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- | The crankshaft is interchangeable between early A12, A12GX, late A12, late A13 and A12A. Only the flywheel bolts differ, after [[A-series_Engine_Changes#1974|1974]] using metric bolts. | + | The crankshaft is interchangeable between early A12, A12GX, late A12, late A13 and A12A. Only the flywheel bolts differ, using metric bolts starting with the [[A-series_Engine_Changes#1974|A-engine Redesign]]. |
= Overview = | = Overview = | ||
All Datsun A-series crankshafts are forged, and stroke comes in four sizes: | All Datsun A-series crankshafts are forged, and stroke comes in four sizes: | ||
- | * 70mm (2.76 in.) stroke: A12/A12A/A13(1980) | ||
- | * 77mm (3.03 in.) stroke: A13(1974)/A14 | ||
- | * 82mm (3.23 in.) stroke: A15 | ||
- | [http://datsun1200.com/modules/myalbum/photo.php?lid=17133 http://datsun1200.com/uploads/thumbs/17133.jpg] | + | * 70mm (2.76 in.) stroke: A12/A12A/A13(1980) |
+ | * 77mm (3.03 in.) stroke: A13(1974)/A14 | ||
+ | * 82mm (3.23 in.) stroke: A15 | ||
+ | |||
+ | Crankshaft Stroke: | ||
+ | <br>{{Photo!|14241.jpg}} | ||
+ | |||
+ | <img size=400>http://datsun1200.com/uploads/photos/17133.jpg</img> [http://datsun1200.com/modules/myalbum/photo.php?lid=17133 album] | ||
= Flywheel Bolts = | = Flywheel Bolts = | ||
- | * 1966-1973: crank uses english-system 3/8" x 24 UNF bolts | + | The flywheel bolts are special washerless bolts, do not use generic bolts. |
- | ** 12315-18000 BOLT-flywheel & drive plate 6 A10 | + | |
- | ** 12315-H1001 BOLT-FLY WHEEL 6 A12 MANUAL | + | |
- | ** Will ARP 206-2802 work? For BMC A-series engines (UHL Under Head Length 0.900") $18 USD/set of 6 | + | |
- | * 1974-up: crank uses Metric M10 1.25 bolts (from '73-7) | + | Buy at [http://www.datsun1200.asia/search?q=flywheel&search_button.x=0&search_button.y=0 Bprojects] |
- | ** A12,A13,A14,A12A,A15 | + | <br>{{Album|26245}} |
- | ** 12315-H6900 BOLT-FLYWHEEL 6 $4.83 USD | + | |
- | ** replaced 12315-H6200 | + | * 3/8 inch bolts: 1966-1973 crank uses Imperial system 3/8" x 24 UNF bolts |
- | ** Will ARP 203-2802 work? For 4AGE engines (UHL Under Head Length 1.050") $22 USD/set of 8 | + | * 10mm bolts: 1974-up crank uses Metric M10 1.25 bolts (from '73-7) |
+ | |||
+ | 12315-H1001 BOLT-FLY WHEEL 6 B110 MANUAL $4.38 | ||
+ | 12315-H1000 BOLT-FLY WHEEL 6 B110 AUTOMATIC $3.51 | ||
+ | 12330-20300 PILOT-CONVERTER B110 AUTOMATIC $18.66 | ||
+ | 12333-20300 PLATE-CRANK CONVERTER B110 AUTOMATIC $9.44 | ||
+ | |||
+ | Hex head: 14 mm | ||
+ | Thread length: 20mm | ||
+ | Head bottom length: 22mm | ||
+ | Whole length: 29mm | ||
+ | |||
+ | 1966-1973: crank uses english-system 3/8" x 24 UNF bolts | ||
+ | * 12315-18001 BOLT-flywheel & drive plate 6 A10 (requires washers) | ||
+ | ** {{Ref|12314-18001|}} WASHER-flywheel for A10 only | ||
+ | ** {{Ref|12314-18002|}} WASHER-flywheel (from engine # A10-87871) | ||
+ | * 12315-H1001 BOLT-FLYWHEEL 6 MANUAL (3/8", uses no washers) | ||
+ | * ARP bolts - buy at [http://www.datsun1200.asia/search?q=flywheel&search_button.x=0&search_button.y=0 Bprojects] | ||
+ | * Will [[ARP]] 206-2802 work? For BMC A-series engines | ||
+ | (UHL Under Head Length 0.900") $18 USD/set of 6 | ||
+ | * [[Flywheel#High_Strength_Bolts|Pitroad-ARP bolts]] | ||
