Bearings

Revision as of 10:44, 8 January 2016; view current revision
<-Older revision | Newer revision->

If you get new bearings, keep in mind that inexpensive bearings do wear over time. Datsun used triple alloy bearings which do not wear out, but only if the engine loses oil pressure they will be damaged, or if debris gets into the oil.

Measuring Bearing Clearance

Measure Bearing Crush when installing new bearings.

It is difficult to tell by visual inspection if bearings are worn. It is normal to have some pattern on them.

Direct measurement: The best way to check is to use plastic thread. Buy the Plastigauge (just a couple of dollars) and put it back together. The amount the thread is squished tells how much actual clearance it has.

Plastigauge see wikipedia article

Indirect measurement: Measure the journals with a precision micrometer, then calculate the clearance.

It is suggested to measure clearance after fitting/refitting bearing shells to confirm actual clearance.

Datsun Factory Service Manual:

Measuring Main Bearing Clearance

Regarding rod bearings, it says "Measure connecting rod bearing clearance in the same manner".

Inspection

Scratched bearing indicates debris in the oil
post

Lightly scratched, but still in spec
post

Main bearings look OK, so measure clearance to be sure
post

Bad conrod bearing next to good one
Troubleshoot Bearing Problem

Problem: Bearing shows abnormal wear in center
post

Connecting Rod Bearings

A12/A13/A14/A15
12111-20900 BEARING-CONNECTING ROD STD <> 12111-20900
12111-20901 BUSHING-CONNECTING ROD UNDERSIZE 8
12111-20902 BUSHING-CONNECTING ROD UNDERSIZE 12
12111-20903 BUSHING-CONNECTING ROD UNDERSIZE 25 (0.25 mm undersize)
12111-20904 BUSHING-CONNECTING ROD UNDERSIZE 50 (0.50 mm undersize)
12111-20905 BUSHING-CONNECTING ROD UNDERSIZE 75 (0.75 mm undersize)
12111-20906 BUSHING-CONNECTING ROD UNDERSIZE 100

B10
12111-18000 BUSHING-connecting rod (standard size) F500 (8) except coupe
12111-20900 BUSHING-connecting rod (standard size) F770 (8) coupe

F-770 is comprised (1) a topmost layer of babbitt (2) a nickel barrier layer (3) a copper lead matrix base layer and (4) a steel backing layer.

1984 Nissan Competition Catalog said: The -25720 ... bearing shell produces the most desirable bearing clearance for racing purposes when applied to a standard size crankshaft. The other shells exist in order to obtain proper clearance when compensating for the variations in the crankshaft or connecting rod journals.

8 each required:
* 12111-25720 .0590"
* 12111-25721 .0588"
* 12111-25722 .0585"
* 12111-25723 .0592"
* 12111-25724 .0583"

Main Bearings

Crankshaft bearings

BEARING SET A12/A13/A14/A15
* 12207-H1001 SET-BEARING STD <> 12207-M7201 <> 12207-H1000 $71.58 
* 12208-H1000 SET-BEARING 0.20MM
* 12209-H1000 SET-BEARING 0.25MM
* 12210-H1000 SET-BEARING 0.50MM
* 12211-H1000 SET-BEARING 0.75MM
* 12212-H1000 SET-BEARING 1.00MM

1984 Nissan Competition Catalog said: The ... -H2310 bearing shell produces the most desirable bearing clearance for racing purposes when applied to a standard size crankshaft. The other shells exist in order to obtain proper clearance when compensating for the variations in the crankshaft or connecting rod journals.

MAIN BEARING (#1/#5, SHELL THICKNESS) 4 each required
* 12215-H2310 .0720"
* 12215-H2311 .0718"
* 12215-H2312 .0715"

MAIN BEARING (#2/#4, SHELL THICKNESS) 4 each required
* 12231-H2310 .0720"
* 12231-H2311 .0718"
* 12231-12312 .0715"

MAIN BEARING (CENTER, SHELL THICKNESS) 2 required
* 12247-H2310 .0720"
* 12247-H2311 .0718"
* 12247-H2312 .0715"

12231-H1000 - inner main bearings (#2 & #4)

12233-H1000 - outer main bearings (#1 & #5)

12255-H1000 - center thrust bearing

Thrust Bearing

See: Thrust Clearance

Main Bearing Cradle

Although probably unnecessary, you can fabricate a main bearing cap girdle (ladder frame support) such as many modern engines have. The theory is that it stiffens the block for high HP applications. Also called a main cap girdle.

Garage Nakamura halo cradle

Specs

Bearing Clearance
* Main: 0.020 to 0.062 mm
* Rod: 0.020 to 0.050 mm

Main Bearing Journal diameter
* 49.951 to 49.964 mm

Crankpin Journal diameter
* 44.974 to 44.961 mm

Journal Taper and out of round 
* measure multiple spots
* less than 0.03 mm

End-play
* crank thrust: 0.05 to 0.15 mm

Bearing Crush
* main: 0 to 0.03 mm
* rod: 0.015 to 0.040 mm

Part Numbers

Tri-metal was used as original equipment. Very very durable bearings.

RockAuto.com

ROD BEARING
Nissan 12111-20900 BEARING-CONNECTING ROD STD (8 required)
Mahle/Clevite CB980P (pair) P-series (Tri-Metal)
Mahle/Clevite CB980A4 (set) A-series (Aluminum)
Sealed Power 467320CP

MAIN BEARING
Nissan 12207-M7201 set STD
Sealed Power 7135M

Wheel Bearings

See main article: Wheel bearings