Flywheel

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Datsun 1200 uses a traditional type of flywheel at the back of the engine. The face matches the Clutch while a ring gear is attached to the perimeter for the Starting Motor to turn the engine. It uses a 271mm (10.7 inch) flywheel with a 105-tooth ring gear.

Overview

All flywheels for A-series engines interchange -- for rear-wheel drive vehicles. The A12 flywheel weighs 2.2 lbs (1 kg) less is the main difference. The A12 flywheel is also thinner.

A10              8.0 kg (17.6 pounds)
A12 12310-H1000: 9.5 kg (20.8 pounds) 
A12 12310-H2310: 6.4 kg (14.1 pounds) GX, also sold as 'Race Option'
A14 12310-H7200: 10.7 kg (22.3 lbs)

A14/A15 flywheel is thicker than the A10/A12 flywheel. When fitting the thinner flywheel to A14, remove the Engine Plate to compensate.

A10: 25 mm thick? (does not fit A12 due to different gear angle)
A12: 28 mm thick (fits A10)
A14: 30 mm thick

In 1974 flywheel bolts changed from British Threads to Metric threads. So the bolts are not interchangeable from early to late. See Crankshaft for details.

A12 Flywheel Measurements:

thickness: 28mm
ring gear + backing: 20mm
back rim to flywheel face depth: 5mm
clutch face to inner face depth: 17mm

Lightening

For race cars, a light flywheel allows the engine to rev faster according to this principle:

The more weight, the more time it takes to accelerate

Now a street car wants a heavier flywheel, so that it will:

• smooth out the combustion pulses
• smooth out the drivetrain

These are the factory specs for flywheel weight reduction:

Finished wheight is about 6.5 kgs --a total of 2 kgs removal

Reference: Datsun B110 Competition Tune-Up Manual, Nissan Motor Co. Ltd., Tokyo Japan 1974

Bolts

Nissan flywheel bolts are very strong. Just clean the threads and use a torque wrench to install. ARP does not make A-series flywheel bolts, but in any case the stock bolts are strong.

If using the A-series over 7500 RPM, run new factory bolts and Loctite them.

If using high RPM and an unbalanced custom internals, someone suggested this: look at getting the crank flange dowelled. The flywheel is actually clamped on the head of the bolt not on the shank of the bolt (there is side-to-side play), so three dowels 120° apart should do the job. The end of the crank is soft unlike the journals and easy to drill.

Also see: Harmonic Balancer.

Part Numbers

• 12310-18001 ASS'Y-FLYWHEEL B10
• 12310-18002 ASS'Y-FLYWHEEL B10 (from E/# A10-87871)
• 12310-H1000 FLYWHEEL ASS'Y A12, A12S, A12A, A13S
• 12310-H6200 ASSY-FLYWHEEL A13
• 12310-H7200 FLYWHEEL ASS'Y A14 -7909
• 12310-H7201 FLYWHEEL ASS'Y A14 7910-8010
• 12310-H8900 FLYWHEEL ASS'Y V A14S, A15 8011-
• 12310-H8910 FLYWHEEL ASS'Y A14S, A15 8011-
• 12315-18001 BOLT-flywheel & drive plate (from E/# 87871) (6) B10
  • 12314-18002 WASHER-flywheel
  • replaced 12315-18000 BOLT-flywheel & drive plate (6) B10
    • 12314-18001 WASHER-flywheel
• 12315-H1001 BOLT-flywheel (6, 3/8") B110 -1973
• 12315-H6200 BOLT-FLYWHEEL (6, 10mm) 1974-
• 12313-10600 DOWEL (3) all A-series A10-A15
• 12312-18000 GEAR-ring, flywheel A10/A12/A14
• 12312-18010 GEAR-ring, flywheel A14S 8110-
• 32202-18000 BUSHING-pilot all A-series A10/A12/A13/A14/A15/A12A

The flywheel "Assembly" includes these parts:
* 12312 GEAR-ring, flywheel
* 12313 DOWEL-flywheel

• ATP ZA543 Flywheel Ring Gear $22.79
  • http://www.rockauto.com/catalog/x,carcode,1208483,parttype,5360
  • Outer Diameter=10.655"
  • Inner Diameter 9.451"
  • Pitch=10/12 Width=.400"
  • Teeth=105
  • Chamfer=FRONT #1231218000

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