+ | |||
+ | 1974-up: crank uses Metric M10 x 1.25 bolts (from '73-7) | ||
+ | * A12,A13,A14,A12A,A15 | ||
+ | * 12315-H6900 BOLT-FLYWHEEL 6 (10mm) $4.83 USD > 12315-H6200 | ||
+ | * Will ARP 203-2802 work? For 4AGE engines | ||
+ | (UHL Under Head Length 1.050") $22 USD/set of 8 | ||
+ | |||
+ | 26 Washer for A10 flywheel bolts only (6 needed) | ||
+ | <br>{{Album|26242}} | ||
+ | |||
+ | Imperial flywheel bolts - heads unmarked | ||
+ | <br>{{Album|26244}} | ||
+ | |||
+ | '62' bolts for metric cranks | ||
+ | <br>{{Album|23498}} {{Album|26243}} | ||
= Misc = | = Misc = | ||
Also see: [[Bored And Stroked]] for crankshaft modifications you can perform at home. | Also see: [[Bored And Stroked]] for crankshaft modifications you can perform at home. | ||
+ | * Twin-carb engine ([[Hitachi Twin Carb|A12GX, A12T and A14T]]) crankshafts are the same as a standard engines. | ||
+ | |||
+ | * 1974-up cranks use metric flywheel bolts. Early engines used British threads. See [[A Engine Redesign]] | ||
Apparently there are two forgings of crankshaft: | Apparently there are two forgings of crankshaft: | ||
- | * Heavy duty | ||
- | *: [http://datsun1200.com/modules/myalbum/photo.php?lid=18244 http://datsun1200.com/uploads/thumbs/18244.jpg] | ||
- | * Light weight: thinner straight sided counterweights that also have small scallops out of them. Late model factory crank (from B310 Sunny) | ||
- | *: [http://datsun1200.com/modules/myalbum/photo.php?lid=17135 http://datsun1200.com/uploads/thumbs/17135.jpg] | ||
- | * Twin-carb engine ([[Hitachi Twin Carb|A12GX, A12T and A14T]]) crankshafts are the same as a standard engines. | + | Heavy duty |
+ | <br><img size=400>http://datsun1200.com/uploads/photos/18244.jpg</img> [http://datsun1200.com/modules/myalbum/photo.php?lid=18244 album] | ||
- | * 1974-up cranks use metric flywheel bolts. Early engines used British threads. See [[A Engine Redesign]] | + | Light weight: thinner counterweights that also have small scallops out of them. Late model factory crank (from B310 Sunny) |
- | * Front bolt, that holds the front pulley on, is: | + | <br><img size=400>http://datsun1200.com/uploads/photos/17135.jpg</img> [http://datsun1200.com/modules/myalbum/photo.php?lid=17135 album] |
- | ** Part Number: 12309-78200 ($4.58) | + | |
- | ** M16 x 1.50 (fine) pitch | + | Front bolt, that holds the front pulley on, is: |
- | ** 15mm diameter | + | * Part Number: 12309-78200 ($4.58) |
- | ** 27mm long | + | * M16 x 1.50 (fine) pitch |
- | ** The head is ?mm hex and about 15 mm thick. | + | * 15mm diameter |
- | ** Torque specification: 15-16 kg/m (108-116 ft. lb.) | + | * 27mm long |
+ | * The head is ?mm hex and about 15 mm thick. | ||
+ | * Torque specification: 15-16 kg/m (108-116 ft. lb.) | ||
= Identification = | = Identification = | ||
Line 61: | Line 99: | ||
A15 12200-G3400 MT, 12200-H9700 AT | A15 12200-G3400 MT, 12200-H9700 AT | ||
- | <br>[http://i297.photobucket.com/albums/mm219/ddgonzal/Datsun%201200/wiki/A15crank-1.jpg http://i297.photobucket.com/albums/mm219/ddgonzal/Datsun%201200/wiki/th_A15crank-1.jpg] [http://i297.photobucket.com/albums/mm219/ddgonzal/Datsun%201200/wiki/A15crank-2.jpg http://i297.photobucket.com/albums/mm219/ddgonzal/Datsun%201200/wiki/th_A15crank-2.jpg] | + | <br>{{Photo|A15crank-1.jpg|Datsun%201200/wiki}} {{Photo|A15crank-2.jpg|Datsun%201200/wiki}} |
