has been accessed 42,438 times. This page was last modified 22:02, 4 September 2017. Content is available under Datsun 1200 Club.