A14 | A14 | ||
Line 71: | Line 109: | ||
= Lightened Crankshaft = | = Lightened Crankshaft = | ||
- | Discussion: [http://datsun1200.com/modules/newbb/viewtopic.php?topic_id=37775&forum=1 JTS Cranks] | + | Discussion: [{{Post|234575}} JTS Cranks] |
- | [http://datsun1200.com/modules/myalbum/photo.php?lid=5538 http://datsun1200.com/uploads/thumbs/5538.jpg] [http://datsun1200.com/modules/myalbum/photo.php?lid=7306 http://datsun1200.com/uploads/thumbs/7306.jpg] [http://datsun1200.com/modules/myalbum/photo.php?lid=8478 http://datsun1200.com/uploads/thumbs/8478.jpg] [http://datsun1200.com/modules/myalbum/photo.php?lid=8479 http://datsun1200.com/uploads/thumbs/8479.jpg] [http://datsun1200.com/modules/myalbum/photo.php?lid=8617 http://datsun1200.com/uploads/thumbs/8617.jpg] [http://datsun1200.com/modules/myalbum/photo.php?lid=9665 http://datsun1200.com/uploads/thumbs/9665.jpg] | + | Race-prepped cranks are often: |
+ | * Relieved/polished to reduce chance of cracking | ||
+ | * Lightened for quicker acceleration | ||
+ | * Knife-edge for reduced windage friction | ||
+ | |||
+ | Race-prepped A-series crank: | ||
+ | <br>{{Album|19814}} {{Album|5538}} {{Album|7306}} {{Album|8478}} {{Album|8479}} {{Album|8617}} {{Album|9665}} | ||
+ | |||
+ | A12 crank lightened & edged | ||
+ | <br>{{PB2|ff245|chrislyons8|Red%20B10|3.jpg}} | ||
A14 knife-edged | A14 knife-edged | ||
- | <br>[http://i297.photobucket.com/albums/mm219/ddgonzal/Datsun%201200/wiki/A14_crank-1.jpg http://i297.photobucket.com/albums/mm219/ddgonzal/Datsun%201200/wiki/th_A14_crank-1.jpg] [http://i297.photobucket.com/albums/mm219/ddgonzal/Datsun%201200/wiki/A14_crank-2.jpg http://i297.photobucket.com/albums/mm219/ddgonzal/Datsun%201200/wiki/th_A14_crank-2.jpg] | + | <br>{{Photo|A14_crank-1.jpg|Datsun%201200/wiki}} {{Photo|A14_crank-2.jpg|Datsun%201200/wiki}} |
= Counterweighted Cranks = | = Counterweighted Cranks = | ||
All A-series crankshafts are counterweighted and will rev smoothly to 8500+ RPM. | All A-series crankshafts are counterweighted and will rev smoothly to 8500+ RPM. | ||
+ | |||
+ | Stock crank is counterweighted: there are four counterweights, one for each crank throw: | ||
+ | <br><img size=400>http://datsun1200.com/uploads/photos/17133.jpg</img> [http://datsun1200.com/modules/myalbum/photo.php?lid=17133 album] | ||
+ | |||
+ | A12 "fully" counterweighted billet Pitroad A12 Crankshaft | ||
+ | <br>[http://www.pitroad-ts.com/A-parts-2/engine/crankshaft-full.htm http://www.pitroad-ts.com/A-parts/engine/a12crank-2.jpg] | ||
+ | |||
+ | Fully counterweighted means each journal has two counterweights. Theoretically it means better torsional vibration control. A regular counterweighted crank accelerates faster and has less friction, so a heavier fully counterweighted crank should only be used where torsion vibration is a known problem. | ||
Here is [http://datsun1200.com/modules/newbb/viewtopic.php?post_id=130357#forumpost130357 the difference] between counterweighted and "fully counterweighted" (L/Z cranks shown): | Here is [http://datsun1200.com/modules/newbb/viewtopic.php?post_id=130357#forumpost130357 the difference] between counterweighted and "fully counterweighted" (L/Z cranks shown): | ||
<br><img size=400>http://i85.photobucket.com/albums/k45/b120dat/Picture175.jpg</img> | <br><img size=400>http://i85.photobucket.com/albums/k45/b120dat/Picture175.jpg</img> | ||
- | |||
- | Fully counterweighted means each journal has it's own counterweights. Theoretically it means better torsional vibration control. | ||
Either way, both types of Datsun cranks are precision balanced from the factory. | Either way, both types of Datsun cranks are precision balanced from the factory. | ||
- | [http://datsun1200.com/modules/myalbum/photo.php?lid=17133 A15 crank] is fully counterweighted: there are four counterweights, one for each crank throw. | + | <blockquote>Smaller counterweights == smaller crankcase</blockquote> |
- | <br><img size=400>http://datsun1200.com/uploads/photos/17133.jpg</img> | + | |
- | In comparison, the E16 crank has two counterweights per crank throw, which helps reduce the overall diameter of the crank. | + | The E16 crank has a much larger stroke, so it uses two counterweights per crank throw, which helps reduce the overall diameter of the crank. |
- | <br>Smaller counterweights == smaller crankcase. | + | |
- | A12 full counter Billet [http://www.pitroad-ts.com/A-parts-2/engine/crankshaft-full.htm Pitroad A12 Crankshaft] | ||
- | <br><img size=400>http://www.pitroad-ts.com/A-parts/engine/a12crank-2.jpg</img> | ||
<blockquote>Of full counter crank benefits advantageous to the vibration reduction high-speed and high output, disadvantage weight increase and manufacturing cost. Crankshaft for race for achieving both the lightweight and stiffness UP is | <blockquote>Of full counter crank benefits advantageous to the vibration reduction high-speed and high output, disadvantage weight increase and manufacturing cost. Crankshaft for race for achieving both the lightweight and stiffness UP is | ||
<br> | <br> | ||
<br>[downside] 800 g weight increase</blockquote> | <br>[downside] 800 g weight increase</blockquote> | ||
+ | |||
+ | {{Album|23985}} {{Album|23984}} | ||
= Seals = | = Seals = | ||
+ | {{Main|Crankshaft Seal}} | ||
- | == Rear Main Seal == | + | = Oil Thrower = |
- | === Installation === | + | The thrower goes over the front snout of the crank, before the [[Timing Cover]] and [[Crankshaft Pulley]] are installed |
- | 12279-H2301 Rear Main Seal | + | <br>{{Album|28574}} {{Album|28575}} |
- | [http://i297.photobucket.com/albums/mm219/ddgonzal/sightings/forum/Rear_main_seal.jpg http://i297.photobucket.com/albums/mm219/ddgonzal/sightings/forum/th_Rear_main_seal.jpg] | + | |
- | + | ||
- | Also apply sealant here | + | |
- | [http://i297.photobucket.com/albums/mm219/ddgonzal/sightings/forum/Main_bearing_cap_sealant.jpg http://i297.photobucket.com/albums/mm219/ddgonzal/sightings/forum/th_Main_bearing_cap_sealant.jpg] | + | |
- | + | ||
- | === Removal === | + | |
- | # Remove oil pan | + | |
- | # Remove rear main bearing | + | |
- | # Lift out old seal | + | |
- | + | ||
- | If replacing the rear main seal when changing a clutch, you may remove it with the oil pan still in place: | + | = Specs = |
- | # Puncture seal with an awl, tiny screwdriver, or similar implement. Punch through the eddge of the seal, by gently tapping through with hammer | + | from {{1973SM}} <i>Figure EM-58 Crankshaft</i> |
- | # Carefully pry out slightly and work your way around the circumference until free | + | Main journal diameter 49.951-49.964 mm |
+ | Main journal width 27.00-27.05 mm | ||
+ | crankpin diameter 44.961-44.974 mm | ||
= Part Numbers = | = Part Numbers = | ||
+ | 12200-H5000 CRANKSHAFT A12 | ||
12200-H8500 CRANKSHAFT ASSY B310 A12S, A13S | 12200-H8500 CRANKSHAFT ASSY B310 A12S, A13S | ||
12200-H8515 A12/A12A CRANKSHAFT 70mm/2.76" stroke | 12200-H8515 A12/A12A CRANKSHAFT 70mm/2.76" stroke | ||
Line 138: | Line 183: | ||
SEAL, Front | SEAL, Front | ||
- | 13042-18000 SEAL-OIL CRANKSHAFT FRONT 1 A12 - superceded | + | See main article: [[Crankshaft Seal]] |
- | 13510-H1000 SEAL-OIL CRANKSHAFT FRONT (NOK) 1 A12 0271- 2 13042-18000 $7.24 | + | |
- | [http://www.rockauto.com/catalog/x,carcode,1208483,parttype,5604 RockAuto] | + | |
- | * National 223830 | + | |
- | * Beck/Arnley 0521989 | + | |
- | Specs | + | |
- | * Shaft size: 38 mm | + | |
- | * Housing bore: 55 mm | + | |
- | * Outer diameter: 55.3 mm | + | |
- | * Width: 7 mm | + | |
SEAL, Rear | SEAL, Rear | ||
- | 12279-18000 SEAL-OIL CRANKSHAFT REAR 1 A12 - $81.18 | + | See main article: [[Crankshaft Seal]] |
- | 12279-18010 SEAL-OIL CRANKSHAFT REAR (NDK) 1 A12 0271- 2 12279-18000 NLA | + | |
- | 12279-H2301 | + | |
- | * supercedes 12279-H1000 SEAL-OIL CRANKSHAFT REAR (NOK) 1 A12 0271- $81.18 | + | |
- | 12279-H2311 NDK make | + | |
- | + | ||
- | 12279-H2301 is for all A12/A14/A14 engines. | + | |
- | Seal specifications | + | |
- | * Shaft Size 60 mm | + | |
- | * Housing Bore 82 mm | + | |
- | * Outer Diameter 82.2 mm | + | |
- | * Width 12 mm | + | |
- | [http://www.rockauto.com/catalog/x,carcode,1208483,parttype,5604 aftermarket RockAuto] | + | |
- | * Fel-Pro BS27493 | + | |
- | * National 712006 | + | |
- | * Corteco/Detroit Gasket 17209 | + | |
PILOT BUSHING | PILOT BUSHING | ||
Line 173: | Line 194: | ||
12302-18000 THROWER-OIL CRANKSHAFT 1 A12 - $1.57 | 12302-18000 THROWER-OIL CRANKSHAFT 1 A12 - $1.57 | ||
- | FLYWHEEL BOLTS | + | FLYWHEEL BOLTS - see [[Crankshaft#Flywheel Bolts]] |
- | 12315-H1001 BOLT-FLY WHEEL 6 A12 MANUAL - $4.38 | + | |
- | 12315-H1000 BOLT-FLY WHEEL 6 A12 AUTOMATIC - $3.51 | + | |
- | 12330-20300 PILOT-CONVERTER 1 A12 AUTOMATIC - $18.66 | + | |
- | 12333-20300 PLATE-CRANK CONVERTER 1 A12 AUTOMATIC - $9.44 | + | |
= Damage = | = Damage = | ||
+ | == Flywheel Loosening == | ||
The Datsun factory balanced every engine. But when parts are changed, it will get out of balance. In worst case scenario, this leads to shaking and eventual loosening of the [[flywheel]] bolts. | The Datsun factory balanced every engine. But when parts are changed, it will get out of balance. In worst case scenario, this leads to shaking and eventual loosening of the [[flywheel]] bolts. | ||
Line 189: | Line 207: | ||
<br>[http://datsun1200.com/modules/myalbum/photo.php?lid=24122 http://datsun1200.com/uploads/thumbs/24122.jpg] | <br>[http://datsun1200.com/modules/myalbum/photo.php?lid=24122 http://datsun1200.com/uploads/thumbs/24122.jpg] | ||
[http://datsun1200.com/modules/myalbum/photo.php?lid=24123 http://datsun1200.com/uploads/thumbs/24123.jpg] [http://datsun1200.com/modules/myalbum/photo.php?lid=24124 http://datsun1200.com/uploads/thumbs/24124.jpg] | [http://datsun1200.com/modules/myalbum/photo.php?lid=24123 http://datsun1200.com/uploads/thumbs/24123.jpg] [http://datsun1200.com/modules/myalbum/photo.php?lid=24124 http://datsun1200.com/uploads/thumbs/24124.jpg] | ||
+ | |||
+ | == Cracked Crank == | ||
+ | All A-series crankshafts are forged, but can still crack if abused. | ||
+ | |||
+ | Causes: | ||
+ | * Dropping the crank during or before engine assembly | ||
+ | * Unbalanced engine. After replacing a piston, a rod or the crank, have the engine re-balanced | ||
+ | * Detonation (pinking) can put massive stresses on the engine | ||
+ | |||
+ | The thick forging line can be seen in this photo | ||
+ | <br>{{Album|19917}} {{Album|19916}} | ||
[[Category:Engine Mechanical]] | [[Category:Engine Mechanical]] |
Current revision
The crankshaft is interchangeable between early A12, A12GX, late A12, late A13 and A12A. Only the flywheel bolts differ, using metric bolts starting with the A-engine Redesign.
Contents |
Overview
All Datsun A-series crankshafts are forged, and stroke comes in four sizes:
* 70mm (2.76 in.) stroke: A12/A12A/A13(1980) * 77mm (3.03 in.) stroke: A13(1974)/A14 * 82mm (3.23 in.) stroke: A15
Crankshaft Stroke:
Flywheel Bolts
The flywheel bolts are special washerless bolts, do not use generic bolts.
Buy at Bprojects
* 3/8 inch bolts: 1966-1973 crank uses Imperial system 3/8" x 24 UNF bolts * 10mm bolts: 1974-up crank uses Metric M10 1.25 bolts (from '73-7)
12315-H1001 BOLT-FLY WHEEL 6 B110 MANUAL $4.38 12315-H1000 BOLT-FLY WHEEL 6 B110 AUTOMATIC $3.51 12330-20300 PILOT-CONVERTER B110 AUTOMATIC $18.66 12333-20300 PLATE-CRANK CONVERTER B110 AUTOMATIC $9.44
Hex head: 14 mm Thread length: 20mm Head bottom length: 22mm Whole length: 29mm
1966-1973: crank uses english-system 3/8" x 24 UNF bolts * 12315-18001 BOLT-flywheel & drive plate 6 A10 (requires washers) ** 12314-18001 WASHER-flywheel for A10 only ** 12314-18002 WASHER-flywheel (from engine # A10-87871) * 12315-H1001 BOLT-FLYWHEEL 6 MANUAL (3/8", uses no washers) * ARP bolts - buy at Bprojects * Will ARP 206-2802 work? For BMC A-series engines (UHL Under Head Length 0.900") $18 USD/set of 6 * Pitroad-ARP bolts
1974-up: crank uses Metric M10 x 1.25 bolts (from '73-7) * A12,A13,A14,A12A,A15 * 12315-H6900 BOLT-FLYWHEEL 6 (10mm) $4.83 USD > 12315-H6200 * Will ARP 203-2802 work? For 4AGE engines (UHL Under Head Length 1.050") $22 USD/set of 8
26 Washer for A10 flywheel bolts only (6 needed)
Imperial flywheel bolts - heads unmarked
Misc
Also see: Bored And Stroked for crankshaft modifications you can perform at home.
- Twin-carb engine (A12GX, A12T and A14T) crankshafts are the same as a standard engines.
- 1974-up cranks use metric flywheel bolts. Early engines used British threads. See A Engine Redesign
Apparently there are two forgings of crankshaft:
Heavy duty
album
Light weight: thinner counterweights that also have small scallops out of them. Late model factory crank (from B310 Sunny)
album
Front bolt, that holds the front pulley on, is: * Part Number: 12309-78200 ($4.58) * M16 x 1.50 (fine) pitch * 15mm diameter * 27mm long * The head is ?mm hex and about 15 mm thick. * Torque specification: 15-16 kg/m (108-116 ft. lb.)
Identification
A12: 12200-H5000/12200-H5001 < 12200-H1000/12200-H1001 -7909
A12/A13 70mm 9.51 kg scalloped crank throws, 12200-H8560/12200-H8500 7910- <2,0> 12200-H5001
A14 H62 12200-H6200 starting 1973 -7909
A14 H89, scalloped crank throws, 12200-H8900 starting 0879 <> 12200-H6200
G34 block with scalloped crankshaft
A15 12200-G3400 MT, 12200-H9700 AT
A14 M23 F10 M49 F10
Crankshaft Pulley
Lightened Crankshaft
Discussion: POST JTS Cranks
Race-prepped cranks are often:
- Relieved/polished to reduce chance of cracking
- Lightened for quicker acceleration
- Knife-edge for reduced windage friction
A14 knife-edged
Counterweighted Cranks
All A-series crankshafts are counterweighted and will rev smoothly to 8500+ RPM.
Stock crank is counterweighted: there are four counterweights, one for each crank throw:
album
A12 "fully" counterweighted billet Pitroad A12 Crankshaft
Fully counterweighted means each journal has two counterweights. Theoretically it means better torsional vibration control. A regular counterweighted crank accelerates faster and has less friction, so a heavier fully counterweighted crank should only be used where torsion vibration is a known problem.
Here is the difference between counterweighted and "fully counterweighted" (L/Z cranks shown):
Either way, both types of Datsun cranks are precision balanced from the factory.
Smaller counterweights == smaller crankcase
The E16 crank has a much larger stroke, so it uses two counterweights per crank throw, which helps reduce the overall diameter of the crank.
Of full counter crank benefits advantageous to the vibration reduction high-speed and high output, disadvantage weight increase and manufacturing cost. Crankshaft for race for achieving both the lightweight and stiffness UP is
[downside] 800 g weight increase
Seals
Oil Thrower
The thrower goes over the front snout of the crank, before the Timing Cover and Crankshaft Pulley are installed
Specs
from 1973 Datsun 1200 Service Manual Figure EM-58 Crankshaft Main journal diameter 49.951-49.964 mm Main journal width 27.00-27.05 mm crankpin diameter 44.961-44.974 mm
Part Numbers
12200-H5000 CRANKSHAFT A12 12200-H8500 CRANKSHAFT ASSY B310 A12S, A13S 12200-H8515 A12/A12A CRANKSHAFT 70mm/2.76" stroke 12200-H5720 A12 COMPETITION CRANKSHAFT 70mm/2.76" stroke 12200-H8915 A13/A14 CRANKSHAFT 77mm/3.03" stroke * Weight 26.2 lbs 12200-G3400 A15 CRANKSHAFT 82mm/3.23" stroke
Old Numbers: 12200-H1000 ASSY-CRANKSHAFT 1 A12 MANUAL - $624.02 12200-H1001 CRANKSHAFT 1 A12 -671 12 12200-H1000 superceded 12200-H1000 CRANKSHAFT 1 A12 0671- 2 12200-H1001 superceded 12200-H5000 CRANKSHAFT 1 A12 0572- 2 12200-H1000 $624.02
BEARINGS * See main article: Bearings
SEAL, Front See main article: Crankshaft Seal
SEAL, Rear See main article: Crankshaft Seal
PILOT BUSHING * see Pilot Bushing
SLINGER 12302-18000 THROWER-OIL CRANKSHAFT 1 A12 - $1.57
FLYWHEEL BOLTS - see Crankshaft#Flywheel Bolts
Damage
Flywheel Loosening
The Datsun factory balanced every engine. But when parts are changed, it will get out of balance. In worst case scenario, this leads to shaking and eventual loosening of the flywheel bolts.
I started to hear a hell of a noise and shaking under acceleration and reving ... the flywheel bolts have given up the ghost.
For best practices, see Flywheel#Bolts.
Flywheel bolts failure - crank now needs repair
Cracked Crank
All A-series crankshafts are forged, but can still crack if abused.
Causes:
- Dropping the crank during or before engine assembly
- Unbalanced engine. After replacing a piston, a rod or the crank, have the engine re-balanced
- Detonation (pinking) can put massive stresses on the engine